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	description	The present invention generally relates to a system and method for radiation therapy or diagnostics with beam modulation, such as but not limited to, intensity modulated radiation therapy (IMRT) or diagnostics, and particularly to dynamic beam attenuators for such therapy or diagnostics, wherein the attenuating material and/or the attenuation length are variable. The intensity of the radiation beam used for radiotherapy is required to be time-invariant in some applications or time-varying in other applications. Temporal variation of beam intensity provides additional degree of freedom for stereotactic radiotherapy where beam apertures are varied with respect to gantry angle and/or desired segment. Variation of beam apertures and associated beam intensities can be done while the gantry is either rotating or stationary at a sequence of gantry orientations. The former is called Intensity modulated arc therapy (IMAT) and the latter is called “step-and-shoot” Intensity Modulated Radiation therapy (IMRT). The present invention seeks to provide improved dynamic beam attenuators for therapy or diagnostics, wherein the attenuating material and/or the attenuation length are variable, as is described more in detail hereinbelow. There is thus provided in accordance with an embodiment of the present invention an attenuator system for attenuating a radiation beam, including a first attenuating element placed in a path of a radiation beam for attenuation thereof, a second attenuating element also placed in the path of the radiation beam so as to form an attenuating cascade with the first attenuating element, a first positioner operatively connected to the first attenuating element, which moves the first attenuating element along a first direction, a first processor operatively connected to the first positioner for controlling motion of the first attenuating element, wherein a two-dimensional attenuation distribution of the first attenuating element varies linearly with respect to at least one coordinate. In accordance with an embodiment of the present invention a two-dimensional attenuation distribution of the second attenuating element varies linearly with respect to at least one coordinate. In accordance with an embodiment of the present invention the first and second attenuating elements form an attenuating cascade, wherein the attenuating cascade has an attenuation distribution depending on a position of the first attenuating element. The attenuation distribution of the attenuating cascade may be generally uniform over an area equal to a cross-section of the radiation beam for a range of positions of the first attenuating element. The two-dimensional attenuation distribution of the first and second attenuating elements with respect to the radiation beam may be spatially-continuous and non-uniform over an area significantly larger than that of the radiation beam. The first attenuating element may have a cross-section coplanar with the radiation beam which is triangular in shape and which has an apex with a positive angle slope, and the second attenuating element may have a portion with a cross-section coplanar with the radiation beam which is triangular in shape and which has an apex with a negative angle slope. The magnitudes of the positive and negative angle slopes may be equal. The attenuator system may further include a radiation sensor that senses attenuated radiation that passes through the first and second attenuating elements, the radiation sensor being in operative communication with the first processor, wherein temporal beam modulation is carried out by sensing a beam intensity with the radiation sensor and moving the first attenuating element with the first positioner. The attenuator system may further incorporate a second positioner operatively connected to the second attenuating element, which moves the second attenuating element along a second direction, and a second processor operatively connected to the second positioner for controlling motion of the second attenuating element, In accordance with an embodiment of the present invention one of the first and second attenuating elements has two portions with different slopes and cross-sections. In accordance with an embodiment of the present invention the first and second attenuating elements have cross-sections that vary along a Cartesian coordinate. In accordance with another embodiment of the present invention the first and second attenuating elements have cross-sections that vary along a polar coordinate. There is also provided in accordance with an embodiment of the present invention a radiotherapy system including a radiation beam source which emits a radiation beam, a first attenuating element placed in a path of the radiation beam for attenuation thereof, a second attenuating element also placed in the path of the radiation beam so as to form an attenuating cascade with the first attenuating element, a first positioner operatively connected to the first attenuating element, which moves the first attenuating element along a first direction, a first processor operatively connected to the first positioner for controlling motion of the first attenuating element, wherein a two-dimensional attenuation distribution of the first attenuating element varies linearly with respect to at least one coordinate. There is also provided in accordance with an embodiment of the present invention a method for attenuating a radiation beam, including placing a first attenuating element in a path of a radiation beam for attenuation thereof, placing a second attenuating element also in the path of the radiation beam so as to form an attenuating cascade with the first attenuating element, and moving at least one of the first and second attenuating elements along a first or second direction, respectively, wherein a two-dimensional attenuation distribution of the first attenuating element varies linearly with respect to at least one coordinate. The method may also include forming an attenuating cascade with the first and second attenuating elements form, wherein the attenuating cascade has an attenuation distribution depending on a position of the first attenuating element. The method may further include carrying out temporal beam modulation by sensing a beam intensity and moving at least one of the first and second attenuating elements. Reference is now made to FIG. 1, which illustrates an attenuator system 10 for use with a radiotherapy system, constructed and operative in accordance with a non-limiting embodiment of the present invention. The radiotherapy system includes a radiation beam source 12, such as but not limited to, a LINAC, which emits a radiation beam 14. The radiation beam 14 can be shaped as a pencil-beam, fan-beam, cone-beam and other shapes. A first attenuating element 16 is placed in the path of beam 14 for attenuation thereof. A second attenuating element 18 is placed distal to first attenuating element 16 (i.e., further away from source 12) for further attenuation of beam 14. First and second attenuating elements 16 and 18 may be made of known attenuating materials, such as but not limited to, tungsten. The two-dimensional attenuation distribution of first and second attenuating elements 16 and 18 with respect to the radiation beam may be spatially-continuous and non-uniform over an area significantly larger than that of radiation beam 14. The first attenuating element 16 is operatively connected to a first positioner 20 (such as a motor, linear actuator and the like), which moves first attenuating element 16 along a first direction, such as along a first axis 22, which may be perpendicular to the axis of beam 14. A first processor 24 is operatively connected to first positioner 20 for controlling the motion of first attenuating element 16. Similarly, second attenuating element 18 is operatively connected to a second positioner 26 (such as a motor, linear actuator and the like), which moves second attenuating element 18 along a second direction, such as along a second axis 28, which may be perpendicular to the axis of beam 14. A second processor 30 is operatively connected to second positioner 26 for controlling the motion of second attenuating element 18. The first attenuating element 16 has a cross-section (taken in the same plane as beam 14, as shown in FIG. 1) which is triangular in shape, having an apex with a positive angle slope designated A. (As in conventional mathematical notation, positive angles are measured counterclockwise from the reference horizontal axis, whereas negative angles are measured clockwise.) The second attenuating element 18 has a portion 32 with a cross-section (taken in the same plane as beam 14, as shown in FIG. 1) which is triangular in shape, having an apex with a negative angle slope designated -B. In a preferred embodiment, the magnitudes of A and B are equal. Accordingly, the attenuating material (or attenuation length) varies continuously along at least one coordinate (in the illustrated embodiment, linear, that is, along a Cartesian-coordinate axis 22 or 28). Moving first or second attenuator 16 or 18 in a direction generally perpendicular to the beam (along axis 22 or 28) shifts the two-dimensional attenuating distribution and provides temporal beam modulation. A radiation monitor 34, referred to as radiation sensor 34, may sense (measure) the attenuated radiation that passes through the attenuators to the target. Radiation sensor 34 is in operative communication with first and second processors 24 and 30. Temporal beam modulation may be used for beam intensity stabilization by sensing the instantaneous intensity drift with radiation sensor 34 and compensating with a proper attenuator positioning by moving first and/or second attenuating elements 16/18 with their positioners 20/26. The present invention may also be used for conformal radiation, where different intensities are associated with discrete or continuously varying orientations. For further variety of attenuation, as seen in FIG. 1, one of the first and second attenuators 16 and 18, such as second attenuator 18, can have two portions 32A and 32B with different slopes and cross-sections. Thus, a combination of spatial uniformity (over an area compatible with the beam cross-section) and temporal variation is achieved by the cascading attenuators 16 and 18. In the preferred embodiment wherein the magnitudes of angles A and B are equal, the two respective attenuation distributions are linear and have the same slope but in opposite directions. This results in a combined uniform attenuation irrespective of the relative positions of first and second attenuators 16 and 18. It is noted that the invention can be carried out with one of the attenuators maintained stationary, and moving just one of them relative to radiation beam 14. The advantage of a stationary attenuating object is its small size being equal to the beam cross-section while the size of the moving attenuating object can be an order of magnitude larger. Uniformity and temporal variation can be achieved by an attenuator's variation (and corresponding motion) along a single coordinate. In the embodiment of FIG. 1, the variation is linear along a Cartesian coordinate. Referring to FIGS. 2 and 3A-3B, it is seen first and second attenuating elements 216 and 218 can have cross-sections that vary along a polar coordinate. In such an embodiment, first and second positioners 220 and 226 rotate first and second attenuating elements 216 and 218 about first and second rotation axes 230 and 232, respectively. The scope of the present invention includes both combinations and subcombinations of the features described hereinabove as well as modifications and variations thereof which would occur to a person of skill in the art upon reading the foregoing description and which are not in the prior art.
	description	This patent application claims the priority benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application No. 62/597,571 filed on Dec. 12, 2017, the contents of which are herein incorporated by reference. The disclosed concept relates generally to methods for predicting when a nuclear reactor core will go critical and, more specifically, to a method for determining a global core reactivity bias and the corresponding estimated critical conditions of a nuclear reactor core prior to achieving reactor criticality. In a pressurized water reactor power generating system, heat is generated within the core of a pressure vessel by a fission chain reaction occurring in a plurality of fuel rods supported within the core. The fuel rods are maintained in a spaced relationship within fuel assemblies with the space between fuel rods forming coolant channels through which borated water flows. Hydrogen within the coolant water moderates the neutrons emitted from enriched uranium within the fuel rods to increase the number of nuclear reactions and thus increase the efficiency of the process. Control rod guide thimbles are interspersed within the fuel assemblies in place of fuel rod locations and serve to guide control rods which are operable to be inserted or withdrawn from the core. When inserted, the control rods absorb neutrons and thus reduce the number of nuclear reactions and the amount of heat generated within the core. Coolant flows through the assemblies out of the reactor to the tube side of steam generators where heat is transferred to water in the shell side of the steam generators at a lower pressure, which results in the generation of steam used to drive a turbine. The coolant exiting the tube side of the steam generator is driven by a main coolant pump back to the reactor in a closed loop cycle to renew the process. The power level of a nuclear reactor is generally divided into three ranges: the source or startup range, the intermediate range, and the power range. The power level of the reactor is continuously monitored to assure safe operation. Such monitoring is typically conducted by means of neutron detectors placed outside and inside the reactor core for measuring the neutron flux of the reactor. Since the neutron flux in the reactor at any point is proportional to the fission rate, the neutron flux is also proportional to the power level. Fission and ionization chambers have been used to measure flux in the source, intermediate, and power range of a reactor. Typical fission and ionization chambers are capable of operating at all normal power levels; however, they are generally not sensitive enough to accurately detect low level neutron flux emitted in the source range. Thus, separate low level source range detectors are typically used to monitor neutron flux when the power level of the reactor is in the source range. The fission reactions within the core occur when free neutrons at the proper energy level strike the atoms of the fissionable material contained within the fuel rods. The reactions result in the release of a large amount of heat energy which is extracted from the core in the reactor coolant and in the release of additional free neutrons which are available to produce more fission reactions. Some of these released neutrons escape the core or are absorbed by neutron absorbers, e.g., control rods, and therefore do not cause traditional fission reactions. By controlling the amount of neutron absorbent material present in the core, the rate of fission can be controlled. There are always random fission reactions occurring in the fissionable material, but when the core is shut down, the released neutrons are absorbed at such a high rate that a sustained series of reactions do not occur. By reducing the neutron absorbent material until the number of neutrons in a given generation equals the number neutrons in the previous generation, the process becomes a self-sustaining chain reaction and the reactor is said to be “critical”. When the reactor is critical, the neutron flux is six or so orders of magnitude higher than when the reactor is shut down. In some reactors, in order to accelerate the increase in neutron flux in the shutdown core to achieve practical transition intervals, an artificial neutron source is implanted in the reactor core among the fuel rods containing the fissionable material. This artificial neutron source creates a localized increase in the neutron flux to aid in bringing the reactor up to power. In the absence of a neutron source, the ratio of the number of free neutrons in one generation to those in the previous generation is referred to as the “neutron multiplication factor” (Keff) and is used as a measure of the reactivity of the reactor. In other words, the measure of criticality for a nuclear core is Keff, that is, the ratio of neutron production to total neutron loss contributable to both destruction and loss. When Keff is greater than 1, more neutrons are being produced than are being destroyed. Similarly, when Keff is less than one, more neutrons are being destroyed than are being produced. When Keff is less than one, the reactor is referred to as being “subcritical”. Until relatively recently, there has been no direct method for measuring when criticality will occur from the source range excore detectors. Plant operators typically estimate when criticality will occur through a number of methods. One method for estimating when criticality will occur is made by plotting the inverse ratio of the count rate obtained from the source range detector as a function of the change in conditions being used to bring the plant critical, e.g., withdrawal of the control rods. When the plant goes critical, the source range count rate approaches infinity and hence, the Inverse Count Rate Ratio (ICRR) goes to zero. Due to the physics of the reaction occurring within the core of the reactor, the ICRR curve is almost never linear. The control rod position changes have a significant impact on the shape of the ICRR curve. Therefore, estimating the conditions under which the plant will go critical from the ICRR curve is subject to much uncertainty, but also subject to considerable scrutiny by the United States Nuclear Regulatory Commission and Institute of Nuclear Power Operations. More recently, a method has been devised for directly predicting when the reactor will go critical. The method is described in U.S. Pat. No. 6,801,593. In accordance with the method, the reactivity of the core is increased while monitoring an output of a source range detector. A correction factor linearizes the ICRR so that the curve can be predictably extrapolated. The method thus describes a spatially corrected inverse count rate core reactivity measurement process. However, this method does not address the accuracy of the core reactivity measurement, which is dependent on the accuracy of the measured neutron radiation levels. In particular, it is very important that incremental changes in the measured neutron levels are determined accurately. The largest neutron measurement error component in a properly operating neutron radiation detector is typically caused by what is commonly called a “background signal”. The background signal induces a response in the detector measurement that is not caused by source neutrons. This results in errors in the measured core reactivity changes. In order to improve the accuracy of the neutron population measurement, and obtain a corresponding improvement in accuracy in the ICRR reactivity measurement process, it is necessary to remove any significant background signal component from the measurement before the measurement is used to calculate the reactivity change. Prior to U.S. Pat. No. 7,894,565, there has been no direct method of determining the background signal content in a neutron signal measurement from the typical neutron detectors used in commercial nuclear power facilities. U.S. Pat. No. 7,894,565 provides one such method, but there is still room for improving the estimate when the core will go critical. Additionally, currently a need exists for a method that can determine if the core is performing as designed and whether anomalies exist, before the core goes critical. Currently, such an analysis can only be performed after the core goes critical as part of the low power physics testing process, which has to be successfully concluded before the reactor is brought up to full power. The disclosed concept provides a method of determining the global core reactivity bias for a nuclear reactor core with a Keff less than 1. The method comprises the step of measuring the subcritical neutron flux (i.e., measured neutron detector response) for one or more states of the reactor core. The method also includes the step of calculating a prediction of a spatially-corrected subcritical neutron flux (i.e., predicted neutron detector response) for the one or more states of the reactor core. The method then determines a difference between the measured and the predicted neutron detector response and records the difference as the global core reactivity bias. In one embodiment of the method, the measuring step is taken from the output of the source range detector and, preferably, the measuring, calculating and determining steps are performed under a plurality of steady-state subcritical conditions, i.e. state points. Desirably, the plurality of steady-state subcritical conditions are obtained by re-positioning the control rods while maintaining the other core conditions in steady-state. The method may also include the step of using regression statistics of the measurements and predictions of the neutron detector response and applying a quantitative measured-to-predicted criteria on the regression statistics to detect various core anomalies while the plant is in a subcritical condition and prior to the plant achieving criticality. The method may further include the step of determining the reactivity bias between a predicted core and an actual core (i.e., as-assembled core following initial construction or refueling) by determining the uniform analytical reactivity adjustment, which is the systematic global reactivity bias, required to reconcile the measured neutron flux data with the predicted neutron detector response. The method may be carried out by a processing device programmed to carry out the method. Instructions for carrying out the method may be captured on a machine readable medium for use by a processing device in carrying out the method. FIG. 1 illustrates the primary side of a nuclear electric power generating plant 10 in which a nuclear steam supply system 12 supplies steam for driving a turbine generator (not shown) to produce electric power. The nuclear steam supply system 12 has a pressurized water reactor 14 which includes a reactor core 16 housed within a pressure vessel 18. Fission reactions within the reactor core 16 generate heat, which is absorbed by a reactor coolant, light water, which is passed through the core. The heated coolant is circulated through hot leg piping 20 to a steam generator 22. Reactor coolant is returned to the reactor 14 from the steam generator 22 by a reactor coolant pump 24 through cold leg piping 26. Typically, a pressurized water reactor has at least two and often three or four steam generators 22 each supplied with heated coolant through a hot leg 20, which, along with the cold leg 26 and reactor coolant pump 2 form a primary loop. Each primary loop supplies steam to the turbine generator. One of such loops are shown in FIG. 1. Coolant returned to the reactor 14 flows downward through an annular downcomer, and then upward through the core 16. The reactivity of the core, and therefore the power output of the reactor 14, is controlled on a short term basis by control rods, which may be selectively inserted into the core. Long term reactivity is regulated through control of the concentration of a neutron moderator such as boron dissolved in the coolant. Regulation of the boron concentration affects reactivity uniformly throughout the core as the coolant circulates through the entire core. On the other hand, the control rods affect local reactivity and therefore, result in an asymmetry of the axial and radial power distribution within the core 16. Conditions within the core 16 are monitored by several different sensor systems. These systems include an excore detector system 28, which measures neutron flux escaping from the reactor 14. The excore detector system 28 includes source range detectors used when the reactor is shut down, intermediate range detectors used during startup and shutdown, and power range detectors used when the reactor is above approximately 5% power. Incore detectors are also typically employed during power operation; however, they are not relevant to this application. Estimated critical conditions (ECC) are typically required as part of any reactor startup evolution. ECC is a combination of control rod and primary system conditions (e.g., soluble boron concentration, coolant temperature) that are expected to yield a critical reactor state. It is valuable, from a reactivity management perspective, that the ECC closely match the actual critical conditions of the core (i.e., the true combination of control rod position and primary system conditions that yield a critical reactor state). Furthermore, Plant Technical Specifications include a limiting condition for operation (also referred to as LCO) that the core reactivity be measured within a specified amount of the predicted core reactivity. The associated surveillances are performed prior to commencing power operation (typically >5% rated thermal power) after each core refueling, and generally every month afterward. Various ECC combinations can be determined by nuclear design predictions prior to reactor core operation. However, a more accurate ECC projection can be obtained through ICRR monitoring and evaluation prior to reactor criticality, which can identify the presence of any global core reactivity bias. The global core reactivity bias is defined as the difference between the predicted reactivity state of the core and the actual reactivity state of the core determined by measurement. Subsequently, the bias can be incorporated into an updated ECC projection prior to reactor criticality. ICRR monitoring is a common practice during shutdown/startup conditions that requires a baseline measurement from a neutron detector (MR). Following a reactivity manipulation (e.g., control rod withdrawal) and achievement of a new steady state condition (state point), another measurement is collected (Mi). The ratio of MR/Mi is defined as the ICRR for state point i. As additional reactivity manipulations occur, ICRR can be updated and monitored in terms of changes from the reference measurement, and in turn, how the reactor is progressing towards (or away from) reactor criticality. If the intent is to startup the reactor (i.e., bring the reactor to a critical state), positive reactivity is added to the core (e.g., control rod withdrawal, primary system soluble boron dilution), and the ICRR is expected to approach zero. As described in U.S. Pat. No. 6,801,593, due to the physics of the reactions occurring within the reactor core, the ICRR is not linear unless the reactor is very close to criticality; control rod position changes as part of pre-critical testing and the approach to criticality have a significant impact on the shape of the ICRR curve. Therefore, U.S. Pat. No. 6,801,593 provided a means of linearizing the measured ICRR with changes in control rod position or core conditions. The method described in U.S. Pat. No. 6,801,593 relied on use of spatially-corrected ICRR (ICRRSC) as the measurement parameter, which is a function of neutron detector measurements (MR/Mi), but is dependent on nuclear design by way of spatial correction factors (SCFs). U.S. Pat. No. 6,801,593 defined SCF as a function of the static spatial factor and predicted eigenvalues obtained from subcritical, static calculations with and without fixed neutron sources. Because ICRRSC is partly dependent on design prediction, use of ICRRSC as the primary measurement parameter is inherently subject to masking effects, where an error or bias in the design prediction can influence the measurement as well. Hence, it is desirable from a reactor physics measurement standpoint to eliminate predictive components from measurement results in order to eliminate the potential for masking effects. Therefore, the disclosed concept first defines a linear relationship between measured ICRR (a “pure” measurement, MR/Mi, and with no predictive component) and predicted ICRR (a “pure” prediction, with no measurement component, but that accounts for any spatial effects that may have resulted from changes in plant configuration or core conditions between measurements MR and Mi). After collecting multiple ICRR measurements, measured ICRR can be compared to the predicted ICRR at each state point. It is then possible to quantify a global reactivity bias by determining the uniform reactivity adjustment to the predicted ICRR at each state point that results in ideal behavior, which is defined as a linear fit and a y-intercept of zero when performing a linear fit of measured ICRR versus predicted ICRR. Fundamentally, the prediction is adjusted to match measurement and the adjustment is used to correct the predictions for future evolutions (e.g., final approach to criticality). Recognizing that (1/M) theory is practically represented by monitoring changes in the measured neutron detector response from a baseline or reference condition, Equation (1) is a relationship familiar to nuclear reactor operators.MR(1−kR)∝Mi(1−ki) (1) wherein, MR and Mi are neutron detector responses at the reference state point condition and a subsequent state point condition i, respectively, and kR and ki are the Keff values at the reference state point condition and a subsequent state point condition i, respectively. Re-arrangement of terms yields a new Equation (2). M R M i ∝ 1 - k i 1 - k R ( 2 ) In this form, the left side of the equation is now only the ratio of measured count rates (“raw”, or not-spatially corrected, measured ICRR, IM, i). The right side of the equation is comprised of core eigenvalues that can be predicted by nuclear design calculations (predicted ICRR, IP, i) that take into account spatial effects resulting from changes in control rod positions or primary system conditions at the time of measurement. This separation of measurement from prediction is desirable in order to eliminate the potential for masking effects. In simplified form:IM,i∝IP,i (3) The true regression of Equation (3) can be written as:IM=β1IP+β0 (4)The resultant estimate of the true regression, Equation (5), can be used as a basis for core design validation prior to at-power operation of the plant; specifically, incremental and total measured changes in ICRR can be compared to design prediction while the reactor is shutdown. The results evaluation is not subject to masking effects, and measured-to-predicted agreement (within pre-defined tolerance limits) demonstrates that the core is behaving as designed.ÎM=mIP+b (5)Ideally, the as-built measured core is identical to the as-designed predicted core, so that β1 equals one and β0 equals zero in Equation (4). However, in practice, this is not likely to be the case; some non-trivial differences will likely be present in the line fit of measured vs. predicted ICRR response. Regardless of the cause, it is especially useful to quantify systematic reactivity bias so that it can be used for criticality forecasting and monitoring purposes. Returning to Equation (2), redefining the reference neutron detector measurement as a normalization constant (C) and rearrangement of terms yields the following: M i ∝ [ C · 1 - k R 1 - k i ] ( 6 ) Equation (6) can be simplified and presented as a true regression by combining the normalization constant and predictive terms into a predicted detector response at state point i (Pi) that also accounts for spatial effects as explained previously:Mi=β1Pi+β0 (7)To quantify the global bias, the set of neutron detector measurements will be fit versus their corresponding predicted values. The resultant estimate of the true regression is defined in Equation (8).{circumflex over (M)}i=mPi+b (8) In an ideal situation, the y-intercept of the measured vs. predicted neutron detector response is zero. Assuming the regression estimate is linear and the data points are tightly fit, the global measured-to-predicted reactivity bias can be estimated by determining the amount of reactivity adjustment required to drive the y-intercept (b) to zero for the line fit defined in Equation (8). The uniform reactivity adjustment across all state points (imparted via changes in the Pi values) that produces a line fit with a y-intercept (b) of zero is the estimated core reactivity bias.{circumflex over (M)}i={acute over (m)}*{acute over (P)}i (9) Accordingly, the disclosed concept utilizes a direct comparison of raw subcritical neutron flux measurements with corresponding predictions at each state point condition. This differs from prior power reactor physics testing methodologies, which require correction of the measurement data prior to results evaluation; the benefit of this method, in employing complete separation of measurements and predictions, is the prevention of masking effects (i.e., elimination of interdependency between measurement and prediction). Additionally, the disclosed concept utilizes regression statistics of raw neutron detector measurements to corresponding predictions, and quantitative measured-to-predicted criteria on such, to detect various core anomalies while the plant is in a subcritical condition and prior to the plant achieving criticality. The benefit of this approach is that it provides an added measure of safety since anomalous core conditions can be detected during hot standby testing and can be anticipated during the final approach to criticality. Furthermore, the disclosed concept utilizes a method of determining the reactivity bias between the predicted core and actual core by determining the uniform analytical reactivity adjustment (systematic global reactivity bias) required to reconcile the measured neutron flux data with predictions. This differs from previous power reactor physics test methodologies, for which the reactivity difference is determined based on measured reactivity at critical reactor conditions. The benefit of this approach is that it provides a way to identify anomalous reactivity indication/behavior in the subcritical state as a means of providing reactivity management guidance and/or accident prevention. Also, this method directly provides a reactivity bias offset on the predictive model used in the plant safety analysis. Application of this method requires neutron detector measurements and corresponding core condition predictions that are provided by existing core design codes and account for the subcritical neutron flux distribution. The basic uses of this method are to monitor and project the subcritical state of the core. Associated applications include monitoring of negative reactivity conditions or shutdown margin, and forecasting of estimated critical conditions prior to plant startup. The method amounts to Subcritical Physics Testing, which integrates the monitoring and forecasting function to ultimately execute a series of measured-to-predicted comparisons to confirm the as-built core is operating consistent with design following refueling; results that could only previously been achieved during low power testing after the reactor went critical. A key piece of information needed for the safe and efficient operation of a subcritical reactor core is the negative reactivity of the core; that is, the amount that the core is subcritical, also known as the shutdown margin. Prior to development of the methodology described herein, this information has only been inferred, and not directly measured. The basic uses of this method are to project and monitor the negative reactivity of a subcritical core for any static configuration of interest, i.e., a steady-state combination of control rod position and primary system conditions, through the use of neutron detector signal measurements and advanced subcritical core predictions. A series of subcritical measured-to-predicted comparisons during plant startup forms the basis for the integrated application of this methodology, i.e., the measured-to-predicted comparisons are performed at a number of steady-state subcritical conditions, each of which is referred to as a state point. This method is performed at static and subcritical conditions (vs. the dynamic and critical conditions for traditional low power physics testing). This method is revolutionary in that it is not just an extension of the steps performed during low power physics testing. However, this method achieves the same objective as low power physics testing; following refueling and prior to returning to normal operation, testing is performed to determine if the operating characteristics of the core are consistent with design predictions as a means to ensure the core can be operated as designed. While achieving the same objective as low power physics testing, performing this method yields inherent safety, human performance, and test performance benefits over low power physics testing. Performing measurements at static and subcritical conditions inherently enhances plant safety and reactivity management. This method is seamlessly integrated into routine plant startup activities as opposed to necessitating infrequently performed tests and evolutions and special test exceptions to plant operations, which improves test reliability and human performance. Therefore, this method-based core design verification offers broad benefits for essentially any plant type. It is to be appreciated that methods as described herein can be carried out by a processor or processing device of a computer system or by other means of carrying out the function. Thus, a processor with the necessary instructions programmed directly therein or on a machine readable medium accessed thereby for carrying out such a method or element of a method forms a means for carrying out the method or element of a method. Furthermore, an element described herein of an apparatus embodiment is an example of a means for carrying out the function performed by the element for the purpose of carrying out the invention. While specific embodiments of the disclosed concept have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular embodiments disclosed are meant to be illustrative only and not limiting as to the scope of the disclosed concept which is to be given the full breadth of the appended claims and any and all equivalents thereof.
	abstract	A process for manufacturing a high-temperature ultrasonic transducer, said transducer comprising a steel or metal top electrode, a piezoelectric converter, a steel or metal support ensuring the interface between the converter and the propagation medium of the acoustic waves, a first joint between the support and the piezoelectric crystal, and a second joint between the converter and the top electrode, comprises, to produce said gold-and-indium-based joints, a brazing and diffusing operation comprising the following steps: a first step of increasing temperature to a first temperature comprised between about 150° C. and about 400° C. and of maintaining this first temperature for a first length of time corresponding to a first plateau; and a second step of increasing temperature to a second temperature comprised between about 400° C. and about 1000° C. and of maintaining this second temperature for a second length of time corresponding to a second plateau.
	abstract	An exposure apparatus which draws a pattern on a substrate with electron beams. The apparatus includes a substrate stage which supports the substrate, a transfer stage which moves the substrate stage, an electromagnetic actuator which moves the substrate stage relative to the transfer stage, a first measurement system which measures a position of the transfer stage, a second measurement system which measures a position of the substrate stage, a controller which controls the electromagnetic actuator on the basis of measurement results obtained by the first and second measurement systems, a deflector which deflects electron beams with which the substrate is irradiated, and a filter which performs filtering for a measurement result obtained by the second measurement system and supplies the filtered measurement result to the deflector.
050283820	summary	FIELD OF THE INVENTION This invention deals with the manufacture of nuclear fuel bundles comprising assembling a group of individual fuel rod elements and structural components into a designed array of the fuel elements and thereby producing typical composite fuel bundles or assemblages for service in conventional water cooled and moderated, power generating nuclear reactor plants. The invention comprises an improvement in the manufacturing method and subsequent handling which reduces and minimizes damage to the assembled components, and in turn provides an enhanced nuclear fuel product. BACKGROUND OF THE INVENTION Fissionable fuel materials such as oxides of uranium, plutonium or thorium, and combinations thereof, are typically formed into small cylindrical pellets and housed within sealed tubes or elongated containers sometimes referred to in the art as "cladding". The sealed fuel containers protect the fuel from reacting with the coolant, or any foreign matter entrained therein, and prevent the escape of any fission products from the fuel, which are normally highly radioactive and corrosive, into the coolant and in turn contamination of the overall system. Thus the enduring integrity of the sealed container housing the fissionable fuel is therefore of the utmost importance. Large capacity power generating nuclear fission reactor plants normally employ several hundreds of such sealed tubular containers housing fissionable fuel. To facilitate the periodic refueling, which commonly is performed by replacing fractional portions of the total fuel at intervals and rearranging other fractional portions, the tubular fuel containers, or fuel elements consisting of same, are conventional assembled into bundles or groups of approximately 40 to 90 elements which can be handled and manipulated as a single composite unit. Elongated or tubular containers housing fissionable nuclear fuel materials are therefore assembled into a designed array conventionally comprising a group of spaced apart, parallel aligned tubular containers of fuel secured by mechanical means. A typical fuel bundle comprises, for example, an eight by eight or nine by nine array of spaced fuel containers. The tubular fuel containers usually are several feet in length, such as about 14 feet, and approximately one-half inch in diameter and are each spaced from the others a fraction of an inch. The spacing is required to permit an ample flow of heat removing coolant, such as water, over the full exterior surface of all tubular fuel containers for effective heat transfer and thus effective operation. To inhibit such elongated fuel elements from bowing and vibrating due to high heat and velocities of coolant flowing thereabout, whereby they can contact each other and in any case impede or unbalance coolant flow, it is necessary to retain the tubular fuel elements in their spaced apart array or relation by means of a plurality of spacing units positioned at intervals along their length. Typical spacing units for tubular fuel elements comprise a frame having a multiplicity of crossing components or lattice which form or provide a plurality of opening arranged in the designated pattern for spacing the parallel aligned fuel elements. A group of the tubular fuel elements are each inserted into and passed through the aligned opening of a series such spacing units positioned at the intervals along the length of the elements in a predetermined pattern or distance. Thus with each elongated fuel element of a group traversing several spacing units at intervals which provide intermediate restraint and support transverse of the group, the spaced apart, parallel aligned fuel elements are each restrained from lateral bowing and vibration which could damage their structure or impede effective coolant flow intermediate and around each fuel container. A common commercial embodiment of a nuclear reactor fuel bundle has about seven such spacer units securing all tubular fuel elements extending therethrough which are positioned at intervals along the length of the grouped array of elements. Spacing units for securing bundles of fuel rod elements frequently contain spring and stop members which press against the fuel rod elements in metal to metal contact as a means of securely gripping and holding the fuel rod elements in position. The assembled bundle of a group of spaced apart, parallel aligned array of the tabular fuel elements secured to each other by traversing through the openings of a series of spacing units positioned at intervals along their length additionally have each of their ends supported in sockets of tie plates. This bundle assembly is also typically surrounded by an open ended tubular channel of suitable cross-section such as square, to direct the flow of coolant longitudinally along the surface of the fuel elements and guide the neutron absorbing fission control rod units which move reciprocally longitudinally intermediate the channel surrounded bundle of fuel elements. Typical fuel bundle assembles of the foregoing common construction are disclosed in Letters U.S. Pat. No. 3,350,275, issued October 1967 and U.S. Pat. No. 3,654,077, issued Apr. 4, 1972. The disclosed contents of said patents, and those cited therein, are incorporated herein by reference. Structural components utilized within the reactor core of fissionable fuel, such as the tubular containers housing the fuel and their spacing units, etc. must be fabricated from a durable metal which has a low neutron absorbing capacity, or cross section, so as not to impede the neutron incited fission chain reaction. The preferred material most commonly used comprises alloys of zirconium which have a neutron absorption capacity in the order of about one-fifteenth of that of stainless steel. However zirconium alloys are under certain circumstances susceptible to corrosion which can result in its structural failure. To impede a destructive form of self-perpetuating corrosion peculiar to zirconium and its alloys referred to in the art as modular corrosion, components produced from zirconium alloys, such as fuel containers, are commonly treated to form a specific oxide surface layer which resists modular corrosion and surface attack under reactor conditions. SUMMARY OF THE INVENTION This invention comprises an improved method of assembling bundles of nuclear fuel elements transversely passing through a series of spacing units positioned at intervals which reduces the potential for a subsequent occurrence of destructive corrosion, and the enhanced assembled product. The improved method utilizes unique measures for preventing any damage or abrasion to the metal surfaces of the metal components of a nuclear fuel bundle while undergoing assembly and thereafter during shipping and handling, until installed within a nuclear reactor fuel core for operation. OBJECTS OF THE INVENTION It is a primary object of this invention to provide an improved method of producing nuclear fuel bundles, and an enhanced product of the method. It is also an object of this invention to provide a method of assembling nuclear fuel bundles which reduces the potential for surface damage to metal components. It is another object of this invention to provide a method of assembling nuclear fuel bundles which reduces the potential for subsequent corrosion damage to the bundle components. It is still another object of this invention to provide an improved low cost and effective method of manufacturing nuclear fuel bundles which enhances the structural integrity and durability of the nuclear fuel bundles in reactor service. It is a further object to provide a nuclear fuel bundle of assembled nuclear fuel elements secured together in a spaced apart, parallel grouping secured in such an array by each passing transversely through a series of spacing units at intervals which is essentially free of damage or abrasion attributable to assembly, and/or thereafter during shipping and handling.
039986942	description
	summary
061047732	description	DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the figures of the drawing in detail and first, particularly, to FIG. 1 thereof, there is seen a welding apparatus having a copper electrode 2 which is assembled from two identical halves, with a through bore 3 in which a fuel rod cladding tube 4 being filled with nuclear fuel and made of a zirconium alloy is located. The two identically constructed parts of the copper electrode 2 surround the cladding tube 4 located in the through bore 3 and touch the outer surface of the cladding tube 4 over a large surface area. A carrier body 6 for a counter electrode which is also provided, is displaceable relative to the copper electrode 2 in the direction of a longitudinal axis 5 of the cladding tube 4, and includes a copper sheath 7 disposed coaxially with the cladding tube 4 and therefore with the duct 3 in the copper electrode 2. A seal plug, locking plug or stopper 8 for the fuel rod, which is likewise formed of a zirconium alloy, is loosely inserted into the copper sheath 7. The copper electrode 2 has a cylindrical step or shoulder 9 formed therein at an end of the through bore 3 facing toward the copper sheath 7. The cylindrical step 9 has a diameter which is greater than the diameter of the through bore 3. The step 9 forms a cylindrical void, into which the end of the cladding tube 4 protrudes from one end and into which the end of the seal plug 8 protrudes from the other end. Dot-dash lines in FIG. 2 indicate the original shape of the cladding tube 4 and the seal plug 8. In its original shape, the seal plug 8 has an external cone 10 at an end surface, which tapers toward the longitudinal axis 5 of the cladding tube and therefore also toward the longitudinal axis of the seal plug 8, which coincides with the longitudinal axis 5. One end of the cladding tube 4 rests with its inner edge on the cone 10. In order to weld the cladding tube 4 to the seal plug 8, an electrical current source is connected to the copper electrode 2 and to the copper sheath 7. At the same time, through the use of the carrier body 6, the seal plug 8 is pressed against the cladding tube 4, and the material at the point of contact between the seal plug 8 and the cladding tube 4 is upset by the amount of the forward feed 11 (upset distance). In FIG. 1, the initial condition of the cladding tube 4 and seal plug 8 at the beginning of the welding process is shown above the longitudinal axis 5 of the cladding tube 4 shown in dot-dashed lines. Below this longitudinal axis 5, the final state can be seen, after completion of the welding process and disconnection of the copper electrode 2 and the copper sheath 7 from the current source. As FIG. 1 shows, in this final state the seal plug 8 engages the cladding tube 4, and at a transition point between the cladding tube 4 and the seal plug 8, an annular bead 12 with a cylindrical outer jacket surface 13 is present on the outer surface of the cladding tube 4. FIG. 2 shows that an annular outwelling, outflow or squeezing out of material 14 is formed inside the cladding tube 4. Both the annular bead 12 and the outwelling of material 14 are formed of the material of the original cladding tube and the original seal plug, which in the present case is zirconium alloy. Due to the two seams or joints that are located between the two parts of the copper electrode 2, there may be two humps 17 on the outer jacket surface 13 of the annular bead 12, each of which extends along a jacket line of the jacket surface 13. The annular bead 12 as well as the outwelling of material 14 solidify again from a welding melt and have the microscopic structure shown in FIG. 3. The flow of the material caused by the welding is indicated by arrows 16. As can be learned from FIG. 3, there is a depression 15 of the cladding tube 4, as seen in the encompassing direction relative to the longitudinal axis 5, which is located in the cylindrical jacket surface 13 of the annular bead 12. This depression 15 contains the material having the same microscopic structure as in the cladding tube 4, that is the zirconium alloy of the cladding tube 4. On the inside of the cladding tube 4, an internal lining 18 of high-purity zirconium can be seen. This corrosion-sensitive lining continues on the surface of the outwelling of material 14 and is not part of the material solidified from the welding melt and thus has not penetrated as far as the outside. The cylindrical outer jacket surface 13 of the annular bead 12 can remain mechanically unmachined. As a result, not only is there a savings in production costs, but damage to the cladding tube 4 at the annular bead 12 is also avoided. Moreover, machining chips, which in the case of a zirconium alloy could even self-ignite very easily, are avoided.
	abstract	A method of calculating and using a constraint for fuel rods is provided. The method may utilize pin nodal exposures and pin nodal powers to obtain the constraint, calculate rod average exposures and rod average powers (kW/ft) in each fuel assembly, and develop maps from the calculated rod average exposures and powers (kW/ft) to operate design, optimization, licensing, and/or monitoring applications.
	claims	1. A narrow band x-ray filter comprising:a substrate; anda sheaf of one or more reflection units stacked upon each other on the substrate, each reflection unit includinga first set of at least two discrete spacers on a respective underlying structure,a reflector disposed on the first set of spacers so as to form a void between the respective underlying structure and the reflector, anda first set of at least two discrete shims disposed on the first set of at least two spacers, each shim being at least substantially the same thickness as the reflector. 2. The filter of claim 1, wherein each reflector includes:a base layer; anda stack of one or more mirrors, each mirror includinga heavy Z metal layer, anda layer of carbon on the metal layer. 3. The filter of claim 2, wherein the heavy Z metal includes at least one of gold, platinum and iridium. 4. The filter of claim 3, wherein each stack includes 2-200 mirrors. 5. The filter of claim 1, wherein the filter further includes a top member on the sheaf. 6. The filter of claim 1, wherein the sheaf includes between 2 and 300 reflection units. 7. An apparatus, to produce a substantially narrow band x-ray beam; the apparatus comprising:a source of a first x-ray beam; anda narrow band x-ray filter having a first end, a second end and a focal point located nearer to the first end than to the second end, andthe source being disposed substantially at the focal point such that a substantially narrow band x-ray beam emanates from the second end of the filter; andthe filter being configured and disposed so as to receive at the focal point at least a majority of the cross-section of the first x-ray beam;wherein the filter includes the following,a substrate, anda sheaf of one or more reflection units stacked upon each other on the substrate, each reflection unit including the following,a first set of at least two discrete spacers on a respective underlying structure,a reflector disposed on the first set of spacers so as to form a void between the respective underlying structure and the reflector, anda first set of at least two discrete shims disposed on the first set of at least two spacers, each shim being at least substantially the same thickness as the reflector. 8. The apparatus of claim 7, wherein the filter is configured and disposed so as to receive at the focal point substantially the entire cross-section of the first band x-ray beam. 9. The apparatus of claim 7 wherein the filter is an X-ray telescope such that the narrow band x-ray beam is formed of substantially parallel x-rays. 10. The apparatus of 7, wherein the narrow band x-ray beam is formed of x-ray that diverge from the second end of the filter. 11. The apparatus of 7, wherein each reflector includes:a base layer; anda stack of one or more mirrors, each mirror including the following,a heavy Z metal layer, anda layer of carbon on the metal layer. 12. The apparatus of claim 7, wherein: the filter is movable in at lease one dimension; and the apparatus further comprises an adjustment unit to move the filter in the at least one dimension. 13. The apparatus of claim 7, wherein the first x-ray beam is a broad band x-ray beam. 14. An apparatus to make an x-ray image of a subject, the apparatus comprising:a source of a first x-ray beam; anda narrow band x-ray filter having a first end, a second end and a focal point located nearer to the first end than to the second end,the source being disposed substantially at the focal point such that a substantially narrow band x-ray beam emanates from the second end of the filter, andthe filter being configured and disposed so as to receive at the focal point at least a majority of the cross-section of the first x-ray beam;an x-ray detector arranged to receive the narrow band x-ray beam so that a subject disposed between the second end of the filter and the detector casts an image thereon;wherein the filter includes the following,a substrate, and,a sheaf of one or more reflection units stacked upon each other on the substrate, each reflection unit including the following,a first set of at least two discrete spacers on a respective underlying structure,a reflector disposed on the first set of spacers so as to form a void between the respective underlying structure and the reflector,a first set of at least two discrete shims disposed on the first set of at least two spacers, each shim being at least substantially the same thickness as the reflector,each reflector including a base layer, anda stack of one or more mirrors, each mirror including the following,a heavy Z metal layer, anda layer of carbon on the metal layer. 15. A method of making a narrow band x-ray filter, the method comprising;providing a substrate; andstacking two or more reflection units in succession upon the substrate such that the two or more reflection units are aligned according to a plurality of radial planes that share a common origin, respectively;wherein the step of stacking, for each reflection unit, the following,disposing a first set of at least two discrete spacers on a respective underlying structure,disposing a reflector on the first set of spacers so as to form a void between the respective underlying structure and the reflector, anddisposing a first set of at least two discrete shims on the first set of at least two spacers, each shim being at least substantially the same thickness as the reflector. 16. The method of claim 15, further comprising:mechanically connecting the two or more successively-stacked units to the substrate so as to form a sheaf of reflection units. 17. The method of claim 15, wherein each reflector includes:a base layer; anda stack of one or more mirrors, each mirror includinga heavy Z metal layer, anda layer of carbon on the metal layer. 18. The method of claim 17, wherein the heavy Z metal includes at least one of gold, platinum and iridium. 19. The method of claim 17, wherein each reflector includes 2-200 mirrors. 20. The method of claim 15, further comprising:disposing a top member on the sheaf. 21. The method of claim 15, wherein the sheaf includes between 2 and 300 reflection units. 22. The method of claim 15, wherein the step of stacking, for each reflection unit, includes:disposing a first set of at least two rails on a respective underlying structure, anddisposing a reflector on the first set of rails so as to form a void between the respective underlying structure and the reflector. 23. The method of claim 22, wherein:the step of stacking further includes the following,configuring each rail to exhibit, in cross section, a shape resembling a staircase including at least first and second steps;a first step portion of the rail, being located relatively upward from the respective underlying structure, corresponds to a first surface upon which the reflector is disposed; anda second step portion of the rail corresponds to a second surface which can support another rail disposable thereon. 24. The method of claim 15, wherein the step of stacking includes orienting each reflection unit such that leading edges of the reflection units are subjected to substantially the same angle of incidence with respect to a source of x-rays located at the common origin.
051851040	summary	BACKGROUND OF THE INVENTION The present invention relates to a method of treatment of a high-level radioactive waste generated, for example, from reprocessing of spent nuclear fuels. In particular, it relates to a method for treating a high-level radioactive waste which comprises heating the radioactive waste at a high temperature, separating part of the elements contained in the radioactive waste by utilizing sublimation or boiling of each element in its various chemical forms during the heating step, and recovering a resultant residue as a solidified material. The high-level radioactive waste generated from reprocessing of the spent fuels contains transuranium elements and Tc (technetium) having long half-lives; Cs (cesium) and Sr (strontium) that are noteworthy elements from the aspect of treatment, storage and disposal because they are responsible for the major proportion of heat generation; and valuable platinum group metals such as Ru(ruthenium), Rh(rhodium) and Pd(palladium). It is therefore very important to separate and recover them prior to solidification of the waste, and to utilize them as a radiation source, a heat generation member and a noble metal, from the point of view of effectively utilizing resources. The following three methods are heretofore known as prior art techniques for recovering these elements from the high-level radioactive waste: 1) A solvent extraction method wherein the intended nuclides are separated by using a special solvent from the high-level radioactive waste generated from the reprocessing steps; 2) An ion-exchange method wherein the intended nuclides are separated by using an ion-exchange resin from the high-level radioactive waste generated from the reprocessing steps; and 3) A lead extraction method for platinum group elements wherein lead is added to glass at the time of the glass melting step of a vitrification process to thereby move platinum group elements to molten lead and separate them with the molten lead. However, these prior art techniques described above are not free from the following disadvantages, respectively: 1) Since a new-type solvent is introduced to the reprocessing step in the additional solvent extraction method, the solvent treatment step becomes complicated and efficiency of the main solvent extraction step lowers conseqently. 2) Flammable materials are produced when the ion-exchange resin comes into contact with a nitric acid solution of the radioactive waste. Therefore, the ion-exchange method involves safety problems. 3) The lead extraction method for platinum group elements in the vitrification process can separate the platinum group elements but secondary treatment is necessary in order to extract them from lead. Furthermore, none of these prior art methods can reduce the volume of the high-level radioactive waste at a high rate, whichever method may be employed. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method for treatment of a high-level radioactive waste which solves the problems with the above-described prior art techniques and can separate and recover valuable elements in the radioactive waste in an extremely simple manner. It is another object of the present invention to provide a method of treatment of a high-level radioactive waste which does not generate a secondary waste and can obtain a highly volume-reduced solidified material. According to the present invention, in order to accomplish the above-described objects, there is provided a method of treatment of a high-level radioactive waste comprising heating the radioactive waste at a high temperature to vaporize part of the elements contained in the radioactive waste, and cooling the resultant vapor to collect the elements. In one embodiment of the present invention, the radioactive waste is reduction-heated at a high temperature to vaporize part of the elements contained in the radioactive waste, and the resultant vapor is then cooled to collect the elements. The high-level radioactive waste is ordinarily a nitric acid solution obtained as an extraction residue in the reprocessing step of spent nuclear fuels, and contains almost all of the nuclear fission products and actinides in spent nuclear fuels. In the present invention, the nitric acid solution is heat-treated so as to evaporate the moisture and nitric acid in the solution and to obtain a calcined material, which is further heated at a temperature ranging from about 500.degree. to about 3,000.degree. C. and more preferably, from about 1,000.degree. to about 2,500.degree. C. According to another embodiment of the present invention, in a first stage treatment, those elements which sublimate or boil in the form of oxides are heat-treated at a normal or reduced pressure to vaporize those elements. The resultant vapor is then cooled by a plurality of cooling/collecting units whose temperatures are differently set so as to correspond to sublimation or boiling points of each compound or element, thereby collecting the respective elements separately. In a second stage treatment, the remaining high-level radioactive waste is heated in the presence of a reducing agent such as hydrogen to reduce the radioactive waste, and those elements which sublimate or boil in the form of metal are vaporized. The resultant vapor is then cooled, in the same manner as in the first stage treatment, by the cooling/collecting units whose temperatures are set so as to correspond to sublimation or boiling points of the respective elements, thereby collecting the respective elements separately. Needless to say, those elements which are reduced to metals during heating in the first stage treatment can be separated by sublimation or boiling without reduction in the second stage treatment. A voloxidation method is known as a technique for removing radioactive materials from spent fuels but this method is merely directed to non-metallic elements such as krypton, iodine, tritium and the like. The present invention is directed to metallic elements and not only removes radioactive materials with high boiling points by heating the high-level radioactive waste at a high temperature, but also can remove both Cs and Sr, that are high heat-generation elements and pose problems during disposal, by combining the heat-treatment with the reduction reaction. The resultant residue comprises metals or a mixture of the metals and oxides, and can be recovered as a volume-reduced high-level radioactive solid. Almost all of the elements have boiling points or sublimation points different from those of other elements. Some elements contained in the high-level radioactive waste have a relatively low sublimation point or boiling point in the form of an oxide or metal. For example, the boiling point is 690.degree. C. for metallic cesium, 311.degree. C. for technetium oxide, 765.degree. C. for metallic cadmium and 1,384.degree. C. for metallic strontium. By utilizing the difference in these boiling points, therefore, each valuable element can be separated and recovered by heat-treating the high-level radioactive waste at a high temperature to obtain the oxides thereof or by reducing them by hydrogen or the like to obtain metals, causing their sublimation or boiling, and cooling stepwise the resulting vapor ,mixture at the predetermined temperatures. After the removal of Cs and Sr, the amount of heat generated from the high-level solid waste is reduced to about 10% and therefore the burying density for disposal can be improved drastically. Incidentally, if Cs alone is removed, the amount of heat generation becomes only 50% and a large effect cannot be expected. The boiling points of oxides of Sr are at least 2,430.degree. C. and that of metallic Sr is 1,384.degree. C. as described above. Accordingly, strontium can only be separated by the method of the present invention wherein the heating step is combined with the reduction reaction. Incidentally, vaporization of each element can be effected at a lower temperature if the heating step or the reduction-heating step is carried out under a reduced pressure.
043280706	description	DETAILED DESCRIPTION OF THE INVENTION The invention proposed, in comparison to previously proposed inertial confinement fusion drivers, promises to reduce greatly the driver power, and also substantially to relax the focusing requirement. The concept is explained in FIG. 1. The thermonuclear pellet T is placed in the center of a spherical cavity with the initial radius r=r.sub.o and which is several times larger than the pellet radius r.sub.p. The cavity is formed by a pusher P consisting of dense material, preferably uranium. Inside the cavity is a low density gas of a sufficiently high atomic weight, for example krypton. The pusher of the spherical cavity is surrounded by an ablator A. If beams B are projected onto the ablator A the pusher will be imploded with the velocity v. The fact that the outer ablator radius is larger than the pellet radius greatly relaxes the focusing requirements compared to direct pellet fusion. Because the beams are here only of modest power and because the outer ablator radius of the cavity is larger than the pellet radius the implosion velocity too will be here smaller than required for direct pellet fusion. The imploding pusher upon its impact on the krypton gas generates a shock wave, provided the gas density is sufficiently high to make the collision mean free path small compared to the cavity radius. Because of the many atomic transitions in the krypton gas and which are excited at the high temperature behind the shock front, the kinetic energy in the shock front will be rapidly converted into photons with the result that the cavity will be filled with black body radiation. If the density of the krypton gas is sufficiently low, but still sufficiently high to make a shock wave, one can ensure that the cavity itself is optically transparent. Then, if the implosion velocity of the cavity is sufficiently high the losses of radiation through the cavity wall can be made sufficiently low and the thusly formed black body radiation is highly compressed. The imploded black body radiation confined by the dense pusher wall will thereby expose the pellet surface to a power flux rising in proportion to T.sup.4. Furthermore, since the opacity of the pellet surface rises in proportion to T.sup.-3.5 the total power absorbed by it will rise in proportion to T.sup.7.5. The temperature of the black body radiation, if perfectly confined by the walls of the cavity, rises insentropically according to VT.sup.3 =const., where V is the cavity volume. For r.sub.p <<r one has Tr .perspectiveto. const. and the photon power flux transmitted to the pellet rises in proportion of r.sup.-7.5. By the absorption of the black body radiation in the pellet surface, the pellet is then itself ablatively imploded. If the implosion velocity V is constant one has for the time dependence of the cavity radius r=r.sub.o (1-t/t.sub.o), with t.sub.o =r.sub.o /v. Therefore, the total radiation power delivered to the pellet surface rises as EQU P(t)=4.pi.r.sup.2.sub.p .sigma.T.sub.o .sup.4 (1-t/t.sub.o).sup.-4 (1) where .sigma.=5.75.times.10.sup.-5 erg/cm.sup.2 sec .degree.K..sup.4 is the Stefan-Boltzmann constant. The total power absorbed rises as EQU P.sub.a (t).varies.(1-t/t.sub.o).sup.-7.5 (2) It thus follows that the power absorbed is strongly peaked at the end of the implosion process near t=t.sub.o. This simply means that during the implosion process the kinetic implosion energy of the pusher is first converted and intermediately stored in the form of black body radiation and only at the end of the implosion process delivered at high peak power to the pellet. This intermediate storage of the available energy into black body radiation makes it possible to work with a greatly reduced initial driver power. Furthermore, since unlike in laser fusion, the wave length is here much shorter and in the soft X-ray region, much larger pellet compression should be possible. The reason for this is that the plasma frequency of the target must be well matched to the frequency of the incoming radiation to assure good energy deposition in the target surface and hence high ablation implosion efficiencies. The minimum required velocity for the cavity implosion can be estimated from the requirement that the power of the black body radiation shall be .about.10.sup.14 Watt onto a pellet surface of .about.10.sup.-1 cm.sup.2. According to the Stefan-Boltzmann law this power is reached at a temperature of T.perspectiveto.3.6.times.10.sup.6 .degree.K. However, to store an energy of .about.10.sup.7 Joule in the form of black body radiation this would require a cavity volume of V=75 cm.sup.3. This rather large volume suggests to go to higher temperatures which not only reduces the required cavity volume but also increses the radiation power which is inversely proportional to it. As a reasonable compromise we choose the initial temperature to be 5.times.10.sup.6 .degree.K. which during the cavity implosion shall rise to .about.10.sup.7 .degree.K., implying a reduction in the cavity radius by a factor two and representing a very modest implosion. At a temperature of 10.sup.7 .degree.K. the final cavity volume is just 1.3 cm.sup. 3. The maximum total power incident at the pellet inside the cavity and reached at T=10.sup.7 .degree.K. is then 5.75.times.10.sup.15 Watt. The intitial and final cavity radius are here 1.4 cm and 0.7 cm. Since the ablator radius is of the same order, the beam focusing requirements can be easily met using light ion beams, one of the cheapest drivers. If a solid wall, in our case the pusher wall, moves into a gas of atomic weight A a shock wave moves ahead of the wall with the temperature behind the shock front given by (1) ##EQU1## where R is the gas constant, and Z the degree of ionization approximately given by ##EQU2## From (3) and (4) one can compute v to reach a desired value of T. For T=5.times.10.sup.6 .degree.K. and A=200 one finds v=46 km/sec, and for krypton with A=83, v.perspectiveto.71 km/sec. In the considered temperature range the collision cross section is .about.10.sup.-16 cm.sup.2. This requires to make the atomic number density of the shock heated gas not less than .about.10.sup.18 cm.sup.-3. To make the gas optically transparent the photon path length .lambda..sub.p =(.rho..eta.).sup.-1 (.rho. gas density) has to be larger than the cavity radius r.about.1 cm. The opacity coefficient .eta. is here given by (2) ##EQU3## where g.perspectiveto.1 is the Gaunt and t the guillotine factor. In stellar atmospheres one puts t.perspectiveto.10 but because of the great level density in high atomic weight material one may probably put t.perspectiveto.1. It thus follows that at T.perspectiveto.10.sup.7 .degree.K. and for .rho..ltorsim.0.3 g/cm.sup.3, corresponding to an atomic number density of .ltorsim.10.sup.31 cm.sup.-3, the optical path length is larger than .about.1 cm. Therefore, at an atomic number density of .about.10.sup.18 cm.sup.-3, as required for shock heating, the gas is optically transparent. To make the gas pressure smaller than the radiation pressure requires to put the atomic number density less than 10.sup.21 cm.sup.-3. Therefore, after the gas, having an atomic number density of .about.10.sup.18 cm.sup.-3, has been shock heated the work done by the pusher is primarily against the radiation pressure. Of crucial importance for the feasibility of the concept is the confinement of the black body radiation in the imploding cavity. The velocity by which the radiation can escape through the cavity wall is given by the radiative heat flux (a=4.sigma./c) ##EQU4## where .lambda..sub.p =(.eta..rho.).sup.-1 is the photon path length in the dense pusher wall. Putting j=aT.sup.4 v.sub.d, where v.sub.d is the photon diffusion velocity and .differential.(aT.sup.4)/.differential.x.about.aT.sup.4 /x, where x is the distance travelled by the diffusion wave, one finds ##EQU5## For T.perspectiveto.10.sup.7 .degree.K. and .rho.=18 g/cm.sup.3 one has according to (5) .lambda..sub.p =(.rho..eta.).sup.-1 .perspectiveto.2.times.10.sup.-4 cm. Putting x.ltorsim.1 cm, setting an upper value for the photon permitted to diffuse out of the cavity, one finds that v.sub.d .gtorsim.20 km/sec. Therefore, if v>v.sub.d, the photon gas in the cavity will be compressed. More detailed calculations show, that at an implosion velocity of .gtorsim.50 km/sec the photon losses through the pusher wall are not very significant. The high final temperature of .about.10.sup.7 .degree.K. implies that the typical radiation frequency, given by h.nu..about.kT and which is in the soft X-ray domain, is matched to a plasma frequency of .about.10.sup.4 times compressed hydrogen. The proposed target bombardment by black body radiation is therefore much better suited to reach high target densities than the much longer wave lengths of laser beams. Furthermore, unlike laser beams, no stimulated Brillouin back-scattering occurs and the radiation reflected from the target surface is here not lost since all the radiation is trapped inside the cavity. The required low implosion velocity of .about.50 km/sec makes the proposed concept also an interesting candidate for impact fusion since those velocities should be attainable with relative ease by magnetic propulsion techniques. How this could be incorporated into an impact fusion target is shown in FIG. 2, where an incoming hypervelocity projectile generates and compresses black body radiation inside a conical cavity. If light ion beams are used to implode the cavity, the reduction in the implosion velocity from .about.200 km/sec down to .about.50 km/sec reduces the required beam power down to 1.5.times.10.sup.12 Watt. Light ion beams at these power levels and at the relaxed focusing requirement down to .gtorsim.1 cm.sup.2 can be already produced and therefore make them an especially promising candidate for the realization of the proposed invention. REFERENCES (1) L. D. Landau and E. M. Lifshitz, Fluid Mechanics, Pergamon Press, London 1959, pp. 331, 358. (2) M. Schwarzschild, Structure and Evolution of Stars, Princeton University Press, 1958, p. 67 ff.
	abstract	The invention relates to a radiation detector, a method of manufacturing a radiation detector and a lithographic apparatus comprising a radiation detector. The radiation detector has a radiation-sensitive surface. The radiation-sensitive surface is sensitive for radiation with a wavelength between 10-200 nm. The radiation detector has a silicon substrate, a dopant layer, a first electrode and a second electrode. The silicon substrate is provided in a surface area at a first surface side with doping profile of a certain conduction type. The dopant layer is provided on the first surface side of the silicon substrate. The dopant layer has a first layer of dopant material and a second layer. The second layer is a diffusion layer which is in contact with the surface area at the first surface side of the silicon substrate. The first electrode is connected to dopant layer. The second electrode is connected to the Silicon substrate.
	claims	1. A system for the detection of special nuclear materials (SNM) in a first volume comprising:an associated-particle neutron generator positioned to emit neutrons toward at least a portion of the first volume;a plurality of gamma ray detectors that eachare positioned around the portion of the first volume,are capable of nanosecond timing, andproduce output data that correlates to the quantity of gamma rays received by the detector within a timing gate; anda device that acquires and processes the output data from each gamma ray detector to produce an identification output signal when the output data indicates that each of at least n adjacent detectors of the plurality of gamma ray detectors detected at least one gamma ray within their respective defined periods of time,where n>2 and the timing gates of the detectors are related. 2. The system of claim 1 wherein the plurality of gamma ray detectors are noble liquid detectors. 3. The system of claim 1 wherein the device locates fissionable material within a voxel within the first volume. 4. The system of claim 1 also comprising an alpha particle detector. 5. The system according to claim 1 wherein the plurality of gamma ray detectors collectively cover at least about fifty percent of the solid angle that the surface of the first volume subtends as observed from the cross-sectional center of the larger space. 6. The system of claim 4 wherein background noise caused by gamma rays not originating from SNM is reduced by adjusting the detector timing gate coincident with the detection of an alpha particle. 7. The system of claim 4 wherein the alpha particle detector is pixilated. 8. The system of claim 1 wherein the gamma ray detector is pixilated. 9. The system of claim 1 wherein gamma ray detection signals are collected in a time gate of 20 nanoseconds or less. 10. A method of interrogating a sample volume for the detection of fissionable materials comprising:a. impacting a sample with neutrons from an associated-particle neutron generator;b. detecting gamma rays emitted from fissionable material impacted by ballistic neutrons generated by the neutron generator by means of a number n of detectors during a timing gate, where n is three or more and the timing gates for the respective detectors are related; andc. outputting to a user interface a signal indicating the coincident detection of gamma rays by each of at least n adjacent detectors. 11. The method of claim 10 wherein the detectors are positioned around the sample. 12. The method of claim 10 wherein the starting point of the timing gate is adjusted as a function of the timing of the detection of an alpha particle. 13. The method of claim 10 wherein the number n is at least four. 14. The method of claim 12 wherein a pixilated alpha particle detector provides angular separation and on the order of nanosecond timing of the detection of gamma rays and yields depth of field to establish the location of SNM in a sample volume, and outputting to a user interface the detection of gamma rays and the location of SNM within a sample volume. 15. The method of claim 13 wherein the detectors each have pixels that detect the gamma rays, the method further comprising calculating the location of the intersection of arcs extended from the pixels actually detecting the gamma rays, outputting to a user interface the detection of gamma rays and the location of SNM within a sample volume. 16. The method of claim 10, wherein the detectors are noble liquid detectors.
	claims	1. A control rod drive mechanism (CRDM) comprising:a hollow lead screw engaged by a CRDM motor;a lifting rod having an upper end disposed in the hollow lead screw, the lifting rod supporting at least one control rod;latches secured to the lead screw and configured to latch the upper end of the lifting rod to the lead screw;a latch engagement mechanism configured to close the latches onto the upper end of the lifting rod;cam bars configured to move to an inward position to cam the latches closed responsive to operation of the latch engagement mechanism; anda latch holding mechanism configured to hold the latches closed, the latch holding mechanism including latch holding elements that engage upper ends of corresponding cam bars to hold the cam bars in the inward position,wherein the latch holding mechanism is separate from the latch engagement mechanism, andwherein the latch holding elements are configured to move in a horizontal plane responsive to a holding force applied to hold the cam bars in the inward position. 2. The CRDM of claim 1 further comprising:a bar linkage configured to drive the cam bars inward to cam the latches closed responsive to operation of the latch engagement mechanism, the latch holding mechanism configured to hold the cam bars in the inward position to keep the latches closed. 3. The CRDM of claim 1 wherein the latch engagement mechanism operates responsive to lowering the latches over the upper end of the lifting rod and is not effective to keep the latches closed when the latches are raised again after the latch engagement mechanism operates. 4. The CRDM of claim 2 wherein the latch holding mechanism is located at a top of the CRDM. 5. The CRDM of claim 4 wherein the latch holding mechanism comprises a magnetic coupling including an electromagnet that when energized magnetically holds the cam bars in the inward position. 6. The CRDM of claim 1 wherein the holding force is magnetic. 7. A control rod drive mechanism (CRDM) comprising:a hollow lead screw engaged by a CRDM motor;a lifting rod having an upper end disposed in the hollow lead screw, the lifting rod supporting at least one control rod;latches secured to the lead screw and configured to latch the upper end of the lifting rod to the lead screw;a latch engagement mechanism configured to close the latches onto the upper end of the lifting rod;a latch holding mechanism configured to hold the latches closed; anda bar linkage including cam bars, the bar linkage configured to drive the cam bars inward to cam the latches closed responsive to operation of the latch engagement mechanism, the latch holding mechanism configured to hold the cam bars in the inward position to keep the latches closed,wherein the latch engagement mechanism is not effective to keep the latches closed when the latches are supporting the weight of the lifting rod and supported at least one control rod, andwherein the bar linkage is configured to bias the latches closed under the force of gravity. 8. The CRDM of claim 7 wherein the latch holding mechanism is not effective to close the latches. 9. The CRDM of claim 7 wherein the latch engagement mechanism operates responsive to lowering the latches over the upper end of the lifting rod and is not effective to keep the latches closed when the latches are raised again after the latch engagement mechanism operates.
062623281	description	DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT In accordance with the present invention, it has been found that a hydrogen absorbing composition may be used in a container or any other environment in which hydrogen gas is produced or is present. The hydrogen-absorbing composition disclosed in U.S. patent application Ser. No. 09/094,293 and incorporated herein by reference, is prepared by a method generally as follows. A first solution (solution A) is prepared by mixing an alcohol such as ethanol and water at a ratio of 1 part ethanol to 2.7 parts water by volume. Drops of hydrochloric acid are added to the solution to reach a pH value of 1.6. A second solution (solution B) is prepared by mixing alcohol (ethanol) and tetraethyl orthosilicate (TEOS) at a ratio of 1 part ethanol to 2 parts TEOS by volume. Solution A is slowly added to solution B with continuous mixing. The combined solutions are continuously mixed for about 30 minutes until a sol is achieved. To the sol solution, metal particles are added which have been prepared as follows. A metal alloy, such a LaNi0.25Al0.75 or other metal hydride is repeatedly reacted with hydrogen in a cyclic process which results in the production of a metal hydride fines. The desired alloy fines have a particle size of less than 45 microns. The fines/particles are slowly exposed to air and surface oxidized until a thin layer of metal oxide has slowly formed on the surfaces of the metal fines. The surface oxidation prevents further oxidation of the inner portions of the metal particles. The oxidation is done at a slow, controlled rate to prevent the entire particle from becoming oxidized which renders the material useless for hydrogen absorption. Once the controlled oxidation has occurred, the metal particles are stable in the presence of air and can be easily handled for use in the composition of the present invention. The metal hydride particles described and prepared above, are added to the sol at a ratio of about 20 grams of metal to 240 cc of sol. The mixture is placed on a rotating mixer which maintains the metal particles in a suspension within the sol. The mixing continues for about 24 hours until the sol has solidified. The solidified sol-gel with the dispersed metal hydride particles is removed from the mixer and placed in a sealed container for about 10 days. During the 10 day seasoning time, a liquid phase gradually appears. Following seasoning, the seal is removed and the liquid is allowed to evaporate at room temperature. Following evaporation of the liquid phase, the remaining solid product is vacuum dried at ambient temperature to remove any residual volatile compounds. While under vacuum, the temperature is increased to 300.degree. C. over a 30 minute time interval (curing) which is maintained along with the negative pressure for two hours. The heat treated material, hereinafter "composite", is allowed to cool to room temperature. Following cooling, the composite is mechanically broken to a useful size range of final product which is between 20 to 8 mesh (0.5 to 1 mm particle size). The final product can then be used in a conventional gas separation column or apparatus to remove hydrogen gas from a gas stream. The composite provided above is particularly useful for absorbing hydrogen from gas streams which contain known metal hydride gaseous poisons. These metal hydride poisons have no effect on the composition's ability to absorb hydrogen. With regard to the present invention, as seen in FIG. 1, a closed container 1, seen here as a waste drum, is provided containing a material 5 which produces hydrogen gas emissions 7. In a first embodiment, the container 1 is used to store waste comprising Pu-238 and high activity fraction of Pu-239. As a result of a radiolysis reaction, hydrogen gas is produced, creating an over pressurization and explosion concern during the transportation and long-term storage of the waste. In a first embodiment of the invention, the container 1 comprises various layers for protection, including a primary containment vessel 2 which holds the stored waste. At the upper portion of the primary containment vessel 2 is a vent structure 11 which allows the hydrogen gas 7 to escape from the primary containment vessel 2 to the secondary containment vessel 3. The secondary containment vessel 3 also comprises a secondary vent system 9 which vents to an outer containment area 4. The secondary vent system 9, however, is in communication with a hydrogen absorbing composition 13. The hydrogen absorbing composition 13 removes the hydrogen gas 7 from the container 1 environment, thus, eliminating the danger of over-pressurization and the build-up of dangerous hydrogen gas concentrations. The hydrogen absorbing composition 13 continues to remove hydrogen gas 7 from the container 1 even in the presence of gases that are poisonous to the hydrogen absorber. The present invention is not limited to a sealed or vented container, however. In a second embodiment of the invention, the hydrogen absorber is used in conjunction with a chamber housing a battery or battery systems which emit hydrogen gas. Battery systems generate hydrogen gas emissions such that the danger of a build up of hydrogen gas emissions is a concern. If the system is a vented system, then the concentration of hydrogen gas in the environment to which the system is vented must be controlled. If the system is a closed system, H.sub.2 build-up or over-pressurization of the system must be avoided. As seen in FIG. 2, a housing 21 for a battery system is provided. The housing 21 comprises a vent system 23 having at least one venting route. In the second embodiment, two venting routes are provided 27 and 29. The presence of the two venting routes allows sufficient quantities of hydrogen gas to be carried out of the housing 21 and also allows outside air to be brought in. The vent system 23 is in communication with a hydrogen absorber 25 which removes the hydrogen gas from the housing environment prior to releasing the air to the outside environment. Hydrogen absorber 25 may be placed within the actual exhaust vent 27. Alternatively, hydrogen absorber 25 may be placed anywhere within the interior of housing 21 where it would be operative to remove hydrogen gas and thereby maintain a hydrogen gas concentration below a critical threshold value. In instances where the exhausting of hydrogen gas build-up from the battery housing 21 into the surrounding environment is not feasible, the venting routes 27 and 29 may be removed or sealed to provide a sealed container environment. The hydrogen storage composition can be molded to any desired shape or size. The composition is useful within any sealed environment where released hydrogen gas may create pressurization problems or accumulate to explosive concentrations. As discussed above, specific embodiments of the present invention are discussed in terms of a shipping and storage container for radioactive waste and an external housing for a battery. However, any sealed container, broadly defined herein to include a room, compartment, container, package, sealed vessel, or similar environment, may be useful in the present invention. The present hydrogen storage composition is also useful for providing a system for preventing dangerous concentrations of hydrogen gas from accumulating in poorly ventilated environments as well. For instance, battery compartments associated with electric vehicles or electrical generation and storage may benefit from the inclusion of the hydrogen storage composition. Such compartments have an inherent risk associated with hydrogen gas generation and release. The use of a hydrogen storage composition in the compartments will provide an additional safeguard against excessive hydrogen gas accumulation. It is also envisioned that the present hydrogen storage composition may be useful in some situations where hydrogen getters are used. For instance, inside a sealed incandescent lamp bulb, the hydrogen absorber composition may be provided within the bulb interior to remove evolved hydrogen and thereby prolong the useful life of the lamp. Additional applications of the present invention include providing a sealed protective enclosure around possible ignition sources of hydrogen prone environments. For instance, traditional ventilation techniques for battery rooms or other environments where hydrogen gas accumulations may occur, can be supplemented with enclosures, the enclosures having hydrogen absorbing materials therein. The enclosures are used to provide a sealed housing for light switches, electrical equipment, lighting sources and other spark or ignition sources. In this manner, possible ignition sources are sealed against hydrogen infiltration and accumulation. Upon reading the above detailed description, it will be apparent to those skilled in the art that many changes and substitutions can be made to the preferred embodiment herein described without departing from the spirit and scope of the present invention as defined by the appended claims.
	abstract	An ion implantation system and method are disclosed in which glitches in voltage are minimized by modifications to the power system of the implanter. These power supply modifications include faster response time, output filtering, improved glitch detection and removal of voltage blanking. By minimizing glitches, it is possible to produce solar cells with acceptable dose uniformity without having to pause the scan each time a voltage glitch is detected. For example, by shortening the duration of a voltage to about 20-40 milliseconds, dose uniformity within about 3% can be maintained.
	claims	1. A scintillator panel comprising:a radiation-transmitting substrate;a reflective metal thin film disposed on said substrate;a protective film covering an entire surface of said reflective metal thin film; anda scintillator deposited on said protective film,and wherein said protective film has a function to protect said reflective metal thin film against said scintillator. 2. A scintillator panel according to claim 1, wherein said reflective metal thin film is directly disposed on said substrate. 3. A scintillator panel according to claim 1, wherein said reflective metal thin film is substantially made of a material containing a substance selected from the group consisting of Al, Ag, Cr, Cu, Ni, Ti, Mg, Rh, Pt, and Au. 4. A scintillator panel according to claim 1, wherein said protective film is an inorganic film. 5. A scintillator panel according to claim 4, wherein said protective film is substantially made of a material containing a substance selected for the group consisting of LiF, MgF2, SiO2, TiO2, Al2O3, MgO and SiN. 6. A scintillator panel according to claim 4, wherein said protective film is a metal oxide film. 7. A scintillator panel according to claim 6, wherein said protective film is an oxidized material of said reflective metal thin film. 8. A scintillator panel according to claim 1, wherein said protective film is an organic film. 9. A scintillator panel according to claim 8, wherein said protective film is substantially made of polyimide. 10. A scintillator panel according to claim 1, wherein said protective film includes an inorganic film and an organic film. 11. A scintillator panel according to claim 1, further comprised of an organic film covered said scintillator. 12. A scintillator panel according to claim 11, wherein said organic film further covers at least an outer periphery of said protective film. 13. A scintillator panel according to claim 12, wherein said organic film further covers an entire surface of said substrate. 14. A radiation image sensor characterized in that an image sensing element is arranged to face said scintillator of said scintillator panel of claim 1. 15. A scintillator panel characterized by comprising:a radiation-transmitting substrate;a reflective metal thin film disposed on said substrate;a protective film disposed on said reflective metal thin film; anda scintillator deposited on said protective film at a position except an edge portion thereof,wherein said reflective metal thin film transmits radiation and reflects light irradiated from said scintillator,and wherein said protective film has a function to protect said reflective metal thin film against said scintillator. 16. A scintillator panel according to claim 15, wherein said reflective metal thin film is directly disposed on said substrate. 17. A scintillator panel according to claim 15, wherein said reflective metal thin film is substantially made of a material containing a substance selected from the group consisting of Al, Ag, Cr, Cu, Ni, Ti, Mg, Rh, Pt, and Au. 18. A scintillator panel according to claim 15, wherein said protective film is an inorganic film. 19. A scintillator panel according to claim 18, wherein said protective film is substantially made of a material containing a substance selected for the group consisting of LiF, MgF2, SiO2, TiO2, Al2O3, MgO and SiN. 20. A scintillator panel according to claim 18, wherein said protective film is a metal oxide film. 21. A scintillator panel according to claim 20, wherein said protective film is an oxidized material of said reflective metal thin film. 22. A scintillator panel according to claim 14, wherein said protective film is an organic film. 23. A scintillator panel according to claim 20, wherein said protective film is substantially made of polyimide. 24. A scintillator panel according to claim 15, wherein said protective film includes an inorganic film and an organic film. 25. A scintillator panel according to claim 15, further comprised of an organic film covered said scintillator. 26. A scintillator panel according to claim 25, wherein said organic film further covers at least part of a surface of said substrate. 27. A scintillator panel according to claim 26, wherein said organic film further covers an entire surface of said substrate. 28. A radiation image sensor characterized in that an image sensing element is arranged to face said scintillator of said scintillator panel of claim 15. 29. A scintillator panel comprising: a radiation-transmitting substrate; a metal thin film formed on said substrate, which is radiation-transmittable and reflects light of a predetermined wavelength; a protective film formed on said metal thin film; and a scintillator comprising a large number of columnar crystals which are deposited on said protective film and which convert radiation into light of wavelengths that can be reflected by said metal thin film, said protective film preventing contact between said metal thin film and said scintillator, further comprised of:an intermediate film disposed between said substrate and said metal thin film to adhere said substrate and said metal thin film. 30. A scintillator panel according to claim 29, wherein said substrate is any one of a glass substrate, an aluminum substrate, or a substrate which has carbon as a main component. 31. A scintillator panel according to claim 30, wherein said substrate that has carbon as a main component contains amorphous carbon. 32. A scintillator panel according to claim 29, wherein said substrate is a conductive substrate, and said intermediate film prevents contact between said substrate and said metal thin film. 33. A scintillator panel according to claim 32, wherein said conductive substrate is either an aluminum substrate or a substrate that has carbon as a main component. 34. A scintillator panel according to claim 29, wherein said metal thin film is made of material containing a substance selected from the group consisting of Al, Ag, Cr, Cu, Ni, Ti, Mg, Rh, Pt, and Au. 35. A scintillator panel according to claim 29, wherein said protective film comprises an inorganic film. 36. A scintillator panel according to claim 35, wherein said inorganic film is made of material containing a substance selected from the group consisting of LiF, MgF2, SiO2, TiO2, Al2O3, MgO, and SiN. 37. A scintillator panel according to claim 29, wherein said protective film comprises an organic film. 38. A scintillator panel according to claim 37, wherein said organic film is made of material containing a substance selected from the group consisting of polyimide and xylylene-type materials. 39. A scintillator panel according to claim 29, wherein said protective film is formed from an inorganic film and an organic film. 40. A scintillator panel according to claim 29, wherein said scintillator is covered by an organic film. 41. A scintillator panel according to claim 40, wherein said organic film furthermore extends to at least one part of the surface of said substrate. 42. A scintillator panel according to claim 41, wherein said organic film covers substantially the entire surface of said substrate. 43. A scintillator panel according to claim 29, wherein said intermediate film comprises either an organic film or an inorganic film, or a combination of the two. 44. A scintillator panel according to claim 29, wherein said metal thin film is adhered to said intermediate film and said protective film and sealed by both. 45. A scintillator panel according to claim 44, wherein said intermediate film substantially envelops said substrate. 46. A scintillator panel according to claim 44, wherein said intermediate film is a film formed on the substrate by CVD. 47. A scintillator panel according to claim 44, wherein said intermediate film is a xylylene-type film. 48. A radiation image sensor comprising:the scintillator panel according to claim 29; andan image-sensing element for capturing optical images obtained by converting radiation which is outputted from a surface opposite to said substrate of said scintillator panel. 49. A radiation image sensor according to claim 48, wherein said image-sensing element is disposed facing the scintillator side of said scintillator panel. 50. A scintillator panel comprising: a radiation-transmitting substrate; a metal thin film formed on said substrate, which is radiation-transmittable and reflects light of a predetermined wavelength; a protective film formed on said metal thin film; and a scintillator comprising a large number of columnar crystals which are deposited on said protective film and which convert radiation into light of wavelengths that can be reflected by said metal thin film,wherein said protective film prevents contact between said metal thin film and said scintillator, and said scintillator panel further comprises an intermediate film disposed between said substrate and said metal thin film for improving the adhesion between said substrate and said metal thin film. 51. A scintillator panel comprising:a radiation-transmitting substrate;a metal reflective film formed on one surface of said substrate;a protective organic film which covers said metal reflective film and which also covers at least the side walls of said substrate;an alkali halide-type scintillator which is formed as a large number of needle crystals by deposition on said protective organic film over said metal reflective film; anda moisture-proof organic film covering said scintilltor;wherein said protective organic film prevents scintillator components from becoming attached to said substrate and said metal reflective film during the deposition of said scintillator, and said moisture-proof organic film covers the scintillator including the scintillator components which are attached to said protective organic film. 52. A scintillator panel according to claim 51, wherein said protective organic film substantially further covers the other surface of said substrate. 53. A scintillator panel according to claim 51, wherein said protective organic film is an organic film formed by vapor phase epitaxy. 54. A scintillator panel according to claim 51, wherein said protective organic film comprises a first protective organic film on said metal reflective film side and a second protective organic film on said substrate side, the peripheral edges of said first protective organic film being laminated to said second protective organic film on the peripheral edges or in the area outside these peripheral edges of said metal reflective film. 55. A making method for a scintillator panel, comprising the steps of:forming a metal reflective film on one surface of a radiation-transmitting substrate;forming a protective organic film which covers an area extending from at least one surface of said substrate, including said metal reflective film, to the side walls of said substrate;forming a scintillator through the growth of a large number of needle crystals by depositing alkali halide-type scintillator components on only a predetermined part of the surface of said protective organic film which is substantially on said metal reflective film, while preventing the scintillator components from becoming attached to said metal reflective film and said substrate using said protective organic film; andforming a moisture-proof organic film covering said scintillator including the scintillator components which have become attached to outside of said predetermined part. 56. A making method for a scintillator panel according to claim 55, wherein the step of forming said protective organic film is performed using vapor phase epitaxy. 57. A making method for a scintillator panel according to claim 55, wherein the step of forming said protective organic film comprises the steps of:forming a first protective organic film which covers said metal reflective film, and also covers at least the exposed surfaces of said substrate on the periphery of said metal reflective film; andforming a second protective organic film in a frame shape, covering an area extending from the peripheral edges of said first protective organic film to the side walls of said substrate. 58. A making method for a scintillator panel according to claim 55, wherein the step of forming said protective organic film comprises the steps of:forming a second protective organic film in a frame shape, covering an area extending from the side walls of said substrate to the peripheral edges of said metal reflective film;and forming a first protective organic film which covers said metal reflective film, and which is laminated to said second protective organic film at the peripheral edges of said metal reflective film. 59. A scintillator panel comprising:a radiation-transmitting substrate;a metal reflective film formed on one surface of said substrate;a first protective organic film covering said metal reflective film;an alkali halide-type scintillator formed as a large number of needle crystals by deposition on the part of said first protective organic film covering said metal reflective film;a frame-shaped second protective organic film covering an area extending from the side walls of said scintillator to at least the side wall parts of said substrate; anda moisture-proof organic film covering said scintillator and the surface of said second protective organic film. 60. A scintillator panel comprising:a radiation-transmitting substrate;a metal reflective film formed on one surface of said substrate;a first protective organic film covering said metal reflective film;an alkali halide-type scintillator formed as a large number of needle crystals by deposition on the part of said first protective organic film covering said metal reflective film;a moisture-proof organic film covering an area extending from said scintillator to at least the side walls of said substrate; anda frame-shaped second protective organic film covering an area extending from the side walls of said scintillator to at least the side walls of said substrate said second protective organic film covering the moisture-proof organic film at least at a position where the moisture-proof organic film covers a periphery of the first protective organic film. 61. A scintillator panel according to claim 60, wherein said second protective organic film extends to a surface opposite the scintillator formation surface of said substrate. 62. A scintillator panel according to claim 60, wherein a plurality of through holes is formed in a section on the outside of the scintillator formation area of said substrate, and which is covered by said second protective organic film. 63. A scintillator panel according to claim 60, wherein said second protective organic film is opaque in respect of at least light generated by said scintillator. 64. A making method for a scintillator panel, comprising the steps of:forming a metal reflective film on one surface of a radiation-transmitting substrate;forming a first protective organic film on said metal reflective film;forming a scintillator through the growth of a large number of needle crystals by depositing alkali halide-type scintillator components on the part of said first protective organic film covering said metal reflective film;forming a second protective organic film covering an area extending from the side walls of said scintillator to at least the side walls of said substrate; andforming a moisture-proof organic film covering said scintillator and also the surface of said second protective organic film. 65. A making method for a scintillator panel, comprising the steps of:forming a metal reflective film on one surface of a radiation-transmitting substrate;forming a first protective organic film on said metal reflective film;forming a scintillator through the growth of a large number of needle crystals by depositing alkali halide-type scintillator components on the part of said first protective organic film covering said metal reflective film;forming a moisture-proof organic film covering an area extending from said scintillator to at least the side walls of said substrate; andforming a second protective organic film over said moisture-proof organic film, covering an area extending from the side walls of said scintillator to at least the side wall parts of said substrate.
	description	The present application claims priority to and the benefit of U.S. Provisional Patent Application Ser. No. 62/123,540, entitled MO-99 PRODUCTION, which was filed on Nov. 21, 2014, and is hereby incorporated by reference in its entirety. Radioisotopes are useful and have broad applications in the medical sciences and healing arts. For example, the radioisotope Molybdenum-99 (“Mo-99”) may be a source of Technetium-99m (“Tc-99m”), which may be used as a diagnostic and therapeutic tool. For example, Tc-99m may be well suited for radiometric scanning of internal organs due to its short half-life resulting in reduced radiation exposure and its characteristic radiation emissions. Tc-99m is the radioactive decay product of Mo-99. Radioisotope sources have been prepared by separating fission product from irradiated uranium targets or by the irradiation of naturally occurring isotopes (e.g., molybdenum). Production of radioisotopes by neutron activation may result in only a small fraction of the irradiated uranium targets or the naturally occurring isotopes being converted to radioisotopes and the specific activity of the resulting product may be very low and therefore may be of limited medical use. The subject matter disclosed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one exemplary area where some examples described herein may be practiced. The present disclosure generally relates to methods and structures for the production of radioisotopes from thermal neutron irradiation of natural isotopes. The methods and structures contained in the present disclosure may be applicable to the production of other radioisotopes produced via neutron irradiation with neutrons of any preferred energy. The present disclosure may significantly increase the specific activity (e.g., Curies per unit mass) of a radioisotope produced and may greatly reduce a presence of non-active isotopes of associated activation products and/or other undesirable trace materials in a produced radioisotope. Certain aspects associated with using fissile materials for nuclear fission and subsequent fission product separation may be decreased and/or eliminated. For example, certain concerns over safety, proliferation, safeguards, processing, disposal and licensing of radioactive materials may be reduced and/or eliminated. The present disclosure may include methods and structures to provide an irradiation target of size, shape, orientation and electric charge that possesses properties for enhanced emission and sequester of electrically charged positive ions resulting from recoil gamma emission upon capture of thermal or other energy neutrons in an isotope. The present disclosure may include methods and structures for the configuration and composition of positive ions generated in a target material with physical and electrical properties and pathways for the positive ions to travel relatively unimpeded within an electric field created in a fixture and deposit these resulting positive ions on a surface or interior of a negatively charged cathode. For example, during production of Mo-99, a fixture may effectively operate as an electrical capacitor with an electrical current flowing from a positively charged anode to a negatively charged cathode (e.g., cathode collector) as positive ions (e.g., activated Mo-99 ions) serving as electrical charge carriers. The present disclosure may include methods and structures to measure, control and vary an electric field produced in the fixture to manipulate and maximize a yield of radioisotopes derived from the target material and collected on the negatively charged cathode of the fixture. The present disclosure may include methods and structures to provide an irradiation target with sufficient density, composition, and configuration to satisfy the required production demands of a particular radioisotope. These and other aspects, features and advantages of the present invention will become more fully apparent from the following brief description of the drawings, the drawings, the detailed description of preferred embodiments and appended claims. This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential characteristics of the disclosed subject matter, nor is this Summary intended to be used as an aid in determining the scope of the disclosed subject matter. Additional features and advantages will be set forth in the following description and may be learned by the practice of the invention. One of ordinary skill in the art, after reviewing this disclosure, will appreciate that the disclosed methods and structures may have other shapes, sizes, configurations, arrangements, and the like. These and other features of the present invention will become more fully apparent from the following description and appended claims. For purposes of promoting an understanding of the disclosure, reference will now be made to the following embodiments and specific language will be used to describe the same. It will nevertheless be understood that no limitation or restriction of the scope of the disclosure is thereby intended, such alterations and further modifications in the described subject matter, and such further applications of the principles as described herein being contemplated as would normally occur to one skilled in the art to which the subject matter relates. The disclosure is generally directed towards the production of radioisotopes. It will be understood that, in light of the present disclosure, various radioisotopes may be produced such as Mo-99. However, the methods, structures and operations discussed in the disclosure may be applicable to the production of any radioisotope that may be produced via neutron irradiation. Additionally, to assist in the description of the production of radioisotopes, words such as top, bottom, front, rear, right and left are used to describe the accompanying figures. It will be appreciated, however, that the present invention can be located and employed in a variety of desired positions, including various angles, sideways and even upside down. A detailed description of exemplary methods and structures for the production of radioisotopes from the thermal neutron irradiation of selected natural isotopes is set forth below. FIG. 1 is an exemplary schematic of a fixture 100 that may be used for production of radioisotopes. The fixture 100 may include one or more components such as a negative cathode 102, a positive anode 104, a voltage regulator 106, a high surface area target 108, a fixture wall 112, and a collector component 114. The fixture 100 may be used to maintain a particular environment to allow and/or promote production of radioisotopes via neutron capture. For example, the fixture 100 may maintain a vacuum environment within the fixture walls 112. The fixture 100 may be placed within a neutron field. For example the fixture 100 may be placed within a nuclear reactor or other source of neutrons. The voltage regulator 106 may be electrically coupled to the negative cathode 102 and the positive anode 104 of the fixture 100. The voltage regulator 106 may apply a variable voltage between the negative cathode 102 and the positive anode 104. The positive anode 104 may be electrically coupled to the high surface area target 108 and the negative cathode 102 may be electrically coupled to the collector component 114. Adjusting a voltage difference between the high surface area target 108 and the collector component 114 may control and increase a recovery rate of radioisotopes created within the fixture 100. In one configuration, a closed electrical circuit may be created between the high surface area target 108 and the positive anode 104 by an electrical conducting layer positioned on the high surface area target 108. In another configuration, a closed electrical circuit may be created between the high surface area target 108 and the positive anode 104 by an electrical conducting layer passing through the high surface area target 108. The electrical conducting layer may be in direct (e.g., electrical contact) with the high surface area target 108. Connecting the negative cathode 102 and the positive anode 104 to the voltage regulator 106 may complete (e.g., close) the electrical circuit for the collector component 114 and the high surface area target 108 to produce radioisotopes via neutron capture. The high surface area target 108 may be comprised of molybdenum or other isotopes of various isotopic concentrations. The highs surface area target 108 may be located within the vacuum environment created within the fixture 100. The high surface area target 108 and other materials within the fixture 100 may be thermally heated or electrically heated prior to or after being placed within the fixture 100. For example, the high surface area target 108 and other materials within the fixture 100 may be electrically heated via a temporary electrical connection within the fixture 100. Heating the high surface area target 108 and other materials within the fixture 100 may remove contaminants during evacuation of the atmosphere surrounding the high surface area target 108 and other materials within the fixture 100. If contaminants are located on the high surface area target 108, the processes and methods disclosed herein may be inhibited. The high surface area target 108 may be designed to allow for and promote release of positively charged ions from the one or more surfaces of the high surface area target 108. Configurations of the high surface area target 108 may include sheets, wire, gauze, particulates, powders, Nano size-powders, spheres, whiskers, and/or other practicable structures or different combinations. For example, the high surface area target 108 may be a high surface area molybdenum composition made of foils, wires, powders, and/or crystals. The high surface area target 108 may include molybdenum and/or a molybdenum composition, and the target may be constructed from particulates, thin solid and perforated layers, mesh, gauze, metal wool and the like. One of ordinary skill in the art will appreciate, after reviewing this disclosure, that the high surface area target 108 may be made from other materials, composites and the like with suitable properties and characteristics, and the high surface area target 108 may have various appropriate shapes, sizes, configurations, arrangements, and the like. In one embodiment, the high surface area target 108 may be designed in such a way as to increase surface area of the high surface area target 108 to allow more positive ions to be released within the fixture 100 during operation within the field of a neutron flux. The fixture 100 may be exposed to a neutron flux or neutrons of other energy distributions causing the high surface area target 108 to be exposed to the neutron flux. Exposure to a neutron flux may cause the high surface area target 108 to absorb neutrons. Absorbing neutrons may cause nuclei of atoms located within the high surface area target 108 to recoil. When a nucleus of an atom located within the high surface area target 108 recoils, kinetic energy may be created that is sufficient to rupture atomic bonds holding the atom in the high surface area target 108. The kinetic energy delivered to the atom may be within the range from a few eV to MeV, but the kinetic energy may be larger or smaller (in this exemplary embodiment, eV refers to an electron-volt or electron volt and MeV refers to 106 eV). The kinetic energy of the atom may cause the atom to escape from a surface of the high surface area target 108 as a positively charged ion into the vacuum environment within the fixture 100. The high surface area target 108 may be positively charged electrically and may repel any released positively charged ions from reattaching or combining with the high surface area target 108. The released positively charged ions may move towards the negatively charged collector component 114 due to the electric field created by the difference in electric charge between the positively charged high surface area target 108 or positive anode 104 and the collector or negatively charged collector component 114. For example, the negatively charged collector component 114 may be a negatively charged cathode, which electrically attracts and collects the positively charged ions on a surface or an interior of the negatively charged cathode. The negatively charged collector component 114 may be designed to reduce induced radioactivity or parasitic neutron capture by the collector component 114 in a neutron field. In one embodiment, pure graphite may be used as the collector component 114 (e.g., carbon with low hafnium contents and other neutron absorbers) due to graphite's electric and thermal properties and graphite's low activation by neutron absorption. In another embodiment, reactor grade graphite may be used as the collector component 114 due to graphite's electric and thermal properties and graphite's low activation by neutron absorption. The positively charged ions that are collected by the collector component 114 may be separated from the collector component 114 and prepared in appropriate chemical and physical form for distribution and various applications. FIG. 2 is a schematic of an exemplary operational fixture 200. The fixture 200 may be a reusable irradiation container for repetitive production of radioisotopes. The fixture 200 may be used in accordance with at least some embodiments and methods disclosed herein. The fixture 200 may include one or more parts and components such as an outer reusable containment shell 218, a circumferential source material canister 220, and/or a cathode collector 222. The fixture 200 may be used to maintain a particular environment to allow production of radioisotopes via neutron capture. The outer reusable containment shell 218 may be used to create and maintain a vacuum environment for contents located within the fixture 200. The outer reusable containment shell 218 may be made of materials that have low neutron capture cross sections. For example, magnesium, aluminum, and/or zirconium metals and alloys may be used to make the outer reusable containment shell 218. One of ordinary skill in the art will appreciate, after reviewing this disclosure, that the containment shell 218 may be constructed from other materials with appropriate properties and characteristics. The circumferential source material canister 220 may be located within the outer reusable containment shell 218 of the fixture 200. The circumferential source material canister 220 may include a target material to capture neutrons. The target material may be the high surface area target 108 discussed in relation to FIG. 1. For example, the target material may be comprised of molybdenum or other natural isotopes. The shape and form of the circumferential source material canister 220 may be designed in order to increase a surface area of the target material that is exposed to a neutron flux. Increasing the surface area of the source material canister 220 may increase a release rate of positive ions into the vacuum space within the fixture 200. In one embodiment, the target material and any other materials placed within the fixture 200 may be thermally heated or electrically heated before being placed within the fixture 200. In another embodiment, the target material and any other materials placed within the fixture 200 may be thermally heated or electrically heated after being placed within the fixture 200. Heating the target material may remove contaminants during evacuation of the atmosphere in the fixture 200 that may inhibit the processes and methods disclosed herein. The circumferential source material canister 220 may have a positive electrical charge to provide a positive electrical charge to the target material located within the circumferential source material canister 220. Applying a positive electrical charge of selected values to the target material may increase recovery of radioisotopes created within the fixture 200. When the target material located within the circumferential source material canister 220 absorbs neutrons, activated atoms located within the target material may recoil. When an activated atom recoils due to prompt and/or delayed gamma emission, kinetic energy may be created that is sufficient to rupture atomic bonds holding the activated atom in the target material. The kinetic energy delivered to the activated atom may be within the range from a few eV to MeV, but the kinetic energy may be larger or smaller. The kinetic energy of the activated atom may cause the activated atom to escape from a surface of the target material as a positively charged ion into the vacuum environment within the fixture 200. The positive electric charge of the target material may repel any released positively charged ions from reattaching to the target material and may cause the positively charged ions to move within the vacuum environment and be attracted to and collected by the negatively charged cathode 222. The circumferential source material canister 220 and fixture wall 218 may be made of materials that have low neutron capture cross sections. For example, magnesium, aluminum, and/or zirconium metals and alloys may be used to make the circumferential source material canister 220. One of ordinary skill in the art will appreciate, after reviewing this disclosure, that the material canister 220 and other components within the fixture 200 may be constructed from other materials with appropriate nuclear and chemical properties and characteristics. The circumferential source material canister 220 may use compacting, bonding, mechanical rotation and/or screening to prevent movement of the target material towards the cathode collector 222, other than the positively charged ions created within the fixture 200. The circumferential source material canister 220 may prevent macroscopic movement of the target material by, for example, compaction fencing. Compaction fencing may include mesh with openings that are smaller in size than material particles of the target material. The reusable containment shell 218 may also prevent movement of the target material. The reusable containment shell 218 may rotate axially at a speed that is sufficient to restrain the target material particles using centripetal forces as produced in centrifuges. The cathode collector 222 may be at least partially surrounded by the circumferential source material canister 220. The cathode collector 222 may be negatively charged and may attract the positively charged ions released into the vacuum space via neutron capture. The positively charged ions may travel and attach to the surface or interior of the cathode collector 222 and may be held by physical, atomic and/or electrical forces. The positively charged ions that are collected by the cathode collector 222 may be separated from the cathode collector 222 and prepared in chemical and physical form for distribution and utilization. FIG. 3 is a schematic of an exemplary fixture 300 that may be used for production of radioisotopes such as Mo-99. The fixture 300 may have one or more parts and/or components that are similar or identical to the parts and/or components used in connection with the fixture 200 discussed in relation FIG. 2. For convenience, similar or identical parts and/or compounds may, but not necessarily, have the same reference numbers. One of ordinary skill in the art will appreciate, after reviewing this disclosure, that fixtures 200 and 300 may have one or more similar or different parts and/or components depending, for example, upon the intended use of the fixture. One of ordinary skill in the art will also appreciate, after reviewing this disclosure, that fixtures 200 and 300 may have different shapes, sizes, configurations, and/or arrangements depending, for example, upon the intended use of the fixture. As shown in FIG. 3, an anode 324 may be electrically coupled to the circumferential source material canister 220. The anode 324 may provide a positive electric charge of a selected value to the target material located within the circumferential source material canister 220. A cathode 326 may be electrically coupled to the cathode collector 222. The cathode 326 may provide a negative electric charge of a selected value to the cathode collector 222. As discussed above, an electrical connection may be created between the high surface area target and the anode 324 by an electrical conducting layer 328. In another configuration, an electrical connection may be created between the high surface area target and the anode 324 by an electrical conducting layer 328 passing through the high surface area target. The fixture 300 may include a vacuum port 328 and a vacuum 340 may be connected to the vacuum port 328. The vacuum port 328 may allow a vacuum environment to be created within the fixture 300. A device, such as the vacuum 340, may be connected to the the vacuum port 328 and may allow the environmental gas pressure within the outer reusable containment shell 218 to be reduced for enhancing production of the positive ions released from the anode 324. A spatial relationship may exist between the outer reusable containment shell 218, the circumferential source material canister 220, and/or the cathode collector 222. The spatial relationship of components in the containment shell 218 may be maintained by structural supports 330 such as spacers and/or electrical insulators of proper composition and design to support interior components and allow the vacuum environment to surround the circumferential source material canister 220 and the cathode collector 222. The structural supports 330 may isolate a negative electric charge of the cathode collector 222 and a positive electric charge of the circumferential source material canister 220. FIG. 4 is a flowchart of an exemplary method 400 for producing radioisotopes via neutron capture, in accordance with at least some embodiments described herein. The method 400 may be implemented, in some embodiments, by a fixture, such as the fixtures 100, 200 and/or 300 of FIG. 1, 2, or 3 respectively. Although illustrated as discrete blocks, various blocks may be divided into additional blocks, combined into fewer blocks, or eliminated, depending on the desired implementation for maintaining the desired integrity of the system. The method may begin at block 402 where a high surface area target may be inserted into an electrically insulating sleeve. In block 404, materials for a fixture may be selected. The materials may be selected such that neutronic and chemical properties of the fixture minimize interference of production of the high surface area target. In block 406, a second sleeve may be inserted into the fixture with an inner conducting sleeve. In block 408, an electrical conducting layer may be deposited. The electrical conducting layer may be in direct contact with the high surface area target and an anode junction of the fixture. In block 410, a variable electrical potential and/or voltage may be applied to contents of the fixture during neutron irradiation. In block 412, the fixture may be inserted into a selected neutron flux field for capturing neutrons within the high surface area target. In block 414, one or more activated atoms may be plated onto a cathode surface of the fixture. In block 416, the fixture may be removed from the neutron irradiation field and the activated nuclear isotopes may be recovered from a surface of the cathode. In block 418, the one or more activated nuclear isotopes may be processed and prepared for designated applications. One skilled in the art will appreciate that, for this and other processes and methods disclosed herein, the functions performed in the processes and methods may be implemented in differing order and configurations. Furthermore, the outlined steps and operations are only provided as examples, and some of the steps and operations may be optional, combined into fewer steps and operations, or expanded into additional steps and operations without detracting from the essence of the disclosed embodiments. For instance, the high surface area target may include broad spectrum of material configurations such as sheets, wire gauze, particulates, powders, spheres, whiskers, and/or other practicable structures or different combinations derived from isotopes. The cathode surface may include reactor grade graphite with low neutron capture properties. The present disclosure may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the disclosure is, therefore, indicated by the appended claims rather than by the foregoing description and drawings. All changes, which come within the meaning and range of equivalency of the claims, are to be embraced within their scope.
	abstract	In a boiling water fuel assembly, some of the fuel rods are shortened. It is necessary to establish a sufficiently high maximum power for transition to boiling. To optimize this power, spacers are at a constant distance at a bottom and are at a shorter distance at a top. The spacers belonging to upper group have turbulence-generating vanes which, however, do not project above the shortened fuel rods.
	claims	1. Extreme UV radiation focusing mirror of the grazing incidence type, comprising a plurality of nested concave mirrors of different diameters, wherein a bevel is formed on ends of the concave mirrors at sides thereof which are not reflection surfaces. 2. Extreme UV radiation focusing mirror in accordance with claim 1, wherein the concave mirrors have a reflection surface of a shape selected from one of an ellipsoid of revolution, a paraboloid of revolution, and a Wolter shape, and wherein focus positions of the concave mirrors essentially coincide with one another. 3. Extreme UV radiation focusing mirror in accordance with claim 1, wherein the bevel has an angle on a radiation incidence side of the end of the concave mirrors that is a positive angle in a clockwise direction with respect to a direction of travel of incident extreme UV radiation. 4. Extreme UV radiation focusing mirror in accordance with claim 1, wherein the bevel has an angle on a radiation exit side of the end of the concave mirrors that is a negative angle in a clockwise direction with respect to a direction of travel of emerging extreme UV radiation. 5. Extreme UV radiation focusing mirror in accordance with claim 1, wherein the bevel has an angle on a radiation incidence side of the end of the concave mirrors that is a positive angle in a clockwise direction with respect to a direction of travel of incident extreme UV radiation, and wherein the bevel has an angle on a radiation exit side of the concave mirrors that is a negative angle in a clockwise direction with respect to a direction of travel of emerging UV radiation. 6. Extreme UV radiation source device, comprising:a vessel;a raw material supply means for supplying raw material to the vessel which contains at least one of an extreme UV radiation fuel and a compound of an extreme UV radiation fuel;a means for heating and excitation which heats and excites the supplied raw material in the vessel and with which a plasma is produced that emits radiation containing extreme UV radiation;a focusing optical system which is located in the vessel for focusing the radiation which has been emitted from the plasma; anda radiation extracting part with which the focused radiation is extracted from the vessel,wherein the focusing optical system comprises an extreme UV radiation focusing mirror formed of a plurality of nested concave mirrors of different diameters, and wherein a bevel is formed on ends of the concave mirrors at sides thereof which are not reflection surfaces. 7. Extreme UV radiation source device in accordance with claim 6, wherein the bevel has an angle on a radiation incidence side of the end of the concave mirrors that is a positive angle in a clockwise direction with respect to a direction of travel of incident extreme UV radiation. 8. Extreme UV radiation source device in accordance with claim 6, wherein the bevel has an angle on a radiation exit side of the end of the concave mirrors that is a negative angle in a clockwise direction with respect to a direction of travel of emerging extreme UV radiation. 9. Extreme UV radiation source device in accordance with claim 6, wherein the bevel has an angle on a radiation incidence side of the end of the concave mirrors that is a positive angle in a clockwise direction with respect to a direction of travel of incident extreme UV radiation, and wherein the bevel has an angle on a radiation exit side of the concave mirrors that is a negative angle in a clockwise direction with respect to a direction of travel of emerging UV radiation. 10. Extreme UV radiation source device in accordance with claim 6, wherein said bevels form knife edge parts at said ends of the convex mirrors. 11. Extreme UV radiation source device in accordance with claim 1, wherein said bevels form knife edge parts at said ends of the convex mirrors.
	summary
	abstract	A nuclear steam supply system utilizing gravity-driven natural circulation for primary coolant flow through a fluidly interconnected reactor vessel and a steam generating vessel. In one embodiment, the steam generating vessel includes a plurality of vertically stacked heat exchangers operable to convert a secondary coolant from a saturated liquid to superheated steam by utilizing heat gained by the primary coolant from a nuclear fuel core in the reactor vessel. The secondary coolant may be working fluid associated with a Rankine power cycle turbine-generator set in some embodiments. The steam generating vessel and reactor vessel may each be comprised of vertically elongated shells, which in one embodiment are arranged in lateral adjacent relationship. In one embodiment, the reactor vessel and steam generating vessel are physically discrete self-supporting structures which may be physically located in the same containment vessel.
	abstract	An X-ray differential phase contrast imaging device (10) comprises an X-ray source (20) for generating an X-ray beam; a source grating (G0) for generating a coherent X-ray beam from a non-coherent X-ray source (20); a collimator (22) for splitting the coherent X-ray beam into a plurality of fan-shaped X-ray beams (28) for passing through an object (14); a phase grating (G1) for generating an interference pattern and an absorber grating (G2) for generating a Moiré pattern from the interference pattern arranged after the object (14); and a line detector (24) for detecting the Moiré pattern generated by the phase grating (G1) and the absorber grating (G2) from the fan-shaped X-ray beams (28) passing through the object (14). The X-ray source (20), source grating (G0), collimator (22), phase grating (G1), absorber grating (G2) and line detector (24) are fixed to a common gantry (12) and are movable with respect to the object (14), such that a number of interference pattern from different positions of the gantry are detectable for reconstructing a differential phase image of the object (14). At least one grating (G0, G1, G2) comprises, in an alternating manner, groups (36) of grating lines (34) and transparent areas (38). At least one grating (G0, G1, G2) is movable with respect to the gantry (12), such that in a first position of the grating (G1, G2) the fan-shaped X-ray beams (28) pass through the grating lines (34), and in a second position of the grating (G1, G2), the fan-shaped X-ray beams (28) pass through the transparent areas (38).
	abstract	An EUV light source is configured for generating an EUV light for an exposure device. The EUV light source includes a chamber, a target supply device configured for supplying a target into the chamber, an optical system for introducing laser light from a driver laser into the chamber and irradiating the target with the laser light to turn the target into plasma from which EUV light is emitted, and an EUV collector mirror in the chamber. The EUV collector mirror may include a multilayered reflecting surface with grooves and collect the EUV light from the plasma to a focal spot. The grooves can be arranged in a concentric fashion, and be configured for diffracting at least light at a wavelength which is the same as that of the laser light from the driver laser.
	claims	1. A reactor configuration, comprising:a reactor core of a boiling water reactor;a separation device for steam/water separation disposed above said reactor core of the boiling water reactor;a flow space formed between the reactor core and said separation device;an internal cross-sectional area; anda flow component disposed in said flow space, said flow component having a central passage defining a flow cross-sectional area, said flow component having an entry side narrowing in a flow direction for initially reducing said flow cross-sectional area and an exit side expanding in said flow direction for increasing said flow cross-sectional area ahead of said separation device;said flow cross-sectional area, directly after said flow component with respect to the flow direction, being substantially defined by said internal cross-sectional area; andsaid separation device including a cyclone device disposed substantially only in a central region of said flow cross-sectional area. 2. The configuration according to claim 1, wherein the narrowing of said entry side is continuous and the expanding of said exit side is abrupt. 3. The configuration according to claim 2, wherein said flow component is a ring element. 4. The configuration according to claim 1, wherein said separation device includes a drying device disposed near said cyclone device. 5. The configuration according to claim 4, further comprising:a steam outlet connection;said cyclone device having an exit side;said drying device formed to exclusively provide a flow path from said exit side of said cyclone device to said steam outlet connection. 6. The configuration according to claim 5, wherein said drying device has a first dryer unit acting on a steam/water mixture emerging from said cyclone device and a second dryer unit acting on a remainder of the steam/water mixture. 7. The configuration according to claim 6, wherein said first dryer unit is disposed between said cyclone device and said second dryer unit. 8. The configuration according to claim 4, wherein said drying device has a first dryer unit acting on a steam/water mixture emerging from said cyclone device and a second dryer unit acting on a remainder of the steam/water mixture. 9. The configuration according to claim 8, wherein said first dryer unit is disposed between said cyclone device and said second dryer unit. 10. The configuration according to claim 1, wherein said separation device includes a drying device disposed in an annular space surrounding said cyclone device.
	summary
	claims	1. A composite material comprising a magnetic material A and a liquid support B, wherein:the material A is selected from the group consisting of magnetic compounds and magnetic alloys and is in the form of particles, the mean diameter of which is between 0.1 and 2 mm; andthe support fluid B is a conductive fluid selected from the group consisting of metals, metal alloys salts that are liquids at temperatures below the Curie temperature of the material A, and from mixtures thereof. 2. The composite material as claimed in claim 1, wherein the electrically conductive fluid B is a metal that is a liquid by itself or is a mixture of several metals that are liquids at temperatures below the Curie point of the magnetic material A with which they are associated. 3. The composite material as claimed in claim 2, wherein the electrically conductive fluid B is selected from the group consisting of Hg, Ga, In, Sn, As, Sb, alkali metals, and mixtures thereof. 4. The composite material as claimed in claim 1, wherein the electrically conductive fluid B is a molten metal alloy selected from the group consisting of In/Ga/As alloys, Ga/Sn/Zn alloys, In/Bi alloys, Wood's alloy, Newton's alloy, Arcet's alloy, Lichtenberg's alloy and Rose's alloy. 5. The composite material as claimed in claim 1, wherein the electrically conductive fluid B is a salt selected from the group consisting of:alkylammonium nitrates in which the alkyl group comprises from 1 to 18 carbon atoms, guanidinium nitrates, imidazolium nitrates and imidazolinium nitrates;alkali metal chloroaluminates, which are liquids at temperatures above 150° C.; andsalts comprising a BF4−, PF6− or trifluoroacetate anion and a cation chosen from amidinium [RC(═NR2)—NR2]+, guanidinium [R2N—C(═NR2)—NR2]+, pyridiniumimidazoliumimidazoliniumand triazoliumions, in which each substituent R represents, independently of the others, H or an alkyl radical having from 1 to 8 carbon atoms. 6. The composite material as claimed in claim 1, wherein the magnetic material A is selected from the group consisting of magnetic metals, metal oxides, magnetic alloys and magnetic compounds. 7. The composite material as claimed in claim 6, wherein the magnetic material A is selected from the group consisting of iron, iron oxide, cobalt, nickel, steel and iron/silicon alloys. 8. The composite material as claimed in claim 1, wherein the amount of magnetic particles is at most equal to the threshold value above which the dispersion is no longer homogeneous or solids precipitate. 9. The composite material as claimed in claim 1, wherein the material A comprises substantially spherical particles. 10. The composite material as claimed in claim 1, which comprises substantially spherical particles of magnetic material having a means size between 0.1 and 2 mm and particles of magnetic material the size distribution of which is homogeneous, between 1 nm and 50 μm. 11. The composite material as claimed in claim 1, wherein the magnetic material particles may be formed by a batch of a first magnetic material A and by a batch of a second magnetic material A′ chosen from the group defined for A. 12. The material as claimed in claim 1, comprising a magnetic material/electrically conductive fluid B pair selected from the group consisting of Fe/Hg, steel/Hg, Co/Hg, Ni/Hg, Fe/Ga, steel/Ga, Fe/Ga+Sn, and Fe/Wood's alloy. 13. A method for the preparation of a conductive composite material comprising a magnetic material A and an electrically conductive fluid B comprising the steps of:introducing non-ionic magnetic particles, which become magnetic material A, into an electrically conductive fluid B, andapplying a current in the range of 0.1 to 3 A/cm2;wherein the method is implemented electrochemically in an electrochemical cell in which:the electrolyte comprises an ionically conductive medium containing the non-ionic particles, the mean diameter of which is between 0.1 and 2 mm;the cathode consists of a film of the conductive fluid B connected to a potential source capable of delivering a current density between 0.1 and 3 A/cm2;the anode consists of a material that is nonoxidizable under the conditions of the method; andthe cathode is subjected to a negative potential difference relative to the anode. 14. The method as claimed in claim 13, wherein the non-ionic particles are selected from the group consisting of magnetic metals, metal oxides, magnetic alloys and magnetic compounds. 15. The method as claimed in claim 14, wherein the non-ionic particles are selected from the group consisting of iron, iron oxide, cobalt, nickel, steel and Fe—Si alloys. 16. The method as claimed in claim 13, wherein the non-ionic particles are substantially spherical. 17. The method as claimed in claim 13, wherein the non-ionic particles are in the form of a first batch formed from substantially spherical particles having a mean size of between 0.1 and 2 mm and of a second batch formed from micron-scale particles, the size distribution of which is homogeneous, between 1 nm and 50 μm. 18. The method as claimed in claim 13, wherein the non-ionic particles are a mixture of particles selected from the group iron, iron oxide, cobalt, nickel, steel and Fe—Si alloys. 19. The method as claimed in claim 13, wherein the respective amounts of the non-ionic particles, which become magnetic material A, and of conductive fluid B are such that the final concentration of particles of magnetic material A in the conductive fluid B remains less than the value above which the dispersion is no longer homogeneous or solids precipitate, taking into account the degree of solubility of the magnetic material A in the fluid B. 20. The method as claimed in claim 13, wherein the electrically conductive fluid B is selected from the group consisting of metals, metal alloys and salts that are liquids at temperatures below the Curie temperature of the material A, and mixtures thereof. 21. The method as claimed in claim 20, wherein the electrically conductive fluid B is a metal that is a liquid by itself or is a mixture of several metals that are liquids at temperatures below the Curie point of the magnetic material A with which they are associated. 22. The method as claimed in claim 21, wherein the electrically conductive fluid B is selected from the group consisting of Hg, Ga, In, Sn, As, Sb, alkali metals, and mixtures thereof. 23. The method as claimed in claim 20, wherein the electrically conductive fluid B is a molten metal alloy selected from the group consisting of In/Ga/As alloys, Ga/Sn/Zn alloys, In/Bi alloys, Wood's alloy, Newton's alloy, Arcet's alloy, Lichtenberg's alloy and Rose's alloy. 24. The method as claimed in claim 20, wherein the electrically conductive fluid B is a salt selected from the group consisting of:alkylammonium nitrates in which the alkyl group comprises from 1 to 18 carbon atoms, guanidinium nitrates, imidazolium nitrates and imidazolinium nitrates;alkali metal chloroaluminates, which are liquids at temperatures above 150° C.; andsalts comprising a BF4−, PF6− or trifluoroacetate anion and a cation chosen from amidinium [RC(═NR2)—NR2]+, guanidinium [R2N—C(═NR2)—NR2]+, pyridiniumimidazoliumimidazoliniumand triazoliumions, in which each substituent R represents, independently of the others, H or an alkyl radical having from 1 to 8 carbon atoms. 25. The method as claimed in claim 21, wherein one or more elements are added to the metal forming the electrically conductive fluid B, which elements may form a stable liquid phase or a liquid amalgam when said metal is mercury. 26. The method as claimed in claim 13, wherein the ionically conductive medium is formed by a solution of a nonoxidizing acid or of a strong base in a solvent. 27. The method as claimed in claim 26, wherein the solvent is selected from the group consisting of water, polar organic liquids and molten salts. 28. The method as claimed in claim 13, further comprising applying a magnetic field and the current to form magnetic material A in the electrically conductive fluid B.
047708476	description	DETAILED DESCRIPTION A primary application of this invention is the fabrication of nuclear fuel assemblies such as that illustrated in the drawing as a partially cutaway sectional view wherein the cladding containers of the water rods exhibit irradiation growth substantially equivalent to that of fuel rods under operating nuclear reactor conditions. A nuclear fuel assembly 10 comprises a tubular flow channel 11 of generally square cross-section provided at its upper end with a lifting bail 12 on the upper tie plate and at its lower end with a nose piece (not shown due to the lower portion of assembly 10 being omitted). The upper end of the channel 11 is open at 13 and the lower end of the nose piece is provided with coolant flow openings. An array of alternating fuel rods 14 and water rods 15 is enclosed in the channel 11 and supported therein by means of an upper tie plate 16 and a lower tie plate (not shown due to the lower portion being omitted). Liquid coolant ordinarily enters through the openings in the lower end of the nose piece and flows in part into the water rods through inlet holes (not shown) and passes upwardly through the water rods and discharges through outlet holes 17 of the water rods and outlet 13 of the channel at an elevated temperature. Coolant also passes upwardly within the channel in the space between the fuel and water rods. Coolant outside of the water rods typically is discharged from the channel through outlet 13 in at least a partially vaporized condition. The nuclear fuel rods 14 are sealed at their ends by means of end plugs 18 welded to the cladding 19. The end plugs include studs 20 to facilitate the mounting of the fuel rod in the assembly. A void space or plenum 21 is provided at one end of the element to permit longitudinal expansion of pellets of fuel material 22 and accumulation of gases released from the fuel material. A nuclear fuel material retainer means 24 in the form of a helical member is positioned within the void space 21 to provide restraint against the axial movement of the pellet column, especially during handling and transportation of the fuel element. An expansion spring 23 is positioned between the top of each fuel rod and the upper tie plate to accommodate differential axial expansion among fuel rods and between fuel rods and water rods due to irradiation growth. Nuclear water rods 15 are hollow and are sealed at their ends by means of end plugs 25 welded to the cladding 26. The end plugs include studs 27 which facilitate the mounting of the water rods in the assembly similarly to the fuel rods. The water rods comprise inlet holes (not shown) above the lower end plug and outlet holes 17 below the upper end plug 27. If it is desired to have the coolant enter or exit the water rods from selected radial directions, one or both end plugs may comprise studs of square cross section which are then inserted in tie plate holes of corresponding square cross section. Expansion springs 28 are also positioned between the top of each water rod cladding and the upper tie plate to accommodate a certain amount of differential irradiation growth between water rods and fuel rods. The invention is particularly suited to anisotropic metals as isotropic metals undergo little or substantially no irradiation growth. Anisotropic metals are metals which display different properties along different crystallographic directions. The preferred anisotropic metals for application in nuclear reactors are alloys of zirconium. More preferably, the zirconium alloys are Zircaloy-2 and Zircaloy-4. Zircaloy-2 has on a weight basis about 1.5% tin; 0.12% iron; 0.09% chromium and 0.005% nickel and is extensively used in water-cooled reactors. Zircaloy-4 has less nickel than Zircaloy-2 and contains slightly more iron but is otherwise the same as Zircaloy-2. Claddings of the fuel rods and water rods in fuel assemblies such as described above can be fabricated in accordance with principles of the present invention. The claddings are fabricated by mechanical cold-work reductions from a tube shell. The tube shell is typically extruded from a hollow billet of the material. Cold-work reductions can be accomplished by various techniques such as a rocking process in a Pilger mill or machine. In a Pilger machine the thick-walled tube shell is passed through special rolls. These rolls vary in cross sectional shape around their circumference so that the distance between the rolls varies when the rolls rotate. The tube is fixed to a mandrel and is then gripped by a section of the rolls having a greater radius. As the tube advances between the rolls, the wall thickness of the tube is reduced until the rolls have rotated to such an extent that the part of their cross section having a lesser radius is reached and the tube is thus no longer gripped. The tube is then pulled back a select distance wherein again a thick-walled portion of the tube is gripped by the section of the rolls having the greater radius. The mandrel is continuously rotated in order to insure uniform application of the roll pressure around the tube. Several cold-work reduction passes are generally performed to achieve the final dimension of the tube. After each reduction pass, the tube shell is cleaned and heat treated. The severe cold working that takes place in the tube reduction results in distortion of the shapes of the metal crystallites and produces many crystal defects within the crystallites. Cold-worked metals are in a relatively high energy state which is not thermally stable. Heat treatment subsequent to a cold-work reduction pass uses heat to impart mobility to the atoms of the metal and allows them to rearrange themselves into a lower energy state. This is referred to as recrystallization and is a function of both temperature and time, with temperature being the more sensitive parameter. According to the practice of this invention, the tube fabrication schedules differ between fuel rods and water rods. After achieving the final dimensions by a final cold-work reduction pass, fuel rods typically undergo a heat treatment wherein the time and temperature are selected to be sufficient to provide substantially complete recrystallization but insufficient to allow excessive crystalline grain growth. In the case of zirconium alloys, suitable temperatures and times for this heat treatment or annealing step are in the ranges from about 1000.degree. F. to about 1300.degree. F. for about 1 to 15 hours and preferably for about 2 to 5 hours. After achieving final dimensions by a final cold-work reduction pass, water rods are heat treated at a time and temperature which imparts less recrystallization to the alloy than in the fuel rods. Preferably, the heat treatment is selected to provide partial recrystallization, i.e., stress relief, but not full recrystallization of the metal crystalline structure. For zirconium alloys, preferable temperatures for this heat treatment are from about 825.degree. F. to about 950.degree. F. for about 1 to 4 hours. The degree of axial or longitudinal expansion due to irradiation is dependent upon the amount of recrystallization that takes place in the final heat treatment step which determines the energy state of the cladding tube. A completely recrystallized tube has less irradiation growth than a tube that is only partially recrystallized. A fuel rod is subject to elongation in a neutron flux due to two effects, irradiation-induced changes in the crystallographic condition of the metal in the tube and pellet-cladding mechanical interaction. A water rod is subject only to irradiation-induced crystallographic changes. By only partially recrystallizing the metal in the water rods, the elongation due to crystallographic changes is enhanced so that the elongation of the water rods can more closely approximate the elongation due to the sum of the effects operating on fuel rods. The energy state may also be varied, in addition to the final heat treatment, by the degree of the cold-work reduction in the final reduction pass. A large reduction of the wall thickness imparts greater distortions and crystal defects and causes the metal to be in a relatively higher energy state than a smaller reduction. Therefore, it may be desirable to vary the number of cold-work reductions before achieving the desired final dimensions between fuel and water rods so that the size of the final reduction imparts the desired amount of crystal defects to a tube, thereby inducing a selected energy level to the crystalline structure of that tube. By use of a greater cold reduction, a larger inherent irradiation growth potential can be left in a water rod than in a fuel rod having a lesser cold reduction in the final stage of tube forming. The final energy level of a cladding tube results from the combination of cold-work reduction and heat treatment. The two factors are interdependent so that an excessive cold-work reduction may be compensated for by a longer or hotter heat treatment to achieve the desired energy level. For example, in order to produce fuel rods and water rods having substantially equivalent irradiation growth in a boiling water reactor, the following described tube fabrication schedules can be used. A first cladding tube for a fuel rod is fabricated from a billet of Zircaloy-2 alloy conforming to ASTM B353, grade RA-1. The billet is machined and cleaned and has dimensions of approximately 9.0 inches length, about 5.74 inches outside diameter and about 1.66 inches inside diameter. The billet is extruded into a cladding tube shell using an extrusion rate of about 6 inches per minute, a reduction ratio of about 6:1, a temperature of about 1100.degree. F. and an extrusion force of about 3500 tons. All billet surfaces except the bore and floating mandrel are lubricated with a water-soluble lubricant. The final reduction of the tube shell is accomplished by cold work reductions in a Pilger machine. The tube shell before reduction has an outside diameter of about 2.5 inches and a wall thickness of about 0.43 inches. The tube shell is cleaned with a degreaser and then a soap-based alkaline solution. The tube shell is annealed for about 1 hour at approximately 1150.degree. F. A first reduction pass in the Pilger machine is made and produces a tube shell with an outside diameter of about 1.45 inches and a wall thickness of about 0.22 inches. The shell is then cleaned as before and annealed for about 1 hour at about 1150.degree. F. A second reduction pass in the Pilger mill is made and generates a tube with an outside diameter of 0.8 inches and a wall thickness of 0.095 inches. Again, the tube is cleaned and annealed for about 1 hour at about 1150.degree. F. The first tube shell for making a fuel rod then undergoes a third and final reduction in the Pilger mill in which an approximately 76% reduction in wall thickness is made to provide a first cladding tube having an outer diameter of 0.495 inches and a wall thickness of 0.035 inches. The tube is again cleaned and annealed at about 1070.degree. F. for about 2.5 hours to provide the final product. A second cladding tube of Zircaloy-2 to be used as a water rod is fabricated as described above for a fuel rod through the second reduction pass in the Pilger machine. After the second reduction pass, the tube shell is cleaned with a degreaser and a soap-base alkaline solution. The tube shell is then annealed for about 1 hour at about 1150.degree. F. A third reduction pass through the Pilger mill in which about a 60% reduction in wall thickness is made forms a tube shell having an outer diameter of about 0.62 inches and a wall thickness of 0.037 inches. The tube is again cleaned as before and annealed for about 1 hour at about 1150.degree. F. A fourth and final reduction pass through the Pilger mill in which about a 20% reduction in wall thickness is made produces a second cladding tube having an outer diameter of 0.593 inches and a wall thickness of 0.031 inches. Following the final cold-work reduction, the second cladding tube is heat treated for about 4 hours at about 950.degree. F. Both cladding tubes are then cut to length and fabricated into fuel and water rods, respectively.
059441909	summary	FIELD OF THE INVENTION The invention relates to containers for the transport and handling of radiopharmaceutical capsules, e.g., radioactive iodine capsules. BACKGROUND OF THE INVENTION Radiopharmaceutical capsules, e.g., radioactive iodine capsules, are used, for example, in oncology, e.g., in the treatment of thyroid cancer. Because of their radioactivity, such capsules typically are stored and transported in resealable lead canisters or "safes." Previously, such safes have been constructed so that they are either closed, i.e., the radiopharmaceutical capsules is environmentally sealed and the radiation is contained within the safe, or open, i.e., the capsule is environmentally exposed and the radiation is no longer contained. With such safe configurations, the radiopharmaceutical capsule is environmentally exposed even when the capsule is only being assayed, i.e., the radioactive strength of the capsule is being measured by means of a Geiger counter or in an ionization chamber. SUMMARY OF THE INVENTION The present invention provides a radiopharmaceutical capsule safe in which a radiopharmaceutical capsule can be packaged and transported. The radiopharmaceutical capsule is secured within a capsule vial, and the capsule vial, in turn, is secured in the middle of a radiopaque vessel or safe. The radiopharmaceutical capsule safe according to the invention is configured such that when it is only desired to assay the capsule, the upper portion or lid of the safe is turned in one direction and lifted away from the bottom portion of the safe, leaving the capsule vial sealed and secured within the safe bottom. When it is desired to dose the capsule, i.e., to deliver it to a patient, the safe lid is turned in the opposite direction (assuming it has been replaced after assaying) to unscrew the vial cap from the vial, thereby opening the vial and permitting access to the radiopharmaceutical capsule. Thus, according to a first aspect of the invention, the invention provides a radiopharmaceutical capsule safe. The radiopharmaceutical capsule safe includes a safe which, in turn, includes a safe bottom and a safe lid, each of which is formed from radiopaque material such as lead. The safe bottom has a vial bottom-receiving cavity formed therein, and the safe lid has a vial cap-receiving cavity formed therein. The radiopharmaceutical capsule safe also includes a capsule vial which, in turn, includes a vial bottom and a vial cap that is securable to the vial bottom. The vial cap is formed from radiotransmissive material such as plastic, and the vial bottom is configured to receive the radiopharmaceutical capsule therein. The configuration is such that the vial bottom fits within the vial bottom-receiving cavity in the safe bottom, and the vial cap fits within the vial cap-receiving cavity in the safe lid so that the capsule vial is completely encased within the safe when the safe lid is engaged with the safe bottom. By removing the safe lid but leaving the vial cap engaged with the vial bottom, the radiopharmaceutical capsule can be assayed while environmentally sealed within the vial capsule. Preferred embodiments of the invention may include one or more of the following features. The vial bottom can have two or more tabs extending outwardly therefrom, and the vial cap can similarly have two or more cap tabs extending outwardly therefrom. The tabs fit within slots in the vial bottom-receiving cavity and the vial cap-receiving cavity, respectively, and the vial cap can be disengaged from the vial bottom by rotating the safe lid relative to the safe bottom. The slots in the safe lid and/or the slots in the safe bottom can have circumferentially oriented tab-engaging slot extensions that permit limited rotation of the safe lid relative to the vial cap and/or limited rotation of the vial bottom relative to the safe bottom. The slot extensions retain the vial cap and the vial bottom in the respective safe lid or safe bottom. The slots and slot extensions may be provided by means of an upper and/or lower lock ring positioned in the opening of the vial cap-receiving cavity and/or the vial bottom-receiving cavity. The radiopharmaceutical capsule safe preferably includes a two-piece outer jar that consists of a jar bottom and a jar cap engageable with the jar bottom. The radiopaque safe is enclosed within the outer jar, preferably with the safe bottom retained within the jar bottom by means of a retaining member such as a retaining ring located at the open end of the jar bottom. In another aspect, the invention provides a method of packaging a radiopharmaceutical capsule. The method includes providing a safe, which safe includes a safe bottom and a safe lid, each being formed from radiopaque material. The safe bottom and the safe lid are engageable with each other. A capsule vial including a vial bottom and a vial cap is also provided, the vial cap being formed from radiotransmissive material. The vial bottom is disposed in a vial bottom-receiving cavity formed in the safe bottom, the vial cap is disposed in a vial cap-receiving cavity formed in the safe lid, and the radiopharmaceutical capsule is disposed in the vial bottom. The vial cap is engaged to the vial bottom, and the safe lid is engaged to the safe bottom. Preferably, the vial cap is disposed in the vial cap-receiving cavity before the vial cap is engaged with the vial bottom such that the vial cap is engaged with the vial bottom generally simultaneously with the safe lid being engaged with the safe bottom. Furthermore, activated charcoal is preferably disposed in the bottom of the vial bottom-receiving cavity before disposing the vial bottom in the bottom receiving cavity. The radiopaque safe is then preferably sealed within an outer jar that preferably is formed from plastic. In another aspect, the invention provides a method of assaying a radiopharmaceutical capsule. The method includes providing a radiopharmaceutical capsule that is disposed in a sealed capsule vial. The capsule vial is disposed in a sealed, radiopaque safe that has a safe bottom and a safe lid. The safe lid is removed from the safe bottom to expose the vial cap, which is radiotransmissive, while leaving the vial cap engaged with the vial bottom and the vial bottom disposed within the safe bottom. The radiopharmaceutical capsule is then assayed while still sealed within the capsule vial. In another aspect, the invention provides a method of dosing a radiopharmaceutical capsule. The method includes providing a radiopharmaceutical capsule that is disposed in a separate, sealed capsule vial. The capsule vial has a cap and a bottom and is disposed in a sealed, radiopaque safe having a radiopaque safe lid engaged with a radiopaque safe bottom. The vial cap is removed from the vial bottom, to expose the capsule for dosing, by disengaging the safe lid from the safe bottom. Finally, in another aspect, the invention provides a method of assaying and dosing a radiopharmaceutical capsule. A radiopharmaceutical capsule is provided in a sealed vial that is disposed in a sealed, radiopaque safe. The safe lid is removed from the safe bottom to expose the cap of the vial, which is radiotransmissive, while leaving the vial sealed with the vial bottom still disposed in the safe bottom. The radiopharmaceutical capsule is then assayed while still sealed within the capsule vial, and then the safe lid is re-engaged with the safe bottom to reseal the vial within the safe. Subsequently, the vial cap is removed from the vial bottom by disengaging the safe lid from the safe bottom and the radiopharmaceutical capsule is dispensed from the vial.
	claims	1. A method of Fourier ptychographic imaging with embedded pupil function recovery, the method comprising:(a) receiving image data for a plurality of intensity images of a sample, the intensity images acquired sequentially by a light detector while the sample is being illuminated at different oblique incidence angles and the light detector is receiving light issuing from the illuminated sample through an optical system having a lens;(b) Fourier transforming the image data;(c) simultaneously updating a pupil function of the optical system and a sample spectrum, wherein the sample spectrum is updated in overlapping regions with the Fourier-transformed intensity image data, and the overlapping regions correspond to the different oblique illumination angles; and(d) inverse Fourier transforming the updated sample spectrum to determine an image of the sample having a higher resolution than the plurality of intensity images. 2. The method of claim 1, wherein each of the overlapping regions has an area corresponding to the numerical aperture of the lens. 3. The method of claim 2, wherein the lens is an objective lens, wherein the overlapping regions are in the form of circular pupil apertures. 4. The method of claim 3, wherein the numerical aperture of the lens is in a range between about 0.02 and about 0.13. 5. The method of claim 3, wherein the numerical aperture of the lens is about 0.08. 6. The method of claim 2, further comprising calculating an aberration in the optical system using the updated pupil function. 7. The method of claim 6, further comprising adaptively correcting an incident wavefront based on the calculated aberration. 8. The method of claim 6, further comprising determining a substantially aberration-free image of the sample using the calculated aberration. 9. The method of claim 6, further comprising re-focusing the sample using the calculated aberration. 10. The method of claim 2, wherein adjacent overlapping regions overlap in area by between 20% and 90%. 11. The method of claim 1, repeating (c) until the updated sample spectrum is self-consistent. 12. A method of Fourier ptychographic imaging with embedded pupil function recovery, the method comprising:receiving image data for a plurality of intensity images of a sample, the intensity images acquired sequentially by a light detector while the sample is being illuminated at different oblique incidence angles and the light detector is receiving light issuing from the illuminated sample through an optical system having a lens;Fourier transforming the image data;simultaneously updating a pupil function of the optical system and a sample spectrum, wherein the sample spectrum is updated in overlapping regions with the Fourier-transformed intensity image data, and the overlapping regions correspond to the different oblique illumination angles; andcalculating an aberration in the optical system using the updated pupil function. 13. The method of claim 12, further comprising decomposing a phase component of the updated pupil function into coefficients of Zernike polynomials. 14. The method of claim 13, further comprising determining wavefront aberration based on coefficients of lower order modes of Zernike polynomials. 15. The method of claim 13, further comprising determining wavefront aberration based on coefficients of or one or more of a mode associated with defocus aberration, a mode associated with a stigmatism in the x-direction, and a mode associated with a stigmatism in one or two directions. 16. The method of claim 13, further comprising determining coma aberration based on coefficients of one or more modes of Zernike polynomials. 17. The method of claim 12, further comprising adaptively correcting an incident wavefront based on the calculated aberration. 18. The method of claim 12, further comprising inverse Fourier transforming the updated sample spectrum to determine an image of the sample having a higher resolution than the plurality of intensity images. 19. The method of claim 18, further comprising determining a substantially aberration-free image of the sample using the calculated aberration. 20. The method of claim 18, further comprising: decomposing a phase component of the updated pupil function to determine a coefficient of a mode associated with defocus aberration; calculating defocus aberration from the coefficient; and re-focusing the higher resolution image of the sample using the calculated defocus aberration. 21. A Fourier ptychographic imaging system employing embedded pupil function recovery, comprising: a variable illuminator configured to illuminate a sample being imaged at a plurality of oblique illumination angles; an optical system having an objective lens configured to collect light issuing from the illuminated sample; a radiation detector configured to receive light issuing from the illuminated sample and transmitted by the optical system, and configured to acquire a plurality of intensity images based on the light received; a processor configured to: simultaneously update a pupil function and a separate sample spectrum, wherein the sample spectrum is updated in overlapping regions with the Fourier-transformed intensity image data, and the overlapping regions correspond to the different oblique illumination angles; and calculate an aberration in the optical system using the updated pupil function. 22. The Fourier ptychographic imaging system of claim 20, further comprising a wavefront modulator configured to adaptively correct an incident wavefront based on the calculated aberration. 23. The Fourier ptychographic imaging system of claim 20, wherein the objective lens has a numerical aperture between about 0.02 and 0.13. 24. The Fourier ptychographic imaging system of claim 20, wherein the objective lens has a numerical aperture numerical aperture of about 0.08. 25. The Fourier ptychographic imaging system of claim 20, wherein the variable illuminator comprises a circular array of discrete light elements. 26. The Fourier ptychographic imaging system of claim 20, wherein the processor is further configured to decompose a phase component of the updated pupil function into coefficients of Zernike polynomials. 27. The Fourier ptychographic imaging system of claim 25, wherein the processor is further configured to determine wavefront aberration based on coefficients of or one or more of a mode associated with defocus aberration, a mode associated with a stigmatism in the x- direction, and a mode associated with a stigmatism in one or two directions. 28. The Fourier ptychographic imaging system of claim 25, wherein the processor is further configured to determine coma aberration based on coefficients of one or more modes of Zernike polynomials. 29. The Fourier ptychographic imaging system of claim 27, wherein the processor is further configured to determine coma aberration based on coefficients of one or more modes of Zernike polynomials. 30. The Fourier ptychographic imaging system of claim 20, wherein the processor is further configured to inverse transform the updated sample spectrum to determine an image of the sample, wherein the image has a higher resolution than the captured intensity images. 31. The Fourier ptychographic imaging system of claim 27, wherein the processor is further configured to determine a substantially aberration-free image of the sample using the calculated aberration. 32. The Fourier ptychographic imaging system of claim 27, wherein the processor is further configured to:decompose a phase component of the updated pupil function to determine a coefficient of a mode associated with defocus aberration;calculate defocus aberration from the coefficient; andre-focus the higher resolution image of the sample using the calculated defocus aberration. 33. A method of Fourier ptychographic imaging with embedded pupil function recovery, the method comprising:providing plane wave illumination at a plurality of oblique incidence angles to a sample being imaged;collecting light issuing from the sample using an optical system having a lens;acquiring a plurality of intensity images of the sample using a radiation detector;simultaneously updating a pupil function of the optical system and a separate sample spectrum, wherein the sample spectrum is updated in overlapping regions with Fourier transformed intensity image data, wherein the overlapping regions corresponds to the plurality of oblique incidence angles; andinverse Fourier transforming the recovered sample spectrum to recover an image with a higher resolution than the acquired intensity images. 34. The method of claim 33, further comprising determining an aberration from the updated pupil function. 35. The method of claim 34, further comprising adaptively correcting for the determined aberration using a wavefront modulator. 36. The method of claim 34, wherein the overlapping regions overlap by between 20% and 90% in area.
052805042	abstract	A fuel rod for a nuclear reactor is described. The fuel rod contains a zirconium alloy cladding tube, with a thin coating of a burnable poison which has been plasmaarc sprayed on the inside diameter of the cladding tube. Also described is a plasma-arc spraying device and a method for applying a coating to the inside of a small-diameter metal tube.
	claims	1. A radioisotope-powered energy source comprising:a flexible center substrate coated with the radioisotope, wherein the substrate comprises upper and lower surfaces; andtwo substantially identical sequences of layers bonded to the substrate via electrically insulating mesh barriers, one of the sequences being bonded to the upper surface and the other sequence being bonded to the lower surface, wherein the constituent layers of each sequence are bonded to each other via electrically insulating mesh barriers, wherein each sequence comprises the following layers bonded together in the following order:a first low-density alpha particle impact layer,a first high-density beta particle impact layer, anda photovoltaic layer. 2. The energy source of claim 1, wherein each sequence further comprises the following layers interposed between the first beta particle impact layer and the photovoltaic layer:a second low-density alpha particle impact layer,a second radioisotope-coated substrate,a third low-density alpha particle impact layer, anda second high-density beta particle impact layer. 3. The energy source of claim 1, wherein all constituent layers of the energy source are rolled into a cylindrical shape. 4. The energy source of claim 3, wherein each photovoltaic, alpha particle impact, and beta particle impact layer is electrically connected to a capacitor. 5. The energy source of claim 3, wherein the radioisotope is depleted uranium. 6. The energy source of claim 3, wherein the radioisotope is a radioisotope from the Thorium series. 7. The energy source of claim 3, wherein the radioisotope is a radioisotope from the Neptunium series. 8. The energy source of claim 3, wherein the radioisotope is an artificially created radioisotope. 9. The energy source of claim 3, wherein each beta particle impact layer is a beryllium film. 10. The energy source of claim 3, wherein each beta particle impact layer is a carbon film. 11. The energy source of claim 3, wherein each beta particle impact layer is a silver film. 12. The energy source of claim 3, wherein each beta particle impact layer is a gold film. 13. The energy source of claim 3, wherein each alpha particle impact layer is a sodium beta-alumina device. 14. The energy source of claim 3, wherein each alpha particle impact layer is a gallium arsenide diode. 15. The energy source of claim 3, wherein each alpha particle impact layer is a diamond film. 16. A radioisotope-powered energy source comprising:a flexible center substrate coated with the radioisotope, wherein the substrate comprises upper and lower surfaces;first and second electrically insulating mesh barriers coupled to the upper and lower surfaces respectively;first and second low-density alpha particle impact layers coupled to the first and second mesh barriers respectively;third and fourth electrically insulating mesh barriers coupled to the first and second alpha particle impact layers respectively; andfirst and second high-density beta particle impact layers coupled to the third and fourth mesh barriers respectively;fifth and sixth electrically insulating mesh barriers coupled to the first and second beta particle impact layers; andfirst and second photovoltaic layers coupled to the third and fourth electrically insulating mesh barriers. 17. The energy source of claim 16, further comprising the following layers which are interposed between the fifth and sixth mesh barriers and the first and second photovoltaic layers respectively:third and fourth alpha particle impact layers coupled to the fifth and sixth mesh barriers respectively;seventh and eighth electrically insulating mesh barriers coupled to the third and fourth alpha particle impact layers respectively;second and third flexible substrates coated with the radioisotope, wherein the second and third substrates are coupled to the seventh and eighth mesh barriers respectively;ninth and tenth electrically insulating mesh barriers coupled to the second and third substrates respectively;fifth and sixth alpha particle impact layers coupled to the ninth and tenth mesh barriers respectively;eleventh and twelfth electrically insulating mesh barriers coupled to the fifth and sixth alpha particle impact layers respectively; andthird and fourth beta particle impact layers coupled to the eleventh and twelfth mesh barriers respectively and to the first and second photovoltaic layers respectively. 18. A depleted uranium energy source comprising:a flexible center layer of the depleted uranium, wherein the center layer comprises upper and lower surfaces; andtwo substantially identical sequences of layers bonded to the center layer via electrically insulating mesh barriers, one of the sequences being bonded to the upper surface and the other sequence being bonded to the lower surface, wherein the constituent layers of each sequence are bonded to each other via electrically insulating mesh barriers, wherein each sequence comprises the following layers bonded together in a y-direction in the following order:a first low-density alpha particle impact layer,a first high-density beta particle impact layer,a second low-density alpha particle impact layer,a second depleted-uranium-coated substrate,a third low-density alpha particle impact layer,a second high-density beta particle impact layer, anda photovoltaic layer. 19. The depleted uranium energy source of claim 18, wherein the total thickness of the energy source in the y-direction is smaller than the width or length of the energy source in x- and z-directions, and wherein the energy source is rolled into a cylindrical shape.
	description	This application is a continuation-in-part of U.S. patent application Ser. No. 15/892,240 filed Feb. 8, 2018, which is: a continuation-in-part of U.S. patent application Ser. No. 15/838,072 filed Dec. 11, 2017, which is a continuation-in-part of U.S. patent application Ser. No. 15/823,148 filed Nov. 27, 2017, which is a continuation-in-part of U.S. patent application Ser. No. 15/467,840 filed Mar. 23, 2017, which is a continuation-in-part of U.S. patent application Ser. No. 15/402,739 filed Jan. 10, 2017, which is a continuation-in-part of U.S. patent application Ser. No. 15/348,625 filed Nov. 10, 2016, which is a continuation-in-part of U.S. patent application Ser. No. 15/167,617 filed May 27, 2016; and a continuation-in-part of U.S. patent application Ser. No. 15/868,897 filed Jan. 11, 2018, which is a continuation of U.S. patent application Ser. No. 15/152,479 filed May 11, 2016, which is a continuation-in-part of U.S. patent application Ser. No. 14/216,788 filed Mar. 17, 2014, which is a continuation-in-part of U.S. patent application Ser. No. 13/087,096 filed Apr. 14, 2011, which claims benefit of U.S. provisional patent application No. 61/324,776 filed Apr. 16, 2010, all of which are incorporated herein in their entirety by this reference thereto. The invention relates generally to a cancer therapy scanning and/or treatment apparatus and method of use thereof. Cancer Treatment Proton therapy works by aiming energetic ionizing particles, such as protons accelerated with a particle accelerator, onto a target tumor. These particles damage the DNA of cells, ultimately causing their death. Cancerous cells, because of their high rate of division and their reduced ability to repair damaged DNA, are particularly vulnerable to attack on their DNA. Patents related to the current invention are summarized here. Proton Beam Therapy System F. Cole, et. al. of Loma Linda University Medical Center “Multi-Station Proton Beam Therapy System”, U.S. Pat. No. 4,870,287 (Sep. 26, 1989) describe a proton beam therapy system for selectively generating and transporting proton beams from a single proton source and accelerator to a selected treatment room of a plurality of patient treatment rooms. Problem There exists in the art of charged particle cancer therapy a need for safe, accurate, precise, and rapid imaging of a patient and/or treatment of a tumor using charged particles. The invention relates generally to a multi-use magnet in a charged particle cancer therapy system. Elements and steps in the figures are illustrated for simplicity and clarity and have not necessarily been rendered according to any particular sequence. For example, steps that are performed concurrently or in different order are illustrated in the figures to help improve understanding of embodiments of the present invention. The invention comprises a method and apparatus for using a turning magnet of an accelerator of a cancer therapy system, the accelerator comprising first magnet coils and second correction coils wound about a magnet core where: (1) at a first time, the second correction coils are used to correct a magnetic field, resultant from the first magnet coils, used to turn cations and (2) at a second time, after reversing polarity of the correction coils, the correction coils are used to turn anions and/or electrons, the cations and electrons used to treat a tumor of a patient positioned in a treatment position relative to a treatment beam from the accelerator during the first and second time periods. The above described embodiment is optionally used in combination with a proton therapy cancer treatment system and/or a proton tomography imaging system. The above described embodiment is optionally used in combination with a set of fiducial marker detectors configured to detect photons emitted from and/or reflected off of a set of fiducial markers positioned on one or more objects in a treatment room and resultant determined distances and/or calculated angles are used to determine relative positions of multiple objects or elements in the treatment room. Generally, in an iterative process, at a first time objects, such as a treatment beamline output nozzle, a specific portion of a patient relative to a tumor, a scintillation detection material, an X-ray system element, and/or a detection element, are mapped and relative positions and/or angles therebetween are determined. At a second time, the position of the mapped objects is used in: (1) imaging, such as X-ray, positron emission tomography, and/or proton beam imaging and/or (2) beam targeting and treatment, such as positively charged particle based cancer treatment. As relative positions of objects in the treatment room are dynamically determined using the fiducial marking system, engineering and/or mathematical constraints of a treatment beamline isocenter is removed. In combination, a method and apparatus is described for determining a position of a tumor in a patient for treatment of the tumor using positively charged particles in a treatment room. More particularly, the method and apparatus use a set of fiducial markers and fiducial detectors to mark/determine relative position of static and/or moveable objects in a treatment room using photons passing from the markers to the detectors. Further, position and orientation of at least one of the objects is calibrated to a reference line, such as a zero-offset beam treatment line passing through an exit nozzle, which yields a relative position of each fiducially marked object in the treatment room. Treatment calculations are subsequently determined using the reference line and/or points thereon. The inventor notes that the treatment calculations are optionally and preferably performed without use of an isocenter point, such as a central point about which a treatment room gantry rotates, which eliminates mechanical errors associated with the isocenter point being an isocenter volume in practice. In combination, a method and apparatus for imaging a tumor of a patient using positively charged particles and X-rays, comprises the steps of: (1) transporting the positively charged particles from an accelerator to a patient position using a beam transport line, where the beam transport line comprises a positively charged particle beam path and an X-ray beam path; (2) detecting scintillation induced by the positively charged particles using a scintillation detector system; (3) detecting X-rays using an X-ray detector system; (4) positioning a mounting rail through linear extension/retraction to: at a first time and at a first extension position of the mounting rail, position the scintillation detector system opposite the patient position from the exit nozzle and at a second time and at a second extension position of the mounting rail, position the X-ray detector system opposite the patient position from the exit nozzle; (5) generating an image of the tumor using output of the scintillation detector system and the X-ray detector system; and (6) alternating between the step of detecting scintillation and treating the tumor via irradiation of the tumor using the positively charged particles. In combination, a tomography system is optionally used in combination with a charged particle cancer therapy system. The tomography system uses tomography or tomographic imaging, which refers to imaging by sections or sectioning through the use of a penetrating wave, such as a positively charge particle from an injector and/or accelerator. Optionally and preferably, a common injector, accelerator, and beam transport system is used for both charged particle based tomographic imaging and charged particle cancer therapy. In one case, an output nozzle of the beam transport system is positioned with a gantry system while the gantry system and/or a patient support maintains a scintillation plate of the tomography system on the opposite side of the patient from the output nozzle. In another example, a charged particle state determination system, of a cancer therapy system or tomographic imaging system, uses one or more coated layers in conjunction with a scintillation material, scintillation detector and/or a tomographic imaging system at time of tumor and surrounding tissue sample mapping and/or at time of tumor treatment, such as to determine an input vector of the charged particle beam into a patient and/or an output vector of the charged particle beam from the patient. In another example, the charged particle tomography apparatus is used in combination with a charged particle cancer therapy system. For example, tomographic imaging of a cancerous tumor is performed using charged particles generated with an injector, accelerated with an accelerator, and guided with a delivery system. The cancer therapy system uses the same injector, accelerator, and guided delivery system in delivering charged particles to the cancerous tumor. For example, the tomography apparatus and cancer therapy system use a common raster beam method and apparatus for treatment of solid cancers. More particularly, the invention comprises a multi-axis and/or multi-field raster beam charged particle accelerator used in: (1) tomography and (2) cancer therapy. Optionally, the system independently controls patient translation position, patient rotation position, two-dimensional beam trajectory, delivered radiation beam energy, delivered radiation beam intensity, beam velocity, timing of charged particle delivery, and/or distribution of radiation striking healthy tissue. The system operates in conjunction with a negative ion beam source, synchrotron, patient positioning, imaging, and/or targeting method and apparatus to deliver an effective and uniform dose of radiation to a tumor while distributing radiation striking healthy tissue. For clarity of presentation and without loss of generality, throughout this document, treatment systems and imaging systems are described relative to a tumor of a patient. However, more generally any sample is imaged with any of the imaging systems described herein and/or any element of the sample is treated with the positively charged particle beam(s) described herein. Charged Particle Beam Therapy Throughout this document, a charged particle beam therapy system, such as a proton beam, hydrogen ion beam, or carbon ion beam, is described. Herein, the charged particle beam therapy system is described using a proton beam. However, the aspects taught and described in terms of a proton beam are not intended to be limiting to that of a proton beam and are illustrative of a charged particle beam system, a positively charged beam system, and/or a multiply charged particle beam system, such as C4+ or C6+. Any of the techniques described herein are equally applicable to any charged particle beam system. Referring now to FIG. 1A, a charged particle beam system 100 is illustrated. The charged particle beam preferably comprises a number of subsystems including any of: a main controller 110; an injection system 120; a synchrotron 130 that typically includes: (1) an accelerator system 131 and (2) an internal or connected extraction system 134; a radio-frequency cavity system 180; a beam transport system 135; a scanning/targeting/delivery system 140; a nozzle system 146; a patient interface module 150; a display system 160; and/or an imaging system 170. An exemplary method of use of the charged particle beam system 100 is provided. The main controller 110 controls one or more of the subsystems to accurately and precisely deliver protons to a tumor of a patient. For example, the main controller 110 obtains an image, such as a portion of a body and/or of a tumor, from the imaging system 170. The main controller 110 also obtains position and/or timing information from the patient interface module 150. The main controller 110 optionally controls the injection system 120 to inject a proton into a synchrotron 130. The synchrotron typically contains at least an accelerator system 131 and an extraction system 134. The main controller 110 preferably controls the proton beam within the accelerator system, such as by controlling speed, trajectory, and timing of the proton beam. The main controller then controls extraction of a proton beam from the accelerator through the extraction system 134. For example, the controller controls timing, energy, and/or intensity of the extracted beam. The controller 110 also preferably controls targeting of the proton beam through the scanning/targeting/delivery system 140 to the patient interface module 150 or a patient with a patient positioning system. One or more components of the patient interface module 150, such as translational and rotational position of the patient, are preferably controlled by the main controller 110. Further, display elements of the display system 160 are preferably controlled via the main controller 110. Displays, such as display screens, are typically provided to one or more operators and/or to one or more patients. In one embodiment, the main controller 110 times the delivery of the proton beam from all systems, such that protons are delivered in an optimal therapeutic manner to the tumor of the patient. Herein, the main controller 110 refers to a single system controlling the charged particle beam system 100, to a single controller controlling a plurality of subsystems controlling the charged particle beam system 100, or to a plurality of individual controllers controlling one or more sub-systems of the charged particle beam system 100. Referring now to FIG. 42A and FIG. 42B, a multi-layer single-color scintillation detector element 4200, a species of the multi-layer scintillator 4030, is described where each scintillation layer uses the same scintillation material and/or emits the photons in a same wavelength range. As illustrated, the first scintillation layer 4111 is a first red photon emission layer 4210, the second scintillation layer 4114 is a second red photon emission layer 4220, and the third scintillation layer 4116 is a third red photon emission layer 4230. Again, for clarity of presentation, red photons are illustrative of any wavelength range common to all three of the first, second, and third photon emission layers 4210, 4220, 4230. Referring now to FIG. 42B, for a first energy beam, E1, a first intensity/magnitude response shape, R1, or first response curve 4241, such as a relative number of secondary photons, emitted from each of the first, second, and third red photon emission layers 4210, 4220, 4230, is illustrated. Generally, as the residual energy particle beam 267 traverses through the scintillation layers, the residual energy particle beam loses energy and slows down. Slower particles lose more energy per unit distance traversed than the faster particles resulting in still more lost energy and slowing of the particles, which results in a Bragg peak. The number of secondary photons produced is proportional to the amount of energy released by the charged particles into the scintillation material. Thus, as the charged particles progress into the multi-layer scintillator, more photons are generated per millimeter of travel and the shape of the response curve as a function of depth can be related to initial energy of the residual energy particle beam 267 via calibration. Again, energy of the residual energy particle beam 267 is used to generate an image, such as proton computed radiography (pRT) image and/or a proton computed tomography (pCT) image in conjunction with beam scanning, relative movement of the patient 230 relative to the scanning beam, and/or relative rotation of the patient 230 relative to the scanning beam. Referring now to FIG. 1B, an illustrative exemplary embodiment of one version of the charged particle beam system 100 is provided. The number, position, and described type of components is illustrative and non-limiting in nature. In the illustrated embodiment, the injection system 120 or ion source or charged particle beam source generates protons. The injection system 120 optionally includes one or more of: a negative ion beam source, a positive ion beam source, an ion beam focusing lens, and a tandem accelerator. The protons are delivered into a vacuum tube that runs into, through, and out of the synchrotron. The generated protons are delivered along an initial path 262. Optionally, focusing magnets 127, such as quadrupole magnets or injection quadrupole magnets, are used to focus the proton beam path. A quadrupole magnet is a focusing magnet. An injector bending magnet 128 bends the proton beam toward a plane of the synchrotron 130. The focused protons having an initial energy are introduced into an injector magnet 129, which is preferably an injection Lambertson magnet. Typically, the initial beam path 262 is along an axis off of, such as above, a circulating plane of the synchrotron 130. The injector bending magnet 128 and injector magnet 129 combine to move the protons into the synchrotron 130. Main bending magnets, dipole magnets, turning magnets, or circulating magnets 132 are used to turn the protons along a circulating beam path 164. A dipole magnet is a bending magnet. The main bending magnets 132 bend the initial beam path 262 into a circulating beam path 164. In this example, the main bending magnets 132 or circulating magnets are represented as four sets of four magnets to maintain the circulating beam path 164 into a stable circulating beam path. However, any number of magnets or sets of magnets are optionally used to move the protons around a single orbit in the circulation process. The protons pass through an accelerator 133. The accelerator accelerates the protons in the circulating beam path 164. As the protons are accelerated, the fields applied by the magnets are increased. Particularly, the speed of the protons achieved by the accelerator 133 are synchronized with magnetic fields of the main bending magnets 132 or circulating magnets to maintain stable circulation of the protons about a central point or region 136 of the synchrotron. At separate points in time the accelerator 133/main bending magnet 132 combination is used to accelerate and/or decelerate the circulating protons while maintaining the protons in the circulating path or orbit. An extraction element of an inflector/deflector system is used in combination with a Lambertson extraction magnet 137 to remove protons from their circulating beam path 164 within the synchrotron 130. One example of a deflector component is a Lambertson magnet. Typically the deflector moves the protons from the circulating plane to an axis off of the circulating plane, such as above the circulating plane. Extracted protons are preferably directed and/or focused using an extraction bending magnet 142 and optional extraction focusing magnets 141, such as quadrupole magnets, and optional bending magnets along a positively charged particle beam transport path 268 in a beam transport system 135, such as a beam path or proton beam path, into the scanning/targeting/delivery system 140. Two components of a scanning system 140 or targeting system typically include a first axis controller 143, such as a vertical control, and a second axis controller 144, such as a horizontal control. In one embodiment, the first axis controller 143 allows for about 100 mm of vertical or y-axis scanning of the proton beam 268 and the second axis controller 144 allows for about 700 mm of horizontal or x-axis scanning of the proton beam 268. A nozzle system 146 is used for directing the proton beam, for imaging the proton beam, for defining shape of the proton beam, and/or as a vacuum barrier between the low pressure beam path of the synchrotron and the atmosphere. Protons are delivered with control to the patient interface module 150 and to a tumor of a patient. All of the above listed elements are optional and may be used in various permutations and combinations. Ion Extraction from Ion Source For clarity of presentation and without loss of generality, examples focus on protons from the ion source. However, more generally cations of any charge are optionally extracted from a corresponding ion source with the techniques described herein. For instance, C4+ or C6+ are optionally extracted using the ion extraction methods and apparatus described herein. Further, by reversing polarity of the system, anions are optionally extracted from an anion source, where the anion is of any charge. Herein, for clarity of presentation and without loss of generality, ion extraction is coupled with tumor treatment and/or tumor imaging. However, the ion extraction is optional used in any method or apparatus using a stream or time discrete bunches of ions. Ion Extraction from Accelerator Referring now to FIG. 1C, both: (1) an exemplary proton beam extraction system 215 from the synchrotron 130 and (2) a charged particle beam intensity control system 225 are illustrated. For clarity, FIG. 1C removes elements represented in FIG. 1B, such as the turning magnets, which allows for greater clarity of presentation of the proton beam path as a function of time. Generally, protons are extracted from the synchrotron 130 by slowing the protons. As described, supra, the protons were initially accelerated in a circulating path, which is maintained with a plurality of main bending magnets 132. The circulating path is referred to herein as an original central beamline 264. The protons repeatedly cycle around a central point in the synchrotron 136. The proton path traverses through a radio frequency (RF) cavity system 310. To initiate extraction, an RF field is applied across a first blade 312 and a second blade 314, in the RF cavity system 310. The first blade 312 and second blade 314 are referred to herein as a first pair of blades. In the proton extraction process, an RF voltage is applied across the first pair of blades, where the first blade 312 of the first pair of blades is on one side of the circulating proton beam path 264 and the second blade 314 of the first pair of blades is on an opposite side of the circulating proton beam path 264. The applied RF field applies energy to the circulating charged-particle beam. The applied RF field alters the orbiting or circulating beam path slightly of the protons from the original central beamline 264 to an altered circulating beam path 265. Upon a second pass of the protons through the RF cavity system, the RF field further moves the protons off of the original proton beamline 264. For example, if the original beamline is considered as a circular path, then the altered beamline is slightly elliptical. The frequency of the applied RF field is timed to apply outward or inward movement to a given band of protons circulating in the synchrotron accelerator. Orbits of the protons are slightly more off axis compared to the original circulating beam path 264. Successive passes of the protons through the RF cavity system are forced further and further from the original central beamline 264 by altering the direction and/or intensity of the RF field with each successive pass of the proton beam through the RF field. Timing of application of the RF field and/or frequency of the RF field is related to the circulating charged particles circulation pathlength in the synchrotron 130 and the velocity of the charged particles so that the applied RF field has a period, with a peak-to-peak time period, equal to a period of time of beam circulation in the synchrotron 130 about the center 136 or an integer multiple of the time period of beam circulation about the center 136 of the synchrotron 130. Alternatively, the time period of beam circulation about the center 136 of the synchrotron 130 is an integer multiple of the RF period time. The RF period is optionally used to calculated the velocity of the charged particles, which relates directly to the energy of the circulating charged particles. The RF voltage is frequency modulated at a frequency about equal to the period of one proton cycling around the synchrotron for one revolution or at a frequency than is an integral multiplier of the period of one proton cycling about the synchrotron. The applied RF frequency modulated voltage excites a betatron oscillation. For example, the oscillation is a sine wave motion of the protons. The process of timing the RF field to a given proton beam within the RF cavity system is repeated thousands of times with each successive pass of the protons being moved approximately one micrometer further off of the original central beamline 264. For clarity, the approximately 1000 changing beam paths with each successive path of a given band of protons through the RF field are illustrated as the altered beam path 265. The RF time period is process is known, thus energy of the charged particles at time of hitting the extraction material 330, described infra, is known. With a sufficient sine wave betatron amplitude, the altered circulating beam path 265 touches and/or traverses a extraction material 330, such as a foil or a sheet of foil. The foil is preferably a lightweight material, such as beryllium, a lithium hydride, a carbon sheet, or a material having low nuclear charge components. Herein, a material of low nuclear charge is a material composed of atoms consisting essentially of atoms having six or fewer protons. The foil is preferably about 10 to 150 microns thick, is more preferably about 30 to 100 microns thick, and is still more preferably about 40 to 60 microns thick. In one example, the foil is beryllium with a thickness of about 50 microns. When the protons traverse through the foil, energy of the protons is lost and the speed of the protons is reduced. Typically, a current is also generated, described infra. Protons moving at the slower speed travel in the synchrotron with a reduced radius of curvature 266 compared to either the original central beamline 264 or the altered circulating path 265. The reduced radius of curvature 266 path is also referred to herein as a path having a smaller diameter of trajectory or a path having protons with reduced energy. The reduced radius of curvature 266 is typically about two millimeters less than a radius of curvature of the last pass of the protons along the altered proton beam path 265. The thickness of the extraction material 330 is optionally adjusted to create a change in the radius of curvature, such as about ½, 1, 2, 3, or 4 mm less than the last pass of the protons 265 or original radius of curvature 264. The reduction in velocity of the charged particles transmitting through the extraction material 330 is calculable, such as by using the pathlength of the betatron oscillating charged particle beam through the extraction material 330 and/or using the density of the extraction material 330. Protons moving with the smaller radius of curvature travel between a second pair of blades. In one case, the second pair of blades is physically distinct and/or is separated from the first pair of blades. In a second case, one of the first pair of blades is also a member of the second pair of blades. For example, the second pair of blades is the second blade 314 and a third blade 316 in the RF cavity system 310. A high voltage DC signal, such as about 1 to 5 kV, is then applied across the second pair of blades, which directs the protons out of the synchrotron through an extraction magnet 137, such as a Lambertson extraction magnet, into a transport path 268. Control of acceleration of the charged particle beam path in the synchrotron with the accelerator and/or applied fields of the turning magnets in combination with the above described extraction system allows for control of the intensity of the extracted proton beam, where intensity is a proton flux per unit time or the number of protons extracted as a function of time. For example, when a current is measured beyond a threshold, the RF field modulation in the RF cavity system is terminated or reinitiated to establish a subsequent cycle of proton beam extraction. This process is repeated to yield many cycles of proton beam extraction from the synchrotron accelerator. In another embodiment, instead of moving the charged particles to the extraction material 330, the extraction material 330 is mechanically moved to the circulating charged particles. Particularly, the extraction material 330 is mechanically or electromechanically translated into the path of the circulating charged particles to induce the extraction process, described supra. In this case, the velocity or energy of the circulating charged particle beam is calculable using the pathlength of the beam path about the center 136 of the synchrotron 130 and from the force applied by the bending magnets 132. In either case, because the extraction system does not depend on any change in magnetic field properties, it allows the synchrotron to continue to operate in acceleration or deceleration mode during the extraction process. Stated differently, the extraction process does not interfere with synchrotron acceleration. In stark contrast, traditional extraction systems introduce a new magnetic field, such as via a hexapole, during the extraction process. More particularly, traditional synchrotrons have a magnet, such as a hexapole magnet, that is off during an acceleration stage. During the extraction phase, the hexapole magnetic field is introduced to the circulating path of the synchrotron. The introduction of the magnetic field necessitates two distinct modes, an acceleration mode and an extraction mode, which are mutually exclusive in time. The herein described system allows for acceleration and/or deceleration of the proton during the extraction step and tumor treatment without the use of a newly introduced magnetic field, such as by a hexapole magnet. Charged Particle Beam Intensity Control Control of applied field, such as a radio-frequency (RF) field, frequency and magnitude in the RF cavity system 310 allows for intensity control of the extracted proton beam, where intensity is extracted proton flux per unit time or the number of protons extracted as a function of time. Still referring FIG. 3, the intensity control system 225 is further described. In this example, an intensity control feedback loop is added to the extraction system, described supra. When protons in the proton beam hit the extraction material 330 electrons are given off from the extraction material 330 resulting in a current. The resulting current is converted to a voltage and is used as part of an ion beam intensity monitoring system or as part of an ion beam feedback loop for controlling beam intensity. The voltage is optionally measured and sent to the main controller 110 or to an intensity controller subsystem 340, which is preferably in communication or under the direction of the main controller 110. More particularly, when protons in the charged particle beam path pass through the extraction material 330, some of the protons lose a small fraction of their energy, such as about one-tenth of a percent, which results in a secondary electron. That is, protons in the charged particle beam push some electrons when passing through extraction material 330 giving the electrons enough energy to cause secondary emission. The resulting electron flow results in a current or signal that is proportional to the number of protons going through the target or extraction material 330. The resulting current is preferably converted to voltage and amplified. The resulting signal is referred to as a measured intensity signal. The amplified signal or measured intensity signal resulting from the protons passing through the extraction material 330 is optionally used in monitoring the intensity of the extracted protons and is preferably used in controlling the intensity of the extracted protons. For example, the measured intensity signal is compared to a goal signal, which is predetermined in an irradiation of the tumor plan. The difference between the measured intensity signal and the planned for goal signal is calculated. The difference is used as a control to the RF generator. Hence, the measured flow of current resulting from the protons passing through the extraction material 330 is used as a control in the RF generator to increase or decrease the number of protons undergoing betatron oscillation and striking the extraction material 330. Hence, the voltage determined off of the extraction material 330 is used as a measure of the orbital path and is used as a feedback control to control the RF cavity system. In one example, the intensity controller subsystem 340 preferably additionally receives input from: (1) a detector 350, which provides a reading of the actual intensity of the proton beam and/or (2) an irradiation plan 360. The irradiation plan provides the desired intensity of the proton beam for each x, y, energy, and/or rotational position of the patient/tumor as a function of time. Thus, the intensity controller 340 receives the desired intensity from the irradiation plan 350, the actual intensity from the detector 350 and/or a measure of intensity from the extraction material 330, and adjusts the amplitude and/or the duration of application of the applied radio-frequency field in the RF cavity system 310 to yield an intensity of the proton beam that matches the desired intensity from the irradiation plan 360. As described, supra, the protons striking the extraction material 330 is a step in the extraction of the protons from the synchrotron 130. Hence, the measured intensity signal is used to change the number of protons per unit time being extracted, which is referred to as intensity of the proton beam. The intensity of the proton beam is thus under algorithm control. Further, the intensity of the proton beam is controlled separately from the velocity of the protons in the synchrotron 130. Hence, intensity of the protons extracted and the energy of the protons extracted are independently variable. Still further, the intensity of the extracted protons is controllably variable while scanning the charged particles beam in the tumor from one voxel to an adjacent voxel as a separate hexapole and separated time period from acceleration and/or treatment is not required, as described supra. For example, protons initially move at an equilibrium trajectory in the synchrotron 130. An RF field is used to excite or move the protons into a betatron oscillation. In one case, the frequency of the protons orbit is about 10 MHz. In one example, in about one millisecond or after about 10,000 orbits, the first protons hit an outer edge of the target material 130. The specific frequency is dependent upon the period of the orbit. Upon hitting the material 130, the protons push electrons through the foil to produce a current. The current is converted to voltage and amplified to yield a measured intensity signal. The measured intensity signal is used as a feedback input to control the applied RF magnitude or RF field. An energy beam sensor, described infra, is optionally used as a feedback control to the RF field frequency or RF field of the RF field extraction system 310 to dynamically control, modify, and/or alter the delivered charge particle beam energy, such as in a continuous pencil beam scanning system operating to treat tumor voxels without alternating between an extraction phase and a treatment phase. Preferably, the measured intensity signal is compared to a target signal and a measure of the difference between the measured intensity signal and target signal is used to adjust the applied RF field in the RF cavity system 310 in the extraction system to control the intensity of the protons in the extraction step. Stated again, the signal resulting from the protons striking and/or passing through the material 130 is used as an input in RF field modulation. An increase in the magnitude of the RF modulation results in protons hitting the foil or material 130 sooner. By increasing the RF, more protons are pushed into the foil, which results in an increased intensity, or more protons per unit time, of protons extracted from the synchrotron 130. In another example, a detector 350 external to the synchrotron 130 is used to determine the flux of protons extracted from the synchrotron and a signal from the external detector is used to alter the RF field, RF intensity, RF amplitude, and/or RF modulation in the RF cavity system 310. Here the external detector generates an external signal, which is used in a manner similar to the measured intensity signal, described in the preceding paragraphs. Preferably, an algorithm or irradiation plan 360 is used as an input to the intensity controller 340, which controls the RF field modulation by directing the RF signal in the betatron oscillation generation in the RF cavity system 310. The irradiation plan 360 preferably includes the desired intensity of the charged particle beam as a function of time and/or energy of the charged particle beam as a function of time, for each patient rotation position, and/or for each x-, y-position of the charged particle beam. In yet another example, when a current from extraction material 330 resulting from protons passing through or hitting material is measured beyond a threshold, the RF field modulation in the RF cavity system is terminated or reinitiated to establish a subsequent cycle of proton beam extraction. This process is repeated to yield many cycles of proton beam extraction from the synchrotron accelerator. In still yet another embodiment, intensity modulation of the extracted proton beam is controlled by the main controller 110. The main controller 110 optionally and/or additionally controls timing of extraction of the charged particle beam and energy of the extracted proton beam. The benefits of the system include a multi-dimensional scanning system. Particularly, the system allows independence in: (1) energy of the protons extracted and (2) intensity of the protons extracted. That is, energy of the protons extracted is controlled by an energy control system and an intensity control system controls the intensity of the extracted protons. The energy control system and intensity control system are optionally independently controlled. Preferably, the main controller 110 controls the energy control system and the main controller 110 simultaneously controls the intensity control system to yield an extracted proton beam with controlled energy and controlled intensity where the controlled energy and controlled intensity are independently variable and/or continually available as a separate extraction phase and acceleration phase are not required, as described supra. Thus the irradiation spot hitting the tumor is under independent control of: time; energy; intensity; x-axis position, where the x-axis represents horizontal movement of the proton beam relative to the patient, and y-axis position, where the y-axis represents vertical movement of the proton beam relative to the patient. In addition, the patient is optionally independently translated and/or rotated relative to a translational axis of the proton beam at the same time. Beam Transport The beam transport system 135 is used to move the charged particles from the accelerator to the patient, such as via a nozzle in a gantry, described infra. Nozzle After extraction from the synchrotron 130 and transport of the charged particle beam along the proton beam path 268 in the beam transport system 135, the charged particle beam exits through the nozzle system 146. In one example, the nozzle system includes a nozzle foil covering an end of the nozzle system 146 or a cross-sectional area within the nozzle system forming a vacuum seal. The nozzle system includes a nozzle that expands in x/y-cross-sectional area along the z-axis of the proton beam path 268 to allow the proton beam 268 to be scanned along the x-axis and y-axis by the vertical control element and horizontal control element, respectively. The nozzle foil is preferably mechanically supported by the outer edges of an exit port of the nozzle or nozzle system 146. An example of a nozzle foil is a sheet of about 0.1 inch thick aluminum foil. Generally, the nozzle foil separates atmosphere pressures on the patient side of the nozzle foil from the low pressure region, such as about 10−5 to 10−7 torr region, on the synchrotron 130 side of the nozzle foil. The low pressure region is maintained to reduce scattering of the circulating charged particle beam in the synchrotron. Herein, the exit foil of the nozzle is optionally the first tracking plane 760. tracking sheet, or sheet of the charged particle beam state determination system 250, described infra. Tomography/Beam State In one embodiment, the charged particle tomography apparatus is used to image a tumor in a patient. As current beam position determination/verification is used in both tomography and cancer therapy treatment, for clarity of presentation and without limitation beam state determination is also addressed in this section. However, beam state determination is optionally used separately and without tomography. In another example, the charged particle tomography apparatus is used in combination with a charged particle cancer therapy system using common elements. For example, tomographic imaging of a cancerous tumor is performed using charged particles generated with an injector, accelerator, and guided with a delivery system that are part of the cancer therapy system, described supra. In various examples, the tomography imaging system is optionally simultaneously operational with a charged particle cancer therapy system using common elements, allows tomographic imaging with rotation of the patient, is operational on a patient in an upright, semi-upright, and/or horizontal position, is simultaneously operational with X-ray imaging, and/or allows use of adaptive charged particle cancer therapy. Further, the common tomography and cancer therapy apparatus elements are optionally operational in a multi-axis and/or multi-field raster beam mode. In conventional medical X-ray tomography, a sectional image through a body is made by moving one or both of an X-ray source and the X-ray film in relative to the patient during the exposure. By modifying the direction and extent of the movement, operators can select different focal planes, which contain the structures of interest. More modern variations of tomography involve gathering projection data from multiple directions by moving the X-ray source and feeding the data into a tomographic reconstruction software algorithm processed by a computer. Herein, in stark contrast to known methods, the radiation source is a charged particle, such as a proton ion beam or a carbon ion beam. A proton beam is used herein to describe the tomography system, but the description applies to a heavier ion beam, such as a carbon ion beam. Further, in stark contrast to known techniques, herein the radiation source is optionally stationary while the patient is rotated. Referring now to FIG. 2, an example of a tomography apparatus is described and an example of a beam state determination is described. In this example, the tomography system 200 uses elements in common with the charged particle beam system 100, including elements of one or more of the injection system 120, the accelerator 130, a positively charged particle beam transport path 268 within a beam transport housing 261 in the beam transport system 135, the targeting/delivery system 140, the patient interface module 150, the display system 160, and/or the imaging system 170, such as the X-ray imaging system. The scintillation material is optionally one or more scintillation plates, such as a scintillating plastic, used to measure energy, intensity, and/or position of the charged particle beam. For instance, a scintillation material of scintillation detector element 205 of a scintillation detector system 210 or scintillation plate is positioned behind the patient 230 relative to the targeting/delivery system 140 elements, which is optionally used to measure intensity and/or position of the charged particle beam after transmitting through the patient. Optionally, a second scintillation plate or a charged particle induced photon emitting sheet, described infra, is positioned prior to the patient 230 relative to the targeting/delivery system 140 elements, which is optionally used to measure incident intensity and/or position of the charged particle beam prior to transmitting through the patient. The charged particle beam system 100 as described has proven operation at up to and including 330 MeV, which is sufficient to send protons through the body and into contact with the scintillation material. Particularly, 250 MeV to 330 MeV are used to pass the beam through a standard sized patient with a standard sized pathlength, such as through the chest. The intensity or count of protons hitting the plate as a function of position is used to create an image. The velocity or energy of the proton hitting the scintillation plate is also used in creation of an image of the tumor 220 and/or an image of the patient 230. The patient 230 is rotated about the y-axis and a new image is collected. Preferably, a new image is collected with about every one degree of rotation of the patient resulting in about 360 images that are combined into a tomogram using tomographic reconstruction software. The tomographic reconstruction software uses overlapping rotationally varied images in the reconstruction. Optionally, a new image is collected at about every 2, 3, 4, 5, 10, 15, 30, or 45 degrees of rotation of the patient. Herein, the scintillation material or scintillator, of the scintillation detection system, is any material that emits a photon when struck by a positively charged particle or when a positively charged particle transfers energy to the scintillation material sufficient to cause emission of light. Optionally, the scintillation material emits the photon after a delay, such as in fluorescence or phosphorescence. However, preferably, the scintillator has a fast fifty percent quench time, such as less than 0.0001, 0.001, 0.01, 0.1, 1, 10, 100, or 1,000 milliseconds, so that the light emission goes dark, falls off, or terminates quickly. Preferred scintillation materials include sodium iodide, potassium iodide, cesium iodide, an iodide salt, and/or a doped iodide salt. Additional examples of the scintillation materials include, but are not limited to: an organic crystal, a plastic, a glass, an organic liquid, a luminophor, and/or an inorganic material or inorganic crystal, such as barium fluoride, BaF2; calcium fluoride, CaF2, doped calcium fluoride, sodium iodide, NaI; doped sodium iodide, sodium iodide doped with thallium, NaI(Tl); cadmium tungstate, CdWO4; bismuth germanate; cadmium tungstate, CdWO4; calcium tungstate, CaWO4; cesium iodide, CsI; doped cesium iodide; cesium iodide doped with thallium, CsI(Tl); cesium iodide doped with sodium CsI(Na); potassium iodide, KI; doped potassium iodide, gadolinium oxysulfide, Gd2O2S; lanthanum bromide doped with cerium, LaBr3(Ce); lanthanum chloride, LaCl3; cesium doped lanthanum chloride, LaCl3(Ce); lead tungstate, PbWO4; LSO or lutetium oxyorthosilicate (Lu2SiO5); LYSO, Lu1.8Y0.2SiO5(Ce); yttrium aluminum garnet, YAG(Ce); zinc sulfide, ZnS(Ag); and zinc tungstate, ZnWO4. In one embodiment, a tomogram or an individual tomogram section image is collected at about the same time as cancer therapy occurs using the charged particle beam system 100. For example, a tomogram is collected and cancer therapy is subsequently performed: without the patient moving from the positioning systems, such as in a semi-vertical partial immobilization system, a sitting partial immobilization system, or the a laying position. In a second example, an individual tomogram slice is collected using a first cycle of the accelerator 130 and using a following cycle of the accelerator 130, the tumor 220 is irradiated, such as within about 1, 2, 5, 10, 15 or 30 seconds. In a third case, about 2, 3, 4, or 5 tomogram slices are collected using 1, 2, 3, 4, or more rotation positions of the patient 230 within about 5, 10, 15, 30, or 60 seconds of subsequent tumor irradiation therapy. In another embodiment, the independent control of the tomographic imaging process and X-ray collection process allows simultaneous single and/or multi-field collection of X-ray images and tomographic images easing interpretation of multiple images. Indeed, the X-ray and tomographic images are optionally overlaid and/or integrated to from a hybrid X-ray/proton beam tomographic image as the patient 230 is optionally in the same position for each image. In still another embodiment, the tomogram is collected with the patient 230 in the about the same position as when the patient's tumor is treated using subsequent irradiation therapy. For some tumors, the patient being positioned in the same upright or semi-upright position allows the tumor 220 to be separated from surrounding organs or tissue of the patient 230 better than in a laying position. Positioning of the scintillation material, in the scintillation detector system 210, behind the patient 230 allows the tomographic imaging to occur while the patient is in the same upright or semi-upright position. The use of common elements in the tomographic imaging and in the charged particle cancer therapy allows benefits of the cancer therapy, described supra, to optionally be used with the tomographic imaging, such as proton beam x-axis control, proton beam y-axis control, control of proton beam energy, control of proton beam intensity, timing control of beam delivery to the patient, rotation control of the patient, and control of patient translation all in a raster beam mode of proton energy delivery. The use of a single proton or cation beamline for both imaging and treatment eases patient setup, reduces alignment uncertainties, reduces beam state uncertainties, and eases quality assurance. In yet still another embodiment, initially a three-dimensional tomographic X-ray and/or proton based reference image is collected, such as with hundreds of individual rotation images of the tumor 220 and patient 230. Subsequently, just prior to proton treatment of the cancer, just a few 2-dimensional control tomographic images of the patient are collected, such as with a stationary patient or at just a few rotation positions, such as an image straight on to the patient, with the patient rotated about 45 degrees each way, and/or the X-ray source and/or patient rotated about 90 degrees each way about the y-axis. The individual control images are compared with the 3-dimensional reference image. An adaptive proton therapy is optionally subsequently performed where: (1) the proton cancer therapy is not used for a given position based on the differences between the 3-dimensional reference image and one or more of the 2-dimensional control images and/or (2) the proton cancer therapy is modified in real time based on the differences between the 3-dimensional reference image and one or more of the 2-dimensional control images. Charged Particle State Determination/Verification/Photonic Monitoring Still referring to FIG. 2, the tomography system 200 is optionally used with a charged particle beam state determination system 250, optionally used as a charged particle verification system. The charged particle state determination system 250 optionally measures, determines, and/or verifies one of more of: (1) position of the charged particle beam, such as a treatment beam 269, (2) direction of the treatment beam 269, (3) intensity of the treatment beam 269, (4) energy of the treatment beam 269, (5) position, direction, intensity, and/or energy of the charged particle beam, such as a residual charged particle beam 267 after passing through a sample or the patient 230, and/or (6) a history of the charged particle beam. For clarity of presentation and without loss of generality, a description of the charged particle beam state determination system 250 is described and illustrated separately in FIG. 3 and FIG. 4A; however, as described herein elements of the charged particle beam state determination system 250 are optionally and preferably integrated into the nozzle system 146 and/or the tomography system 200 of the charged particle treatment system 100. More particularly, any element of the charged particle beam state determination system 250 is integrated into the nozzle system 146, a dynamic gantry nozzle, and/or tomography system 200. The tomography system detects secondary electrons, resultant from the positively charged particles, and/or uses a scintillation material of a scintillation detector element 205, scintillation plate, or scintillation detector system 210. The nozzle system 146 or the dynamic gantry nozzle provides an outlet of the charged particle beam from the vacuum tube initiating at the injection system 120 and passing through the synchrotron 130 and beam transport system 135. Any plate, tracking plane, sheet, fluorophore, or detector of the charged particle beam state determination system is optionally integrated into the nozzle system 146. For example, an exit foil of the nozzle is optionally a first sheet 252 of the charged particle beam state determination system 250 and a first coating 254 is optionally coated onto the exit foil, as illustrated in FIG. 2. Similarly, optionally a surface of the scintillation material is a support surface for a fourth coating 292, as illustrated in FIG. 2. The charged particle beam state determination system 250 is further described, infra. Referring now to FIG. 2, FIG. 3, and FIG. 4A, four tracking planes and/or four sheets, such as a first tracking plane 260 or a first sheet 252, a second tracking plane 270 or second sheet, a third tracking plane 280 or third sheet, and a fourth tracking plane 290 or fourth sheet are used to illustrate detection sheets and/or photon emitting sheets upon transmittance of a charged particle beam. Each sheet is optionally coated with a photon emitter, such as a fluorophore, such as the first sheet 252 is optionally coated with a first coating 254. Without loss of generality and for clarity of presentation, the four tracking planes are each illustrated as units, where the light emitting layer is not illustrated. Thus, for example, the second tracking plane 270 optionally refers to a support sheet, a light emitting sheet, and/or a support sheet coated by a light emitting element. The four tracking planes are representative of n tracking planes, where n is a positive integer. Referring now to FIG. 2 and FIG. 3, the charged particle beam state verification system 250 is a system that allows for monitoring of the actual charged particle beam position in real-time without destruction of the charged particle beam. The charged particle beam state verification system 250 preferably includes a first position element or first beam verification layer, which is also referred to herein as a coating, luminescent, fluorescent, phosphorescent, radiance, or viewing layer. The first position element optionally and preferably includes a coating or thin layer substantially in contact with a sheet, such as an inside surface of the nozzle foil, where the inside surface is on the synchrotron side of the nozzle foil. Less preferably, the verification layer or coating layer is substantially in contact with an outer surface of the nozzle foil, where the outer surface is on the patient treatment side of the nozzle foil. Preferably, the nozzle foil provides a substrate surface for coating by the coating layer. Optionally, a binding layer is located between the coating layer and the nozzle foil, substrate, or support sheet. Optionally, the position element is placed anywhere in the charged particle beam path. Optionally, more than one position element on more than one sheet, respectively, is used in the charged particle beam path and is used to determine a state property of the charged particle beam, as described infra. Still referring to FIG. 2 and FIG. 3, the coating, referred to as a fluorophore, yields a measurable spectroscopic response, spatially viewable by a detector or camera, as a result of transmission by the proton beam. The coating is preferably a phosphor, but is optionally any material that is viewable or imaged by a detector where the material changes, as viewed spectroscopically, as a result of the charged particle beam hitting or transmitting through the coating or coating layer. A detector or camera views secondary photons emitted from the coating layer and determines a position of a treatment beam 269, which is also referred to as a current position of the charged particle beam or final treatment vector of the charged particle beam, by the spectroscopic differences resulting from protons and/or charged particle beam passing through the coating layer. For example, the camera views a surface of the coating surface as the proton beam or positively charged cation beam is being scanned by the first axis controller 143, vertical control, and the second axis controller 144, horizontal control, beam position control elements during treatment of the tumor 220. The camera views the current position of the charged particle beam or treatment beam 269 as measured by spectroscopic response. The coating layer is preferably a phosphor or luminescent material that glows and/or emits photons for a short period of time, such as less than 5 seconds for a 50% intensity, as a result of excitation by the charged particle beam. The detector observes the temperature change and/or observe photons emitted from the charged particle beam traversed spot. Optionally, a plurality of cameras or detectors are used, where each detector views all or a portion of the coating layer. For example, two detectors are used where a first detector views a first half of the coating layer and the second detector views a second half of the coating layer. Preferably, at least a portion of the detector is mounted into the nozzle system to view the proton beam position after passing through the first axis and second axis controllers 143, 144. Preferably, the coating layer is positioned in the proton beam path 268 in a position prior to the protons striking the patient 230. Referring now to FIG. 1 and FIG. 2, the main controller 110, connected to the camera or detector output, optionally and preferably compares the final proton beam position or position of the treatment beam 269 with the planned proton beam position and/or a calibration reference, such as a calibrated beamline, to determine if the actual proton beam position or position of the treatment beam 269 is within tolerance. The charged particle beam state determination system 250 preferably is used in one or more phases, such as a calibration phase, a mapping phase, a beam position verification phase, a treatment phase, and a treatment plan modification phase. The calibration phase is used to correlate, as a function of x-, y-position of the first axis controller 143 and the second axis controller 144 response the actual x-, y-position of the proton beam at the patient interface. During the treatment phase, the charged particle beam position is monitored and compared to the calibration and/or treatment plan to verify accurate proton delivery to the tumor 220 and/or as a charged particle beam shutoff safety indicator. Referring now to FIG. 5, a position verification system 179 and/or a treatment delivery control system 112, upon determination of a tumor shift, an unpredicted tumor distortion upon treatment, and/or a treatment anomaly optionally generates and or provides a recommended treatment change 1070. The treatment change 1070 is optionally sent out while the patient 230 is still in the treatment position, such as to a proximate physician, through a communication system to a remote physician located outside of the treatment room and not in a direct line of sight of the patient in the treatment position, such as no line of sight through a window between a control room and the patient in the treatment room, and/or over the internet to a remote physician, for physician approval 1072, receipt of which allows continuation of the now modified and approved treatment plan. Referring now to FIG. 43A and FIG. 43B, a multi-layer multi-color scintillation detector element 4300, a species of the multi-layer scintillator 4030, is described where at least two z-axis layers differ in wavelength ranges of emitted secondary photons. As illustrated, the first scintillation layer 4111 is the first red (R) photon emission layer 4210, the second scintillation layer 4114 is a green (G) photon emission layer 4320, and the third scintillation layer 4116 is a blue (B) photon emission layer 4330. Again, for clarity of presentation, red, green, and blue photons are illustrative of a set of wavelength ranges of the respective first, second, and third photon emission layers 4210, 4220, 4230 and emission wavelengths include ultraviolet and infrared light. Use of different scintillation materials emitting light in differing wavelength regions is optionally and preferably used to enhance resolution of a depth of penetration and/or an original energy of the residual energy particle beam 267 through reduction of cross-talk between layers. To clarify, in the case of a standard camera using a Bayer matrix, elements covered by filters are used to detect red, green, or blue light, where standard detector arrays provide x/y-plane resolution and the standard Bayer matrix yields z-axis resolution of position the charged particle beam. Optionally and preferably, one or more two-dimensional detector arrays are optically coupled to a set of transmission filters with out of emission band blocking elements are keyed, respectively, to wavelengths of emissions from a set emission layers with corresponding emission elements in the multi-layer scintillator 4030. Referring still to FIG. 43A and FIG. 43B, the multi-layer multi-color scintillation detector element 4300 is further described. For clarity of presentation and without loss of generality, a blue (B) emission scintillation layer, such as the third emission layer 4330 has a greater responsivity, photons emitted per millimeter of beam travel, than a green (G) emission scintillation layer, such as the second emission layer 4320, which has a greater responsivity than a red (R) emission scintillation layer, such as the first red (R) photon emission layer 4210 described in the second example. Thus, in a first case of a red scintillator used in each of the first, second, and third scintillation layers, the first response curve 4241, described in the first example, is generated. Similarly, in a second case of a green scintillator used in each of the first, second, and third scintillation layer, a second response curve 4242 is generated. Similarly, in a third case of a blue scintillator used in each of the first, second, and third scintillation layer, a third response curve 4243 is generated. Referring now to FIG. 43B, for a given depth, the more responsive blue emission scintillation layer yields a higher signal than the less responsive green emission scintillation layer, which yields a greater response than the still less responsive red emission scintillation layer. Further, the spread between the exemplary response curves increases with depth of penetration of the charged particles into the multi-layer scintillator 4030 as a greater lost energy, resultant in the higher response, slows the charged particles more resulting in a still greater loss of energy of the charged particle, as described supra. Thus, three unique response curves are generated; in this example, all of the response curves having a non-linear shape. Referring still to FIG. 43A and FIG. 43B and referring now to FIG. 43C, the multi-layer multi-color scintillation detector element 4300 is further described. In FIG. 43C, the first response of the first red (R) photon emission layer 4210 at the first depth is plotted with both the second response of the green photon emission layer 4320 at the second depth and the third response of the blue photon emission layer 4330 at the third depth. By effectively using the first point of the first response curve 4241, the second point of the second response curve 4242, and the third point of the third response curve 4243, relative to the first, second, and third response curves, an amplified response curve with a greater slope and an enhanced curve shape is generated, which is referred to herein as a first multi-color response curve 4251. The first multi-color response curve is combined and compared with additional multi-color response curves, as further described infra. Referring now to FIG. 44, a stacked detector element 4400 of the beam state, position and/or residual energy, determination system 4000 is described. The stacked detector element includes multiple sub-stacks, where each sub-stack is a unit block of two or more scintillation layers of different wavelength of emission. As illustrated, for clarity of presentation and without loss of generality, the stacked detector element 4400 comprises four repeating sub-stacks with three scintillation layers per sub-stack. As illustrated, the first sub-stack 4301 is a first set of red, green, and blue scintillation layers, such as the multi-layer multi-color scintillation detector element 4300. A second sub-stack 4302, a third sub-stack 4303, and a fourth sub-stack 4304 are repeating units of the first sub-stack 4301, where the set of sub-stacks are optionally close packed along the z-axis and/or as illustrated have a small gap between each sub-stack. More generally, the sub-stack comprises any number of scintillation layers and any number of scintillation colors where the scintillation colors are ordered in any order along the z-axis of the charged particles. Further, the stacked detector element 4400 optionally contains different types of sub-stacks, such as 2, 3, 4, or more color sub-stacks. Still further, each layer of a given sub-stack type is optionally any thickness, such as thicker or thinner than a neighboring layer along the z-axis. Still referring to FIG. 44, a set of response curves 4250 are plotted for a first residual charged particle beam 267 at a first energy, E1, that transmits through the stacked detector element 4400. As illustrated, a first member of the set of response curves is the first multi-color response curve 4251, described supra, related to the charged particles passing through the first sub-stack 4301. As the charged particles penetrate into the second sub-stack 4302, the charged particles continue to lose energy, which results in a second multi-color response curve 4252 comprising larger element-by-element responses compared to responses from the first sub-stack 4302. More particularly, the red scintillator response is larger from the second sub-stack 4302 than from the first sub-stack 4301. Larger responses from the green and blue scintillation materials also result, which combined with the material responsivity differences results in a distinct shape of the second response curve 4252 relative to a shape of the first response curve 4251. Similarly, passage of the charged particles through the third sub-stack 4303 and the fourth sub-stack 4304 results in a third multi-color response curve 4253 and a fourth multi-color response curve 4254 with a third and fourth distinct shape, respectively. Similarly, the set of response curves 4250 are also plotted for a second residual charged particle beam 267 at a second lower energy, E2, that terminates, such as in a Bragg peak, within the stacked detector element 4400. More particularly, a fifth, sixth, seventh, and eighth multi-color response curve 4255, 4256, 4257, 4258 are illustrated for the lower second energy, relative to the first higher energy, E1, residual charged particle beam. The lower energy beam, E2 versus E1, results in: (1) a larger response for a given depth and (2) in a larger curvature shape in each sub-stack, relative to the first residual charged particle beam due to a larger loss of energy, as described supra. If the set of emission layers is limited to one scintillation material, the response signals reduce to a Bragg peak with gaps along the z-axis. For example, referring still to FIG. 44, if only the first red emission scintillation layer of each sub-stack is plotted, the points fit a Bragg peak curve, with loss of the benefit of different responsivities of differing scintillation materials/colors. As further described infra, initial energy of the residual charged particle beam 267 is determined using any 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more points from the union of the response curves with or without a Bragg peak-like sudden stoppage of the charged particles within the stacked detector element 4400 or the multi-layer scintillator 4030. Still referring to FIG. 44, as a given response curve, which changes for changing initial energy levels of the residual charged particle beam 267 is based on scintillator material types as a function of depth, once calibrated the initial energy of the residual charged particle beam 267 is determined using: a response at any given depth; a difference in response between any two depths; 2, 3, or more responses in a given sub-stack; responses from single layers in 2, 3, or more sub-stacks; responses from 2, 3, or more sub-stacks; responses from a common scintillator material at two or more depths; responses from a common scintillator material in 2, 3, or more sub-stacks; a shape of a response curve of a given sub-stack; a shape of a response curve comprising points from 2, 3, or more sub-stacks; and/or a shape of a response curve from two or more scintillation layers. Still referring to FIG. 44, the inventor notes that error is reduced in determination of the initial energy of the residual charged particle beam 267 using: an increasing number of points in a given response curve from a given sub-stack; an increasing number of points from two or more sub-stacks; an increasing number of points from two or more layers of the multi-layer scintillator 4030; using two or more scintillation materials with different responsivities due to the change in response being large; a gap, along the z-axis, between two or more layers, which increases the change in response between the two or more layers; a beam slowing material, such as other scintillation layers, between two or more scintillation layers. Reduction in error of determination of the initial energy of the residual charged particle beam 267, by way of additional data points, increases precision and/or accuracy of an image generated using the residual energies, such as a proton computed radiography (pRT) image; a proton computed tomography (pCT) image; and/or a positively charged particle radiography and/or tomography image. Still referring to FIG. 44, shapes of the set of response curves 4250, shapes of combinations of members of the set of response curves 4250, and/or individual members of the set of response curves are optionally used, after calibration, to determine a full Bragg peak profile, including a position of the Bragg peak, even without observation of the Bragg peak for a given scintillation color. The inventor notes that the set of response curves represents multiple Bragg peak profiles, one for each scintillation color utilized in the multi-layer scintillator. The inventor further notes that multiple Bragg peaks enhances accuracy and/or resolution of the energy of the residual charged particle beam 760 as a result of the rapid drop off of a given Bragg peak relative to a thickness of a given scintillation layer and the opportunity to catch multiple points, a very sensitive and accurate measurement, of a Bragg peak falloff from different scintillation layers given multiple Bragg peaks occurring for different colors across junctions of layers in the set of layers in the multi-layer scintillator detector element 4110. Dual Particle Accelerator Referring now to FIGS. 45-49, use of a single synchrotron to accelerate multiple treatment beams, comprising positive and/or negative ions and/or particles, such as an electron, is described. Referring now to FIG. 45, a dual accelerator 4510, such as the synchrotron 130, in a multi-beam type treatment system 4500 is used to accelerate cations 4520, such as H+ or C6+ and, by reversing the polarity of the main bending magnets 132, or a portion thereof as described infra, the synchrotron 130 is used to accelerate anions 4530 and/or an atomic particle, such as an electron, e−. Herein, for clarity of presentation and without loss of generality, H+, C6+ and e− are used as examples of any atomic anion, cation, or particle with a positive or negative charge. Herein, carbon stripped of all electrons is referred to as C6+, a carbon atom stripped of all electrons, and/or a carbon charge state of six. Similarly, C4+ or C6+ are referred to as multiply charged carbon atoms. Thus, more generally, the synchrotron 130 is used to accelerate any multiply charged cation having a mass-to-charge ratio, m/Q, where m is mass, such as an atomic mass, of the atom and Q is the charge of the cation, such as C6+ has a mass-to-charge ratio of 12/6 or 2 and H+ has a mass-to-charge ratio of 1/1 or 1. Referring now to FIG. 46, a multiple particle accelerator system 4600, which is an example of the charged particle beam system 100, is illustrated with multiple injector systems, such as a first injector system 4610, a second injector system 4620, and a third injector system 4630, such as used to inject a proton, a carbon atom stripped of all electrons, and an electron, respectively. Referring now to FIG. 47, a cross-section of a single turning magnet 4700, such as the main bending magnet 132, of the synchrotron 130 and/or the beam transport system 135 is provided. The turning magnet 4700 includes a first magnet half 4701 and a second magnet half 4702 and a gap 4710 running therebetween through which protons circulate in the synchrotron 130 and/or are transported through the beam transport system 135. The gap 4710 is preferably a flat gap, allowing for a magnetic field across the gap 4710 that is more uniform, even, and intense. In use, a magnetic field runs sequentially from a first magnet core 4720, across the gap 4710, through a second magnet core 4730, through a second magnet return yoke 4732, and through a first magnet return yoke 4722 to arrive back at the first magnet core 4720, or vise-versa. An insulator 4795 is optionally used to direct the magnetic field through the gap 4710. Still referring to FIG. 47, coils generating the magnetic field loop, described in the preceding paragraph, are described. Herein, winding coils refer to: (1) optionally and preferably, a first magnet coil 4750 wound around the first magnet core 4720 and a second magnet coil 4760 wound around the second magnet core 4730 and (2) optionally and preferably, a first correction coil 4770 and a second correction coil 4780, described infra, which are also wound around the first magnet core 4720 and second magnet core 4730, respectively. The first and second correction coils 4770, 4780 are optionally used in a position inside, outside, on top, or on the bottom relative to their respective first and second magnet coils 4750, 4760. Alternatively, positions of the first and second correction coils 4770, 4780 and the first and second magnet coils 4750, 4760 are reversed compared to their illustrated positions in FIG. 47. Still referring to FIG. 47, the first and second correction coils 4770, 4780 supplement the first and second magnet coils 4750, 4760. More particularly, the first and second correction coils 4770, 4780 have correction coil power supplies that are separate from winding coil power supplies used with the first and second magnet coils 4750, 4760. The correction coil power supplies typically operate at a fraction of the power required compared to the main winding coil power supplies, such as about 1, 2, 3, 5, 7, or 10 percent of the power and more preferably about 1 or 2 percent of the power used with the main magnet winding coils. The smaller operating power applied to the correction coils allows for more accurate and/or precise control of the correction coils. The correction coils are used to adjust for imperfection in the turning magnets. Optionally, separate correction coils are used for each turning magnet allowing individual tuning of the magnet field for each turning magnet, which eases quality requirements in the manufacture of each turning magnet. As further described infra, the first and second correction coils 4770, 4780 are optionally used to accelerate electrons and/or guide transport of electrons, such as used to directly treat and/or indirectly treat, via generation of secondary X-rays, the tumor 220 of the patient 230. Still referring to FIG. 47, the charged particle beam moves through the gap 4710 with an instantaneous velocity, v. Current running through the first and second magnet coils 4750, 4760 results in a magnetic field, B, running through the single turning magnet 4700. In a first example, at a first time, in conjunction with use of the first injector 4610 injecting a positively charged cation, such as a proton, current flows in a first direction around/through the winding coils resulting in a first magnetic field, B1, running in a first direction, which pushes the positively charged particle inward toward a central point of the synchrotron 130, which turns the charged particle beam in an arc. In a second example, at a second time, in conjunction with use of the third injector 4630 injecting a negatively charged particle, such as an electron, current flows in a second direction, opposite the first direction, around/through the winding coils resulting in a second magnetic field, B2, running in a second direction, which pushes the negatively charged particle beam inward toward a central point of the synchrotron 130, which again turns the charged particle beam in an arc, such as through the synchrotron 130 and/or along the beam transport system 135. Thus, referring still to FIG. 47 and referring now to FIG. 48, at the first time, the cation, such as the proton, is accelerated by the synchrotron 130 and delivered via the beam transport system 135 and at the second time, an electron is accelerated by the synchrotron 130 and delivered via the beam transport system 135 to the patient 230. As illustrated, the proton, having a large mass and a larger mass-to-charge ratio than the electron, penetrates further into the patient 230 and treats the tumor 220 at first greater treatment depth than a second treatment depth of the tumor 220 by the lower mass and more scattering electron. Referring now to FIG. 49, three beam types are used, a proton beam, an electron beam, and a C6+ beam to treat the tumor 220 of the patient 230, such as at various relative depths based on charge, mass, energy, ion/particle cross-section, absorbance, and/or scattering. The inventor notes that the proton beam is illustrative of any ion having a charge-to-mass ratio of one, the C6+ is illustrative of any ion having a charge-to-mass ration of two, and the electron is illustrative of any particle having a negative charge and that a single synchrotron 130 is used to accelerate all treatment beams. The inventor further notes that the synchrotron 130 optionally accelerates: (1) two or more cation types having a same charge-to-mass ratio and/or (2) accelerates a cation of any charge-to-mass ratio. Referring again to FIG. 46, FIG. 47, and FIG. 49, a multiple beam type treatment system 4900 is described using 2, 3, 4, 5 or more beam types of cations, anions, and/or particles at any 1, 2, 3, 4 or more charge-to-mass ratios. As illustrated, at a first time, t1, the first injector system 4610 and the synchrotron 130 accelerate a proton to a first energy that penetrates a first depth 4910 and/or a first total pathlength into the tumor 220 of the patient 230. As illustrated, at a second time, t2, the third injector system 4630 and the synchrotron 130 accelerate an electron to a second energy that penetrates a second depth 4920 and/or a second total pathlength into the tumor 220 of the patient 230. Due to the scattering of the lighter weight electron in tissue, as illustrated the proton penetrates a greater depth into the patient 230 and the electron is used to treat a surface tumor, a near surface tumor, and/or a section of a tumor near the surface of the skin, such as less than 10, 5, 4, 3, 2, or 1 millimeter from the surface of the skin. Similarly, at a third time, t3, the second injector system 4620 and the synchrotron 130 accelerate C6+ to a third energy that penetrates a third depth 4930 and/or a third total pathlength into the tumor 220 of the patient 230. As the C6+ has a larger mass-to-charge ratio compared to the proton, equation 1,r=E·m·sqrt(2)/(qB) (eq. 1)requires, for a given synchrotron setting, the C6+ has a lower energy than the proton and penetrates to a shallower depth than the proton, where r is a bending radius, E is energy, m is mass, q is charge, and B is a magnetic field. As size/performance of the synchrotron 130 increases to pass the proton through the patient 230, such as in proton tomography, the depth of penetration of the C6+ increases, eventually to the point of doing carbon tomography, where a carbon cation, or other cation with an atomic mass of 2, 3, 4, 5, 6, or more has enough energy to pass through the patient. The inventor notes that a proton accelerator configured to pass protons just to an opposite side of a patient, designated here as one unit, still has the capability of accelerating a larger mass and/or a larger mass-to-charge ratio particle into the person at an effective treatment depth, such as less than 0.75, 0.50, 0.25, or 0.10 of the way through a patient having a thickness of 1.00 unit. Referring again to FIG. 47, use of the first and second correction coils 4770, 4780 and a current controller 4790 to accelerate electrons with and/or preferably without use of the first and second magnet coils 4560, 4570 is described. More particularly, the smaller first and second correction coils 4770, 4780, such as with less than 10, 5, 2, or 1 percent of a maximum current passing through the first and second magnet coils 4560, 4570 when accelerating a cation, are still capable of turning the smaller mass electron and thus are optionally used to accelerate and guide the electron to the body for tumor treatment. The inventor notes that the electrons are optionally used to generate X-rays, such as by striking a heavy metal, such as tungsten, where the resultant secondary X-rays are guided, also referred to in the art as collimated, into the tumor 220 of the body 230. The tungsten or X-ray generating material, upon being struck by an electron, is optionally and preferably removable and replaceably placed proximate the patient 230, such as within 1, 2, 3, 5, or 10 cm of the patient. The current controller 4790 optionally uses a first switch 4792 to turn on/off the first and/or second magnet coils 4750, 4560, and/or uses a second switch 4794 to turn on/off the first and/or second correction coils 4770, 4780. Additionally, the current controller 4790 is optionally used to change/reverse polarity of the first and second correction coils 4770, 4780 to go from a first mode of correction of the first and second magnet coils 4560, 4570, such as for turning guiding protons or cations, to a second mode of turning/guiding electrons. Thus, the first and second correction coils 4770, 4780 in combination with the current controller 4790 allows the synchrotron to accelerate protons or cations and then switch to accelerating electrons with the same alignment of the rotatable gantry support 1210 and/or position of the nozzle system 146 relative to the patient 230. Still yet another embodiment includes any combination and/or permutation of any of the elements described herein. The main controller, a localized communication apparatus, and/or a system for communication of information optionally comprises one or more subsystems stored on a client. The client is a computing platform configured to act as a client device or other computing device, such as a computer, personal computer, a digital media device, and/or a personal digital assistant. The client comprises a processor that is optionally coupled to one or more internal or external input device, such as a mouse, a keyboard, a display device, a voice recognition system, a motion recognition system, or the like. The processor is also communicatively coupled to an output device, such as a display screen or data link to display or send data and/or processed information, respectively. In one embodiment, the communication apparatus is the processor. In another embodiment, the communication apparatus is a set of instructions stored in memory that is carried out by the processor. The client includes a computer-readable storage medium, such as memory. The memory includes, but is not limited to, an electronic, optical, magnetic, or another storage or transmission data storage medium capable of coupling to a processor, such as a processor in communication with a touch-sensitive input device linked to computer-readable instructions. Other examples of suitable media include, for example, a flash drive, a CD-ROM, read only memory (ROM), random access memory (RAM), an application-specific integrated circuit (ASIC), a DVD, magnetic disk, an optical disk, and/or a memory chip. The processor executes a set of computer-executable program code instructions stored in the memory. The instructions may comprise code from any computer-programming language, including, for example, C originally of Bell Laboratories, C++, C #, Visual Basic® (Microsoft, Redmond, Wash.), Matlab® (MathWorks, Natick, Mass.), Java® (Oracle Corporation, Redwood City, Calif.), and JavaScript® (Oracle Corporation, Redwood City, Calif.). Herein, any number, such as 1, 2, 3, 4, 5, is optionally more than the number, less than the number, or within 1, 2, 5, 10, 20, or 50 percent of the number. Herein, an element and/or object is optionally manually and/or mechanically moved, such as along a guiding element, with a motor, and/or under control of the main controller. The particular implementations shown and described are illustrative of the invention and its best mode and are not intended to otherwise limit the scope of the present invention in any way. Indeed, for the sake of brevity, conventional manufacturing, connection, preparation, and other functional aspects of the system may not be described in detail. Furthermore, the connecting lines shown in the various figures are intended to represent exemplary functional relationships and/or physical couplings between the various elements. Many alternative or additional functional relationships or physical connections may be present in a practical system. In the foregoing description, the invention has been described with reference to specific exemplary embodiments; however, it will be appreciated that various modifications and changes may be made without departing from the scope of the present invention as set forth herein. The description and figures are to be regarded in an illustrative manner, rather than a restrictive one and all such modifications are intended to be included within the scope of the present invention. Accordingly, the scope of the invention should be determined by the generic embodiments described herein and their legal equivalents rather than by merely the specific examples described above. For example, the steps recited in any method or process embodiment may be executed in any order and are not limited to the explicit order presented in the specific examples. Additionally, the components and/or elements recited in any apparatus embodiment may be assembled or otherwise operationally configured in a variety of permutations to produce substantially the same result as the present invention and are accordingly not limited to the specific configuration recited in the specific examples. Benefits, other advantages and solutions to problems have been described above with regard to particular embodiments; however, any benefit, advantage, solution to problems or any element that may cause any particular benefit, advantage or solution to occur or to become more pronounced are not to be construed as critical, required or essential features or components. As used herein, the terms “comprises”, “comprising”, or any variation thereof, are intended to reference a non-exclusive inclusion, such that a process, method, article, composition or apparatus that comprises a list of elements does not include only those elements recited, but may also include other elements not expressly listed or inherent to such process, method, article, composition or apparatus. Other combinations and/or modifications of the above-described structures, arrangements, applications, proportions, elements, materials or components used in the practice of the present invention, in addition to those not specifically recited, may be varied or otherwise particularly adapted to specific environments, manufacturing specifications, design parameters or other operating requirements without departing from the general principles of the same. Although the invention has been described herein with reference to certain preferred embodiments, one skilled in the art will readily appreciate that other applications may be substituted for those set forth herein without departing from the spirit and scope of the present invention. Accordingly, the invention should only be limited by the Claims included below. Still referring to FIG. 22, a sixth input to the automated radiation treatment plan development system 2200 comprises information related to collapse and/or shifting of the tumor 220 of the patient 230 during treatment. For instance, the radiation treatment plan 2210 is automatically updated, using the automated radiation treatment plan development system 2200, during treatment using an input of images of the tumor 220 of the patient 230 collected concurrently with treatment using the positively charged particles. For instance, as the tumor 220 reduces in size with treatment, the tumor 220 collapses inward and/or shifts. The auto-updated radiation treatment plan is optionally auto-implemented, such as without the patient moving from a treatment position. Optionally, the automated radiation treatment plan development system 2200 tracks dosage of untreated voxels of the tumor 220 and/or tracks partially irradiated, relative to the prescribed dosage 2221, voxels and dynamically and/or automatically adjusts the radiation treatment plan 2210 to provide the full prescribed dosage to each voxel despite movement of the tumor 220. Similarly, the automated radiation treatment plan development system 2200 tracks dosage of treated voxels of the tumor 220 and adjusts the automatically updated tumor treatment plan to reduce and/or minimize further radiation delivery to the fully treated and shifted tumor voxels while continuing treatment of the partially treated and/or untreated shifted voxels of the tumor 220. Automated Adaptive Treatment Referring now to FIG. 23, a system for automatically updating the radiation treatment plan 2300 and preferably automatically updating and implementing the radiation treatment plan is illustrated. In a first task 2310, an initial radiation treatment plan is provided, such as the auto-generated radiation treatment plan 2126, described supra. The first task is a startup task of an iterative loop of tasks and/or recurring set of tasks, described herein as comprising tasks two to four. In a second task 2320, the tumor 220 is treated using the positively charged particles delivered from the synchrotron 130. In a third task 2330, changes in the tumor shape and/or changes in the tumor position relative to surrounding constituents of the patient 230 are observed, such as via any of the imaging systems described herein. The imaging optionally occurs simultaneously, concurrently, periodically, and/or intermittently with the second task while the patient remains positioned by the patient positioning system. The main controller 110 uses images from the imaging system(s) and the provided and/or current radiation treatment plan to determine if the treatment plan is to be followed or modified. Upon detected relative movement of the tumor 220 relative to the other elements of the patient 230 and/or change in a shape of the tumor 230, a fourth task 2340 of updating the treatment plan is optionally and preferably automatically implemented and/or use of the radiation treatment plan development system 2200, described supra, is implemented. The process of tasks two to four is optionally and preferably repeated n times where n is a positive integer of greater than 1, 2, 5, 10, 20, 50, or 100 and/or until a treatment session of the tumor 220 ends and the patient 230 departs the treatment room 922. Automated Treatment Referring now to FIG. 24, an automated cancer therapy treatment system 2400 is illustrated. In the automated cancer therapy treatment system 2400, a majority of tasks are implemented according to a computer based algorithm and/or an intelligent system. Optionally and preferably, a medical professional oversees the automated cancer therapy treatment system 2400 and stops or alters the treatment upon detection of an error but fundamentally observes the process of computer algorithm guided implementation of the system using electromechanical elements, such as any of the hardware and/or software described herein. Optionally and preferably, each sub-system and/or sub-task is automated. Optionally, one or more of the sub-systems and/or sub-tasks are performed by a medical professional. For instance, the patient 230 is optionally initially positioned in the patient positioning system by the medical professional and/or the nozzle system 146 inserts are loaded by the medical professional. Optional and preferably automated, such as computer algorithm implemented, sub-tasks include one or more and preferably all of: receiving the treatment plan input 2200, such as a prescription, guidelines, patient motion guidelines 2230, dose distribution guidelines 2220, intervening object 2210 information, and/or images of the tumor 220; using the treatment plan input 2200 to auto-generate a radiation treatment plan 2126; auto-positioning 2122 the patient 230; auto-imaging 2124 the tumor 220; implementing medical profession oversight 2138 instructions; auto-implementing the radiation treatment plan 2320/delivering the positively charged particles to the tumor 220; auto-reposition the patient 2321 for subsequent radiation delivery; auto-rotate a nozzle position 2322 of the nozzle system 146 relative to the patient 230; auto-translate a nozzle position 2323 of the nozzle system 146 relative to the patient 230; auto-verify a clear treatment path using an imaging system, such as to observe presence of a metal object or unforeseen dense object via an X-ray image; auto-verify a clear treatment path using fiducial indicators 2324; auto control a state of the positively charge particle beam 2325, such as energy, intensity, position (x,y,z), duration, and/or direction; auto-control a particle beam path 2326, such as to a selected beamline and/or to a selected nozzle; auto implement positioning a tray insert and/or tray assembly; auto-update a tumor image 2410; auto-observe tumor movement 2330; and/or generate an auto-modified radiation treatment plan 2340/new treatment plan. Treatment Beam Progression Referring now to FIGS. 25-32, treatment beam progression is described. More particularly, reduction in systematic errors by control of order and/or position of treatment of tumor voxels is described. Referring now to FIG. 25 and FIG. 26, row-by-row voxel treatment of a tumor, the tumor not illustrated for clarity of presentation, is compared with non-row treatment of a tumor, referred to herein as a controlled beam progression treatment and/or a controlled random beam position treatment system. Referring now to FIG. 25, a first voxel of the tumor is treated, then second, third, fourth, fifth, and sixth voxels are sequentially treated with the treatment beam 269. Subsequently, second, third, fourth, . . . , nth rows are treated until all voxels in an x/y-plane of the tumor are treated, the first nine treatment voxels are illustrated. In stark contrast, referring now to FIG. 26, the treatment beam 269 over time will treat all of the x/y-plane pixels, but in a random order as a function of x-axis position and y-axis position. Referring now to FIGS. 25-32, for clarity of presentation and without loss of generality, the beam is illustrated as a function of time moving along a first axis, such as the x-axis, relative to a second axis, such as the y-axis. However, the beam is optionally scanned along and/or moved randomly along the x-axis, the y-axis, the z-axis, any pair of axes, and/or along all three axes as a function of time. Further, the x, y, and z-axes are optionally treated at m, n, or o positions, where m, n, and o are positive integers. Systematic Beam Position Errors A charged particle cancer therapy system uses a complex instrument in a complex setting. Many changes to the beam output as a function of time versus a planned treatment result, such as during scanning the beam position, delivering an intended beam energy, and/or delivering an intended beam energy. Many known factors impact precision and accuracy of the beam state, where various calibration and/or control systems minimize precision and accuracy error. However, physics dictates that absolute control of the treatment beam state in terms of precision and accuracy is not possible. Further, unknown parameters may lead to errors, such as systematic errors, in the beam state accuracy and precision. Two known and controlled errors are illustrated in the following examples. In a seventh example, the rolling floor 1320 forms a continuous loop in the cantilevered three hundred sixty degree rotatable gantry system. In an eighth example, an actual position of the cantilevered rotatable gantry system is monitored, determined, and/or confirmed using the fiducial indicators 2040, described, infra, such as a fiducial source and/or a fiducial detector/marker placed on any section of the gantry 490, patient positioning system 1350, and/or patient 230. Floor Force Directed Gantry System Referring now to FIG. 17, a wall mounted gantry system 1700 is illustrated, where a wall mounted gantry 499 is bolted to a first wall 1710, such as a first buttress, with a first set of bolts 1714, optionally using a first mounting element 1712, and mounted to a second wall 1720, such as a second buttress 1720, such a through a second mounting element 1722, with a second set of bolts 1714. The inventor notes that in this design, forces, such as a first force, F1, and a second force, F2, are directed outward into the first wall 1710 and the second wall 1720, respectively, where at least twenty percent of resolved force is along the x-axis as illustrated. Thus, the wall mounted gantry system 499 must be designed to overcome tensile stress on the bolts, greatly increasing mounting costs of the wall mounted gantry system 499. Further, the wall mounted gantry 499 design thus requires that the walls of the building are specially designed to withstand the multi-ton horizontal forces resultant from the wall mounted gantry 499. Further, as the wall mounted gantry 1700 must rotate about an axis of rotation to function, the wall mounted gantry 1700 cannot be connected to front and back walls, but rather can only be mounted to side walls, such as the first wall 1710 and the second wall 1720 as illustrated. Thus, when the wall mounted gantry 499 rotates, the center of mass of the wall mounted gantry 499 necessarily moves into a position that is not between the end mounting points, such as the first mounting element 1712 and the second mounting element 1722. With movement of the center of mass of the wall mounted gantry 499 outside of the supports, the gantry must be configured with additional systems to prevent the wall mounted gantry system 499 from tipping over. In stark contrast, referring now to FIG. 18, in a floor mounted gantry system 1800 the gantry 490 is optionally and preferably designed to rest directly onto a support, such as the floor 1310, with no requirement of a wall mounted system. As illustrated, the mass of the gantry 490 results in only downward forces, such as a third force, F3, into ground or a first pier 1810 and as a fourth force, F4, into ground and/or a second pier 1820. Generally, in the floor mounted gantry system, the center of mass of the gantry 490 is inside a footprint of the piers, such as the first pier 1810 and the second pier 1820 and maintains a footprint inside the piers even as the gantry rotates due to use of additional piers into or out of FIG. 18 and/or due to use of the counter mass in the counterweighted gantry system 1100. Referring now to FIG. 19, an example of the gantry superstructure 1600 is illustrated incorporating the gantry 490, the gantry support arm 498, the counterweight system 1120, the rotatable beamline section 138, and the rolling floor system 1300. The rotatable gantry support 1210 is illustrated with the optional hybrid cancer treatment-imaging system 1400. Further, the first pier 1810 and the second pier 1820 of the floor mounted gantry system 1800 are illustrated, which are representative of any number of underfloor gantry support elements designed to support the gantry 490, where the underfloor gantry support elements are out of a rotation path of the gantry support arm 498 and the rotatable beamline section 138. Referenced Charged Particle Path Referring now to FIG. 20, a charged particle reference beam path system 2000 is described, which starkly contrasts to an isocenter reference point of a gantry system, as described supra. The charged particle reference beam path system 2000 defines voxels in the treatment room 922, the patient 230, and/or the tumor 220 relative to a reference path of the positively charged particles and/or a transform thereof. The reference path of the positively charged particles comprises one or more of: a zero vector, an unredirected beamline, an unsteered beamline, a nominal path of the beamline, and/or, such as, in the case of a rotatable gantry and/or moveable nozzle, a translatable and/or a rotatable position of the zero vectors. For clarity of presentation and without loss of generality, the terminology of a reference beam path is used herein to refer to an axis system defined by the charged particle beam under a known set of controls, such as a known position of entry into the treatment room 922, a known vector into the treatment room 922, a first known field applied in the first axis controller 143, and/or a second known field applied in the second axis controller 144. Further, as described, supra, a reference zero point or zero point 1002 is a point on the reference beam path. More generally, the reference beam path and the reference zero point optionally refer to a mathematical transform of a calibrated reference beam path and a calibrated reference zero point of the beam path, such as a charged particle beam path defined axis system. The calibrated reference zero point is any point; however, preferably the reference zero point is on the calibrated reference beam path and as used herein, for clarity of presentation and without loss of generality, is a point on the calibrated reference beam path crossing a plane defined by a terminus of the nozzle of the nozzle system 146. Optionally and preferably, the reference beam path is calibrated, in a prior calibration step, against one or more system position markers as a function of one or more applied fields of the first known field and the second known field and optionally energy and/or flux/intensity of the charged particle beam, such as along the treatment beam path 269. The reference beam path is optionally and preferably implemented with a fiducial marker system and is further described infra.
059354399	claims	1. An elongated suction strainer system for connection to a suction pipe of a recirculation system for removing solids from fluid flowing into the suction pipe, said elongated suction strainer system comprising: a plurality of internal core tubes connected in series and each including a core wall defining a generally cylindrical core chamber and a plurality of spaced fluid inlets opening to said core chamber, each said core tube having first and second ends being adapted to support the suction strainer; and a series of exterior filtering structures connected to and at least partially bounding said core wall of said core tube, said filtering structure having a plurality of spaced perforations passing therethrough, and a plurality of plate assemblies spaced sequentially along and surrounding said core wall of each core tube; whereby fluid is drawn through the perforations in the filtering structure and the fluid inlets in the core wall into the core chamber by the recirculation system and thereafter pumped to its destination. a plurality of internal core tubes, each including a core wall having at least one open end and a plurality of spaced fluid inlets between the open ends, said core wall defining a generally cylindrical core chamber, at least one of said core tubes of said plurality of core tubes including a core wall having two open ends; and an exterior filtering structure including a plurality of concentric plate assemblies spaced sequentially along and surrounding at least one of said internal core tubes, and a plurality of partial plate assemblies spaced sequentially along and partially surrounding at least one of said internal core tubes, said filtering structure including a plurality of spaced perforations opening to said core tubes; said plurality of internal core tubes being sequentially aligned and connected end to end along a common longitudinal axis, whereby fluid passes through the perforations in said filtering structure and the fluid inlets in the core wall to the chamber therein for delivery to its destination. a suction pipe protruding into the reservoir through a reservoir wall; an elongated suction strainer including an elongated, hollow core tube defining an internal chamber between two opposed ends, said tube being connected to said suction pipe with the chamber in fluid communication with said pipe; and a plurality of fluid inlets defined along said tube placing the reservoir in fluid communication with said internal passage; wherein said suction strainer is supported by said two opposing ends of said core tube from said reservoir walls. an end supported internal core tube including a core wall defining a generally cylindrical core chamber and a plurality of spaced fluid inlets opening to said core chamber, said core wall being constructed and arranged to support said elongated suction strainer; and an exterior filtering structure connected to and at least partially bounding said core wall of said core tube and having a plurality of plate assemblies spaced sequentially along and concentrically mounted to said core wall and partial plate assemblies eccentrically mounted to said core wall, said filtering structure defining a plurality of spaced perforations passing therethrough to provide fluid communication between the core chamber and the fluid source; wherein fluid in the core chamber is thereafter drawn into the recirculation system substantially free of solids. a perforated plate inner ring; a perforated plate outer ring circumferentially aligned with and spaced from said perforated plate inner ring; a circumferential spacer positioned between said inner ring and said outer ring; and a pair of perforated disc plates oppositely arranged on said circumferential spacer, each of said pair of perforated disc plates having an inner periphery defining a central opening sized and shaped to receive said core tube and an outer periphery, said outer ring being positioned between said disc plates adjacent each outer periphery and said inner ring being positioned between said disc plates adjacent each inner periphery. a series of core tubes each having opposed first and second ends, a core wall defining a core chamber, and a series of spaced fluid inlets formed in said core wall and opening to said core chamber, external filtering structures mounted along said core tubes, each including a plurality of plate assemblies mounted in spaced series along the length of said core tubes and having a plurality of perforations formed therein to enable fluid to flow therethrough and into said core tubes through said fluid inlets; and a T-connection mounted between a series of said core tubes and having a core tube portion defining a bore therethrough and a suction pipe portion defining a channel opening in communication with said suction pipe; whereby as fluid is drawn through said perforations of said plate assemblies and into said core tube, solids and particulate matter are strained from the fluid. 2. The elongated suction strainer of claim 1, wherein said exterior filtering structure further includes a plurality of partial plate assemblies spaced along and eccentrically mounted to the core wall. 3. The elongated suction strainer of claim 1, wherein said ends of said core wall are each connected to the suction pipe of the recirculation system. 4. The elongated suction strainer of claim 3, wherein each of said ends of said core wall include a core tube extension sized and shaped to be attached to the suction pipe of the recirculation system. 5. The elongated suction strainer of claim 4, wherein each said core tube extension includes a flange for facilitating connection to the suction pipe of the recirculation system. 6. The elongated suction strainer of claim 1, wherein one of said ends of said core wall is aligned with and connected to the suction pipe of the recirculation system and wherein the other of said ends of said core wall is connected to a support structure. 7. The elongated suction strainer of claim 1, wherein said first end of said core wall is connected to a first support structure and said second end is connected to a second support structure. 8. An elongated suction strainer connected to the suction pipe of a recirculation system for removing solids from liquid flowing into the suction pipe, said elongated suction strainer being supported by the suction pipe and structural members and comprising: 9. The elongated suction strainer of claim 8, wherein said elongated suction strainer further comprises a T-connection having a core tube portion and a suction pipe portion, said core tube portion including a core wall surface defining a generally cylindrical bore therethrough and having open ends, and said suction pipe portion including a suction wall surface defining a channel for connecting said bore to the suction pipe, and wherein said open ends of said core wall surface of said T-connections are aligned with and connected to said core walls of two said core tubes. 10. The elongated suction strainer of claim 9, wherein said core tube portion defines a plurality of apertures spaced along a portion of said core wall surface and opening to said bore, and wherein said partial plate assemblies surround that area of core wall surface having apertures therethrough. 11. The elongated suction strainer of claim 8, wherein one of said ends of said core wall of one of said core tubes of said plurality of core tubes is aligned with and connected to the suction pipe of a recirculation system and one of said ends of said core wall of another of said core tubes of said plurality of core tubes is aligned with and connected to the suction pipe of a recirculation system, and wherein at least one of said core tubes is attached to one of the structural members within the suppression pool so that said plurality of core tubes are supported by the suction pipe and the structural member. 12. The elongated suction strainer of claim 8, wherein said ends of said core walls include a core tube extension sized and shaped to be attached to the suction pipe of the recirculation system. 13. The elongated suction strainer of claim 8, wherein said core tube extension includes a flange for facilitating connection to the suction pipe of the recirculation system. 14. A suction system for removing solids from fluid contained in a reservoir formed of reservoir walls within a nuclear power plant or like facility, said system comprising: 15. The suction system of claim 14, wherein said two opposed ends of the core tube of said elongated suction strainer are each connected to said suction pipe, said suction pipe being constructed and arranged to independently support said elongated suction strainer within the reservoir. 16. The suction system of claim 14, further comprising a structural member protruding into the reservoir through the reservoir wall and wherein said structural member is attached to one of the ends of the core tube of said elongated suction strainer to provide support therefor. 17. The suction system of claim 16, wherein said structural member includes spaced first and second structural members and wherein the first structural member is mounted to one of the ends of the core tube and wherein the second structural member is mounted to the other of the ends of the core tube and wherein said suction pipe is connected to the core tube intermediate said first and second structural members. 18. The suction system of claim 17, wherein the core tube includes at least one T-connection intermediate the opposed ends of the core tube, said T-connection having a core tube portion defining a bore therethrough and a suction pipe portion defining a channel opening into the bore, the core tube portion being connected to the core tube with the bore in fluid communication with the internal passage and the suction pipe portion being connected to said suction pipe with the channel in fluid communication with said suction pipe. 19. The suction system of claim 18, wherein said at least one T-connection defines a plurality of apertures spaced along at least a portion of the core tube portion placing the bore in fluid communication with the reservoir. 20. The suction system of claim 14, wherein said elongated suction strainer comprises a plurality of suction strainer sections, each of said suction strainer sections having a hollow core tube, each of the hollow core tubes being aligned and connected end to end along a common longitudinal axis to provide fluid communication between the reservoir and said suction pipe. 21. An elongated suction strainer for connection to a suction pipe of a recirculation system for removing solids from fluid passing into the recirculation system from a fluid source, said elongated suction strainer comprising: 22. The elongated suction strainer of claim 21, wherein the ends of said core tube are aligned with and connected to the suction pipe of the recirculation system. 23. The elongated suction strainer of claim 22, wherein each of the ends of said core tube include a core tube extension sized and shaped to be attached to the suction pipe of the recirculation system. 24. The elongated suction strainer of claim 23, wherein each said core tube extension includes a flange for facilitating connection to the suction pipe of the recirculation system. 25. The elongated suction strainer of claim 21, further comprising a reservoir having at least one structural member therein, and wherein one of the ends of said core tube is aligned with and connected to the suction pipe of the recirculation system and wherein the other of the ends of said core tube is connected to the at least one structural member within said reservoir. 26. The elongated suction strainer of claim 21, wherein a plate assembly of said plurality of plate assemblies comprises: 27. The elongated suction strainer of claim 20, wherein said internal core tube comprises a plurality of circumferentially spaced longitudinal ribs extending along the core wall for supporting said exterior filtering structure on said core tube. 28. An elongated suction strainer for connection to a suction pipe of a recirculation system having a reservoir defined by a reservoir wall, said strainer comprising: 29. The elongated suction strainer of claim 28 and wherein said T-connection further includes a plurality of apertures spaced along said core tube portion through which fluid is drawn. 30. The elongated suction strainer of claim 28 and wherein an end of a core tube opposite said T-connection is supported on said reservoir wall.
	abstract	A lens system for use with a phase plate in a transmission electron microscope comprises a phase plate placed after the back-focal plane of the objective lens in an imaging system mounted downstream of the objective lens. Phase lenses image the back-focal plane of the objective lens onto the phase plate such that the position and tilt of the electron beam relative to the optical axis are made conjugate. An alignment coil may direct the electron beam going out of the phase lenses toward the phase plate. A second alignment coil may direct the electron beam going out of the phase plate toward the imaging lenses located after the phase plate.
053032721	claims	1. A key manipulating apparatus for manipulating inner and outer springs for firmly holding nuclear fuel rods in a plurality of grid cells of a plurality of grids in a fuel assembly, wherein said grids consist essentially of inner straps assembled with outer straps to form said grid cells and said inner and outer springs are formed respectively on said inner straps and on said outer straps so as to protrude into said grid cells and to hold said fuel rods by contacting the surface of said fuel rods; said apparatus comprising: (a) a support for supporting said grids; (b) outer spring manipulator means, disposed on said support at a position to correspond with said outer springs formed on said outer straps, for manipulating said outer springs so as to retract said outer springs from said grid cells; and (c) inner key manipulating means for manipulating said inner springs so as to retract said inner springs formed on said inner straps from said grid cells by inserting a key into each grid cell of said grids, and rotating said key around the axis thereof; said outer straps are provided with through slits at both sides of said outer springs formed on said outer straps; and said outer spring manipulator means comprises a plurality of hook manipulator means; said hook manipulator means comprising: a pair of hook stems having a set of opposing hooks disposed on opposing end side surfaces of said hook stems for grabbing an outer spring; and retraction means for inserting said hook stems into the grid cell through said slits and moving said opposing hook stems toward each other for grabbing and withdrawing said outer spring from the grid cell through the slit. (a) a support base disposed on the ground; (b) a L-shaped support body for supporting said grid on internal surfaces thereof; (c) a frame disposed freely rotatably on each end section of said grid support so as to form a pair of locking frames for locking said grid; (d) a frame locking means disposed on one of said locking frames for joining said frames separatably. (a) two slide guide means extending out of said support body; (b) key insertion device extending lengthwise and engaged slidingly to said slide guide means; (c) pinions disposed freely rotatably on said key insertion device, engaging with said key at the center axis thereof; (d) racks coupled to said pinions; (e) key rotation means for moving said racks along the direction of extension of racks towards and away from the grid. 2. An apparatus for manipulating springs as claimed in claim 1, wherein said support comprises: 3. An apparatus for manipulating springs as claimed in claim 2, wherein each of said frames are provided with a clamping part, which is freely movable transversely to the fuel rod direction, disposed on an interior surface thereof and operates by contacting the outer surface of said grid. 4. An apparatus for manipulating springs as claimed in claim 2, wherein said frame locking means for said pair of locking frames is a fluid-operated cylinder disposed on one frame of said pair of locking frames, and a tip end of said cylinder is freely insertable into a cavity formed in the other frame of said pair of frames. 5. An apparatus for manipulating springs as claimed in claim 1, wherein said retraction means of said hook manipulator means comprises: a first sliding plate and a second sliding plate disposed in a support body for supporting a grid; and cam mechanisms for providing relative movements of said first sliding plate and said second sliding plate. 6. An apparatus for manipulating springs as claimed in claim 5, wherein said cam mechanisms include cams operatively connected with both said first sliding plate and said second sliding plate by means of through holes disposed on said first sliding plate and said second sliding plate; and a rack and pinion drive for rotating said cams. 7. An apparatus for manipulating springs as claimed in claim 1, wherein said inner key manipulator comprises: 8. An apparatus for manipulating springs as claimed in claim 7, wherein said key insertion device is provided with means for moving said device towards and away from said support body.
	summary
053923251	summary	FIELD OF THE INVENTION This invention generally relates to the catalytic reaction of two or more molecular species having dilute concentrations in fluids flowing in pipes at elevated temperatures. In particular, the invention relates to reducing the corrosion potential of components exposed to high-temperature (i.e., about 150.degree. C. or greater) water. BACKGROUND OF THE INVENTION In a boiling water reactor ("BWR"), the high-temperature (.about.288.degree. C.) water coolant is highly oxidizing due to dissolved radiolytically produced chemical species, such as oxygen and hydrogen peroxide. These molecules and/or compounds are generated as water passes through the reactor core and is exposed to very high gamma and neutron flux levels. Because of the resultant high electrochemical potential ("ECP"), reactor structural materials, such as stainless steels and nickel-based alloys, can suffer stress corrosion cracking ("SCC"). It is well known that SCC occurs at higher rates when oxygen is present in the reactor water in concentrations of about 5 ppb or greater. Stress corrosion cracking is further increased in a high radiation flux where oxidizing species, such as oxygen, hydrogen peroxide, and short-lived radicals are produced from radiolytic decomposition of the reactor water. Such oxidizing species increase the ECP of metals. Electrochemical corrosion is caused by a flow of electrons from anodic and cathodic areas on metallic surfaces. The ECP is a measure of the thermodynamic tendency for corrosion phenomena to occur, and is a fundamental parameter in determining rates of, e.g., SCC, corrosion fatigue, corrosion film thickening, and general corrosion. The useful lifetime of reactor components, such as piping and pressure vessel internal structures, can be limited by SCC. To date, SCC has resulted in a large inspection and repair cost in the nuclear industry and could eventually lead to premature decommissioning of BWR plants due to economic considerations. A number of countermeasures have been developed to mitigate SCC in BWRs by sufficiently reducing either the stress level, the material susceptibility to cracking, or the "aggressiveness" of the environment. Of the various mitigation strategies, reducing the environmental aggressiveness (i.e., oxidizing potential) can provide the broadest, most comprehensive approach, since the environment contacts all the potentially susceptible surfaces of interest. The primary strategy to reduce the ECP of the water to some benign value has been to add hydrogen gas to the reactor feedwater in sufficient quantity that hydrogen is available to chemically recombine, in the presence of a radiation field, with dissolved oxygen and hydrogen peroxide to form water. This process is called hydrogen water chemistry (HWC). If the hydrogen concentration is sufficient, the resultant ECP can be reduced below the SCC threshold value. As used herein, the term "threshold value" means a corrosion potential at or below a range of values of about -230 to -300 mV based on the standard hydrogen electrode ("SHE") scale. Stress corrosion cracking proceeds at an accelerated rate in systems in which the ECP is above the critical potential, and at a substantially lower rate in systems in which the ECP is below the critical potential. Water containing oxidizing species such as oxygen increases the corrosion potential of metals exposed to the water above the critical potential, whereas water with little or no oxidizing species present results in corrosion potentials below the critical potential. In a BWR, the radiolysis of the primary water coolant in the reactor core causes the net decomposition of a small fraction of the water to the chemical products H.sub.2, H.sub.2 O.sub.2 and O.sub.2. For steady-state operating conditions, equilibrium concentrations of O.sub.2, H.sub.2 O.sub.2, and H.sub.2 are established in both the water which is recirculated and the steam going to the turbine. This concentration of O.sub.2, H.sub.2 O.sub.2, and H.sub.2 is oxidizing and results in conditions that can promote SCC in susceptible structural materials. When HWC is used to make the bulk coolant sufficiently reducing, the nitrogen isotope .sup.16 N, which is normally present in the water phase during reactor operation, partitions into the steam phase. This results in an increase in .sup.16 N gamma activity in the steam lines and turbine systems, which can exceed regulatory personnel radiation exposure limits at hydrogen addition levels needed for broad SCC protection. To reduce the .sup.16 N gamma activity to acceptable levels at these plants, it is now necessary to add shielding at strategic locations, which can be costly. In most cases, this consideration has limited use of HWC to protection of only those components where the ECP can be reduced below the SCC threshold without a significant increase in steam-phase .sup.16 N. SUMMARY OF THE INVENTION The present invention is a method and apparatus for protecting selected high-cost-impact reactor systems, such as piping, against SCC by reducing the ECP of these systems without an unacceptable increase in steam-phase .sup.16 N. The apparatus is a catalytic recombiner installed upstream of the piping or other system requiring SCC protection. The recombiner will facilitate the reaction of a small (stoichiometric) hydrogen addition with the dissolved oxygen and hydrogen peroxide present in the water entering the selected system. Thus, the ECP of the water exiting the recombiner will be reduced below the SCC threshold value and SCC will be prevented downstream of the recombiner at all system locations up to the point where the water either mixes with coolant containing higher concentrations of oxygen and/or hydrogen peroxide, or again passes through the reactor core, where radiolysis reoccurs. The instant invention consists of a catalytic recombiner constructed from a material with a catalytically active surface that facilitates the recombination of dissolved oxygen and hydrogen peroxide with hydrogen which is added as a gas to the water upstream of the recombiner. To increase the catalytic recombiner efficiency, the active surface area must be maximized per unit flow volume, consistent with the allowed system pressure drop. For any given system being protected, the allowable pressure drop increase due to the presence of the recombiner is set by the system design. To accomplish this chemical reaction process, the invention utilizes a recombiner having a high surface-to-volume ratio and constructed from a noble-metal alloy known to be an efficient catalyst in high-temperature water. The recombiner is constructed of relatively thin metal sheets of noble-metal alloy (e.g., at least about 1 wt. % palladium in stainless steel), fabricated into shells, plates, or continuous strips and configured to allow insertion into the upstream portion of the system to be protected. The recombiner may take the form of a cartridge of compact, rugged, modular design that can be designed for a wide range of pipe sizes and flow velocities. The recombiner structure includes means for mixing reactants between channels of the mass exchanger, thereby minimizing segregation and enhancing overall efficiency. The catalytic recombiner is arranged and situated such that all (except perhaps a small leakage flow) water phase which ultimately flows through the component to be protected will first flow over the surfaces of the catalytic material. The catalytic surfaces react with the water radiolysis products O.sub.2 and H.sub.2 O.sub.2 in the liquid phase to form H.sub.2 O in accordance with reactions such as (but not limited to) the following: ##STR1## Reaction (3) is followed by reaction (1) to produce water. Thus, the catalytic recombiner of the invention provides a means for substantially reducing oxygen concentration in fluids, thereby lowering the ECP and reducing the likelihood of SCC in susceptible downstream components. Although the invention is disclosed in the context of BWRs, it can be used with compressible or incompressible fluids, such as air or water at elevated temperatures, in a variety of technical applications that involve the catalytic reaction of undesirable compounds in solution. For example, the principle of the invention can be applied in systems for converting CO in exhaust systems (such as catalytic converters on automobiles) or systems for converting CO.sub.2 into H.sub.2 O (such as scrubbers in fossil fuel plants).
	description	The present invention claims priority to U.S. Provisional Patent Application No. 61/294,673, filed Jan. 13, 2010; the content of which is incorporated herein by reference in its entirety. The present invention is related to nuclear fuels, and, more particularly, to metal nuclear fuel. World electricity demand is expected to double by 2030 and quadruple by 2050. The world electricity demand increase is forecasted to come from developed countries and, to an even larger extent, developing countries. To meet this rapid growth in demand, nuclear power may be a realistic, cost-effective energy source. Increased energy supply from other sources, such as contribution from natural gas powered generation may be constrained by high and volatile gas prices, greenhouse gas emissions, and concerns over longer-term dependence on unstable sources of supply. Meanwhile, forms of alternative energy (solar, wind, biomass, hydroelectric, etc.) may be useful in satisfying some of the increased demand. They do not, however, scale sufficiently and cannot provide enough additional electric generating capacity in most markets to meet any significant part of the new electricity demand. Coal power plants may provide some additional supply, but burning mass quantities of coal presents serious political obstacles given the negative environmental impacts. Conventional nuclear power plants may also meet part of the added demand. Conventional nuclear power plants, however, have obstacles to overcome. New types of nuclear fuels may be required. A description of a novel nuclear power plant is found in U.S. Non-Provisional patent application Ser. No. 12/696,851, filed Jan. 29, 2010, and PCT Patent Application No. PCT/US2010/035412, filed May 19, 2010; the contents of which are incorporated by reference herein in their entireties. A sheathed, annular metal fuel system is described. A metal fuel pin system is described that includes an annular metal nuclear fuel alloy. A sheath may surround the metal nuclear fuel alloy, and a cladding may surround the sheath. A gas plenum may also be present. Mold arrangements and methods of fabrication of the sheathed, annular metal fuel are also described. Additional features, advantages, and embodiments of the invention are set forth or apparent from consideration of the following detailed description, drawings and claims. Moreover, it is to be understood that both the foregoing summary of the invention and the following detailed description are exemplary and intended to provide further explanation without limiting the scope of the invention as claimed. Embodiments of the present invention may include sheathed, annular metal nuclear fuels, mold arrangements for sheathed, annular metal nuclear fuels, and methods for fabrication of sheathed, annular metal nuclear fuels. In certain embodiments, several fabrication techniques may be used separately and/or individually to create the sheathed, annular metal nuclear fuels. For example, fabrication of annular metal fuels may be performed by bottom pour casting of a solid slug of metal fuel into a zirconium or similar type of tube in a graphite mold. Embodiments of the present invention may include fabrication and irradiation of an annular metal fuel slug with a zirconium sheath that is fit tightly to a cladding, which may be steel, with a helium bond. This combination can provide a number of important attributes that each feature, when taken individually, would not. Fabrication Process FIG. 1 shows a mold arrangement 101 for bottom pour casting according to one embodiment. The following are beneficial attributes of bottom pour casting when compared to the traditional technique of metal fuel fabrication by injection casting: a. Graphite molds are reusable, which eliminates the waste produced with fuel particles stuck to the quartz molds from injection casting. b. The range of alloy compositions is not limited, as with injection casting where softening of the quartz molds during casting limits the maximum melting temperature of the alloy that can be cast. c. Annular slugs can be cast where annular geometry is not practical with injection casting. d. The inclusion of a sheath is practical with bottom pore casting. e. The elimination of volatile element loss is possible with bottom pour casting by use of over-pressure of an inert gas. f. Bottom pour casting lends itself to remote application. Metal fuel 103 may be melted in a graphite or similar type crucible with a small over pressure of an inert gas to minimize volatile component loss. The metal alloy may be uranium-zirconium, uranium-molybdenum, with or without the additions of plutonium and other transuranic elements. Thorium based alloys may also be fabricated in such a manner. Embodiments of the present invention may accommodate metallic thorium alloy fuel. There is renewed interest in the use of thorium alloy fuels, particularly in countries, such as India, that do not have an indigenous inventory of uranium. Results of early research in the United States showed that thorium metal fuels, when irradiated, exhibited interconnected porosity and gas release, in a manner similar to the traditional uranium alloy fuels. As such, embodiments of the present invention may utilize thorium based alloys in fuel pins and/or fabrication techniques for improved performance of thorium-based fuels. Tight tolerances are unnecessary with metal fuels due to the low smear density and plastic properties of the fuel when under irradiation. The range of alloy compositions should not be as limited as in the case of injection cast fuel where the softening of quartz molds was a limitation. The liquid alloy metal fuel 103 may be bottom poured from the crucible into a graphite mold or block 105, as shown on FIG. 1. The graphite mold 105 may include one or more cylindrical holes 107 lined with zirconium tubes 109. The tubes 109 may be refractory metal tubes other than zirconium. In an approximate center of each tube 109 may be a steel rod or a threaded solid graphite rod 111. The steel rod or a threaded solid graphite rod 111 may be coated with a thin ceramic layer, such as titanium nitride. Other ceramics may also be used. The steel rod or a threaded solid graphite rod 111 may be threaded 113 into the graphite mold 105. After the metal fuel 103 is cast into the graphite mold 105, a product removed from the graphite mold 105 may be an annular fuel slug, with a central hole, and a zirconium sheath. The fabrication technique of embodiments of the present invention can produce significantly less waste compared to the past method of injection casting where the fuel material often stuck to quartz molds. Furthermore, the residual heel in the bottom of the crucible with bottom pour casting can be minimized compared to that found with injection casting. An alternative to casting into a mold with a zirconium tube in the mold is to place a thin zirconium tube or a tube of a refractory alloy into the cladding with a reasonably tight fit and then put the annular fuel slug into the cladding with the zirconium tube already in place. A potential advantage with this method is that the zirconium tube may be continuous for a long core length in the event that the fuel slug casting length is limited. Fuel slugs could be stacked on one another without a discontinuity in the sheath. A helium gas bond may also be used to create an adequate heat transfer path during early stages of irradiation. FIG. 2 shows a cross-section of an annular fuel slug/pin 201 with a central hole 203 and zirconium sheath 205, according to one embodiment. A steel or other similar material cladding jacket 207 may surround the zirconium sheath 205 and annular fuel slug 201. The zirconium sheath 205 may be used to provide a barrier between the annular fuel slug 201 and the cladding 207 at the very high residence times that are proposed for certain reactors. The dimensions of the annular fuel slug 201 and sub-components thereof may be varied based upon specific uses. Inclusion of the zirconium sheath 205 in a fuel pin 201 may provide a method to protect the steel cladding 207 from chemical attack during the extremely long irradiation exposures for fast reactor fuels. During irradiation, elements in the metal fuel 103 interchange by diffusion with elements in the cladding 207 material such that the useful thickness of the cladding 207 diminishes, which can possibly lead to cladding rupture. A zirconium sheath 205 may retard this exchange of elements by diffusion. Other types of sheath materials may not provide this protection. Another issue of concern is that a low-melting alloy may form at the interface between the fuel 103 and cladding 207 from either of two phenomena. First, iron in the cladding 207 may alloy with the fuel elements, for example uranium, and form a low melting composition. Second, lanthanide fission products may migrate to the fuel cladding interface and form a low melting alloy. A low melting alloy next to the cladding 207 can likely cause premature rupture. In either case, the zirconium sheath 205 may prevent the formation of the low melting alloys. Other types of sheath materials may not provide this protection. FIG. 3 shows a sheathed, annular metal fuel system 301, according to one embodiment. The annular fuel slug 201 with the zirconium sheath 205 may be placed into the cladding jacket 207. Tolerances on the annular fuel slug 201 may be such that the fit in the cladding 207 leaves little gap. A gas plenum 303 in the cladding jacket 207 may be filled with helium gas 305 to create adequate heat transfer. An end cap 307 and/or a bottom spade 309 may also be included in the sheathed, annular metal fuel system 301. Purpose of the Fabrication Process Traditional metal fuel can yield high burnup because a gap between fuel and cladding can allow the fuel to swell unimpeded from fission gas accumulation until the fission gas bubbles interconnect and the fission gas is released to the plenum above the fuel. The gap between fuel and cladding in the traditional metal fuel can result in an effective density of 75% or less. As such, interconnection of the gas pores may occur before the metal fuel reaches the cladding. Instead of a gap between fuel and cladding as in traditional metal fuels, an effective fuel density of 75% or less may also be achieved by a central hole in the fuel slug. Thus, the fuel at least in part swells inward instead of outward to achieve interconnected porosity. With traditional metal fuels there may be significant axial growth of the metal fuel prior to cladding contact. In embodiments of the present invention, the annular fuel slug may be in contact with the sheath and cladding at the beginning of life and thus the axial growth may be much less than that of traditional metal fuels. When uranium-zirconium or uranium-plutonium-zirconium fuel pins of traditional metal fuels are irradiated, the zirconium may tend to diffuse to the surface of the fuel slug and form a protective barrier between the fuel and the cladding. The zirconium layer formed by this diffusion mechanism is not always uniform and, thus, protection between fuel and cladding may be intermittent. In previous systems, metal fuel was injection cast into zirconium tubes as a technique to eliminate quartz molds, based on the prior art belief that the zirconium tubes would provide a protective barrier between fuel and cladding. In traditional systems, the fuel slug, along with the zirconium tube, was placed into a cladding with a sodium bond and irradiated. The gap between the fuel slug and the cladding was large for the 75% effective fuel density. When the fuel swelled the zirconium tube could split. Consequently, the tube did not function effectively as a protective barrier. In embodiments of the present invention, the annular fuel slug with the zirconium sheath may be tightly fit into the cladding tube. Thus, when the annular fuel slug swells there may be little outward motion of the fuel as the annular fuel slug may swell toward the center. Consequently, the zirconium tube is not as likely to fracture and can remain intact as a protective barrier. Furthermore, since there is little gap between the annular fuel slug and cladding, a liquid sodium bond may be unnecessary. Helium gas may also be used as a preferred heat transfer medium, but other materials may also be used. In traditional metal fuels, the sodium bond, after low burnup, may be squeezed into the plenum. With the helium bond, sodium filling of the cladding tubes and bond inspection can be eliminated. With no sodium bond, the length of the fuel pin may be substantially reduced. A shorter fuel pin may result in a shorter assembly and consequently a smaller reactor vessel, with significant cost saving. Sodium bonded metal fuel typically must be heated from the top downward to liquefy the bond sodium before the fuel pins can be introduced into the reactor pool of sodium. This may require a special fuel loading machine. Also, for certain reactors, the entire core may be loaded as several cassettes. Heating these cassettes from the top down can require large and special equipment. Embodiments of the present invention seek to avoid these issues. Furthermore, elimination of sodium bonding opens the opportunity to ship and store fuel assemblies, after cleaning, with water cooling. Embodiments of the present invention may also include systems and methods for generating energy using the sheathed, annular metal fuels. The sheathed, annular metal fuels may be irradiated to generate energy. In embodiments of the present invention, volatile component loss, such as americium, may not be an issue because a small overpressure when melting the alloy may eliminate loss. The radioactive elements in spent nuclear fuel are the fission products, with some elements having relatively short half-lives and the minor actinides having very long half-lives. As such, the minor actinides dictate the duration that a repository must be proven reliable because of the residual radioactivity. Also, the minor actinides fix the capacity of the repository due to the heat generated from the decay of the minor actinides. The pyro-process for the reprocessing of nuclear fuel, both ceramic and metal, removes the minor actinides from the spent fuel and the minor actinides are then used to alloy with new metal fuel. Metal fuel is an ideal host for the minor actinides. The traditional method for the fabrication of metal fuel is by injection casting, which depends upon evacuating the system prior to the high-temperature injection of the molten alloy into quartz molds. The minor actinide americium is very volatile and thus is difficult to keep in the liquid phase during the evacuation process. The bottom pour casting method, detailed in this patent, does not require evacuation and in fact an overpressure of inert gas may be used to substantially eliminate the loss of americium during the casting process. The present invention may allow for ease of remote fabrication in a hot-cell environment where the reprocessed fuel is highly radio active. The fabrication technique may be well-suited for the remote fabrication of reprocessed fuel. Eventually, most, if not all nuclear reactors will operate on reprocessed fuel. Reprocessed fast reactor fuel must be processed and fabricated in a remote environment, such as a hot cell. The technique for fuel fabrication must utilize equipment that is compact and readily maintainable in a hot cell. The bottom pour casting method for the fabrication of metal fuel is ideal in this regard for remote utilization. In certain embodiments, the fuel may appear as traditional metal fuel after initial irradiation and thus the large data base for traditional fuel may be applicable. For example, when annular metal fuel is irradiated the fuel will swell into the annulus. When the diameter of the annulus is sized such that the smear density in the fuel, when the annulus closes due to fuel swelling, is 75% or less, then interconnected porosity and fission gas release occurs. Furthermore, the microstructure of the fuel then appears as that of a traditional metal fuel. It is important that interconnected porosity and an identical microstructure to that of traditional metal fuel occur in the annular fuel because then a bridge can be established to the extensive data base for traditional metal fuel. As such, an extensive and expensive development program can be avoided for the licensing of annular fuel. Although the foregoing description is directed to the preferred embodiments of the invention, it is noted that other variations and modifications will be apparent to those skilled in the art, and may be made without departing from the spirit or scope of the invention. Moreover, features described in connection with one embodiment of the invention may be used in conjunction with other embodiments, even if not explicitly stated above.
	description	This application claims priority to the German Application No. 10 2005 014 188.9, filed Mar. 29, 2005 which is incorporated by reference herein in its entirety. The invention relates to a device for recording projection images with: A radiation source mounted on a support and movable around the object and A radiation detector mounted on the opposite side of the support from the object and movable around the object in accordance with the movement of the radiation source, which receives radiation emitted by the radiation source and creates projection images of the object from this. This type of device is known from DE 101 33 657 A1. The known device features a C-arm which can be rotated around the object, which features a radiation source at one end and a radiation detector at the other. To enable the radiation detector to be moved as close as possible to the object to be investigated, the radiation detector is supported so that it can rotated on the C-arm. As a result of the ability to rotate the radiation detector into any position relative to the C arm, the radiation detector can be aligned so that, despite that fact that it is as close as possible to the object to be examined, for example a patient, a patient table or such like, it does not collide with it. Thus the radiation detector of the known device does not have to be exchanged in particular applications. Instead it is possible to adapt the device to the relevant application by rotating the radiation detector. A disadvantage of the known device is that a radiation detector with a rectangular-shaped detector surface can only be rotated if it is in a position which allows the radiation detector to be rotated without colliding with anything. If the distance is too small the corners of the radiation detector collide with the obstacle. However there is the opportunity of basically rotating the radiation detector before it approaches an obstacle so that it can be moves as close as possible to the obstacle. The other option is to first move the radiation detector back if it is established that it is necessary to rotate the radiation detector. After the radiation detector is rotated it is moved towards the obstacle again. However in practice both these methods are rather cumbersome. An object of the invention is thus to create a device for recording projection images which allows obstacles to be negotiated in a flexible manner. This object is achieved by a device with the features of the independent claim. Advantageous embodiments and developments are specified in their dependent claims. The outstanding feature of the device is that a translation movement can be performed with the radiation detector opposite the support. The option of performing a translation movement in relation to the support enables the radiation detector to be moved into the immediate vicinity of an obstacle in such a way that the movement of the support can be continued without interruption. In particular it is not necessary to first move the support with the radiation detector back in order to bring the radiation detector into the appropriate position and subsequently move the support with the radiation detector up to the obstacle again. In addition the device provides a large degree of flexibility since the radiation detector, on approaching an obstacle, does not have to be moved into the appropriate position in advance. In a preferred embodiment is the radiation detector can be moved relative to the support while remaining at the same distance from it. This is sufficient if the support is in a position in which the spacing between the radiation detector and the object does not change with this type of movement. In a further preferred embodiment the radiation detector is a position to perform the translation movement with a simultaneous change to the distance between the support and the radiation detector. This facility ensures that the distance between the radiation detector and the object to be investigated can remain largely the same in each case. Furthermore provision can be made for the radiation source to be able to perform one of the translation movements which follows the translation movement of the radiation detector. In this way the imaging geometry can be largely retained if the radiation detector is moved. Furthermore a monitoring device can be provided which is used to monitor the movement of the radiation detector and the radiation source for possible collisions. If there is a danger of a collision, the monitoring device initiates a translation movement of the radiation detector and if necessary of the radiation source through which the collision is avoided. FIG. 1 shows an x-ray device 1 with an x-ray source 2 and an x-ray detector 3. The x-ray source 2 and the x-ray detector 3 are each accommodated on the ends of a C-arm 4. The x-ray source 2 sends x-ray radiation 5 indicated by dashed lines in FIG. 1 to the x-ray detector 3. An x-ray hitting the x-ray detector 3 at a right angle is designated in this case as the central ray 6. The x-ray radiation 5 passes through a patient 7 located on a patient bed 8. The patient bed 8 is mounted on a support 9 with bearings in the support enabling the patient bed to be moved in a lengthwise direction 10 and in an up-and-down direction 11. In addition the patient bed 8 can also move on bearings so that the patient bed 8 can be rotated around a vertical axis. The C-arm 4 is mounted via a support 12 on a pedestal 13. The C-arm 4 mounted on the support 12 can on the one hand be rotated around a pivot axis 14. In this case the C-arm 4 performs a pivot movement 15. Furthermore the C-arm 4 can execute a tilting movement 16, whereby the C-arm 4 is moved in a circumferential direction in a bearing mounted on the support 12 not shown in FIG. 1. Finally the bearing for the pedestal 13 also allows a rotational movement 17 around a vertical axis. It is further possible for the pedestal 13 to be able to be moved on rails. In this manner for example the support 12 can be moved into a position next to the patient bed 8. Despite the many possibilities for positioning the x-ray source 2 and the x-ray detector 3 as well as the patient 7, situations can occur in which, as shown in FIG. 2, there is a danger of a collision 18 between the patient bed 8 and the C-arm 4. These types of collisions occur especially with biplanar x-ray devices with two C-arms or where space constraints come into play. These types of space constraints arise especially when the x-ray device 1 is combined with a system for magnetic navigation. In this case 8 magnetic pole shoes are located alongside the patient bed 8 which restrict the options for moving the C-arm 4 out of the way. Imaging of caudal regions of the body 19 cannot then be undertaken. If the C-arm 4, as shown in FIG. 2 is in an anterior-posterior orientation, a forwards movement 20 of x-ray source 2 and x-ray detector 3 allows imaging of at least part of the caudal body region 19. The imaging geometry does not change in this case through the forwards movement 20 of x-ray source 2 and x-ray detector 3. It should be pointed out that with an anterior-posterior orientation of the C-arm 4 of the central ray 6 assumes a right angle to the longitudinal axis of the patient bed 8. In FIG. 3 the C-arm 4 is angled for caudal imaging by a tilting movement 21. If the x-ray source 2 and the x-ray detector 3 are now moved in accordance with the forwards movement 20 in FIG. 2 so that the distance between the end of the C-arm 4 and the x-ray detector 3 or the x-ray source 2 remains unchanged, with this type of forwards movement the distances between the x-ray source 2 and the area of the patient's body 7 to be examined as well as between the area of the patient's body to be examined and the x-ray detector change. As a consequence the imaging geometry would change. The imaging geometry can however be largely preserved by the x-ray source 2 and the x-ray detector 3 not only executing the forwards movement 20 but also a lifting movement 22. By executing the forwards movement 20 and the lifting movement 22 the imaging geometry remains unchanged and the size of the area for which an image can be recorded can be increased. With a right-anterior-oblique or a left-anterior-oblique setting of the C-arm 4 it can be necessary for the x-ray source 2 and the x-ray detector 3 to be able to execute a sideways movement to the left or to the right. The left or right directional specifications relate in this case to the sideways directions, if the C-arm 4 is located in the anterior-posterior position and the observer is looking in the direction of the pivot axis 14 towards the ends of the C-arm 4. Preferably the x-ray source 2 and the x-ray detector 3 are thus able to be moved with three degrees of freedom. In the anterior-posterior position these are the translation movements to the right and left, upwards and downwards and also backwards and forwards. FIG. 4 finally shows a special case which frequently occurs for x-ray images recorded in the area of a skull 23 of the patient 7. The hallmark of this situation is that the physician needs a specific angulation of the C-arm 4 to record an image of a specific anatomical structure. It is not possible to do without this angulation. When extended surface area x-ray detectors 3 are used however the necessary angulation cannot be achieved, since this would lead to a collision 24 with the body of the patient 7. A backwards movement 25 in combination with a lifting movement 26 however makes the desired angulation possible. In this case the user does not obtain any additional surface for recording an image, such as described in conjunction with FIGS. 2 and 3, but rather a larger angulation area. The option of moving the x-ray detector 3 enables the large-area x-ray detectors 3 which are preferred per se to be used in this case. With the exemplary embodiment shown in FIG. 4 the physician loses imaging surface. This is no disadvantage however, since the lost detector surface is not needed for illumination of the skull 23. To avoid imposing an unnecessary radiation strain on the patient 7 and to exploit the complete shifted surface of the x-ray detector 3, the display of the collimator in the area of the x-ray source 2 can be adapted. With a modified exemplary embodiment the x-ray source 2 can also be shifted. The exemplary embodiments described here provide a series of advantages. On the one hand the area over which an image can be recorded is increased when there is a danger of a collision of the C-arm 4 with the patient bed 8. On the other hand the angulation area is increased when large-area x-ray detectors are used. The x-ray device 1 thus has the advantages that are produced in each case when using x-ray detectors 3 with a larger and smaller imaging surface. It should be pointed out that exemplary embodiments described here each include a C-arm 4. In accordance with the exemplary embodiments described here biplanar x-ray devices, which feature at least two C-arms 4 each with an x-ray source 2 and an x-ray detector 3, can be modified accordingly. It should also be mentioned that the forwards movement 20, the lifting movement 22 as well as the backwards movement 25 can be initiated by a monitoring device in each case which identifies the danger of a collision and controls the movement of the x-ray source 2 and of the x-ray detector 3 suitably. The monitoring device can for example be a computer system that contains in a memory unit the allowed range of values for the position parameters. If the limits of the allowed parameter values are approached the translation movement is then initiated. In addition it is possible to equip the edges of the x-ray detector 3 with sensors with the aid of which the monitoring device can identify when an obstacle is being approached.
	description	FIG. 4 is a diagram illustrating the entire configuration of an X-ray reduction projection exposure apparatus. In FIG. 4, X-rays (vacuum-ultraviolet rays or soft X-rays) are emitted from an undulator source 101, serving as a radiation source. The optical path of the X-rays is deflected by an illuminating system comprising a convex total-reflection mirror 102 and a concave multilayer-film reflecting mirror 103, and the X-rays are then projected onto a reflection mask 104. A multilayer film for effecting regular reflection of X-rays is formed on the reflection mask 104, and a predetermined circuit pattern is formed on the multilayer film. The X-rays reflected by the reflection mask 104 reach a wafer 106 after passing through a reduction projection optical system 105 having a plurality of reflection mirrors, to image the circuit pattern on the wafer 106 with a predetermined projection magnification (for example, ⅕). The reflection mask 104 is fixed and held on a mask stage 107, and the wafer 106 is fixed and held on a wafer stage 108. The reflection mask 104 and the wafer 106 are aligned with each other by the mask stage 107 and the wafer stage 108, respectively, and the scanning movement of the mask stage 107 holding the reflection mask 104 and the wafer stage 108 holding the wafer 106 is performed in a synchronized manner. Since the wavelength of the X-rays used for exposure is between about 20 nm and 4 nm, the theoretical resolution determined by the wavelength of the exposure light is improved. Since vacuum-ultraviolet rays and soft X-rays are greatly attenuated by a gas, the inside of the entire apparatus is held in a vacuum or in a reduced pressure of a light-element gas, such as helium or the like. In the present invention, an electrostatic chuck (unipolar type) which is suitable for the use in a vacuum or in a reduced pressure is used for a mechanism for fixing and holding the reflection mask 104 on the mask stage 107. The electrostatic chuck functions based on the principle that charges having a sign opposite to that of an electrode are excited on an insulator provided on the chuck""s surface to cause a dielectric polarization phenomenon to occur, so that an electrostatic force is applied to an object to be attracted. The attracting force F of the electrostatic chuck is represented by the following expression: F=S/2xc3x97xcex5xc3x97(V/d)2, where S is the area of the electrode of the electrostatic chuck, xcex5 is the dielectric constant of the insulator, V is the applied voltage, and d is the thickness of the insulator on the surface. The above-described expression may be modified in accordance with various conditions. In a bipolar electrostatic chuck which is easy to handle and in which an object to be attracted need not be grounded, the attracting force is less than half the value of the above-described electrostatic chuck (unipolar type). For example, when using high-purity Al2O3, which is little contaminated with metal, for the insulator on the surface, the attracting force is about 25 g/cm2. If the pattern region of the reflection mask is 200 mm square with a thickness of a few xcexcm, and the base is 210 mm square with a thickness of 10 mm and is made of Si, the mass of the reflection mask is about 1 Kg. If a time period of 0.5 sec is required for exposure of one shot, it is necessary to scan a distance of 200 mm in a time period equal to or less than 0.5 sec. Hence, if a scanning speed of 400 mm/sec is obtained within 0.05 sec, the maximum acceleration of the mask stage is 8 m/sec2. When the mask is supported in a direction parallel to the direction of gravity, the maximum acceleration applied to the mask after adding the acceleration due to gravity is about 18 m/sec2, i.e., the force applied to the mask in the scanning direction is 18 N. Since the attracting force of the electrostatic chuck is 21xc3x9721xc3x970.025xc3x979.8=100 N, the coefficient of friction must be equal to or greater than 0.18 N in order to prevent the reflection mask from dropping. In general, the surface of the electrostatic chuck is very precisely processed to an excellent flatness, and therefore has a low coefficient of friction. Hence, the mask may drop in the worst case. Accordingly, in the present invention, the attracting force of the mask by the electrostatic chuck is changed in accordance with a situation in order to prevent the mask from dropping. A specific configuration for that purpose will now be described. First Embodiment FIG. 1 is a cross-sectional view as seen from the side, illustrating the configuration of a mask supporting device, which is used in a mask stage of an X-ray projection exposure apparatus, according to a first embodiment of the present invention. In FIG. 1, a reflection X-ray mask 1, serving as an optical element, comprises a base 1a comprising an Si substrate, and a pattern region 1b. The pattern region 1b is formed on the base 1a according to a thin-film forming method, such as magnetron sputtering, or the like. The pattern region 1b comprises a region having a low reflectivity for X-rays, such as vacuum-ultraviolet rays or soft X-rays, and a pattern portion having a high reflectivity for the X-rays. The pattern portion comprises an X-ray absorbing member (for example, made of gold or tungsten) formed on a patterned X-ray reflecting multilayer film obtained by alternately laminating at least two kinds of substances having different refractive indices for vacuum-ultraviolet rays or soft X-rays. The mask supporting device for holding the mask 1 comprises an electrostatic chuck 2 for attracting the mask 1, a plurality of pin-shaped projections 6 formed on portions thereof, a pressure sensor (attracting-force detection means) 11 for detecting an attracting force for the mask 1, an attraction control unit 12 for calculating the attracting force from the result of detection of the pressure sensor 11, a voltage control unit 10 for outputting a voltage for controlling the attracting force from the attracting force calculated by the attraction control unit 12, and a driving control unit 9 for effecting scanning movement of the mask 1. A supply tube 7 for supplying voids formed between the projections 6 with a cooling gas (such as helium or the like), and a recovering tube 8 for recovering the gas introduced into the voids are also provided. The electrostatic chuck 2 comprises a first insulating layer 3 and a second insulating layer 4. A first electrode 5a and a second electrode 5b for generating the attracting force are formed between the first insulating layer 3 and the second insulating layer 4, and the pin-shaped projections 6 are formed on the first insulating layer 3. In this configuration, when a voltage is applied from the voltage control unit 10 to the first electrode 5a and the second electrode 5b of the electrostatic chuck 2, static electricity is generated and charges having a sign different from that of the voltage are excited on the surface of the first insulating layer 3. At that time, the dielectric polarization phenomenon appears on the surface of the first insulating layer 3, and an electrostatic force is applied to the mask 1. The mask 1 is thereby attracted and fixed by being supported on the pin-shaped projections 6 formed on the electrostatic chuck 2. Since a so-called pin-chuck shape is provided in the above-described manner and the ratio of the area of portions of the distal ends of the pin-shaped projections 6 contacting the back of the mask 1 to the entire area of the mask 1 is arranged to be equal to or less than 10% (more preferably, less than 2%), the deformation of the mask 1 due to the presence of dust between the mask 1 and the electrostatic chuck 2 is prevented. In addition, since cooling gas flows in the voids between the projections 6, the mask 1, placed in a vacuum in which cooling is difficult to perform, is effectively cooled from the back to suppress the distortion of the mask pattern. The pressure sensor 11 for detecting the attracting force for the mask 1 is disposed on the surface of the electrostatic chuck 2, and the attracting force for the mask 1 is calculated by the attraction control unit 12 from a detection signal from the pressure sensor 11. In order to increase the illuminating region for the mask 1, the electrostatic chuck 2 is subjected to scanning movement by the control of the driving control unit 9. The attraction control unit 12 calculates the acceleration of the electrostatic chuck 2 from position information relating to the electrostatic chuck 2 detected by the driving control unit 9, and transmits an instruction to the voltage control unit 10 so that the following relationship is satisfied: {(the mass of the mask)xc3x97(acceleration due to gravity+the maximum acceleration of the mask while being moved)/(the maximum coefficient of static friction between the mask and the mask chuck)}xc3x97(safety factor) less than the attracting forcexe2x80x83xe2x80x83(1), wherein (the attracting force) is defined by: (the generating electrostatic force)xe2x88x92(the differential pressure between the pressure of the cooling gas and the atmosphere pressure of the inside of the entire apparatus). The voltage control unit 10 controls the attracting force by changing the voltage applied to the first electrode 5a and the second electrode 5b in accordance with the instruction from the attraction control unit 12. Expression (1) may be satisfied by controlling the attracting force to be constant and controlling the acceleration instead of the attracting force by providing an instruction from the attraction control unit 12 to the driving control unit 9. According to the above-described configuration, the drop of the mask 1 from the electrostatic mask 2 is prevented. Second Embodiment FIGS. 2(a) and 2(b) are diagrams illustrating the configuration of a mask supporting device according to a second embodiment of the present invention: FIG. 2(a) is a perspective view; and FIG. 2(b) is a cross-sectional view as seen from the side. In the mask supporting device of the first embodiment, a bipolar electrostatic chuck is used. In the mask supporting device of the second embodiment, a unipolar electrostatic chuck having a strong attracting force is used. By using such a unipolar electrostatic chuck, reliability in the attraction of the mask is improved. The second embodiment has the same structure as the first embodiment, except as noted below. In FIGS. 2(a) and 2(b), only the configuration of components added in the second embodiment which are not found in the first embodiment, is illustrated, and the attraction control unit, the voltage control unit and the driving control unit shown in the first embodiment are not illustrated. Since the operations of these units are the same as in the first embodiment, a description thereof will be omitted. When attracting a mask on the unipolar electrostatic chuck, the mask must be grounded. However, since the mask is conveyed within the exposure apparatus and is mounted on and detachable from the electrostatic chuck, it is difficult to always ground the mask. Accordingly, in the mask supporting device of the second embodiment, the mask is grounded only when it is attracted on the electrostatic chuck so as not to hinder the conveyance of the mask. In FIGS. 2(a) and 2(b), a mask 21 comprises a base 21a comprising an Si substrate, and a pattern region 21b which is formed on the base 21a. The mask supporting device for attracting and holding the mask 21 comprises an electrostatic chuck 22 for attracting the mask 21, and an earth pawl 26 for grounding the mask 21. The electrostatic chuck 22 comprises a first insulating layer 23 and a second insulating layer 24, and an electrode 25,. for generating an attracting force, is formed between the first insulating layer 23 and the second insulating layer 24. The earth pawl 26 is connected to a minus (xe2x88x92) terminal of a power supply 27, and a plus (+) terminal of the power supply 27 is connected to the electrode 25. In this configuration, when the plus (+) potential of the power supply 27 is applied to the electrode 25 of the electrostatic chuck 22, charges of a different sign are excited on the surface of the first insulating layer 23. At that time, the dielectric polarization phenomenon appears on the surface of the first insulating layer 23, and an electrostatic force is applied to the mask 21. The mask 21 is thereby attracted and fixed to the electrostatic chuck 22. The earth pawl 26 is fixed relative to the electrostatic chuck 22 so as to be movable in the z direction shown in FIG. 2(b) to contact the base 21a of the mask 21, so that the mask 21 can be grounded and masks having different thicknesses can be attracted. By disposing the earth pawl 26 at a side of the base 21a, the earth pawl 26 also has the function of preventing the mask 21 from dropping. An object which can be attracted by the electrostatic chuck 22 is a conductor or a semiconductor. When attracting a mask 21 having a base 21a made of an insulator, the mask 21 is attracted by forming a conductive layer of a metal on the back and the sides of the mask 21 by vacuum deposition or the like and contacting the conductive layer to the earth pawl 26. According to the above-described configuration, a unipolar electrostatic chuck having a strong attracting force can be used for the mask supporting device, and reliability in the attraction of the mask can be improved. Since a sufficient attracting force can be obtained even with a material having a relatively low dielectric constant, a material with low metal contamination can be adopted. When semiconductor devices are manufactured using an exposure apparatus including the mask supporting device of the second embodiment, the production yield of the devices can be increased. Furthermore, since masks having different thicknesses can be attracted, the tolerances in the thickness of the mask required in the manufacture of the mask can be increased. Hence, the cost in the manufacture of the mask can be reduced. Since the earth pawl 26 also has the function of preventing the mask 21 from dropping, reliability in the attraction of the mask is improved. In addition, since a grounding mechanism which does not hinder the conveyance of the mask 21 is adopted, reliability in the conveyance of the mask is also improved. Third Embodiment FIG. 3 is a cross-sectional view as seen from a side illustrating the configuration of a mask supporting device according to a third embodiment of the present invention. The mask supporting device of the third embodiment includes temperature control means for controlling an electrostatic chuck to be a desired temperature. The third embodiment has the same structure as the first embodiment, except as noted below. In FIG. 3, only the configuration of components added in the third embodiment, which are not found in the first embodiment, is illustrated, and the attraction control unit and the voltage control unit shown in the first embodiment are not illustrated. Since the operations of these units are the same as in the first embodiment, a description thereof will be omitted. In FIG. 3, a mask 31 comprises a base 31a comprising a Si substrate, and a pattern region 31b which is formed on the base 31a. The mask supporting device for attracting and holding the mask 31 comprises an electrostatic chuck 32 for attracting the mask 31, a chuck base 38 having a low coefficient of linear expansion and high stiffness on which the electrostatic chuck 32 is fixed, a temperature sensor 37 for detecting the temperature of the chuck base 38, a temperature-adjusting-medium supply device 42 containing a temperature adjusting or controlled medium for changing the temperature of the chuck base 38 by changing the temperature of the temperature adjusting or controlled medium, a temperature control unit 41 for controlling the temperature-adjusting-medium supply device 42 based on a detection signal from the temperature sensor 37, and a driving control unit 44 for effecting scanning movement of the electrostatic chuck 32. The electrostatic chuck 32 comprises a first insulating layer 33 and a second insulating layer 34. An electrode 35 for generating an attracting force is formed between the first insulating layer 33 and the second insulating layer 34. A plurality of pin-shaped projections 36 are formed on the surface of the first insulating layer 33. In addition, a supply tube 45 for supplying voids formed between projections 36 with a cooling gas, and a recovering tube 46 for recovering the gas introduced into the voids are provided. In this configuration, when a voltage is applied from a voltage control unit (not shown) to the electrode 35 of the electrostatic chuck 32, charges having a sign different from that of the voltage are excited on the surface of the first insulating layer 33. At that time, the dielectric polarization phenomenon appears on the surface of the first insulating layer 33, and an electrostatic force is applied to the mask 31. The mask 31 is thereby attracted and fixed on the pin-shaped projections 36 formed on the electrostatic chuck 32. The temperature sensor 37 comprises, for example, a platinum resistance temperature sensor, and has a resolution of about 0.01xc2x0 C. By being directly buried at a sufficiently deep position in the chuck base 38, the temperature sensor 37 can very precisely detect the temperature of the chuck base 38. A channel 39 is provided in the chuck base 38 in order to receive a temperature-adjusting or controlled medium subjected to temperature control. The temperature-adjusting or controlled medium is supplied from the temperature-adjusting-medium supply device 42 via flexible tubes 43 made of a metal or Teflon which has a low gas discharge rate in a vacuum. The chuck base 38 comprises, for example, a ceramic material, such as SiC, SiN or the like, or low-thermal-expansion glass, in which thermal strain is very small due to a low coefficient of linear expansion. The temperature control unit 41 controls the temperature-adjusting-medium supply device 42 based on an output signal from the temperature sensor 37 in order to control the temperature of the temperature-adjusting or controlled medium to be supplied to the chuck base 38. The electrostatic chuck 32 generates a sufficient force to attract the mask 31, and prevents the thermal expansion of the mask 31, having absorbed exposure light in lateral directions, by the attracting forcexc3x97the coefficient of friction of the electrostatic chuck 32. In order to prevent position deviation in lateral directions due to thermal expansion, the temperature of the electrostatic chuck 32 is very precisely controlled. More specifically, variations in the temperature of the electrostatic chuck 32 are very precisely controlled within a range equal to or less than 0.01xc2x0 C. In general, in an exposure apparatus, exposure is performed after very precisely aligning a mask with a wafer. In order to precisely perform the alignment, as disclosed in Japanese Patent Laid-Open Application (Kokai) No. 2-100311 (1990), a fine movement mechanism using a displacement member, comprising an elastic member having a low stiffness, such as a leaf spring or the like, and an actuator, comprising a piezoelectric element, are required for a mechanism for driving the wafer or the mask. The fine movement mechanism vibrates when the temperature adjusting medium flows because of its low stiffness, thereby degrading accuracy in the line width of the transferred pattern. In order to solve such a problem, the mask supporting device of the third embodiment uses only a coarse movement mechanism having a high stiffness for the driving mechanism, and a fine movement mechanism is provided in a mechanism for driving the wafer. The device also includes means for measuring the amount of shift of the interval between patterns on the exposed wafer, and expanding or contracting the electrostatic chuck by changing the temperature of the electrostatic chuck so as to minimize the amount of the shift. When the electrostatic chuck 32 is expanded or contracted, since the mask 31, attracted and constrained thereon, is simultaneously expanded or contracted, it is possible to correct the position deviation of the pattern of the mask 31. The temperature of the electrostatic chuck 32 is corrected by measuring, in advance, the relationship between the amount of shift of the pattern of the wafer after exposure and the change in the temperature of the electrostatic chuck 32, and by controlling the temperature of the electrostatic chuck 32 by the temperature control unit 41 so as to minimize the amount of shift of the interval between patterns on the wafer based on the obtained data. The amount of shift of the interval between patterns on the wafer may be obtained from a signal from alignment adjusting means (not shown) for performing alignment between the mask and the wafer, instead of measuring the interval between exposed patterns. Instead of using a temperature adjusting medium, the temperature of the electrostatic chuck 32 may be adjusted by precisely controlling the temperature at a high speed using, for example, a Peltier-effect element as disclosed in Japanese Patent Laid-Open Application (Kokai) No. 5-21308 (1993). FIG. 5 is a flow chart of a method for manufacturing semiconductor devices (semiconductor chips of ICs (integrated circuits), LSIs (large-scale integrated circuits) or the like, liquid-crystal panels, CCDs (charge-coupled devices) or the like) using the above-described X-ray projection exposure apparatus. In step 1 (circuit design), circuit design of semiconductor devices is performed. In step 2 (mask manufacture), masks, on which designed circuit patterns are formed, are manufactured. In step 3 (wafer manufacture), wafers are manufactured using a material, such as silicon or the like. Step 4 (wafer process) is called a preprocess, in which actual circuits are formed on the wafers by means of photolithography using the above-described masks and wafers. Step 5 (assembly) is called a postprocess which manufactures semiconductor chips using the wafers manufactured in step 4, and includes an assembling process (dicing and bonding), a packaging process (chip encapsulation), and the like. In step 6 (inspection), inspection operations, such as operation-confirming tests, durability tests, and the like, of the semiconductor devices manufactured in step 5 are performed. The manufacture of semiconductor devices is completed after passing through the above-described processes, and the manufactured devices are shipped (step 7). FIG. 6 is a detailed flow diagram of the above-described wafer process (step 4). In step 11 (oxidation), the surface of the wafer is oxidized. In step 12 (CVD (chemical vapor deposition)), an insulating film is formed on the surface of the wafer. In step 13 (electrode formation), electrodes are formed on the surface of the wafer by vacuum deposition. In step 14 (ion implantation), ions are implanted into the wafer. In step 15 (resist process), a photosensitive material is coated on the wafer. In step 16 (exposure), the circuit pattern on the mask is exposed and printed on the wafer using the above-described X-ray projection exposure apparatus. In step 17 (development), the exposed wafer is developed. In step 18 (etching), portions other than the developed resist image are etched off. In step 19 (resist separation), the resist, which becomes-unnecessary after the completion of the etching, is removed. By repeating these steps, a final circuit pattern made of multiple patterns is formed on the wafer. The individual components shown in outline or designated by blocks in the drawings are all well known in the X-ray projection exposure apparatus and device manufacturing method arts and their specific construction and operation are not critical to the operation or the best mode for carrying out the invention. While the present invention has been described with respect to what are presently considered to be preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, the present invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
048636746	description	DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows the schematic process of charging or unloading the reactor vessel 1 with spherical operating elements. A cavity housing or container 2 surrounds the reactor vessel 1. The cover 3 of the cavity is bounded or enclosed by an external housing 4 which is equipped with a gate 5. A travelling frame 6 may be moved into or out of the building through gate 5. The travelling frame 6 uses a hydraulic lifting device 7 to carry transport container 8, thereby eliminating the need for a stationary lifting device in the building 4. The transport container is taken over by a mobile crane and placed on a transport carriage 10 after it has attained its horizontal position 9. FIG. 2 shows the area of the nuclear reactor installation taking part in the manipulation of the spherical operating elements 11. A pile 12 of spherical operating elements 11 is surrounded by a reflector 13. The operating elements may be fuel elements. The reflector exhibits channels 14 to receive the absorber rods 15. The operational lifetime of the stationary pile is in the range of several years. At the conclusion of the operating period, all of the operating elements are removed from the reactor vessel 1 and replaced by new ones. The transport container 8 is set onto the cover 3 of the cavity so that the transport container bottom 16 overlaps the cover access opening 17. A closure cover 19 (FIG. 3) fastened by screws 18 to the transport container is removed to expose bores 22, 22a prior to transport container placement. The bores 22, 22a pass through 21, 21a which are secured to the transport container bottom 16 by screws 20. The shielding cover 19 carries two shielding stoppers 23 to insure the shielding effect. The shielding stoppers 23 project into the bores 22, 22a when the closure cover is in place. A ball valve 24 actuable from the side of the transport container is arranged above each of the inserts and fastened by screws 25. The ball valves 24 are arranged in the bottom 16 and enable closure of the bottom passages leading above the bores 22, 22a. The ball valves 24 may be actuated by a rotational movement. A variable gas flow blower 26 rests on a supporting frame 27 connected the reactor vessel 1. A suction line 29 equipped with a closure fitting 28 leads to the bore 22a of the bottom 16 and suctions gas from the transport container 8 when the ball valve 24 is open. The bottom passage containing the suction line terminates below a filter in the form of an intermediate bottom 30 in order to prevent suctioning of dust particles from the transport container. The intermediate bottom is stable enough to support a pebble filling extending to the line 31. A stopper 64 located in the intermediate bottom 30 is opened during a subsequent unloading of the transport container for removal of burned operating elements. The pressure line 32 of the blower 26 conducts the gas suctioned in through a closure slide 33 associated with the reactor container in the direction of the arrow 34 into the reactor vessel pebble pile 12. A pebble conveyor line 36 is always maintained with its end facing the pile 12 at the height of the surface of the pile and rotated in a pendulum motion around its axis by a rotating and advance unit 35 mounted on the closure slide 33. As seen from FIGS. 2a and 2b, the pebble conveyor line 36 may be a corrugated pipe with internal longitudinal ribs 37. The operating elements 11 to be conveyed are better guided and more rapidly transported in a corrugated pipe than in a smooth pipe. The frontal side of the pebble conveyor line 36 facing the pile 12 is bevelled off and thus exhibits a non-horizontal outline. With a pendulum or reciprocating rotation of the pebble conveyor line 36 in the direction of the arrow 38 around its axle 39 the operating elements 11 enter the bevelled opening of the pebble conveyor line 36 easier. This increases the conveying capacity and blockage of the opening is avoided. The pebble conveyor line 36 extends concentrically through the rotating and advance line 35 and reaches with the ball valve 24 to open a guide tube resembling a walking stick. The guide tube 40 is fastened to the inside of the transport unit bottom 16 and extends approximately vertically upwards and reaches with its bent end the vicinity of the cover of the transport container 8. A covering sleeve 41 concentrically encompasses the pebble conveyor line 36 arranged between the rotating and advance unit 35 and the bottom 16. The sleeve 41 is fastened to the lower side of the transport container bottom by screws 42. The sleeve 41 is connected to the rotating and advance unit 35 by the insertion of folding bellows 43 in a dust-tight manner. The sleeve is assembled in the area of separation points 44 to enable mounting the pebble conveyor line 30. A spring 45 maintains the cover sleeve 41 to stabilize the connection to the folding bellows 43. FIGS. 4 to 6 show the configuration of the rotating and advance unit 35. The pebble conveyor line 36 extends through the center passage 46 and is supported slidingly over the rolls 47. A holding device 48 is rigidly connected to a housing 49 of the rotating and advance unit. Clamping jaws 50 may be pressured against the pebble conveyor line 36 by pressure medium passages 51 acting on the setting elements 52. In this holding position the pebble conveyor line 36 may be rotated by the rotating drive 53 engaging a toothed wheel 54 connected to the housing 49. The toothed wheel 54 is displaceably supported by groove bearings 55 relative to the support elements 56. The support elements 56 are in turn fastened with screws to the closure slide 33. A stepping piston 58, which by pressure medium connnections 59, 60 carries out a stroke of approximately 30 mm, is connected by the screws 61 to a transport device 62. The transport device is equipped through pressure medium line 63 with clamping jaws 50a similar to those of the holding device 48. Following the release by the holding device 48 of the pebble conveyor line 36, the transport device 62 may displace the latter always by a stroke of the stepping piston 58 in the vertical direction. The rotating and advancing unit 35 utilizes the stepping piston 58 in cooperation with the transport device 62 clamping jaws 50a and the holding device 48 clamping jaws 50, to axially displace the pebble conveyor line 36. To insert the pebble conveyor line the stepping piston 58 is raised. Clamping jaws 50a are then activated and clamping jaws 50 are deactivated whereupon the stepping piston 58 is advanced. Clamping jaws 50a are then deactivated and jaws 50 are activated. To further advance the pebble conveyor line the above is repeated; to withdraw the pebble conveyor line the above is reversed. The clamping jaws 50, 50a and the stepping piston 58 are operated by the introduction of pressure medium through the various pressure medium connections and lines in a fashion similar to pneumatic or hydraulic operating devices. If the pebble pile 12 is to be removed from the reactor vessel 1, a transport container 8 is brought into a loading position on the cover 3 of the cavity 2, following the removal of the closure cover 19 and the opening of the ball valves 24. The nuclear reactor installation is rendered pressureless, the cooling gas interposed and returned to the primary cooling loop after reloading. After the blower has been connected on the suction side to the transport container 8 and on the compression side to the reactor vessel 1, the constantly circulating gas flow moves the pebbles into the transport container. The pebble conveyor line 36 is maintained constantly at the height of the surface of the pile 12 and optionally rotated in a reciprocating fashion or the manner of a pendulum by the rotating and advance unit 35. The same apparatus is used in the loading of new operating elements. However, the container has thinner walls. Furthermore, it has no guide tube, so that the operating elements are free to drop into the reactor vessel 1. The gas flow with a reduced velocity serves as a brake for the pebbles.
054405998	description	DESCRIPTION OF THE PREFERRED EMBODIMENTS The fuel rods support grid according to the invention is generally designated by the numeral 10 and includes a first set of parallel strips 12 which are slottedly interlocked with a second set of parallel strips 14 which are arranged at right angles to the first set. The intersections defined between each of the first and second sets of strips are welded to provide a permanent interconnection. As seen in FIG. 2, the strips have integral tabs 18 which extend upwardly from their upper or downstream edges. These tabs are each so shaped that they can be bent along a pair of bend lines 20 such as are shown in FIG. 2 to form a pair of "side-supported" vanes 22. As will be appreciated, the tabs 18 are coplanar with the strips 12 so that the bend lines extend generally in the direction of coolant flow through the grid 10. The vanes 22 in accordance with the first embodiment are bent by predetermined amounts in opposite directions as indicated in FIG. 1. That is, one vane is bent "outwardly" so as to extend in the direction of the viewer, while the other is bent "inwardly" and away from the viewer. A flat upper edge portion 24 is defined at the apex of the tab 18 as it appears after the vanes are bent at the predetermined angles with respect to the tab 18. In the embodiment illustrated in FIGS. 3 and 4, the grid 10' has integral side-supported vanes 22' which are contiguous and are side-supported by the integral tabs 18' formed on the strips 12'. In this instance also, the vanes are formed by bending the tab along bend lines 20'. In this embodiment, the bend lines converge at a point and in a manner which eliminates the upper edge portion 24. The contiguous side-supported vanes 22' which result from the bending of the tab can be seen in the plan view of FIG. 3. As shown in FIGS. 1 and 3, the flow directing vanes 22 and 22' are such as to create coolant flow components which leave the mixing vanes generally in the direction indicated by the small arrows. In a third embodiment, shown in FIG. 5, the strip 12" is provided with a predetermined number of integral tabs 18" each of which is bent along bend lines 20" to form pairs of side-supported elongated vanes 22". In this instance, each pair of vanes are separated by an edge portion 24". The base width "X" of each support tab 18" is selected to endow it and the vanes which are integral therewith with a desired amount of mechanical support and rigidity which is sufficient to enable the required mixing and longevity requirements to be met. The dimension "X" is constrained by factors such as the fuel rod pitch and the number of mixing vanes per intersection. Before bending, the side-supported mixing vanes and the strips which are used in the first, second, or third embodiment, for example, can be fixedly interconnected using a weld nugget technique. To facilitate this type of welding, cut-outs 26 can be formed in each strip 12 to accommodate the nuggets which are created. FIG. 6 illustrates a fourth embodiment which features contiguous mixing vanes 22"' formed by bending the sides of the integral support tab 18"' along bend lines 20"'. Similar to the above embodiments, the bend lines 20"' are coplanar with the strips 12 and converge generally in the direction of coolant flow through the grid. Thus, the mixing vanes according to the present invention are stronger than existing vanes, result in lower pressure drop, and produce equal or superior critical heat flux performance relative to the existing spacer grid designs. Moreover, grids made according to the principles of the invention utilizing the side-supported mixing vanes have bend angles which are easier to maintain under operating and fuel reconstitution conditions. FIG. 7 shows the preferred embodiment of the present invention. In this arrangement, the spacer grid assembly 500 is comprised of a set of strips 501 which are slotted on the top side, interlocked with the set of strips 502 which are slotted on their bottom side, and welded together at the intersection joints. The strips 501 slotted on the top do not have any vanes, only rod support features, and, as such, can be used in the fabrication of unvaned spacer grid assemblies as well as vaned spacer grid assemblies. The strips 502 slotted on the bottom have vanes on the top side that are located at the desired intersection joints. The assembling of the interlocking strips is greatly simplified compared to the prior art because the interleaving of the "slots-top" strips 501 (no vanes) and the "slots-bottom" strips 502 (vaned) does not require the vanes to pass by any rod support features. The flow directing vanes 22' provided according to the principals of the invention are formed by bending portions of a tab 18' which are integral with the grid strip (see FIG. 4). This results in the each vane 22' being supported along its side rather than along its base as in the case of the prior art arrangements. The angle of the bend axis can be varied to achieve the desired flow characteristics with typical angles being in the 20.degree. to 40.degree. range. The angle to which the vane is bent can also be varied, the preferred embodiment is 90.degree. but angles of more or less than 90.degree. can be used. The bending of the vane 22' along its side rather than its base stiffens the vane so it is much less vulnerable to damage due to a change in the bend angle, and provides significantly more support for loads imposed on the vane by the fuel rod end cap during initial rod insertion or reconstitution. Also with regards to rod insertion, the slope of the upper edge of the vane is such that it would guide a fuel rod end cap into its intended cell. The orientation of the vane 22' after bending has the narrow portion of the vane toward the bottom (near the top of the main grid strips) and the wide portion of the vane toward the top. Since the wider portion of the vane blocks or redirects more flow than the thinner portion, and since it is further removed axially from the main body of the spacer grid assembly, it helps to decouple the hydraulic effect of the vane from that of the grid, thereby reducing the pressure drop and increasing the free-stream flow deflected by the vane 504 compared to a vane aligned in the prior art orientation. The portion of the integral tab 18' that remains in the plane of the strip not only serves to reinforce the vane but also to minimize lateral leakage of the flow that has been redirected by the vane attached to the tab. The "sidewall" forces more of the flow to continue up the underside of the vane and exit at the end of the vane 22', as intended. High pressure water tests with electrically heated rods have been performed in 6.times.6 rod arrays with side-supported mixing vanes to assess the performance of the side-supported mixing vanes relative to grids without vanes. The power required to cause Departure from Nucleate Boiling was measured in these tests. A comparison of the performance of the side-supported vaned grids relative to grids without vanes is provided in FIG. 11. More specifically, FIG. 11 presents a plot of the ratio of test section power to cause Departure from Nucleate Boiling to the test section power predicted to cause Departure from Nucleate Boiling in the absence of the mixing vanes. This ratio is plotted vs. the temperature of water at the inlet to the test section. The side-supported vanes clearly improve Departure from Nucleate Boiling performance since the ratio is everywhere greater than 1. It will be noted that while a typical configuration of the preferred embodiment is shown in FIG. 7 with the pre-bend tab geometry of FIG. 7 shown in FIG. 4, it is within the scope of the invention to use alternative vane geometries to tailor the desired flow characteristics. Two possible examples are shown in FIGS. 2 and 6. By alternating the direction of bending of the vanes, various swirl patterns within an array of fuel rods 508 can be achieved (see FIGS. 8, 9 and 10). In view of the above disclosure, the various possible changes and modifications which are possible without departing from the scope of the present invention will be self evident to those skilled in the art of spacer grid designs.
	claims	1. A covering worksuit being disposable and individual for protection against radioactive particles, comprising a trunk part and a trouser part, which is of one piece with the trunk part and which extends down from the trunk part,the trunk part and the trouser part having a wall, which is flexible and dustproof,the covering worksuit comprising a first zip closure, which extends from top to bottom and on a front between a left edge and a right edge of the wall at least in the trunk part, the first zip closure having a first side attached in a dustproof manner to the left edge of the wall and a second side attached in a dustproof manner to the right edge of the wall, the first side and the second side configured to be connected together according to a first meshing line dustproof in a closed state of the first zip closure and configured to be separated from each other along the first meshing line in an open state of the first zip closure,wherein the covering worksuit comprises at least one other closure, which extends from top to bottom between two other opposite edges of the wall in at least one of the legs of the trouser part and which comprises two strips respectively attached in a dustproof manner to the two other opposite edges of the wall, the two strips configured to be connected to each other according to at least one other meshing line dustproof in a closed state of the at least one other closure and being able to be separated from each other along the at least one other meshing line in an open state of the at least one other closure,at least one connection point connecting together the two strips beyond the at least one other meshing line present between the first zip closure and the at least one other closure in the closed state,at least one breaking member provided on at least one of the first zip closure, of the at least one other closure to be able to break the at least one connection point by pulling on the at least one breaking member,the first zip closure further extending from top to bottom between the two opposite edges of the wall in the other of the legs of the trouser part,the at least one connection point located on the first side or on the second side of the first zip closure,the first zip closure comprising a slider configured to connect the first side and the second side together along the first meshing line by raising the slider along them and to separate the first side and the second side from each other along the first meshing line by lowering the slider along the first side and the second side,the at least one breaking member being formed by the slider, which is configured to break the at least one connection point by lowering the slider along the at least one connection point and along the first side and the second side. 2. The covering worksuit according to claim 1, wherein the at least one other closure is another zip closure, comprising another slider configured to connect the two strips together along the at least one other meshing line by movement of the other slider from bottom to top along the two strips and configured to separate the two strips from each other along the at least one other meshing line by movement of the other slider from top to bottom along the strips. 3. The covering worksuit according to claim 1, wherein the two strips of the at least one other closure mesh with each other along the at least one other meshing line in the closed state of the at least one other closure,the two strips of the at least one other closure being configured to be separated from each other along the at least one other meshing line by pulling on one and/or the other of the two strips. 4. The covering worksuit according to claim 1, wherein the at least one connection point is located in a crotch area of the trouser part or in a lower abdomen area of the trouser part. 5. The covering worksuit according to claim 1, wherein the trunk part ends at a top end with a dustproof collar, having a left front part and a right front part connected together by a dustproof front closure strip located beyond an upper end of the first zip closure. 6. The covering worksuit according to claim 5, wherein a free front and side tag and a second free front and side tag are attached in front of the front closure strip. 7. The covering worksuit according to claim 1, wherein the covering worksuit comprises stitching lines visible on a wrong side of the covering worksuit and invisible on a right side of the covering worksuit. 8. The covering worksuit according to claim 1, wherein the covering worksuit comprises sleeves configured for passing the arms therethrough, wherein the sleeves comprise a second wall being dustproof, are connected at a top of the trunk part, a free end edge of the sleeves surrounds an end opening configured for passing at least the index finger, middle finger, ring finger and little finger of the hand therethrough, the sleeves further comprise at least one hole configured for passing the thumb therethrough, distinct from the end opening and separated from the free end edge by an end part of the second wall. 9. The covering worksuit according to claim 1, wherein the covering worksuit comprises a tightening elastic situated in a sheath in a waist of the covering worksuit. 10. The covering worksuit according to claim 1, wherein the covering worksuit comprises reinforcements at knees of the trouser part. 11. The covering worksuit according to claim 1, wherein the covering worksuit comprises at least one transparent outer wall, which is located to the right and/or the left of the first zip closure on the front in the trunk part and which forms at least one pocket with at least one other underlying wall. 12. The covering worksuit according to claim 1, wherein the covering worksuit comprises a removable stomach pouch having a transparent outer wall, the removable stomach pouch having an upper part comprising a fourth zip closure and fasteners configured to be connected and disconnected relative to a front upper part of the trunk part. 13. A covering worksuit being disposable and individual for protection against radioactive particles, comprising a trunk part and a trouser part, which is of one piece with the trunk part and which extends down from the trunk part,the trunk part and the trouser part having a wall, which is flexible and dustproof,the covering worksuit comprising a first zip closure, which extends from top to bottom and on a front between a left edge and a right edge of the wall at least in the trunk part, the first zip closure having a first side attached in a dustproof manner to the left edge of the wall and a second side attached in a dustproof manner to the right edge of the wall, the first side and the second side configured to be connected together according to a first meshing line dustproof in a closed state of the first zip closure and configured to be separated from each other along the first meshing line in an open state of the first zip closure,the covering worksuit comprising:at least one second closure, which extends from top to bottom between two second opposite edges of the wall in one of the legs of the trouser part and which comprises two second strips respectively attached in a dustproof manner to the two second opposite edges of the wall, the two second strips being able to be connected to each other according to a second meshing line, dustproof in a closed state of the second closure, and configured to be separated from one another along the second meshing line in an open state of the second closure, andat least one third closure, which extends from top to bottom between two third opposite edges of the wall in the other of the legs of the trouser part and which comprises two third strips respectively attached in a dustproof manner to the two third opposite edges of the wall, the two third strips configured to be connected to each other according to a third meshing line, dustproof in a closed state of the third closure, and configured to be separated from one another along the third meshing line in an open state of the third closure, anda first connection point that connects together upper ends of the two second strips of the second closure beyond the second meshing line and is present between the first zip closure and the at least one second closure in the closed state of them, anda second connection point that connects together upper ends of the two third strips of the third closure beyond the third meshing line and is present between the first zip closure and the at least one third closure in the closed state of them, andat least one breaking member comprising a tab attached to one of the second strips and to one of the third strips close to each other and close to the first connection point and to the second connection point, to allow breaking the first connection point and the second connection point by pulling on the tab, separating the two second strips from each other along the second meshing line and separating the two third strips from each other along the third meshing line. 14. The covering worksuit according to claim 13, wherein the at least one second closure is a second zip closure, comprising a second slider configured to connect the two second strips together along the second meshing line by movement of the second slider from bottom to top along the two second strips and configured to separate the two second strips from each other along the second meshing line by movement of the second slider from top to bottom along the second strips,the at least one third closure is a third zip closure, comprising a third slider configured to connect the two third strips together along the third meshing line by movement of the third slider from bottom to top along the two third strips and configured to separate the two third strips from each other along the third meshing line by movement of the third slider from top to bottom along the third strips. 15. The covering worksuit according to claim 13, wherein the two second strips of the at least one second closure mesh with each other along the second meshing line in the closed state of the at least one second closure,the two second strips of the at least one second closure configured to be separated from each other along the second meshing line by pulling on one and/or the other of the two second strips,the two third strips of the at least one third closure mesh with each other along the third meshing line in the closed state of the at least one third closure,the two third strips of the at least one third closure configured to be separated from each other along the third meshing line by pulling on one and/or the other of the two third strips. 16. The covering worksuit according to claim 13, wherein the first connection point is located in a crotch area of the trouser part or in a lower abdomen area of the trouser part,the second connection point is located in the crotch area of the trouser part or in the lower abdomen area of the trouser part. 17. The covering worksuit according to claim 13, wherein the trunk part ends at a top end with a dustproof collar, having a left front part and a right front part connected together by a dustproof front closure strip located beyond an upper end of the first zip closure. 18. The covering worksuit according to claim 17, wherein a first free front and side tags and a second free front and side tag are attached in front of the front closure strip. 19. The covering worksuit according to claim 13, wherein the covering worksuit comprises stitching lines visible on a wrong side of the covering worksuit and invisible on a right side of the covering worksuit. 20. The covering worksuit according to claim 13, wherein the covering worksuit comprises sleeves configured for passing the arms therethrough, wherein the sleeves comprise a second wall being dustproof, are connected at a top of the trunk part, a free end edge of the sleeves surrounds an end opening configured for passing of at least the index finger, middle finger, ring finger and little finger of the hand therethrough, the sleeves further comprise at least one hole configured for passing the thumb therethrough, distinct from the end opening and separated from the free end edge by an end part of the second wall. 21. The covering worksuit according to claim 13, wherein the covering worksuit comprises a tightening elastic situated in a sheath in a waist of the covering worksuit. 22. The covering worksuit according to claim 13, wherein the covering worksuit comprises reinforcements at knees of the trouser part. 23. The covering worksuit according to claim 13, wherein the covering worksuit comprises at least one transparent outer wall, which is located to the right and/or the left of the first zip closure on the front in the trunk part and which forms at least one pocket with at least one other underlying wall. 24. The covering worksuit according to claim 13, wherein the covering worksuit comprises a removable stomach pouch having a transparent outer wall, the removable stomach pouch having an upper part comprising a fourth zip closure and fasteners configured to be connected and disconnected relative to a front upper part of the trunk part. 25. A covering worksuit being disposable and individual for protection against radioactive particles, comprising a trunk part and a trouser part, which is of one piece with the trunk part and which extends down from the trunk part;the trunk part and the trouser part having a wall, which is flexible and dustproof;the covering worksuit comprising a first zip closure, which extends from top to bottom and on a front between a left edge and a right edges of the wall at least in the trunk part, the first zip closure having a first side attached in a dustproof manner to the left edge of the wall and a second side attached in a dustproof manner to the right edge of the wall, the first side and the second side configured to be connected together according to a first meshing line dustproof in a closed state of the first zip closure and configured to be separated from each other along the first meshing line in an open state of the first zip closure;the covering worksuit comprising:at least one second closure, which extends from top to bottom between two second opposite edges of the wall in one of the legs of the trouser part and which comprises two second strips respectively attached in a dustproof manner to the two second opposite edges of the wall, the two second strips configured to be connected to each other according to a second meshing line, dustproof in a closed state of the second closure, and configured to be separated from one another along the second meshing line in an open state of the second closure; andat least one third closure, which extends from top to bottom between two third opposite edges of the wall in the other of the legs of the trouser part and which comprises two third strips respectively attached in a dustproof manner to the two third opposite edges of the wall, the two third strips configured to be connected to each other according to a third meshing line, dustproof in a closed state of the third closure, and configured to be separated from one another along the third meshing line in an open state of the third closure;a connection part, which, in the closed state, comprises:a first connection flank, which connects together lower ends of the first side and of the second side of the first zip closure, beyond the first meshing line and which is present in the closed state between the first zip closure on the one hand and the at least one second closure and the at least one third closure on the other hand;a second connection flank, which connects together upper ends of the two second strips of the at least one second closure beyond the second meshing line and which is present in the closed state between the first zip closure and the at least one second closure;and a third connection flank connecting together upper ends of the two third strips of the at least one third closure beyond the third meshing line and which is present in the closed state between the first zip and the at least one third closure;the first zip closure comprising a slider configured to connect the first side and the second side together along the first meshing line by raising the slider along them and to separate the first side and the second side from each other along the first meshing line by lowering the slider along the first side and the second side;a breaking member being formed by the slider, which is configured to break the first connection flank, the second connection flank and the third connection flank by lowering the slider along the connection part. 26. The covering worksuit according to claim 25, wherein the at least one second closure is a second zip closure, comprising a second slider configured to connect the two second strips together along the second meshing line by movement of the second slider from bottom to top along the two second strips and configured to separate the two second strips from each other along the second meshing line by movement of the second slider from top to bottom along the second strips,the at least one third closure is a third zip closure, comprising a third slider configured to connect the two third strips together along the third meshing line by movement of the third slider from bottom to top along the two third strips and configured to separate the two third strips from each other along the third meshing line by movement of the third slider from top to bottom along the third strips. 27. The covering worksuit according to claim 25, wherein the two second strips of the at least one second closure mesh with each other along the second meshing line in the closed state of the at least one second closure,the two second strips of the at least one second closure configured to be separated from each other along the second meshing line by pulling on one and/or the other of the two second strips,the two third strips of the at least one third closure mesh with each other along the third meshing line in the closed state of the at least one third closure,the two third strips of the at least one third closure configured to be separated from each other along the third meshing line by pulling on one and/or the other of the two third strips. 28. The covering worksuit according to claim 25, wherein the connection part is located in a crotch area of the trouser part or in a lower abdomen area of the trouser part. 29. The covering worksuit according to claim 25, wherein the trunk part ends at a top end with a dustproof collar, having a left front part and a right front part connected together by a dustproof front closure strip located beyond an upper end of the first zip closure. 30. The covering worksuit according to claim 29, wherein a first free front and side tags and a second free front and side tag are attached in front of the front closure strip. 31. The covering worksuit according to claim 25, wherein the covering worksuit comprises stitching lines visible on a wrong side of the covering worksuit and invisible on a right side of the covering worksuit. 32. The covering worksuit according to claim 25, wherein the covering worksuit comprises sleeves configured for passing the arms therethrough, wherein the sleeves comprise a second wall being dustproof, are connected at a top of the trunk part, a free end edge of the sleeves surrounds an end opening configured for passing at least the index finger, middle finger, ring finger and little finger of the hand therethrough, the sleeves further comprise at least one hole configured for passing the thumb therethrough, distinct from the end opening and separated from the free end edge by an end part of the second wall. 33. The covering worksuit according to claim 25, wherein the covering worksuit comprises a tightening elastic situated in a sheath in a waist of the covering worksuit. 34. The covering worksuit according to claim 25, wherein the covering worksuit comprises reinforcements at knees of the trouser part. 35. The covering worksuit according to claim 25, wherein the covering worksuit comprises at least one transparent outer wall, which is located to the right and/or the left of the first zip closure on the front in the trunk part and which forms at least one pocket with at least one other underlying wall. 36. The covering worksuit according to claim 25, wherein the covering worksuit comprises a removable stomach pouch having a transparent outer wall, the removable stomach pouch having an upper part comprising a fourth zip closure and fasteners configured to be connected and disconnected relative to a front upper part of the trunk part.
	abstract	An apparatus and method for irradiating a product or product stack with a relatively even radiation dose distribution is provided. The apparatus comprises a radiation source, an adjustable collimator, a turn-table capable of receiving a product stack and a control system capable of adjusting the adjustable collimator to vary the geometry of the radiation beam as the product stack is rotated in the radiation beam. Also disclosed is the modulation of the radiation beam energy and power and varying the angular rotational velocity of the product stack in a radiation beam to achieve a low dose uniformity ratio in the product stack.
	claims	1. A synthesizer for producing radiopharmaceuticals comprising:a) a stationary processor having a disposable kit interface planar structure disposed substantially vertically and at least:i) a plurality of rotary actuators protruding horizontally from said interface surface,ii) a plurality of push-on fluidic connectors protruding horizontally from said interface surface, andiii) structure for releasably interfacing a disposable kit to said rotary actuators and push-on connectors by means of linear actuators that provide translation in a horizontal direction; andb) at least one disposable kit having:i) a processor interface planar structure disposed substantially vertically containing at least:1) a plurality of rotary slide valves having rotors adapted to interface with said rotary actuators and apertures for making fluidic connections to flexible tubing, and2) a plurality of push-on fluidic connectors adapted to interface with said processor push-on fluidic connectors and having fittings for making fluidic connections to flexible tubing, andii) a reagent and reactor vessel mounting structure affixed to said processor interface planar structure and disposed generally horizontally opposite said processor containing at least:1) a plurality of vessel mounting structures, said mounting structures having fittings for making fluidic connections to flexible tubing, and2) a plurality of flexible tubes for connecting said fittings of one vessel mounting structure to another and to said rotary slide valve apertures and push-on connectors. 2. The synthesizer of claim 1 wherein said processor structure for releasably interfacing a disposable kit further comprises a pair of side supports with slots disposed to allow said kit processor interface planar structure to slide vertically and at least one support rod protruding horizontally form said processor and having a shorter length than the maximum extension of said linear actuators. 3. The synthesizer of claim 1 wherein said processor further comprises a vessel heater affixed to actuators that move in a vertical direction with sufficient upward extent to heat a reactor vessel attached to said kit and sufficient downward extent to clear said reactor vessel during horizontal kit translation. 4. The synthesizer of claim 1 wherein said kit processor interface planar structure has a plurality of holes and said kit reagent and reactor vessel mounting structure has a plurality of corresponding fingers having a curved ends, said holes and fingers disposed so that insertion of said fingers in said holes locks said reagent and reactor vessel mounting structure to said processor interface planar structure. 5. The synthesizer of claim 1 wherein said kit rotary slide valves each comprise a circular cavity in said processor interface planar structure having a base with at least one tubing pass through hole, an elastomer planar stator disposed in said cavity having corresponding holes sufficiently undersized to secure tubing inserted therein, and a two-sided planar rotor disposed adjacent said stator having at least one fluidic channel on the side adjacent said stator and a rotary actuator engagement feature on the opposite side. 6. The synthesizer of claim 5 wherein said kit rotary slide valve rotor is comprised of a radiation resistant polymer selected from the group consisting of VITON and Buna N rubbers and having a Shore A hardness of about 65–75. 7. The synthesizer of claim 6 wherein said rotary valves are about 10 mm in diameter and said rotary actuators have spring loaded rotary valve engagements providing a force against said rotor in the range of about 30–45 N. 8. The synthesizer of claim 1 wherein the maximum horizontal width of said processor and said kit in a direction parallel to said interface structures is less than about 16 cm. 9. The synthesizer of claim 1 further comprising a radiation shielded container disposed below said structure for releasably interfacing a disposable kit so that after release said kit falls into said container. 10. A disposable kit for producing radiopharmaceuticals in conjunction with a stationary processor comprising:a) a plurality of rotary slide valves having rotors with engagement features adapted to interface with rotary actuators and apertures for making fluidic connections to flexible tubing;b) a plurality of push-on fluidic connectors with openings adapted to interface with mating push-on fluidic connectors and having fittings for making fluidic connections to flexible tubing, wherein said plurality of rotary slide valves and said plurality of push-on fluidic connectors are arrayed on a processor interface planar structure and oriented to interface in a single processor direction; andc) a reagent and reactor vessel mounting structure affixed to said processor interface planar structure and disposed generally horizontally opposite said processor direction and containing at least:1) a plurality of vessel mounting structures, said mounting structures having fittings for making fluidic connections to flexible tubing, and2) a plurality of flexible tubes for connecting said fittings of one vessel mounting structure to another and to said rotary slide valve apertures and push-on connectors. 11. The disposable kit of claim 10 wherein said kit processor interface planar structure has a plurality of receptacles and said kit reagent and reactor vessel mounting structure has a plurality of corresponding fingers having a curved ends, said receptacles and fingers disposed so that insertion of said fingers into said receptacloes locks said reagent and reactor vessel mounting structure to said processor interface planar structure. 12. The disposable kit of claim 10 wherein said kit rotary slide valves each comprise a circular cavity in said processor interface planar structure having a base with at least one tubing pass through hole, an elastomer planar stator disposed in said cavity having corresponding holes sufficiently undersized to secure tubing inserted therein, and a two-sided planar rotor disposed adjacent said stator having at least one fluidic channel on the side adjacent said stator and a rotary actuator engagement feature on the opposite side. 13. The disposable kit of claim 12 wherein said kit rotary slide valve rotor is comprised of a radiation resistant polymer selected from the group consisting of VITON and Buna N rubbers and having a Shore A hardness of about 65–75 and a diameter of about 10 mm so that a force against said rotor in the range of about 30–45 N is sufficient to provide a leak tight seal against a hydrostatic pressure of 100 kPa (14.5 psi). 14. A method of producing radiopharmaceuticals comprising the steps of:1) providing a stationary processor having a disposable kit interface planar structure disposed substantially vertically and at least a plurality of rotary actuators protruding horizontally from said interface structure, a plurality of push-on fluidic connectors protruding horizontally from said interface structure, and structure for releasably interfacing a disposable kit to said rotary actuators and push-on connectors by means of linear actuators that provide translation in a horizontal direction; and2) providing at least one disposable kit having:a) a processor interface planar structure containing at least a plurality of rotary slide valves, having rotors adapted to interface with said rotary actuators and apertures for making fluidic connections to flexible tubing, and a plurality of push-on fluidic connectors adapted to interface with said processor push-on fluidic connectors and having fittings for making fluidic connections to flexible tubing, andb) a reagent and reactor vessel mounting structure affixed to said processor interface planar structure and disposed generally perpendicularly and containing at least a plurality of vessel mounting structures, said vessel mounting structures having fittings for making fluidic connections to flexible tubing, and a plurality of flexible tubes for connecting said fittings of one vessel to another and to said rotary slide valve apertures and push-on connectors;3) mounting at least one reactor vessel to said kit vessel mounting structure;4) filling reagent vessels with predetermined reagents, adding fluidic seals, and mounting said vessels to said kit vessel mounting structure;5) fluidically interconnecting said disposable kit rotary valves, push-on connectors, and vessel mounting structure fittings in a predetermined fluidic configuration;6) making fluidic connections to said reagent vessels through said seals;7) interfacing said disposable kit to said stationary processor; and8) operating said processor to produce radiopharmaceuticals. 15. The method of claim 14 wherein steps 2–5 are preformed at a geographical location remote from said processor. 16. The method of claim 15 wherein steps 2–5 are performed at a central geographic location using a plurality of kits and distributed to a plurality of remote production facilities to carry out steps 6–8. 17. The method of claim 14 wherein said radiopharmaceutical is FDG. 18. The method of claim 14 where said disposable kits have a fluidic output fitting and a fluidic input fitting and the method further comprises, in step 7, interfacing one or more kits, each to a processor, and connecting outputs of one or more kits to inputs of other kits and, in step 8, operating two or more processors in sequence to produce a radiopharmaceutical. 19. The method of claim 14 further comprising the added steps of releasing said disposable kit into a shielded container and interfacing a second disposable kit to process a second batch of radiopharmaceuticals.
	abstract	The invention relates to an apparatus and a method for a scanning probe microscope, comprising a measuring assembly which includes a lateral shifting unit to displace a probe in a plane, a vertical shifting unit to displace the probe in a direction perpendicular to the plane, and a specimen support to receive a specimen. A condenser light path is formed through the measuring assembly so that the specimen support is located in the area of an end of the condenser light path.
	abstract	A device to implant impurities into a semiconductor wafer has a process chamber having a wall, a pressure compensation unit, a disk to support a plurality of semiconductor wafers within the process chamber. The disk has a radially extending slot arranged among the wafers. A beam gun is positioned within the process chamber to shoot an ion beam at the semiconductor wafers. A cryo pump minimizes the pressure within the process chamber. A first ion gauge is positioned between the process chamber and the cryo pump. A second ion gauge extends through the wall of the process chamber. A switching device selectively connects the first or second ion gauge to the pressure compensation unit. A faraday receives ions from the ion gun filter after the ions travel through the slot in the disk. A current meter counts the number of electrons flowing to the disk faraday to neutralize the ions.
	description	This invention relates to the field of positron moderation in general and more specifically to methods and apparatus for high-efficiency moderation of positrons from high-energy sources, such as linear accelerators (LINAC), gamma-ray sources, or nuclear reactor-based sources. Positrons are the anti-particle of an electron, each having the same mass as an electron, but opposite charge. When a positron and electron combine, they annihilate, converting 100% of their mass into energy. Positrons are currently used in a wide range of applications including medicine, fundamental physics research, and materials characterization. High intensity positron sources may be critical in the creation of the world's first gamma-ray laser. Antimatter has the highest energy density of any known substance, and positrons have been studied by NASA as a possible propellant for high performance in-space propulsion systems. Currently, the most intense source of positrons in the world produces 109 cold positrons per second. At this production rate, it would take over 10 million years to accumulate a milligram of positrons. In order to realize these newer concepts, a much more intense source of positrons must be developed. In order to solve the problem of producing a significant quantity of positrons, there is a need to find new ways to moderate positrons with large energies (>1 MeV). As such, an objective of embodiments of the present invention is to develop new methods for moderation of hot positrons that enable production of positrons at rates several orders of magnitude larger than current methods. In an example embodiment, an apparatus for moderation of positrons may comprise an array of electrodes (cathodes and anodes) in a planar, quadruple, or octopole arrangement. The apparatus may also provide an electric field for FAM. Cathodes may be coated with a wide-band-gap-semiconductor (WBGS) material or other material that supports FAM, with a vacuum gap between the cathode and anode. Such an electrode arrangement eliminates the need for surface deposited electrodes and is scalable to higher positron energies by increasing the number of layers (planar geometry) or electrode elements (quadrupole or octopole geometry). The goal of such example apparatuses is to provide a sufficiently high electric field in the moderator material to attain field assisted moderation (FAM). In addition, the overall cumulative moderator material thickness may be large enough to ensure that a large fraction of incident positrons will thermalize in the structure, while at the same time, each individual element of the structure should be thin enough to allow positrons to drift to the surface before annihilating with an electron. In one example embodiment, an apparatus for moderation of positrons is provided. The apparatus comprises a vacuum chamber and at least one cathode structure positioned within the vacuum chamber. The apparatus further comprises a moderator material attached to at least a portion of the at least one cathode structure. The moderator material is configured to receive positrons from a positron source. The apparatus further comprises at least one anode positioned within the vacuum chamber and spaced apart from the at least one cathode structure and moderator material so as to define a vacuum gap between the moderator material and the at least one anode. The apparatus further comprises a voltage source connected to the at least one cathode structure and the at least one anode. The voltage source is configured to apply a positive potential to the at least one cathode structure and a negative potential to the at least one anode to create an electric field that is configured to cause the positrons received by the moderator material to drift toward the surface of the moderator material and into the vacuum gap. In some embodiments, the apparatus may further comprise a magnetic field source configured to produce a magnetic field throughout the at least one cathode structure and the at least one anode. The magnetic field may be perpendicular to the electric field and configured to cooperate with the electric field to encourage the positrons to drift through the vacuum gap toward a harvesting area. In some embodiments, the apparatus may further comprise an electron source. The positron source may comprise a converter positioned within the vacuum chamber proximate the at least one cathode structure. The electron source may be configured to emit electrons toward the converter, and the converter may be configured to produce positrons upon collision of the electrons with the converter. In some embodiments, the apparatus may further comprise a neutron source configured to emit neutrons toward the at least one cathode structure. The at least one cathode structure may be configured to emit gamma-rays upon capture of the neutrons by the at least one cathode structure. The at least one anode may be configured to produce positrons upon collision of the gamma-rays with the at least one anode such that the at least one anode acts as the positron source. In some embodiments, the at least one cathode structure may comprise at least two cathode structures and the at least one anode may comprise at least two anodes. The at least two cathode structures and the at least two anodes may be positioned along a plane so as to form a planar array. In some embodiments, the at least one cathode structure may define a cylindrical shape. The at least one anode may comprise four anodes spaced radially from the at least one cathode structure and each of the anodes may define a cylindrical shape. In some embodiments, the at least one cathode structure may define a cylindrical shape. The at least one anode may comprise eight anodes spaced radially from the at least one cathode structure and each of the anodes may define a cylindrical shape. In some embodiments, the at least one cathode structure may comprise a cathode and an insulator material positioned between the moderator material and the cathode. The insulator material may be configured to increase electrical resistance between the cathode and the moderator material. In yet another example embodiment, an apparatus for moderation of positrons is provided. The apparatus comprises a vacuum chamber and at least one cathode structure positioned within the vacuum chamber. The apparatus further comprises a moderator material attached to at least a portion of the at least one cathode structure. The moderator material is configured to receive positrons from a positron source. The apparatus further comprises at least one anode positioned within the vacuum chamber. The apparatus further comprises a voltage source connected to the at least one cathode structure and the at least one anode. The voltage source is configured to apply a positive potential to the at least one cathode structure and a negative potential to the at least one anode to create an electric field that is configured to cause the positrons received by the moderator material to drift toward the surface of the moderator material. The apparatus further comprises a magnetic field source configured to produce a magnetic field throughout the at least one cathode structure and the at least one anode. The magnetic field is perpendicular to the electric field and configured to cooperate with the electric field to encourage the positrons to drift toward a harvesting area. In yet another embodiment, a method for moderation of positrons is provided. The method comprises providing an apparatus comprising a vacuum chamber and at least one cathode structure positioned within the vacuum chamber. The apparatus further comprises a moderator material attached to at least a portion of the at least one cathode structure. The moderator material is configured to receive positrons from a positron source. The apparatus further comprises at least one anode positioned within the vacuum chamber and spaced apart from the at least one cathode structure and moderator material so as to define a vacuum gap between the moderator material and the at least one anode. The apparatus further comprises a voltage source connected to the at least one cathode structure and the at least one anode. The method further comprises establishing an electric field across the apparatus by applying a positive potential to the at least one cathode structure and applying a negative potential to the at least one anode. The electric field is configured to cause the positrons received by the moderator material to drift toward the surface of the moderator material and into the vacuum gap. The method further comprises extracting the positrons that drift away from the moderator material through the vacuum gap. In some embodiments, the method may further comprise establishing a magnetic field across throughout the at least one cathode structure and the at least one anode. The magnetic field may be perpendicular to the electric field and configured to cooperate with the electric field to encourage the positrons to drift through the vacuum gap toward a harvesting area. In some embodiments, the method may further comprise causing emission of electrons toward the positron source. The positron source may comprise a converter positioned within the vacuum chamber proximate the at least one cathode structure. The converter may be configured to produce positrons upon collision of the electrons with the converter. In some embodiments, the method may further comprise causing emission of neutrons toward the at least one cathode structure. The at least one cathode structure may be configured to emit gamma-rays upon capture of the neutrons by the at least one cathode structure. The at least one anode may be configured to produce positrons upon collision of the gamma-rays with the at least one anode such that the anode acts as the positron source. In yet another embodiment, a method for moderation of positrons is provided. The method comprises providing an apparatus comprising a vacuum chamber and at least one cathode structure positioned within the vacuum chamber. The apparatus further comprises a moderator material attached to at least a portion of the at least one cathode structure. The moderator material is configured to receive positrons from a positron source. The apparatus further comprises at least one anode positioned within the vacuum chamber and a voltage source connected to the at least one cathode structure and the at least one anode. The method further comprises establishing an electric field across the apparatus by applying a positive potential to the at least one cathode structure and applying a negative potential to the at least one anode. The electric field is configured to cause the positrons received by the moderator material to drift toward the surface of the moderator material. The method further comprises establishing a magnetic field throughout the at least one cathode structure and the at least one anode. The magnetic field is perpendicular to the electric field and is configured to cooperate with the electric field to encourage the positrons to drift toward a harvesting area. The method further comprises extracting the positrons from the harvesting area. In another embodiment, an apparatus for moderation of positrons is provided. The apparatus comprises an array of cathode structures of planar or cylindrical geometry which are coated with a thin electrically insulating material and moderator material on both sides and placed within a vacuum chamber. The apparatus further comprises an array of solid or mesh anodes of planar or cylindrical geometry placed within the vacuum chamber and adjacent to and electrically isolated from each cathode structure. The apparatus further comprises a voltage source electrically connected to each electrode (e.g., cathode and anode). The voltage source is capable of delivering a positive potential to each cathode and a negative potential to each anode. The apparatus further comprises a magnet positioned adjacent or exterior to said cathode and anodes so that at least a portion of said cathode and anode is contained within a magnetic field. The apparatus further comprises a vacuum gap between each cathode structure and anode element, whereby an electric field produced by said voltage source exists with a direction perpendicular to said magnetic field. In some embodiments, the cathode material may comprise a positron source. In some embodiments, the apparatus may further comprise a positron source located adjacent to said cathode and anodes. In some embodiments, the cathode and anodes may be made of material suited for pair production of positrons (e.g., platinum, tungsten, etc.) and the moderator may be made of wide band gap semiconductor material (e.g., silicon carbide, gallium arsenide, gallium nitride, diamond, etc.) suitable for high velocity drift in the presence of an electric field. In some embodiments, a method using the apparatus may be provided. The method may comprise producing positrons via a pair-production process by collisions of high energy photons, electrons, or neutrons with atoms in said cathode and anode material. In some embodiments, the method may further comprise establishing an electric field between the cathodes and anodes to cause implanted positrons to drift towards a surface of the moderator material. Additionally, the method may comprise establishing a magnetic field throughout the volume of said moderator structure in the direction orthogonal to said electric field. The method may further comprise extracting low energy positrons by E×B charged particle drift out through said vacuum gaps. In some embodiments, the cathode and anodes may be made of material suited for transmission of positrons (e.g., aluminum, etc.) and the moderator may be made of wide band gap semiconductor material (e.g., silicon carbide, gallium arsenide, gallium nitride, diamond, etc.) suitable for high velocity drift in the presence of an electric field. In some embodiments, a method using the apparatus may be provided. The method may comprise producing positrons via a pair-production process by collisions of high energy photons, electrons or neutrons with atoms in said source material, located adjacent to the moderator structure and made of material suited for pair production (e.g., platinum, tungsten, etc.). In some embodiments, the method may further comprise establishing an electric field between the cathodes and anodes to cause implanted positrons to drift towards a surface of the moderator material. Additionally, the method may comprise establishing a magnetic field throughout the volume of said moderator structure in the direction orthogonal to said electric field. The method may further comprise extracting low energy positrons by E×B charged particle drift out through said vacuum gaps. The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the inventions are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout. Positrons generated in the laboratory may be produced via two methods; nuclear beta decay and pair production. Each method produces positrons with a large energy distribution which is dependent on the source type. See FIG. 1. In order to be useful, each positron must be stored. However, storage of positrons requires their kinetic energy to be low enough that their movement may be affected by electric and magnetic fields. Therefore, positron sources must produce positrons with a near-thermal kinetic energy distribution (less than a few electronvolts) in order to be useful for positron collection. Indeed, cooling the ‘hot’ positrons from the source, or moderation, has been done using a variety of methods, but none with efficiencies>7×10−3. Radioactive sources of positrons produce the lowest average energy positrons of any production method, although they are limited in their maximum intensity. Typical radioactive sources emit positrons with an energy distribution extending up to 1 MeV, while LINAC based positron sources have much higher positron energy distributions with average energies up to a few tens of a MeV. LINAC facilities obtain electron energies up to 6 GeV (Jefferson Lab) with currents of 200 μA giving a positron energy distribution shown in FIG. 1. These high electron energies cause the positrons to emit with corresponding high energies that limit the ability of moderators to capture and cool positrons. For example, for a typical radioactive source such as Na-22, around 90% of the positrons pass through the moderator un-cooled, 9% of the positrons annihilate in the bulk of the moderator, and up to 1% of the positrons are thermalized and are emitted from the surface due to the negative work function of the moderator material (up to several eV). On the other hand, for a LINAC source with much higher positron production rate and an average positron energy>5 MeV, the fraction of moderated positrons drops to 10−6. The challenge with solid positron moderators is to minimize losses due to annihilations in the bulk of the solid moderator, while still having a thick enough structure to thermalize a significant portion of the positrons. Thus, an optimal thickness is arrived at for most traditional thin film moderators in the range of a few microns. The efficiency of modern positron moderators is currently limited by the short diffusion length of positrons inside the bulk, typically a few or tens of nanometers. In the presence of an electric field, however, positrons will gain a drift velocity in the direction of the field, increasing their diffusion length. This technique is referred to as field assisted moderation (FAM). FAM has been used to increase positron diffusion length in a diamond thin film by applying a potential to a deposited gold mesh. While this method has previously demonstrated the enhanced mobility of positrons in an electric field, efficiency was decreased due to enhanced annihilation at the deposited gold mesh lines. FAM has also been demonstrated in frozen rare-gases and in wide band-gap semiconductor materials by surface charging via electron bombardment, although the method is limited by the absolute magnitude of electric field that can be applied. FIG. 2 illustrates a schematic representation showing a front view of an example apparatus for moderation of positrons. FIG. 2A illustrates a schematic representation of a cross-section of the apparatus taken along line 2A in FIG. 2. In the depicted embodiment of FIGS. 2 and 2A, the apparatus 50 may comprise elements that are generally planar shaped (e.g., rectangular). As used herein, such an example apparatus may be used for positron moderation that may be termed Planar Array Field Assisted Moderation (PAFAM). The apparatus 50 and its components may be positioned inside a vacuum chamber 27 evacuated to a suitably low pressure. The apparatus 50 may comprise at least one cathode structure 23 positioned within the vacuum chamber 27. In some embodiments the cathode structure 23 may comprise a cathode 3 configured to receive a positive potential from a voltage source 12. In the depicted embodiment, three rectangular cathode structures 23 are positioned in parallel along a longitudinal direction (DL) to form a planar array. While the depicted embodiment illustrates three cathode structures, embodiments of the present invention are not meant to be limited to three cathode structures, as indeed any number of cathode structures may be used. The apparatus 50 may also comprise a moderator material 4 attached to at least a portion of the at least one cathode structure 23. The moderator material 4 is configured to receive (e.g., at least partially slow down and/or trap) positrons that contact the moderator material 4. In the depicted embodiment, the moderator material 4 coats both sides of the cathode structure 23 (e.g., the moderator material 4 lies adjacent to each side of the cathode structure 23). The moderator material 4 may comprise any of a wide range of wide-band-gap-semiconductor (WBGS) materials (e.g., Silicon Carbide, Gallium Arsenide, Gallium Nitride, Diamond, etc.) or other suitable FAM capable materials In some embodiments the cathode structure 23 may comprise both a cathode 3 and an insulating material 2. In such an embodiment, the insulating material 2 may be attached to at least a portion of the cathode 3 and may be positioned between the moderator material 4 and the cathode 3. The insulating material 2 may be configured to increase the electrical resistance between the cathode 3 and the moderator material 4, which may increase the time it takes for the surfaces of the moderator material 4 to become charged. The apparatus 50 may comprise at least one anode 5 positioned within the vacuum chamber. In some embodiments the anode 5 may comprise an anode configured to receive a negative potential from a voltage source 12. In the depicted embodiment, three anodes 5 are positioned along a longitudinal direction (DL) to form a planar array with the cathode structures 23. While the depicted embodiment illustrates three anodes, embodiments of the present invention are not meant to be limited to three anodes, as indeed any number of anodes may be used. In some embodiments, the at least one anode 5 may be spaced apart from the at least one cathode structure 23 and the moderator material 4 so as to define a vacuum gap 52 between the moderator material 4 and the at least one anode 5. In the depicted embodiment, spacers 6 are used to position the anodes 5 apart from the cathode structures 23. The vacuum gap 52 provides additional area for the positron to drift so as to avoid collision with an electron, thereby resulting in annihilation, which may occur when the positron collides with the anode 5. The apparatus 50 may comprise a voltage source 12 connected to the at least one cathode structure 23 and the at least one anode 5. The voltage source 12 may be configured to apply a positive potential 13 to the at least one cathode structure 23 and a negative potential 14 to the at least one anode 5 to create an electric field (E). In some embodiments, the positive potential 13 and negative potential 14 may be applied in a DC or pulsed-mode to match the time-domain behavior of the positron source (such as will be described in greater detail herein). The electric field (E) may be configured to cause the positrons received by (e.g., implanted in, partially or otherwise) the moderator material 4 to drift away from the moderator material 4, such as toward the surface of the moderator material 4. Additionally, in embodiments with a vacuum gap 52, the electric field (E) may be configured to cause the positrons to drift away from the moderator material 4 toward the vacuum gap 52. In some embodiments, the apparatus 50 may comprise a magnetic field source 53, such a magnetic coil assembly, configured to produce a magnetic field (B) in at least a portion of the at least one cathode structure 23 and the at least one anode 5. The magnetic field (B) may be perpendicular to the electric field (E) and configured to cooperate with the electric field (E) to encourage the positrons to drift toward a harvesting area 54. In the depicted embodiment, the magnetic field (B) is configured to cooperate with the electric field (E) to encourage the positrons to drift through the vacuum gap 52 toward the harvesting area 54. In the depicted embodiment, the harvesting area 54 is an area outside of the plane of the at least one cathode structure 23 and at least one anode 5, where the positrons may be extracted and harvested for later use. In addition, in embodiments with a magnetic field (B) and an electric field (E), positrons released from the moderator material 4 may undergo an E×B drift, so as to move in either direction 9 (e.g., into the page of FIG. 2A) or 10 (e.g., out from the page of FIG. 2A). In some embodiments, the cathode 3 and anode 5 extend slightly out from the moderator material 4 to enhance E×B drift of the positrons in directions 9 and 10 (e.g., toward the harvesting area 54). Embodiments of the present invention seek to provide apparatuses and methods for the moderation of positrons. As noted above, there may be different ways to produce positrons. Indeed, the example apparatuses and methods presented herein may be suited for use with different methods of production of positrons. For example, FIGS. 2 and 2A illustrate use of an electron source and an electron converter to produce positrons for the apparatus 50. In another example embodiment, FIGS. 3 and 3A illustrate a similar apparatus 50′ in which positrons are produced from neutrons. The embodiment illustrated in FIGS. 3 and 3A will be described in greater detail herein. In this regard, it should be noted that many different positron production techniques are possible and should be considered as within the scope of the present invention. For example, a gamma-ray source (e.g., an Undulator) may be used with some embodiments of the present invention. In such an embodiment, the cathode or anode material may act to produce positrons from interaction with the gamma-rays. With reference to FIGS. 2 and 2A, in some embodiments, the apparatus 50 may comprise an electron source and a positron source. In the depicted embodiment, the positron source may comprise a converter 1 positioned within the vacuum chamber proximate the at least one cathode structure 23. The electron source (e.g., a LINAC, a cyclotron, etc.) may be configured to emit electrons 44 toward the converter 1. The converter 1 may be configured to produce positrons (e.g., represented by arrows 7) upon collision of the electrons 44 with the converter 1. In some embodiments, the converter 1 may comprise a wide range of materials including high-Z (e.g., Tungsten) converter materials suited for production of positrons from incident high energy electrons. Referring to FIG. 2A, in some cases, a positron (P) may be emitted from the converter 1 (e.g., represented by arrows 7) and received by a first moderator material 4. Depending on the energy of the positron (P), the positron (P) may travel through the first moderator material 4 and through the first cathode structure 23, all the while reducing its energy (e.g., cooling). Eventually, when the energy is low enough, the positron (P) may be received by (e.g., implanted in) a moderator material (e.g., shown in FIG. 2A). The electric field (E) may cause the positron (P) to drift toward the surface of the moderator material 4 (e.g., away from the cathode 3 and toward the anode 5). Additionally, the magnetic field (B) may cause the positron (P) to drift with the magnetic field (e.g., along arrow 11). In such a way, the positron (P) may drift away from the moderator material 4, into the vacuum gap 52, and into the harvesting area 54 for extraction. In such a manner, the apparatus 50 may be used to moderate and extract a positron. In some embodiments, the converter 1 is smaller than the at least one cathode structure 23 and the at least one anode 5. In particular, the converter 1 may produce positrons that travel in many different directions. Thus, in some embodiments, the cathode structure 23 with moderator material 4 may be larger than the converter 1 in order to allow more of the positrons to be received by the moderator material 4. In some embodiments, the apparatus 50 may comprise an additional electric field source 8. In some embodiments, a positive electric potential 28 may be applied to a hollow cylindrical end-cap electrode 8 by the voltage source 12 to create a second electric field (E2) that causes positrons that drift outside of the at least one cathode structure 23 and at least one anode 5 in a direction opposite to the magnetic field (B) to reflect back towards the at least one cathode structure 23 and at least one anode 5. Thus, the second electric field (E2) encourages positrons to redirect into the magnetic field (B) and toward the harvesting area to enable their extraction. FIG. 3 illustrates a schematic representation showing a front view of another example apparatus for moderation of positrons. FIG. 3A illustrates a schematic representation of a cross-section of the apparatus taken along line 3A in FIG. 3. With reference to FIGS. 3 and 3A, in another example embodiment, apparatus 50′ may be configured to receive positrons produced from neutrons. In other respects, the apparatus 50′ may be configured in a similar manner to apparatus 50 and with other embodiments described herein. In some embodiments, the apparatus 50′ may comprise a neutron source and a positron source. The neutron source (not shown) may be configured to emit neutrons 34 toward the at least one cathode structure 23. The cathode structure 23 may be configured to emit gamma-rays 35 upon capture of the neutrons 34 by the cathode 3 of the at least one cathode structure 23. The anode 5, in turn, may be configured to produce positrons 7 upon collision of the gamma-rays 35 with the at least one anode 5 such that the at least one anode 5 acts as the positron source. As a result, similar to other example embodiments, a positron (P) may be received by the moderator material 4. The electric field (E) may cause the positron (P) to drift toward the surface of the moderator material 4 (e.g., away from the cathode 3 and toward the anode 5). Additionally, the magnetic field (B) may cause the positron (P) to drift with the magnetic field (e.g., along arrow 11). In such a way, the positron (P) may drift away from the moderator material 4, into the vacuum gap 52, and into the harvesting area 54 for extraction. In such a manner, the apparatus 50′ may be used to moderate and extract positrons. As noted above, any example embodiment of the present invention (e.g., apparatus 50, 50′) may include more than one cathode structure and anode positioned along a longitudinal direction (DL). Indeed, in some cases, dependent on the amount of energy a positron has, the positron may pass through a vacuum gap 52 and penetrate through the nearest anode 5 into the next vacuum gap 52 and into the next set of moderator material 4 and cathode structure 23. In such a manner, the positron may become slowed down and/or received by the next moderator material 4. This process may continue based on the energy of the positron and the number of cathode structures 23 and anodes 5. Thus, in some embodiments, to ensure maximum efficiency, the total number of cathode structures 23 and anodes 5 may be selected to correspond to the projected energy of the positrons 7, such that the total depth of the apparatus may be larger than the maximum positron implantation depth associated with the particular positron source (e.g., electron source and converter or neutron source). For example, in the case of a neutron source (not shown), to ensure maximum efficiency, the total number of cathode structures 23 and anodes 5 may depend on the energy of the positrons 7 such that the total depth of moderator material may be larger than the maximum positron implantation depth plus the maximum implantation depth of neutrons 34 that bombard the apparatus 50′ (e.g., ranging, as an example, from 1 mm to several cm). Embodiments of the present invention conceive of many types of apparatuses for moderation of positrons, including apparatuses that comprise cathode structures and anodes that are in many different arrangements. For example, FIGS. 4, 4A, 5, and 5A illustrate other example apparatuses 150, 150′ for moderation of positrons that includes anodes that are arranged in a quadrupole form around a cathode structure. Positron moderation that uses such example embodiments may be referred to herein as Quadrupole Array Field Assisted Moderation (QAFAM). Similarly, FIGS. 6, 6A, 7, and 7A illustrate other example apparatuses 250, 250′ for moderation of positrons that include anodes that are arranged in an octopole form around a cathode structure. Positron moderation that uses such example embodiments may be referred to herein as Octopole Array Field Assisted Moderation (OAFAM). Any of the example embodiments (e.g., apparatuses 150, 150′, 250, 250′) may employ any of the features described above with respect to apparatuses 50, 50′. FIG. 4 illustrates a schematic representation showing a front view of another example apparatus for moderation of positrons. FIG. 4A illustrates a schematic representation of a cross-section of the apparatus taken along line 4A in FIG. 4. In particular, FIGS. 4 and 4A show an apparatus 150 configured for moderation of positrons. Similar to other example embodiments, the apparatus 150 may be positioned within a vacuum chamber 127 and may comprise at least one cathode structure 123 and at least one anode 105. However, with reference to FIG. 4, the cathode 103 and anode 105 may each define a cylindrical shape. Additionally, each cathode structure 123 may be radially surrounded by four anodes 105. As described above with respect to other example apparatuses for moderation of positrons, the apparatus 150 may comprise a moderator material 104 configured to receive positrons. Additionally, a voltage source 112 may apply a positive potential 113 to each cathode 103 and a negative potential 114 to each anode 105 in order to create an electric field (E) that causes the positrons to drift toward the surfaces of the moderator material 104 and into the vacuum gap 152. Moreover, a magnetic field (B) may be applied perpendicular to the electric field (E) and may be configured to cooperate with the electric field (E) to cause the positrons to drift out of the vacuum gap 152 and toward the harvesting area 154 for extraction. Such a process is illustrated with the projected path of positron (P) (represented by a dashed line). In addition, depending on where the positrons are emitted from the moderator material 104, they may undergo E×B drift. In some cases, the E×B drift trajectory may include simple rotation around the cathode structure 123, or, in other cases, a diffusion like trajectory (e.g., shown by arrow 122 in FIG. 4) away from the cathode structure 123. Additionally, such a configuration may be useful with any type of positron production. For example, FIGS. 4 and 4A illustrate use of an electron source and an electron converter to produce positrons for the apparatus 150. In another example embodiment, FIGS. 5 and 5A illustrate a similar apparatus 150′ that receives positrons produced from neutrons. With reference to FIGS. 4 and 4A, the apparatus 150 may comprise an electron source (not shown). Additionally, the positron source may include a converter 101 positioned within the vacuum chamber proximate the at least one cathode structure 123. The electron source (not shown) may be configured to emit electrons 144 toward the converter 101 such that upon collision with the converter 101 the electrons 144 produce positrons (e.g., represented by arrows 107). FIG. 5 illustrates a schematic representation showing a front view of another example apparatus for moderation of positrons. FIG. 5A illustrates a schematic representation of a cross-section of the apparatus taken along line 5A in FIG. 5. With reference to FIGS. 5 and 5A, apparatus 150′ may comprise a neutron source and a positron source. The neutron source (not shown) may be configured to emit neutrons 134 toward the at least one cathode structure 123. The cathode structure 123 may be configured to emit gamma-rays 135 upon capture of the neutrons 134 by the at least one cathode structure 123. Additionally, the anode 105 may be configured to produce positrons 107 upon collision of the gamma-rays 135 with the at least one anode 105 such that the at least one anode 105 acts as the positron source. Additionally, in some embodiments, the apparatuses 150, 150′ may comprise an additional electric field source 108 to create a second electric field (E2). The second electric field may be configured to cause positrons that drift outside of the at least one cathode structure 123 and at least one anode 105 in a direction opposite to the magnetic field (B) to reflect back towards the at least one cathode structure 123 and at least one anode 105. In some embodiments, the apparatus 150, 150′ may comprise multiple cathode structures 123, each with four corresponding anodes 105 positioned within the vacuum chamber 127. Indeed, as shown in the depicted embodiments of FIGS. 4 and 5, adjacent cathode structures 123 may share certain anodes 105. In some cases, dependent on the amount of energy a positron has, the positron may pass through a vacuum gap 152 and penetrate through the nearest anode 105 into the next vacuum gap 152 and into the next set of moderator material 104 and cathode structure 123. In such a manner, the positron may become slowed down and/or received by the next moderator material 104. This process may continue based on the amount of energy of the positron and the number of sets of a cathode structure 123 and anodes 105. Thus, in some embodiments, to ensure maximum efficiency, the total number of sets of cathode structure 123 and anodes 105 may be selected to correspond to the projected energy of the positrons 107, such that the total depth/width of the apparatus 150, 150′ may be larger than the maximum positron implantation depth associated with the particular positron source (e.g., electron source and converter or neutron source). Along these lines, only four sets of a cathode structure 123 and anodes 105 are shown with respect to apparatuses 150, 150′; however, any number of sets of a cathode structure 123 and anodes 105 are contemplated by embodiments of the present invention. FIG. 6 illustrates a schematic representation showing a front view of another example apparatus for moderation of positrons. FIG. 6A illustrates a schematic representation of a cross-section of the apparatus taken along line 6A in FIG. 6. In particular, FIGS. 6 and 6A show an apparatus 250 configured for moderation of positrons. Similar to other example embodiments, the apparatus 250 may be positioned within a vacuum chamber 227 and may comprise at least one cathode structure and at least one anode. However, with reference to FIG. 6, the cathode 203 and anode 205 may each define cylindrical shapes. Additionally, each cathode structure 223 may be radially surrounded by eight anodes 205. As described above with respect to other example apparatuses for moderation of positrons, the apparatus 250 may comprise a moderator material 204 configured to receive positrons. Additionally, a voltage source 212 may apply a positive potential 213 to each cathode 203 and a negative potential 214 to each anode 205 in order to create an electric field (E) that causes the positrons to drift away from the moderator material 204 and into the vacuum gap 252. Moreover, a magnetic field (B) may be applied perpendicular to the electric field (E) and configured to cooperate with the electric field (E) to cause the positrons to drift out of the vacuum gap 252 and into the harvesting area 254 for extraction. Such a process is illustrated with the projected path of positron (P). In addition, depending on where the positrons are emitted from the moderator material 204, they may undergo E×B drift. In some cases, the E×B drift trajectory may include simple rotation around the cathode structure 223, or, in other cases, a diffusion like trajectory (e.g., shown by arrow 222) away from the cathode structure 223. Additionally, such a configuration may be useful with any type of positron production. For example, FIGS. 6 and 6A illustrate use of an electron source and an electron converter to produce positrons for the apparatus 250. In another example embodiment, FIGS. 7 and 7A illustrate a similar apparatus 250′ that receives positrons produced from neutrons. With reference to FIGS. 6 and 6A, the apparatus 250 may comprise an electron source (not shown). Additionally, the positron source may include a converter 201 positioned within the vacuum chamber proximate the at least one cathode structure 223. The electron source (not shown) may be configured to emit electrons 244 toward the converter 201 such that upon collision with the converter 201 the electrons 244 produce positrons (e.g., represented by arrows 207). FIG. 7 illustrates a schematic representation showing a front view of another example apparatus for moderation of positrons. FIG. 7A illustrates a schematic representation of a cross-section of the apparatus taken along line 7A in FIG. 7. With reference to FIGS. 7 and 7A, apparatus 250′ may comprise a neutron source and a positron source. The neutron source (not shown) may be configured to emit neutrons 234 toward the at least one cathode structure 223. The cathode structure 223 may be configured to emit gamma-rays 235 upon collision of the neutrons 234 with the at least one cathode structure 223. Additionally, the anode 205 may be configured to produce positrons 207 upon collision of the gamma-rays 235 with the at least one anode 205 such that the at least one anode 205 acts as the positron source. Additionally, in some embodiments, the apparatuses 250, 250′ may comprise an additional electric field source 208 to create a second electric field (E2). The second electric field may be configured to cause positrons that drift outside of the at least one cathode structure 223 and at least one anode 205 in a direction opposite to the magnetic field (B) to reflect back towards the at least one cathode structure 223 and at least one anode 205. In some embodiments, the apparatus 250, 250′ may comprise multiple sets of one cathode structure 223 and four anodes 205 positioned within the vacuum chamber. Indeed, as shown in the depicted embodiments of FIGS. 6 and 7, adjacent cathode structures 223 may share certain anodes 205. In some cases, dependent on the amount of energy a positron has, the positron may pass through a vacuum gap 252 and penetrate through the nearest anode 205 into the next vacuum gap 252 and set of moderator material 204 and cathode structure 223. In such a manner, the positron may become slowed down and/or received by the next moderator material 204. This process may continue based on the amount of energy of the positron and the number of sets of a cathode structure 223 and anodes 205. Thus, in some embodiments, to ensure maximum efficiency, the total number of sets of cathode structure 223 and anodes 205 may be selected to correspond to the projected energy of the positrons 207, such that the total depth/width of the apparatus 250, 250′ may be larger than the maximum positron implantation depth associated with the particular positron source (e.g., electron source and converter, or neutron source). Along these lines, only four sets of a cathode structure 223 and anodes 205 are shown with respect to apparatuses 250, 250′, however, any number of sets of a cathode structure 223 and anodes 205 are contemplated by embodiments of the present invention. While the above described embodiments with respect to FIGS. 4, 4A, 5, 5A, 6, 6A, 7, and 7A comprise either 4 or 8 anodes surrounding a cathode structure, a greater or fewer number of anodes may be used. Consequently, the present invention should not be regarded as limited to any particular number of anodes with respect to each cathode. Along these same lines, other geometries of cathodes and anodes are also contemplated by embodiments of the present invention. In some embodiments, such as any of the embodiments of the present invention described herein, in order to maximize the number of positrons emitted from the surface of the moderator material 4, 104, 204, wide band gap semiconductor (WBGS) materials that can support high saturation positron drift velocities and long bulk positron lifetimes may be used (see Table 1). In addition, in some embodiments, the distance the positrons must drift is minimized by making the moderator material 4, 104, 204 as thin as possible (e.g., <50 μm). In some embodiments, the fraction of positrons that thermalize in the moderator material 4 are maximized by minimizing the thickness and density of the insulating material 2, 102, 202 and the cathode 3, 103, 203 compared to the moderator material 4, 104, 204. TABLE 1Material and electrical properties of interest for field assisted moderationfor various wide band gap semiconductor (WBGS) materials.Eg is the bandgap energy, ρ the density,Vsat is the electron saturation drift velocity,φ is the electron work function, andτbulk is the bulk positron lifetime.MaterialEg ((e)V)ρ (g/cm3)Vsat (105 m/s)φ (eV)τbulk (ps)Diamond5.53.521.5−3.031052H—GaN3.46.152.5−2.41666H—SiC3.053.212−3140GaAs1.425.312−0.6231 In embodiments of the present invention described herein, the cathode 3, 103, 203 and anode 5, 105, 205 materials may be conductive. In such a manner, a range of metals or metal alloys (e.g., Aluminum, Gold, Tungsten, Platinum) may be used. Additionally, in some embodiments, it may be possible to use the moderator material 4, 104, 204 as the cathode 3, 103, 203 by finding suitable p-type implants to form electrode layers. The thicknesses of the material of the cathode 3, 103, 203 and anode 5, 105, 205 may be small (e.g., <10 μm). In some embodiments, the insulating material 2, 102, 202 may be a composed of a thin (e.g., <5 μm) range of high resistivity materials (e.g., Teflon®, Kapton®). Similarly, in some embodiments, the insulating spacer 6 may be composed of a range of high-resistivity materials (e.g., Teflon, Kapton). FIG. 8 illustrates a flowchart according to an example method for moderation of positrons according to an example embodiment 300. Operation 302 may comprise providing an apparatus for moderation of positrons, such as any apparatus described herein. In particular, the apparatus may comprise at least one cathode structure and at least one anode spaced from the cathode structure so as to define a vacuum gap. Operation 304 may comprise establishing an electric field across the apparatus by applying a positive potential to the at least one cathode structure of the apparatus and applying a negative potential to the at least one anode apparatus. In some embodiments, operation 306 may comprise establishing a magnetic field throughout the at least one cathode structure and the at least one anode, wherein the magnetic field is perpendicular to the electric field. In some embodiments, operation 308 may comprise causing production of positrons within the apparatus. For example, in some embodiments, positrons may be produced by causing emission of electrons toward a converter, wherein the converter is configured to produce positrons upon collision of the electrons with the converter. In other embodiments, positrons may be produced by causing emission of neutrons toward the at least one cathode structure, wherein the at least one cathode structure is configured to emit gamma-rays upon capture of the neutrons by the at least one cathode structure. Additionally, the at least one anode is configured to produce positrons upon collision of the gamma-rays with the at least one anode such that the anode acts as a positron source. Finally, operation 310 may comprise extracting the positrons that drift away from the moderator material, such as through the vacuum gap and into the harvesting area. FIG. 9 illustrates a flowchart according to an example method for moderation of positrons according to an example embodiment 400. Operation 402 may comprise providing an apparatus for moderation of positrons, such as any apparatus described herein. Operation 404 may comprise establishing an electric field across the apparatus by applying a positive potential to the at least one cathode structure of the apparatus and applying a negative potential to the at least one anode apparatus. Operation 406 may comprise establishing a magnetic field throughout the at least one cathode structure and the at least one anode, wherein the magnetic field is perpendicular to the electric field. In some embodiments, operation 408 may comprise causing production of positrons within the apparatus. For example, in some embodiments, positrons may be produced by causing emission of electrons toward a converter, wherein the converter is configured to produce positrons upon collision of the electrons with the converter. In other embodiments, positrons may be produced by causing emission of neutrons toward the at least one cathode structure, wherein the at least one cathode structure is configured to emit gamma-rays upon capture of the neutrons by the at least one cathode structure. Additionally, the at least one anode is configured to produce positrons upon collision of the gamma-rays with the at least one anode such that the anode acts as a positron source. Finally, operation 410 may comprise extracting the positrons that drift away from the moderator material, such as through the vacuum gap and into the harvesting area. Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included herein. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
041394143	claims	1. In a liquid metal-cooled nuclear reactor, apparatus for holding, releasing, and resetting a multiplicity of neutron absorbing masses for the rapid shutdown of the reactor core, comprising: a. a safety duct vertically disposed within and in fixed relation to said reactor, said duct further having a substantially uniform cross-section extending from below said core to the top of said duct above said core; b. a hopper valve positioned at a predetermined location above said core on the vertical axis of said duct, said valve having an upper portion forming shoulder means; c. a plurality of trapdoors, each hinged at the same elevation to the inside of said duct for vertical movement such that when said valve is in said predetermined location said doors rest in a neutral position on said shoulder means whereby said doors and said valve block substantially the entire cross-section of said duct thereby providing support for said absorbing masses in the cocked position above said core; d. actuating means located within said duct for maintaining the predetermined location of said valve and for reciprocally moving said valve a predetermined distance sufficient for said trapdoors to lose contact with said shoulder means; e. a vertically moveable platform which blocks substantially the entire cross-section of the lower portion of said duct; and f. a first lifting means for vertically reciprocating said platform substantially between said hinges and below said reactor core. a. an actuating rod attached to the top of said hopper valve and extending above said masses in the cocked position; b. a first gripper means for selectively holding and releasing said actuating rod; c. a second lifting means for selectively raising and lowering said first gripper means; and d. valve stop means for limiting the downward motion of said hopper valve, said stop means extending upward from below said core along the vertical axis of said duct. a. a lift carriage attached to said platform slideably disposed within said duct and having lift arms which extend above the level of said masses in the cocked position; and b. second gripper means for selectively raising and lowering said lift carriage. a. a central column extending along the axis of said safety duct from an elevation below said reactor core to an elevation below said shoulder means, wherein said hopper valve has an open bottom adapted to slidingly enclose the upper end of said central column; and b. sensor means, located within said central column, said valve, and said actuating rod, for causing said first gripper means to release said actuating rod on the occurrence of a preset critical value of a system parameter. 2. The apparatus of claim 1 wherein said trap doors have stops for limiting the swing thereof. 3. The apparatus of claim 2 wherein said actuating means comprises: 4. The apparatus of claim 3 wherein said first lifting means comprises: 5. The apparatus of claim 4 further comprising a spider assembly attached to said safety duct having a shield surrounding said actuating rod. 6. The apparatus of claim 5 wherein said spider assembly further comprises a lift arm shield surrounding each of said lift arms. 7. The apparatus of claim 3 wherein said stop means comprises:
056169272	summary	BACKGROUND OF THE INVENTION The present invention relates to a frame-supported pellicle used for dustproof protection of a pattern-bearing photomask used in the photolithographic patterning works of, for example, a resist layer in the manufacturing process of various kinds of electronic devices such as semiconductor devices, liquid crystal display panels and the like. More particularly, the invention relates-to a frame-supported pellicle which is easily demountable from the photomask on which it is mounted so as to ensure good replaceability of pellicles in the patterning works. As is known, the photolithographic method is well established in the patterning works for the manufacture of semiconductor devices, such as LSIs, VLSIs and the like, liquid crystal display panels and other fine electronic materials, in which a photoresist layer formed on the surface of a substrate such as a semiconductor silicon wafer is pattern-wise exposed to ultraviolet light through a pattern-bearing transparency called a photomask followed by development of the latent images to form a patterned resist layer. In view of the extremely high fineness and precision required in this patterning work, it is very important that the photomask is absolutely dust-free since, when dust particles are deposited on the photomask, the ultraviolet light passing through the photomask is necessarily scattered by the dust particles to give a great adverse influences on the quality of the reproduced pattern such as fidelity to the photomask pattern and contrast of the reproduced images. It is therefore a usual practice that the photolithographic patterning work is conducted in a clean room under an atmosphere of air freed from any floating dust particles as completely as possible although a perfect dust-free condition can hardly be obtained even in a clean room of the highest class. Accordingly, it is also a usual practice that deposition of dust particles from the atmosphere on to the photomask is prevented by mounting a flame-supported dustproof pellicle on the photomask. The frame-supported dustproof pellicle mentioned above is an integral device consisting of a frame made from a rigid material, such as an aluminum alloy, and having parallel end surfaces and a thin, highly transparent film of a polymeric resin, which is called a pellicle membrane, spread over and adhesively bonded to one end surface of the pellicle frame in a drumhead-like slack-free fashion. Usually, the other end surface of the pellicle frame, reverse to the end surface to which the pellicle membrane is adhesively bonded, is coated with a pressure-sensitive adhesive so as to ensure reliableness of mounting of the pellicle frame on the photomask. When a flame-supported pellicle is mounted on the photomask, the dust particles floating in the atmospheric air and falling therefrom are never deposited directly on the photomask but are deposited on the pellicle membrane. Since the light beams used for the pattern-wise exposure to light are focused at the patterned images on the photomask, the dust particles deposited on the pellicle membrane, which is held apart above the photomask by the height of the pellicle frame, have little adverse influences on the quality of the pattern reproduction in the photolithographic patterning work. Although an assembly of a photomask and a frame-supported pellicle mounted thereon by means of a pressure-sensitive adhesive can be used as such in many times of repeated pattern-wise exposure works as mounted on an exposure machine, it sometimes occurs that the pellicle membrane having a so small thickness is broken in the mounting and demounting procedure of the assembly on and from the exposure machine. Such a trouble takes place more readily after prolonged use of the frame-supported pellicle because exposure to intense ultraviolet light necessarily causes embrittlement of the pellicle membrane due to the photochemical degradation of the polymeric resin forming the membrane. Once the pellicle membrane is broken, needless to say, the broken pellicle must be demounted from the photomask and replaced with a new frame-supported pellicle. The above mentioned replacement of a broken pellicle with a new pellicle, however, is not a so simple matter as it may seem to be. Since the frame-supported pellicle mounted on a photomask is secured at the position by means of a pressure-sensitive adhesive forming an adhesive layer on one end surface of the pellicle frame or between the end surface of the pellicle frame and the surface of the photomask, the pressure-sensitive adhesive adherent to the photomask surface can never be completely removed when the pellicle frame having the broken pellicle membrane is lifted therefrom. Accordingly, it is necessary for replacing the broken pellicle with a new pellicle that the pressure-sensitive adhesive left adherent to the photomask surface is completely removed before a new pellicle is mounted. The adherent adhesive can of course be removed by a mechanical means, for example, by rubbing with a cloth. Such a mechanical cleaning means, however, can hardly be undertaken because the cleaning work unavoidably involves a risk of damages caused on the expensive photomask if not to mention that complete removal of the adherent adhesive requires a considerable time and labor. Alternatively, the adherent pressure-sensitive adhesive can be dissolved away with an organic solvent or, at least, can be swollen, as a consequence of partial crosslinking of the adhesive molecules by the ultraviolet irradiation, with an organic solvent so as to facilitate mechanical removal thereof from the photomask surface. Use of an organic solvent as a remover agent, however, is undesirable because of the possible adverse influences on the workers' health due to the toxicity thereof in addition to the unpleasant odor. Accordingly, it is eagerly desired to develop a means to easily demount a flame-supported pellicle from the photomask surface or to develop a frame-supported pellicle easily demountable from the photomask surface without the above described problems and disadvantages in the conventional frame-supported pellicles in the prior art. SUMMARY OF THE INVENTION The present invention accordingly has an object to provide a frame-supported pellicle which is easily demountable from the photomask surface without the above described problems and disadvantages in the conventional frame-supported pellicles in the prior art relative to the adhesive layer remaining as adherent to the photomask surface when a broken pellicle is removed therefrom. Thus, the present invention provides a frame-supported pellicle which is an integral body comprising: (a) a frame made from a rigid material having substantially parallel end surfaces; PA1 (b) a transparent film of a synthetic resin spread over and adhesively bonded to one end surface of the frame in a slack-free fashion; and PA1 (c) a layer of a pressure-sensitive adhesive on the other end surface of the frame, the adhesive bonding strength of the pressure-sensitive adhesive being reducible by heating or by irradiating with light.
	description	This application is a Rule 1.53(b) Continuation of U.S. Ser. No. 12/014,405, filed Jan. 15, 2008 now U.S. Pat. No. 7,609,806, which in turn is a continuation of Ser. No. 11/607,748, filed Nov. 30, 2006 now U.S. Pat. No. 7,319,735, which in turn is a continuation of Ser. No. 10/496,049, filed Oct. 18, 2004, now U.S. Pat. No. 7,443,949, which is a Section 371 national stage of PCT/US02/33058 filed Oct. 17, 2002, claiming the benefit of U.S. Provisional Application no. 60/350,213, filed Oct. 19, 2001, the entire contents of each of which are incorporated herein by reference. This patent specification is in the field of mammography and specifically mammography employing flat panel, digital x-ray receptors rather than x-ray film. X-ray mammography machines typically use an x-ray source mounted at one end of a rotatable c-arm assembly and an image receptor at the other. Between the x-ray source and the image receptor is a device for compressing and immobilizing a breast. Until recently, the image receptor was typically a screen-film (s/f) cassette, which generated an image related to the detected transmission of x-rays through the breast. These s/f cassettes typically come in standard sizes, e.g., 18 cm×24 cm (small) and 24 cm×30 cm (large), with the large cassette used when the breast is too large to be uniformly compressed by the small cassette. The cassettes are easily attachable and removable from a breast support tray of a conventional mammography system. The device for compressing the breast is often called a paddle, and comes in a variety of sizes to match both the cassette size and the breast size. Such matching is desirable because the use of a small size paddle on a large breast can result in uneven and inadequate breast compression and may not allow full-breast imaging, while using a large paddle on a small breast can impede access to the breast, which is important during the compression cycle in order to optimize the amount of breast tissue brought into the field of view of the image receptor. New mammography systems are now being developed to use digital image receptors as replacements for the screen-film cassettes. These digital image receptors, sometimes called flat panel receptors, or flat panel digital x-ray receptors, are different in many ways from s/f cassettes. They have many advantages, but also tend to be heavier and somewhat thicker. Typically, they are not designed to be removable in normal use, so a system normally will employ only one size image receptor. These characteristics can presents challenges for some imaging procedures and breast sizes, particularly for the mediolateral oblique view (MLO) taken as a part of typical breast x-ray imaging. As with screen-film systems, it is still advantageous to use a compression paddle that matches the breast size. This typically means that the compression paddles will be removable, and there will be a selection of paddle sizes available with the system. A number of x-ray protocols have been used for breast imaging. One common view is the cranio-caudal (CC) view, illustrates in FIG. 5, which images the breast of a standing or sitting patient from above. Another is the mediolateral oblique view (MLO), taken from an oblique or angled view, and also illustrated in FIG. 5. In screen-film mammography systems, the compression paddle typically is centered relative to the proximal edge of the screen-film cassette. In some views, such as the MLO view, and particularly for smaller breasts, this may present some difficulty as the cassette may have to be pressed against the armpit in order to approximately center the breast relative to the proximal edge of the film (the edge closest to and parallel to the chest wall). In such cases, the smaller size cassette can be used. This, plus the relative thinness of the cassette, generally allow for adequate centering. However, when a digital x-ray receptor is used usually only one size is available, and it may be the size comparable to the larger size screen-film cassette. Also, the digital receptor tends to be thicker than a screen-film cassette. Thus, centering the breast can be difficult or impossible in some cases, particularly for the MLO view and patients with smaller breasts, with the result that optimal positioning of the breast may not be possible for some views and patients. To applicants' knowledge, these and other issues regarding compression paddle use with flat panel digital receptors in mammography have not been solved and perhaps have not been even addressed. In a different setting, it has been proposed to move a compression paddle laterally, relative to the proximal edge of the screen-film cassette, but for the different purpose of aligning a cutout in the paddle with a particular portion of the breast. See U.S. Pat. No. 5,199,056. This is believed to require a paddle larger that would normally be used for the breast size so as to maintain even compression when the cutout is off-center relative to the breast. Other earlier proposals are known for features such as collimation that adjusts to film cassette size, source-to-image distance and/or cross-sectional area to be imaged (U.S. Pat. Nos. 3,502,878, 3,863,073, 5,627,869, and 6,149,301), moving a paddle (U.S. Pat. No. 3,971,950), moving a cassette (U.S. Pat. No. 4,989,227), and retracting a cassette holder (U.S. Pat. No. 4,559,641). The cited patents are hereby incorporated by reference in this patent specification. An object of the disclosed system and method is to provide mammography that overcomes known disadvantages of proposals involving the otherwise desirable use of flat panel, digital x-ray receptors. Another object is to employ compression paddles that match both the size and position of the patient's breast relative to the proximal edge of a digital x-ray image receptor so as to improve image quality, patient comfort and the ability of the health professional to position the breast optimally for imaging. Another is to provide automated collimation control that changes x-ray beam collimation in accordance with one or more of the size and position of the compression paddle and of the breast, and the position of a breast platform relative to the receptor, preferably in response to information that is automatically sensed. Another is to provide x-ray exposure control that is responsive to at least one of the size and position of the compression paddle, the position of the breast, and a pre-exposure x-ray measurement, preferably in response to information that is automatically sensed. Another is to provide a scatter-suppression grid that is retracted for image magnification protocols, preferably automatically in response to sensing a breast position for magnification imaging. These and other objects are met in a non-limiting example comprising a mammography system having a flat panel digital x-ray receptor, an x-ray source selectively emitting a collimated x-ray beam toward the receptor, and a compression paddle of a selectable size mounted for selective movement at least along a proximal edge of the x-ray receptor as well as along the x-ray beam. At least for selected breast x-ray protocols, a patient's breast is positioned off-center relative to the proximal edge of the x-ray receptor, and paddle of an appropriate size also is positioned off-center relative the same proximal edge to compress the breast for x-ray imaging. In addition, the system includes one or more of a number of other features. An exposure control can be responsive to information regarding breast thickness along the beam direction to control x-ray exposure for imaging. This information can come from a conventional auto-exposure sensor (AES) resulting from a pre-exposure, low-dose firing of the x-ray source from an output of the digital x-ray receptor during such pre-exposure firing, and/or from sensors for the relative positions of the x-ray source, the x-ray receptor, the compression paddle and/or the breast tray. The system can include a collimation control responsive to information regarding one or more of the size of the paddle, its location along the beam, its location relative to the proximal edge of the receptor, a desired field of view, magnification parameters, and the like. This information can come from appropriate sensors and/or can be input by the health professional carrying out imaging. The system can include a scatter-suppressing grid selectively movable between a position in the path of the imaging beam and a position outside that path (for magnification imaging). Again, information for controlling grid position can come from one or more different sources. And, the system can include a built-in or a separate viewing station receiving x-ray image information from the x-ray receptor and possibly from some or all of the sensors, processing it, and displaying the results as an image and/or in other forms. Referring to FIG. 1, an x-ray source 1 is at one end of a generally C-shaped frame 7 and a flat panel digital x-ray imaging receptor 5 is at the other end. X-ray source 1 includes a collimator schematically illustrated at 40 to confine an x-ray beam 30 emitted from source 1 to a desired footprint at receptor 5, typically no larger than the area of receptor 5 and preferably just enough to image a patient's breast 3 or at least a selected part thereof, as compressed toward receptor 5 by a compression paddle 2 mounted on an arm 6 that in turn mounts to frame 7. A lower platform 11, often called a breast tray, is immediately below the breast, and a scatter-reducing grid 4 is between breast tray 11 and x-ray receptor 5 and is housed in the same enclosure 12 with the receptor. As is known in the art, frame 7 can rotate between horizontal and vertical directions of x-ray beam 30. In use for a CC view, paddle 2 and its supporting arm 6 are moved up, breast 3 is positioned on tray 11 and compressed by bringing paddle 2 down as needed. With suitable collimation by collimators 40 (which typically collimate in two directions, of which only one is illustrated in FIG. 1), beam 30 from source 1 images the breast onto receptor 5 and the resulting electronic image information is transmitted to a viewing station 22 (FIG. 2). The image typically is rectangular. Preferably, the collimation is such that beam 30 illuminates an area of receptor 5 just large enough to show the image of breast 3, or at least a selected part thereof. Importantly, different sizes and shapes of paddles 2 can be mounted to arm 6, and the paddle can be selectively positioned off-center relative to proximal edge 5a of receptor 5 (the left edge in FIG. 1). Referring to FIG. 2, the system can operate in a magnification mode in which the relative positions along x-ray beam 30 of source 1, breast tray 11, and/or receptor 5 are adjusted to provide the desired image magnification. In this example, source 1 and receptor 5 stay in place but tray 11 slides up support 7 to a position spaced up from receptor 5, and the collimation of beam 30 is adjusted as needed. Note that for magnification imaging scatter-reducing grid 4 is withdrawn from the portion of receptor 5 that receives the desired breast image, because the angles of the grid septa typically are not suitable for a magnification view. If these angles can be changed to match the selected magnification, the grid can remain in place. Alternatively and if desired, a different grid that is suitable for the selected magnified view can be introduced in place of grid 4 in FIG. 1. Auto-controls 1a can include (a) an auto-exposure control coupled with an AEC sensor 24 and/or receptor 5 to receive exposure information in a pre-imaging firing of source 1, (b) an auto-collimation control to adjust the collimation of beam 30, (c) an auto-grid control to selectively withdraw grid 4, and (d) an auto-magnification control to adjust parameters for magnification imaging. AEC sensor 24 can be conventional separate sensor that helps determine imaging exposure parameters in a pre-imaging exposure of the immobilized breast at a low x-ray dosage. Alternatively, receptor 5 can be used for that purpose, eliminating the need for a separate AEC sensor, because the output of receptor 5 resulting from a low-dose pre-imaging exposure can provide the information for auto-exposure control. In addition, the output of receptor 5 in response to the pre-imaging exposure can reveal the position of the breast relative to the receptor, and thus provide information for auto-collimation to confine beam 30 to a footprint that matches the breast even when the breast is off-center relative to proximal edge 5a. The auto-collimation control can be an arrangement sensing size and/or the position of one or more of breast 3, paddle 2, and tray 11, using respective sensors and automatically adjusting collimators 40 to confine beam 30 to the required cross-section and position. The auto-grid control can respond to a signal indicating that that magnification imaging will be carried out to withdraw grid 4, for example to the position shown in FIG. 2, using a motor 4a. This signal can come from information provided by respective sensors or it can be input by the health professional using the system. The auto-magnification control can be an arrangement responding the data entered by a health professional through viewing station 22, or in some other way, e.g., based on information from sensors to adjust the system elements involved in magnification. Information for the auto-controls can be provided in various ways. One is from sensors S that keep track of the size and position of paddle 2 along beam 30 and relative to proximal edge 5a of x-ray receptor 5, of the position of breast tray 11 along beam 30, of the position of grid 4, and the setting of collimators 40. Another is inputs from an auto-exposure sensor and/or x-ray receptor 5 resulting from a pre-exposure firing of beam 30 at low dose, with breast 3 in place for imaging. As is known in the art, the output of receptor 5 can be used to detect the position of breast 3 relative to receptor 5, or at least the approximate position of the breast relative to proximal edge 5a. Yet another possible source of information for the auto-controls is inputs from the health professional using the system, through a keyboard or other input devices in viewing station 22 or elsewhere. Information is exchanged between auto-controls 1a, sensors S, and viewing station 22 over appropriate links, shown schematically. Suitable arrangements, including encoders, motors (of which only motor M retracting and restoring grid 4 is expressly illustrated), and other control elements are included in mammography system 10 but, for clarity of the drawings, are not expressly illustrated. FIG. 3 illustrates an example of an arrangement for positioning paddle 2 off-center relative to proximal edge 5a of receptor 5. While such off-center positioning can be used for other views as well, it is most important for views such as the MLO view. As seen in FIG. 3, paddle 2 includes a rib 20 that has a channel slot 20a and is secured to arm 6 with a removable and adjustable lock or detent 21 that passes through channel 20a. In operation, the health professional selects a paddle 2 that is suitable in size and perhaps in shape to the breast to be imaged, removes any existing paddle 2 from arm 6 by pulling out or unscrewing detent 21, and installs the selected paddle 2 by securing it to arm 6 with detent 21 in a position relative to proximal edge 5a that matches the patient's breast's position. Any desired further lateral adjustment can be made by sliding paddle 2 along the direction of the proximal edge 5a, before or during compressing the breast for taking an image. FIGS. 4a, 4b, and 4c illustrate an alternate arrangement for lateral adjustment of paddle 2. Here a paddle 2 of a selected size and possibly shape is removably secured to arm 6, and arm 6 is in turn slidably secured to frame 6 to slide laterally, along the direction of proximal edge 5a of receptor 5. The term “lateral” is used here to designate movement parallel to, or at least generally along, the proximal edge 5a, even when the imaging plane of receptor 5 is oriented for an MLO view or is vertical. For example, FIG. 4 can illustrate a position of paddle 2 for an MLO view of the left breast, FIG. 4b can illustrate a position for a CC view, and FIG. 4c can illustrate a position for an MLO view of the right breast. It should be clear than many other arrangements and variations will be apparent to persons skilled in the technology based on the disclosure in this patent specification and that the above embodiments are only some of examples embodying inventions whose scope is defined by the appended claims.
047132108	summary	This invention relates to a rod grapple and driveline mechanism for placement between a poison containing rod for parasitic neutron absorption required for shutdown of a fission reactor and a rod drive mechanism. More particularly, a rod driveline including a rod release mechanism is shown for operation in a fast neutron breeder reactor where rod release can occur responsive either to loss of electromagnetic rod retention power or alternately thermal rise of the reactor beyond set limits. BACKGROUND OF THE INVENTION Nuclear reactors are shut down by the insertion of rods containing poisons for parasitic neutron absorption. Rod drives are typically connected by drivelines to the rods. A first form of rod driveline includes a mechanical connection, typically threaded, between the driveline and rod. A second type of driveline includes a driveline which can selectively attach and release a rod. This disclosure relates to this second type of driveline. Rod release mechanism from drivelines are known. Moreover, thermally responsive rod release mechanisms are known. A common type of thermally responsive rod release mechanisms includes an electromagnetic coupling between the mechanism and a magnet. When the magnetic portion of the rod adjacent a magnet reaches the Curie point of the metal and becomes non-magnetic, rod release and drop occurs. Rod excursion responsive to reactor overheat is known. See Zebroski U.S. Pat. No. 4,227,967. In this type of device, concentric cylinders of bimetallic differential expansion properties are series connected for maximum thermal excursion. When the reactor is too hot, rod insertion occurs. When the reactor cools and rod drive movement has occurred, rod withdrawal occurs. SUMMARY OF THE INVENTION A control rod driveline and grapple is disclosed for placement between a control rod drive and a nuclear reactor control rod. The control rod is provided with an enlarged cylindrical handle which terminates in an upwardly extending rod to provide a grapple point for the driveline. The grapple mechanism includes a tension rod which receives the upwardly extending handle and is provided with a lower annular flange. A plurality of preferably six grapple segments surround and grip the control rod handle at the flange. Each grapple rod segment grips the flange on the tension rod at an interior upper annular indentation, bears against the enlarged cylindrical handle at an intermediate annulus and captures the upwardly flaring frustum shaped handle at a lower and complementary female segment. The tension rod and grapple segments are surrounded by and encased within a cylinder. The cylinder terminates immediate an outward extending annulus at the lower portion of the grapple segments. Excursion of the tension rod relative to the encasing cylinder causes rod release at the handle. Rod release at the handle occurs by permitting the grapple segments to pivot outwardly and about the annulus on the tension rod so as to open the lower defined frustum shaped annulus and drop the rod. Relative movement between the tension rod and cylinder can occur either due to electromagnetic release of the tension rod within defined limits of travel or differential thermal expansion as between the tension rod and cylinder as where the reactor exceeds design thermal limits. OTHER OBJECTS AND ADVANTAGES An object of this invention is to disclose a simplified mechanical grapple for gripping and releasing a control rod at its handle. According to this aspect of the invention, the rod drive includes an inner tension rod and an outer cylinder. The lower end of the tension rod has an attached annular flange. The grapple includes a plurality of preferable six grapple segments. Each grapple segment pivots at an upper indentation about the flange and receives the rod handle at an lower indentation. Inward and outward movement of the grapple segments with respect to one another is restricted by relative motion between the tension rod and cylinder. The lower end of the cylinder restricts the rod segments towards one another. When the cylinder does not restrict the grapple segments, the handle of the rod can be received at the rod segments. Once the handle is received in the rod segments, the cylinder moves downwardly relative to the tension rod. The cylinder then restricts movement of the grapple segments. With the control rod handle captured, motorized and conventional slow driven movement of the control rod can occur. A further object of this invention is to disclose a control rod grapple that interacts with a rod handle to effect grappling of the handle. According to this aspect, the grapple segments include two bearing surfaces, one for bearing on the top of the control rod handle and the other for bearing on the bottom surface of the flange attached to the tension rod. As the grapple segments come down over the control rod handle, a gathering surface at the bottom of the segments forces the control rod segments apart. Once the handle is fully received within the segments, the two bearing surfaces on the top of the control rod handle and on the bottom of the tension rod flange exert a torque on each rod segment. This torque causes the rod segments to move inwardly too and towards one another. Control rod capture at the handle occurs. An advantage of this interaction between the control rod handle and grapple is that the grapple segments are disposed for capture by the surrounding cylinder. This cylinder maintains control rod handle capture until specific release is triggered, either by thermal excursion above design limits or alternately release of an electromagnetic keeper mechanism. An advantage of the disclosed grapple is that it is actuated by relative movement between the interior tension rod and the exterior cylinder. This relative movement can be mechanical, electromechanical or thermal. A further advantage of the driveline and grapple is that it is ideal for attachment to conventional slow drive units used for reactor control. Specifically, rod grappling can only occur under deliberate motorized drive control of the grapple. First, the driveline must be moved downwardly about the control rod handle. Second, the grapple closes and captures the control rod handle. Third, and only when the control rod handle and grapple are securely attached on the drive move both driveline and rod deliberately upward for reactor energizing. No credible way exists with the disclosed driveline and grapple that will permit rapid rod withdrawal from the reactor. Yet another advantage of the disclosed mechanism is that an electromagnetic connection is required to maintain the control rod within the grapple. Thus, traditional series circuitry for maintaining the electromagnetic grapple closure can be accommodated. Any interruption in the disclosed electromagnetic circuitry will result in the rod being released at the handle by the grapple and correspondent reactor SCRAM. A further object of this invention is to disclose a thermal circuit breaker for use with a sodium cooled fast neutron breeder reactor. According to this aspect of the invention, the tension rod and cylinder are designed for bimetallic differential thermal expansion, the tension rod having a high index of thermal expansion, the cylinder having a low index of thermal expansion. Where a thermal design limit is exceeded in the reactor, the tension rod expands relative to the cylinder causing relative movement beyond a preselected limit at the vicinity of the grapple. With movement of the cylinder with respect to the grapple, the cylinder clears a male annulus at the upper end of the grapple. The grapple segments are free to pivot outwardly. The rod handle is released. Upon completion of the grapple segments pivotal motion, the rod is dropped, typically into a dash pot, and causes correspondent reactor SCRAM. An advantage of this aspect of the invention is that an essentially shock proof thermal circuit breaker is disclosed. Damage to the driveline by extra ordinary causes such as earthquake and the like is highly unlikely; the disclosed thermal circuit breaker will drop rods and cause reactor SCRAM even though connected drives may be disabled. A further advantage of this invention is that it is particularly suited to overhead rod release mechanisms, especially those kinds of overhead rod mechanisms that are commonly prescribed for sodium cooled fast neutron breeder reactors. Yet another advantage of the disclosed grapple is that the grapple is essentially a thermal circuit breaker. SCRAM of a plant can be followed by reconnection of the drive unit at the grapple and resumption of ordinary control rod movement pursuant to drive movement.
	description	This invention was made with Government support under grants awarded by the National Institutes of Health (NIH) pursuant to Grant Nos. 1R43RR022488-01, 2R44RR022488-02, 5R44RR022488-03, and 2R44RR022488-04. The government may have certain rights in this invention. The present invention relates generally to optical apparatuses and methods for forming optical apparatuses. There is no single, universally accepted definition of the range of photon energies which constitute X-rays. However, many skilled in this technology field use the following definitions: EUV (Extreme Ultraviolet) can cover the range of wavelengths from about 100 nm to about 10 nm; X-ray can cover the range of wavelengths from about 10 nm to about 0.01 nm. Soft X-rays, a subset of X-rays, can cover the range of wavelengths from about 10 nm to about 0.1 nm. There is a wide range of applications for radiation in the EUV and X-ray spectral ranges. For wavelengths shorter than approximately 110 nm, there is a lack of viable materials which can be used to fabricate refractive optical elements for applications utilizing the EUV and X-ray spectral ranges. This is due to the fact that all materials absorb significantly at these wavelengths, particularly at thicknesses great enough to form a practical lens element. Therefore, reflective or diffractive optical elements are typically used for wavelengths of radiation shorter than approximately 110 nm. Such reflective elements can range from simple, planar mirrors to more complicated forms such as ellipses, parabolas, and combinations thereof. The ranges of wavelengths which require reflective optics therefore can include both the EUV range and the X-ray range. As the wavelength of the radiation becomes shorter, the requirement on surface roughness for viable optical elements becomes correspondingly stricter as well. A complex relationship exists between the wavelength of the radiation, the angle of incidence of the radiation, the roughness of the reflective surface and the corresponding reflectivity of the incident radiation off of the surface. This can be seen from the results of sample numerical calculations, as shown in FIGS. 1A-1D, which are two-dimensional plots 110-140 illustrating reflectivity versus photon energy for copper surfaces of varying roughness and for different incident angles. The plot 110 illustrates reflectivity versus photon energy for an incident photon angle of 1 degree and surface roughness of 1 nm. The plot 120 illustrates reflectivity versus photon energy for an incident photon angle of 1 degree and surface roughness of 10 nm. The plot 130 illustrates reflectivity versus photon energy for an incident photon angle of 5 degree and surface roughness of 1 nm. The plot 140 illustrates reflectivity versus photon energy for an incident photon angle of 5 degree and surface roughness of 10 nm. As FIGS. 1A-1D illustrate, for high reflectivity it is necessary to have an appropriate combination of shallow angle of incidence and low surface roughness (low relative to the wavelength being reflected). A surface can be brought to a very low roughness level through the use of machining techniques and/or polishing. Diamond-turning, which can involve the use of a specialized lathe combined with cutting tools utilizing a diamond cutting edge, can provide surface roughness as low as 1 nm. However, this can be achieved only in limited circumstances, having to do with the material and geometry of the part being fabricated. Polishing can also be employed to provide a desirable final surface roughness. However, the ability to effectively polish a surface is also dependent on the geometry of that surface. As a general rule, surfaces that are concave with a high degree of curvature are typically more difficult to fabricate to a very low roughness value than those which are flat to convex and have a low degree of curvature. Synchrotrons can provide one flexible source of radiation in both the EUV and X-ray spectral ranges. Synchrotrons are typically part of a large, relatively expensive facility, usually supported by a governmental agency. The radiation from a synchrotron beamline typically is emitted in a very bright, narrow beam. Therefore, focusing optics, such as zone plates described below, can be effectively used as both collection and imaging elements over the EUV and soft X-ray ranges. Applications utilizing synchrotron radiation in the EUV and X-ray spectral ranges and zone plates for focusing can include soft X-ray biological microscopes and EUV exposure studies for semiconductor lithography applications. One source of EUV and X-ray radiation that can be used as an alternative to synchrotrons are plasma based sources. Plasma-based sources can use either a high power pulsed laser system to generate the high temperature plasma required to generate these wavelengths, or they can use a pulsed electrical discharge. As an example, Energetiq Technology, Inc. of Woburn, Mass., offers for sale an EUV and soft X-ray source based on the use of a z-pinch technology that inductively couples pulsed dc energy into a discharge region, such that the required high temperature discharge can be attained to generate both EUV and soft X-ray radiation. As an example of the size of a discharge produced plasma (DPP) source, the z-pinch source from Energetiq Technology can produce an EUV and X-ray emitting spot that is approximately 0.4 to 1.0 mm in diameter. When a DPP radiation source is used in place of a synchrotron radiation source, use of the condenser zone plate becomes less favorable. Useful zone plate throughput is limited theoretically to <20% for light incident within the small acceptance numerical aperture (typically less than 0.02 in the soft X-ray region). In a synchrotron-based system, enough power is available that a 90% (or more) loss of throughput may be acceptable. However, a DPP radiation source appropriate to a small laboratory will have limited output power and such losses would be unacceptable. Therefore a higher throughput condenser lens element is desirable when a DPP radiation source is used. There can also be instances where a higher throughput condenser lens element would be desirable for a synchrotron or other type of source as well. An additional feature of the DPP radiation source (as compared to a laser plasma source) is that the size of the X-ray emitting region is relatively large. This allows use of a de-magnifying optic which concentrates the larger source size, providing higher illumination intensity while still allowing an adequate illuminated field of view. In addition, the larger source size relaxes the mechanical alignment and positioning constraints on the condensing optic. One class of optical elements that can be used as an alternative to a condenser zone plate consists of grazing incidence reflective devices. These are reflective elements configured such that the angle of incidence of the light to be focused is small—typically only a few degrees or less. By keeping the incidence angle small and the surface roughness very low, the throughput of grazing incidence devices can be quite large—in excess of 50%, and approaching 100% for some configurations. Grazing incidence devices can be used in many possible configurations (e.g., Wolter, de-magnifying or magnifying ellipse, tandem ellipse (unity magnification), capillaries). Grazing incidence devices can achieve high throughput (>50%), and are robust and rugged due to their macroscopic size. However, it can be difficult to machine small, high aspect ratio grazing incidence devices. Zone plates can use a non-uniform, circular transmission grating to diffract radiation. Transmission efficiency (throughput) of zone plates are approximately 20% or less. In addition, zone plates are microscopic, fragile and expensive to fabricate, and require very specialized manufacturing facilities. Furthermore, zone plates can suffer from severe chromatic aberration, while reflective optical elements are generally achromatic. One approach to providing an optical apparatus is to construct the optic from a plurality of segments. In one aspect, there is an optical apparatus. The optical apparatus includes a plurality of individually fabricated segments and a holder. Each of the plurality of individually fabricated segments includes an inner annular surface and an outer contact surface opposite to the inner annular surface. Each of the inner annular reflecting surfaces define a longitudinal segment axis. The holder contacts each of the outer contact surfaces of the plurality of individually fabricated segments. Each of the longitudinal segment axes of the plurality of individually fabricated segments are linearly aligned. In another aspect, there is a method for manufacturing an optical apparatus. The method includes providing a plurality of individually fabricated segments and a holder. Each of the plurality of individually fabricated segments include an inner annular surface and an outer contact surface opposite to the inner annular surface. Each of the inner annular reflecting surfaces define a longitudinal segment axis. The method also includes positioning each of the individually fabricated segments in the holder by having the holder contact the outer contact surfaces. Each of the longitudinal segment axes of the plurality of individually fabricated segments are linearly aligned by the outer contact surfaces contacting the holder. In other examples, any of the aspects above can include one or more of the following features. The optical apparatus can be an X-ray grazing incident apparatus. The optical apparatus can be an EUV or soft X-ray grazing incidence apparatus. The inner annular surfaces of the plurality of individually fabricated segments can include an internal reflecting surface that defines a radiation channel. The radiation channel can be aligned along the linearly aligned longitudinal segment axes. The radiation channel can be ellipsoidal or at least substantially ellipsoidal in shape. One or more inner annular surfaces of the plurality of individually fabricated segments can be conical in shape. The individually fabricated segments can include machined segments, electroformed segments, polished segments, or any combination thereof. The individually fabricated segments can include nickel, nickel-copper alloy, copper plated with nickel, aluminum plated with nickel, or any combination thereof. The method can further include machining, electroforming, and/or polishing one or more segments to form one or more of the individually fabricated segments. Any of the above implementations can realize one or more of the following advantages. An optical element formed from individual segments can advantageously provide superior optical performance than that which could be obtained through fabrication of the X-ray optic element as a single mechanical element, because the segmented design can allow for greater design freedom than a single monolithic structure would allow. In addition, the length of a segment can be made small enough such that short machining tools can advantageously be used, thereby avoiding thin, long machining tools that tend to vibrate or distort causing unacceptable surface roughness and/or figure error. The details of one or more examples are set forth in the accompanying drawings and the description below. Further features, aspects, and advantages of the invention will become apparent from the description, the drawings, and the claims. The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. The invention relates to a high-resolution optical element that can be formed from multiple segments, each of which is independently fabricated by techniques such as machining, electroforming and polishing. Optical elements can include EUV optical elements, X-ray optical elements, and/or optical elements directed to any arbitrary spectral range. The individual segments can be assembled into a single, functional optic element by mechanically aligning them on a precision holder. An optical element formed from individual segments can advantageously provide superior optical performance than that which could be obtained through fabrication of the X-ray optic element as a single mechanical element, because the segmented design can allow for greater design freedom than a single monolithic structure would allow. In one embodiment, the invention features a configuration by which a high aspect ratio grazing incidence optic element can be manufactured, while using conventional diamond-turning machining techniques. Constructing the optic element out of a single monolithic mechanical element can require machining small, precise, low-surface roughness features having a high aspect-ratio. This can either be very difficult or impossible to achieve using state-of-the-art diamond machining techniques. Instead, in the subject invention, an optic element can be constructed from multiple, separate segments that are independently machined and mounted together in a precision assembly to form a single optical element. For example, in a cylindrical geometry, the inner surface can be turned to form a section of a concave ellipse, and the outer cylindrical surface can be used to register the segment against a precision mount. An ellipsoid can have the property that all rays emanating from one focus are returned, after a single reflection from an inner ellipsoidal surface, to a second focus. In some embodiments, the inner reflective surface of each segment can be machined to a specific ellipsoidal form such that when two or more segments are assembled, a continuous ellipsoidal focusing element can be obtained. The precision with which the axis of the inner reflecting surface and that of the outer surface coincide can define the optical alignment of multiple segments. In some embodiments, the inner reflective surfaces of the individually fabricated segments can be conical in shape. Conical shapes can advantageously allow for more efficient and/or effective polishing of the surface. Any desired shape for the inner surface of the optical element can advantageously be approximated as a series of conical segments. For example, if the desired shape for the inner surface is an ellipsoid, then conical segments can be formed where the average slope of the conical segments is made to approximate the slope of the desired ellipsoid. The accuracy of the approximation can be increased by decreasing the width of the segments. In general, one or more segments can be machined such that the inner surface forms shapes ranging from simple, planar mirrors to more complicated forms of ellipses, parabolas, other geometric shapes, or any combinations thereof. FIG. 2A shows a diagram of one embodiment of an optic element 210. The optic element 210 can include two or more separately machined segments 212 and a V-block 214, which can be used to precisely mount the individual segments 212. One or more clamps 216 can be used to secure one or more segments 212 to the V-block 214 using screws 218. The length of each of the individual segments 212 can be chosen so that the internal reflecting surface can be machined and/or polished to a desired level of surface roughness. The length of a segment 212 can be made small enough such that short machining tools can advantageously be used, thereby avoiding thin, long machining tools that tend to vibrate or distort causing unacceptable surface roughness and/or figure error. In some embodiments, the length of one or more segments 212 can be between 2 and 30 mm. The material of construction of each of the segments 212 can be one of a number of elements and/or alloys that are stable, resistant to corrosion, and/or able to be machined and/or polished to a low level of surface roughness. Materials of construction can include, for example, nickel, nickel-copper alloy, copper plated with nickel or another protective coating, aluminum plated with nickel or other coating, or any combination of such materials, that can be machined and/or polished adequately. FIG. 2B shows a cross-sectional diagram of the optic element 210. Each segment 212 includes an inner annular surface 222 and an outer contact surface 223, which can be opposite to the inner annular surface 222. The inner annular surface 222 for a particular segment 212 can define a longitudinal axis for that segment. By positioning the segments 212 in the V-block 214, the segments 212 can be aligned such that each of their longitudinal segment axes are linearly aligned with each other. Taken together, each of the inner annular surfaces 222 can define an internal reflecting surface that defines a radiation channel 224. Radiation can enter the channel 224 via opening 226 of the channel 224 and exit via opening 228 of the channel 224. The required surface roughness of the reflecting surface 222 can depend on both the wavelength of radiation and the maximum grazing angle. In some embodiments, the surface roughness of the individual machined segments 212 can be about 4 nm. Surface roughness can be measured, for example, using an interferometric technique. Surface roughness can be improved upon with further refinement to the machining process, and can also be improved upon by adding polishing steps and/or coating steps to the manufacturing process. In some embodiments, the inner diameter of the radiation channel 224 can range from about 1 mm to about 30 mm. In alternative or supplemental embodiments, the thickness of the walls of the segments 212 can range from 0.5 mm to about 40 mm. FIG. 3 shows a two-dimensional plot 300 of the measured optical output from a segmented condenser optic, at its focal point, versus radial position. The results in FIG. 3 are consistent with predictions via numerical modeling of a monolithic condenser optic. In a supplemental or alternative embodiment, a grazing incidence elliptical optic can be made by diamond machining a mandrel, and then electroforming an elliptical reflector onto it. The mandrel can be machined in shorter segments, and then the individual segments can be electroformed separately, and later joined together in a precision mechanical assembly. One skilled in the art will realize the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The foregoing embodiments are therefore to be considered in all respects illustrative rather than limiting of the invention described herein. Scope of the invention is thus indicated by the appended claims, rather than by the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
	abstract	A compact portable LED nail curing lamp has surface-mounted light emitting diode (SMD LED) lights. The lamp provides fast and consistent results producing high gloss finish and even curing of nail polish (e.g., UV-curable gel polish). The nail lamp has a micro USB port, which can be used to power the lamp using a wall adapter, car charger, laptop USB port, or mobile power bank for ultimate portability. In an implementation, a system includes a compact LED nail curing lamp and a mobile power battery pack. The system also includes a cable to connect the nail lamp and the mobile power battery pack. The battery pack provides portable power to the nail lamp so that the nail lamp can be used portably, such as during travel or on an airplane when a wall outlet is unavailable.
	description	This patent application is a continuation-in-part of international patent application WO04095138, filed on Apr. 26, 2004 and hereby incorporated by reference, which claims priority from European Patent application EP3009333, filed on Apr. 24, 2003 and hereby incorporated by reference. This invention relates to a 3D micromachining lithography process, system and product in which penetrating radiations are used for creating buried structures in the interior of a radiation-sensitive material, or for altering the properties of the material itself. Moreover this invention relates to an irradiation system and process by which a beam of charged particles is directed towards a target in air, or in a suitable process gas. Three-dimensional micromachined components are increasingly required for answering the always growing miniaturization needs of industry. In particular 3D micromachined structures are required for the latest generation of microminiaturized sensor, actuators and fluidic devices. The technology of Micro-electro mechanical systems or MEMS is also growing exponentially and relies on the availability of effective fabrication methods of 3D miniaturized structures. There is also an increasing need for devices in which the substrate material is not necessarily machined, but rather some relevant property of the material is altered according to a predefined three-dimensional patter on a microscopic scale. For example refraction index or the magnetic properties of the material could be selectively modified. Such devices are especially sought for in optical and data storage application. Many lithographic techniques exist that can be adapted to produce three-dimensional structures in some material; these techniques however generally fail when deep, high aspect ratio features are required. Among such techniques one can mention the LIGA and X-LIGA processes and the electron beam writing method. There is an increasing demand from industry for 3D micromachined components and it is expected that this demand will continue to grow exponentially. In the last several years the miniaturisation actuators, sensors, etc. has continued apace. Micro-mechanical components are also increasingly integrated with electronic devices in so-called MEMS (micro-electro mechanical systems). There are many lithographic techniques around but only a limited number of techniques are able to produce high aspect ratio, very small microstructures needed in the near future. The LIGA process (German acronym for Lithographie, Galvanoformung and Abformung) is one of the processes currently being used to produce microstructures, electron beam writing is another. The types of irradiation for the exposure steps in these processes can be varied, see FIG. 1 for a comparison of the behaviour in matter of some of these types. In X-LIGA, synchrotron X-ray radiation is used to irradiate through high aspect ratio masks. Today's X-LIGA technology, while offering extremely accurate patterning capabilities, has a limited potential for industrial applications because of the high cost related to the exposure procedure and the manufacturing of masks. Furthermore, the depth of irradiation, i.e. the thickness of the structures, cannot be controlled. UV-LIGA, which uses UV light, is much cheaper and has a minimum feature size larger than 100 nanometers. Electron beams can be highly focussed and can produce very fine structures, well below 100 nm. However electrons are very light and therefore scatter easily in material which results in a loss of resolution at depth. Therefore only 2D structures can be made in shallow photoresist layers. IB-LIGA (Ion Beam LIGA) has been developed as an alternative LIGA technique. It uses high energy (MeV) light ions, mostly protons, to irradiate photoresist materials; both positive and negative photoresist materials can be used. Masks can be used to obtain 2D patterns but the ion beam can also be collimated or focussed to use as a (maskless) direct-write tool. The height of structures can be controlled by the beam energy, e.g. from 14 μm to 160 μm in PMMA for a change in proton beam energy from 0.8 MeV to 3.5 MeV. Sloping (angled) structures can be obtained by varying the incidence angle of the ions. In this way, 3D structures can be obtained with high aspect ratios (up to 100) and sub micrometer lateral resolution. IB-LIGA is a very different technique from Focused Ion Beam (FIB) milling, which uses low energy heavy ions to sputter away surface atoms. FIB milling has a high spatial resolution but the sputter rate is very low which means that making high aspect ratio structures is very time consuming. The throughput of IB-LIGA is much higher than for FIB but much lower than for techniques using masks like X-LIGA and optical lithography. This makes IB-LIGA very suitable for small production runs and rapid prototyping but not for mass production of cheap components. Moreover the above described techniques require that the substrate on which the structures must be obtained should be kept in a vacuum during irradiation. This limits the applicability of this technique in industrial productions. In most irradiation devices, every target change implies an opening of the vacuum chamber, after which long pump-down times are required to attain the necessary level of vacuum. To attenuate this shortcoming, an airlock may be used to introduce samples without breaking the vacuum in the irradiation chamber. An airlock suitable for the required vacuum level is however a complex and delicate piece of equipment, and must be equipped of additional vacuum pumps. Moreover the alignment of the sample is more difficult with an airlock. Another possibility is to perform a batch of irradiation on several samples placed on a revolver or on a similar conveyer. This technique however requires the addition of a complex and large moving equipment within the vacuum chamber, and is also subject to alignment difficulties. Moreover the revolver system is only suitable for batches of limited size, and does not allow continuous production. A common shortcoming of the techniques in which the sample is kept in a vacuum is the difficulty of dissipating the heat produced by the beam's energy lost in the sample and, where present, in the irradiation mask. When a high irradiation current is required, the sample and the mask may be damaged or deformed because of the temperature rise. It is also known that the surface of a substrate can be structured by directing a low-energy ion beam thereupon, in presence of a suitable reactive process gas. For this method, known as Reactive Ion Etching (RIE) the energy of the involved ions is generally rather low. The aim of the present invention is to provide a process and a system for producing miniaturized three dimensional structures or for altering material's properties by an ion beam irradiation which is free from the above shortcomings. The above object is provided by the process, systems and products according to the appended claims. In particular the present invention permits the modification of materials in the interior, and the creation of buried three-dimensional structures. The invention exploits ionising radiation, and in particular high-energy ion beams to achieve new processes, systems and products in various fields. The invention can be applied to 3D Micromachining process, system and product in which penetrating radiation is used for creating 3D buried structures. Another application of the present invention is the irradiation with ion in combination with reactive agents, either introduced by means of a process gas surrounding the target, or internally contained in the material. In this way the target material can be directly etched or its properties can be modified. The device of the invention can also be used in air or in a suitable atmosphere to maximize heat dissipation for both structuring and modification and can be used in combination with a mask to increase throughput. Complex 3D sub-surface structures can be obtained by exploiting the fact that ions deposit most energy per unit length towards the end of their path, which is well defined. In this way buried microcavities can be made in one step without using a two-layer process, laminating, gluing or cutting techniques. Similar results, albeit with some limitation, can be obtained by using slanted beams or by rotating the sample for concentrating the deposited energy within a buried region of said material. The creation of three-dimensional structures within a material by the present invention comprises of course the creation of hollow features, by direct radiation milling or via a subsequent development step, but also the local alteration, according to a defined 3D pattern, of a specific property of a photo-sensitive material. The present invention may therefore be used to improve the wettability or the biocompatibility of appropriate materials, to record information by altering some optical or magnetic or thermal property of the material, to provide components for optical or magnetic applications, or to locally promote chemical or biological reaction thanks to the activation of some appropriate chemical. The process of making structures using IB-LIGA contains three steps: Obtaining a layer of photo-resist. Irradiation the photo-resist material with an ion beam. Developing the irradiated structure A possible final step is galvanising the structures to obtain negatives in more durable form. These steps are discussed in more detail hereafter. There are many photo-resist materials available and there are also many criteria which have to be satisfied. One of these criteria is the type: positive or negative. In positive photo-resist, molecular bonds are broken (chain scission) by irradiation with particles or light after which the irradiated structure can be removed. In negative photo-resist, additional bonds are formed during irradiation (cross-linking) which makes the irradiated structures more durable so that development removes everything else PMMA has been chosen for the first tests because it has good characteristics, it is widely used and therefore easily available in a variety of forms. Currently we are using 3 mm thick sheets of commercially available high molecular weight PMMA (Röhm GS 233) which is synthesised at ambient temperatures to reduce the amount of internal stress. A 3.5 MV single ended Van de Graaff accelerator is used for the irradiation of the photo-resist material. This machine can produce proton or He+ ions with an energy between 0.8 and 3.5 MeV with an energy resolution of about 0.01%. The ion beam is guided through a vacuum tube to the target chamber which is also kept under vacuum. For the present results, the beam is collimated by slits at the entrance of the target chamber. The slits consist of cylinders made of tungsten carbide (WC) of 3 mm diameter. This design is made to minimise slit scattering. There are three sizes of collimator but in most cases the 0.2×0.2 mm2 collimator was used. The range of the ions in PMMA is controlled by the beam energy and the sample can be rotated to change the angle of incidence of the ions. Either static irradiations can be made or the sample can be moved by computer controlled motors to obtain more complex structures. A crucial parameter for the irradiation is the dose, i.e. the number of ions per mm2. The most reliable method of measuring the ion current density (ions/mm2/s) is the use of a Faraday cup at the end of the set-up to measure the current of a well collimated ion-beam with known beam-size. However, this method cannot be used during irradiation because the ion beam is stopped in the sample and the Faraday cup is located behind the sample. Therefore the beam current is measured before and after the irradiation and the average used. This method only introduces a small uncertainty (about 5%) because the beam current proved stable enough. The total dose can be obtained by dividing the beam current by the beam area and multiplying by the time of irradiation. In case the sample is moving, the irradiation time is determined by the speed of the movement. The general procedure for development is derived from the indications which can be found in literature [S. V. Springham, et al, Nucl. Instr. and Meth. B 130 (1997) 155]. It should be noted that one of the components of the development solution is susceptible to breakdown by light and therefore should be stored in the dark. Several instruments have been used to make observations and measurements. The simplest instrument is the optical microscope (Leica DMLM). However, the contrast and magnification are insufficient for detailed observations. The SEM at EI·AJ (Cambridge Instruments stereoscan 90) proved much more useful. Before the observations, the PMMA samples have to be coated with a thin gold layer to improve contrast. However, only relatively small magnifications can be used up to 1500×. For higher magnifications, the electron beam becomes to intense causing damage to the PMMA. The Alphastep 500 of EI·AJ has been used to measure thicknesses (depth of structures) and surface roughness. For the latest measurements an Altisurf 500, also available at EI·AJ, has been used. This system uses a focussed white light beam (beam spot 3 μm) to measure the surface roughness down to a resolution of about 10 nm. The AFM at CSEM, Neuchâtel, has also been used to measure surface roughness at very small scales. According to this aspect of the invention, irradiation tests have been performed on PMMA. Several series of irradiations have been performed to optimise irradiation parameters like dose and development parameters. The optimum value of the dose as a function of beam energy and current density had to be ascertained by performing a series of irradiations with different doses. The irradiations with a collimator need a dose range which is about the same as the accuracy of the dose measurement, e.g. 75-85 nC/cm2 for 2 MeV protons. Some of the results showing the effects of varying irradiation parameters and sample movement are shown in FIGS. 2 and 3. The effect of the different energies on the depth can be clearly seen in FIG. 2 left. The depth of the structures has been measured with the Alphastep for structures made with 1.2 MeV and 2 MeV protons. The measured height is 28 μm and 65 μm respectively. The range of ions in matter can be calculated with one of the software packages available for this purpose, for example the well known program SRIM-2000. The calculated range is 26 μm and 61 μm for 1.2 MeV and 2 MeV protons respectively. These values are in reasonable agreement. It should be noted that to obtain a thickness in μm from the calculation a sample density is needed. However, the density is not known precisely which can already explain a large part of the difference. FIG. 7 report an example of range made with a suitable simulation software. Problems of development arise at the end of the scan or at direction changes (corners) when moving the sample, as can be seen in the FIGS. 3c and 3d. The structure remains underdeveloped at these points because the irradiation dose remains too low. The overhangs visible in FIG. 3c are caused by the fact that the maximum energy transfer takes place close to the end of the range of the ions. This means that even with too low a dose, the bottom part still partially develops while the region closer to the surface does not develop. This leaves an overhang which becomes larger closer to the edge. Making an extra static irradiation at the end of a line scan does not solve the problem because this will result in a partial overdose which causes damage (holes) to the bottom surface. The best solution is minimising the number of end-points in a structure. In FIG. 3c the undercut at the bottom of the structure can also be clearly seen. This is caused by the deviation of the ions from a straight line at very low energies. At low energies the ions are more likely to undergo small angle scattering which causes this beam broadening. The beam broadening can be modelled with the Monte-Carlo simulation program SRIM-2000 mentioned above. Comparing these calculations with experiment is not very useful because the accuracy of the modelling at low energies is limited and it is difficult to obtain experimental values. This undercut becomes more severe for higher beam energies. It can be eliminated by using a layer of photoresist material on a non-photoresist substrate, e.g. Si. The layer thickness should be smaller than about ⅔ of the range of the ions in the photoresist material. A different substrate can be used without risk because the probability for backscattering from within the substrate is very low. Furthermore, the dose needed for the photoresist material is so low that the damage to a non-resist substrate is negligible. Walls with high aspect ratios can be made by moving the line scans closer together. When the scans are made too close together, the undercut will make a hole in the bottom of the wall. The best result obtained so far is a wall of 3 μm thick and 120 μm high, i.e. an aspect ratio of 40. This result has been obtained with a microbeam of 3 MeV protons. The aspect ratio can be further increased using a finite layer thickness of photoresist to eliminate the undercut. Alternatively, higher aspect ratio can be obtained by means of multiple cycles ion beam exposition and development on top of each other. In this way the depth of treatment can be extended without limit. Roughness measurements have been carried out by AFM for roughness with a small periodicity and by Altisurf for a long range surface (150 μm) with a minimum feature size of a few micrometer. Both type of measurements showed that the RA value is about 10 nm for the bottom as well as for the wall side. The present invention is not of course limited to the use of the above mentioned Van de Graaf ion source, but any source of penetrating radiation or high-energy ions could be used together with any set-up for focussing ions or radiation. In particular with a microbeam facility the ion beam is focussed on the target with a magnetic lens system consisting of a quadrupole triplet. The beam can be scanned (moved) in an arbitrary pattern over the sample by use of magnetic scan coils within a scan area of 2.5×2.5 mm2. Alternatively, the sample can be moved. The sample is mounted on a 3-axis motorised manipulator with a total area of movement of 100×25 mm2. During the first tests already a beam size of about 1×1 μm2 has been achieved. According to a further aspect of the invention, we present the structuration of microcavities with ion beam without cutting or opening the material using the fact that the energy deposition by protons in matter is not linear with the depth of penetration. The way a particle deposits its energy in the matter is different if it is a photon, an electron, a proton or a heavy particle. For charged particles, more energy per unit length will be deposited towards the end of its path rather than at its beginning, as shown in FIGS. 4 and 7. The stopping power for ions increases along the ion path, so that the density of deposed energy is maximal at path's end. We exploited this effect to structure our cavities: by giving an adequate energy to protons, they deposit much of their energy in a precise depth, inducing less damage to the upper level which is thus much less developable and remains. In this example a Van-de-Graaf accelerator has been used, which produces and accelerates protons (H+) or helions (He+) with energies from 0.8 up to 3.5 MeV with a energy resolution of 0.01%. The beam then passed by an analysis magnet with which the correct energy is selected, a directional magnet which direct the ions to one of the three lines. The beam is then focalized with a quadrupole magnet and enters the target chamber being collimated by slits of 3 mm diameter made of tungsten carbide (WC). The final collimation is made by a 100×100 μm collimating slit. The dose given to the sample is calculated by measuring the current density [ions/mm2/s] with a Faraday cup, knowing the surface of the beam and the time of irradiation (or the speed of displacement of the sample). The lithography processes comprises the following steps: irradiation of the sample (either with or without mask); development (either wet or dry etching); control and imaging of the obtained structures. High molecular weight PMMA (polymethylmethacrylate) samples (Angst+Pfister PMMA-XT 01.2410.4020, 18×10×2 mm) were fixed on an x-y table inside the chamber. The ion energy was chosen to be at 2.7 MeV. The measured current density was 20 nA/mm2 and the speed of displacement of the table 27 μm/s, giving a total dose of 75 nC/mm2. The sample were developed for 90 minutes at 37° C. using a standard chemistry known as GG-developer and whose description can be found in the scientific literature [S. V. Springham, et al, Nucl. Instr. and Meth. B 130 (1997) 155] (ether monobutyl diethylenelycol, morpholine, ethalonamine and water). An advantageous aspect of the process of the invention is that it can be implemented as a maskless process. By controlling the movements of the XY table, and by modulating the energy and the intensity of the ion beam it is possible to write in a three-dimensional fashion the desired structure in the bulk of the substrate. This means that the desired dose profile can be precisely deposited along a predetermined pattern in X, Y and Z, where Z corresponds to the depth in the material, determined by the beam's energy and by the ionic species used, and X and Y are determined by the movements of the XY table. To observe the quality of the cavities, a SEM (Cambridge Instruments Stereoscan 90) was used. Prior to use this instrument, the dielectric PMMA sample has to be coated with a thin layer of gold (˜100 nm) using a dc-sputtering machine. Several tests were performed before finding the adequate dose. The PMMA sample, fixed on the x-y table, was positioned properly close to the beam and then moved across with a constant speed. A global view of a resulting structure is shown in FIG. 5. The five structures of this group received the same dose (˜75 nC/mm2) which proved to be the best value to obtain reliable cavities. On this sample, a few tests made to calibrate the parameters of exposition were made but are not visible on the picture. Using SRIM program, we calculated the protons penetration depth knowing their initial kinetic energy of 2.7 MeV and obtained 110 μm: this value seems to be correct if we look at the depth of the cavities which is about 120 μm. The cavity itself has the following dimensions: 0.1×0.07×1 mm. A 300× magnified picture is presented in FIG. 6. The surface quality of the cavity edges is optically very good. the surface was also developed but the top layer is still thick enough (˜50 μm). The angled slope at the end of the course is due to the characteristic dose profile. When scanning a line the beginning and end of the path do not receive the same dose because the exposure time of the first and last irradiated parts is less. The bottom surface undercut is due to the dispersion of the protons path. The 2.7 MeV proton trajectories in the PMMA, simulated with SRIM, are depicted in FIG. 7. Their dispersion d along the y-axis at the end of their path leads to an undercut described in FIG. 6. This aspect of the invention is not however limited to the above ion energies and atomic species, which are given by way of example only. In particular the method of the invention could make use of a generic ionic species, according to the dose profile desired, and in particular of all light ions species, and in particular of ions of the species H, He, Li, Be, B, C, N, O, F, Ne. The energy of 2.7 MeV is also given here by way of example, and it is to be understood that the method of the invention could make use of any beam energy, according to the circumstances, and in particular of energies comprised between 0.5 MeV/amu and 8 MeV/amu, and more in particular of ionic beams whose energy is comprised between 1 MeV/amu and 3 MeV/amu. With this way of fabrication, a great potential exists to structure cavities in materials without using two-layers, laminating or cutting techniques. By selecting the ion energy and using a high-precision x-y table, the form, depth and dimensions of so-called “microtunnels” can be precisely controlled thus opening a door to a new technology applied especially in the growing field of microfluidics. The method of the invention allows therefore obtaining complex three-dimensional structures in the bulk of the material, without requiring additional gluing, aligning, bonding or assembly steps. In this way the structure can be obtained in a more economical way and is more robust. The above aspects of the invention exploited the fact that the dose deposited in a material by a beam of charged particles is higher at the end of the range. The same effect of concentrating the dose within a buried region of the material to be structured could however also be achieved by exposing the material do a series of converging beams 501, 502, 503, crossing themselves in the region 512 where the structuring effect is desired (FIG. 8). This way of proceeding can be done by sending several slanted or inclined beams 501, 502, 503, to the target at the same time or, more simply, by delivering the desired integrated dose in several passes performed at different inclination and spaced in time. This technique of converging beams allows using also neutral beams or photon beams, hard X-rays beams or photon beams generated by synchrotron radiation wherein the dose-enhancement at the end of the path is less than in charged particles' beams. The beam energy required for the process according to this aspect of the invention will necessarily vary, according to the energy deposition distribution searched. Typically the energies will be in the same ranges described above for ion and light ion beams. When ions beams are used in combination with the inclined beam technique an even higher dose concentration can be achieved in the desired region. According to another aspect of the invention, an ion beam of characteristics analogous to those described above is applied to a sample of PTFE. In this case structuring of the material can be obtained directly and without the need of a developing step. The geometries achieved are analogous to those obtainable in PMMA. Other materials, whose structure can be modified by the irradiation with ion beams, in particular polymers which are susceptible to molecular scission or cross-linking under irradiation, may be directly structured by this technique. A further aspect of the invention concerns the possibility to use an ion beam to modify the optical or the magnetic properties of a substrate. For example it is possible to induce local refraction index variations high enough to give rise to an optical guide or to an optical circuit. At the same time magnetic patterns can be written in a buried layer of material by altering the magnetic properties according to a predetermined three-dimensional pattern. A further aspect of the invention, now described with reference to FIG. 9, concerns the possibility of irradiating a substrate at atmospheric pressure. according to this aspect of the invention an ion beam generator 32 comprises an evacuated space 33 into which is placed an ion accelerator 45 generating a collimated ion beam 80 having the required composition, intensity and energy. A deflection unit 47 bends the beam 80, electrically or magnetically in order to sweep the surface of the target substrate 40 according to a predetermined pattern. An exit window 37 is installed at the output end of the generator, and the substrate 40 is placed behind. The ion beam 80 crosses the window 37 and impinges on the target substrate 40 which is placed in a volume at atmospheric pressure 31. The window may comprise a kapton or aluminium sheet with a thickness comprised between 5 and 10 micrometers. This implies an energy loss of the order of 50-150 keV for ion beams whose energy and composition is comprised within the limits specified above, for example for an energy comprised between 2 and 6 MeV, preferably between 3 and 5 MeV. Of course many materials lend themselves to the construction of the exit window, mylar and aluminium representing only two current possible choices. Other alternatives, likes windows of carbon, silicon nitride, or other light materials are perfectly possible and bay be adopted within the frame of the present invention. Additionally, it is clear that the constitution of the ion beam generator 32 is not limited to the simplified structure given here by way of example, but may also comprise various additional pieces of known equipment, like deflectors, collimators, filters or ion sources, according to the circumstances. The distance between the window and the substrate will preferably be kept as small as possible, in order to minimize energy loss and multiple scattering in air, compatibly with the necessity of cooling target and window. Typically a distance of about 1-2 mm or less is adopted, however in some cases the target substrate may be in contact with the window. In order to further decrease the multiple scattering in air, and to promote heat dissipation, a flow of a light gas, like H2 or He, may be forced in the space between the window and the target. Also, the space surrounding the target may be filled by a suitable chemically active gas, in order to assist the ablation of the substrate material. It is observed that, for example in Si target in presence of a fluorinated process gas, the high-energy ions turn a part of the target into an amorphous state, which is readily etched. The present invention is not limited to the maskless, direct-write techniques described above, but includes also process in which the selective exposition of the substrate is obtained by a suitable mask opaque to the ions. In this case the mask could also be in the air space between the window and the target, which provides the simplest and most versatile disposition. However, the mask could also be placed in the vacuum space before the window, or a sheet of variable thickness could be used, combining the functions of mask and exit window. When a very high space resolution is required, an ion optics may be employed to de-magnify the mask, and project on the substrate down scaled image of the original mask, as it is shown on FIG. 10. According to this aspect of the invention, the ion beam 88 is formed in a broad parallel pencil, for example, and directed to the mask 80, where it is selectively absorbed, in order to obtain the desired exposition pattern. A ion focussing device 67 project on the target substrate 40 a dimensionally reduced image of the mask 80. A certain focal length l is required for obtain the required dimensional reduction. In this case the mask may be in the vacuum chamber 33, or, preferably, in an airspace 32, separated by two windows 28, 29 from the vacuum chamber 33, as on FIG. 11. Although IB lithography is a major application area of the present invention, this is not limited to structuring and engraving applications, but encloses other surface and bulk treatments which can be obtained by means of an ion beam as well. For example, the system and method of the invention may be employed for ion milling, surface hardening, and surface wettability modifications. Ion irradiation may also be used for improving the biocompatibility of materials, or for engraving nanopores on polymer membranes. Further the method and the apparatus of the present invention may be employed with living cells or living tissues as targets. In this case the energy deposited in the target may activate a radiation-sensitive chemical, according to a well-defined three dimensional pattern. Even if some of the above applications are per se known, it will be appreciated that the system and method of the invention, allowing the treatment of samples in air, permits the application of such treatments in a more practical and economical way to a variety of products. A further embodiment of the present invention will be now described, with reference to FIGS. 11 and 12. According to this embodiment the radiation beam, for example a proton or helium ion beam having the features of the above embodiments, crosses a mask 810 before hitting the target 40. The mask 810 introduces a variable energy loss in the radiation beam, according for example to a variable thickness of the mask, as depicted in FIG. 11. Thanks to the interposition of the mask 810 the energy of the beam hitting the target 40 will vary according to the energy which is lost in the mask 810. Thank to this feature the energy will be deposited in the bulk of the substrate 40 at a variable depth, in the region 612 of FIG. 11. This embodiment allows therefore the creation of multilevel 3D structures, comprising buried features 612 at different depths. The thickness of the mask can vary stepwise, as illustrated, or also in a continuous fashion. In the latter case the depth of the corresponding features in the target 40 will also vary continuously, which allows the creation of slanted structures, as depicted in FIG. 12. The variability of the energy, and therefore of the depth of the resulting structures, can be advantageously obtained by a variable-thickness mask, as illustrated. However it would also be possible, within the frame of the present invention, to use a composite mask comprising material of varying density, or varying dE/dx coefficient, to arrive at the same result. The mask 810 in FIGS. 11 and 12 can be used in two modes: static or dynamic. In the static mode, the mask is placed on the substrate 40 or placed in a fixed position relative to the substrate. The mask can be as large as the substrate and the mask and substrate is moved with respect to the beam to cover the hole area. In the dynamic mode, the mask is placed fixed with respect to the beam and the substrate can be moved behind it. In this case the pattern of the mask can be reproduced many times on the substrate. The three-dimensional mask of varying thickness or variable energy loss, like mask 810, providing a variable energy loss, and defining a three-dimensional microstructure 810 can be used for ion implantation By opportunely varying the exposition and development condition, and in particular by increasing the delivered dose, open structures 613 can be obtained, as visible on FIG. 12. It will be appreciated that this method allows the creation of slanted structures. In a variant, the radiation-sensitive material 40 consists in a photoresist material, for example a positive photoresist or a negative photoresist, and the irradiation is followed by a developing step for obtaining a 3D micro-structure corresponding to the 3D pattern of the energy deposition. The method of the invention allows the realization of three-dimensional nanostructures and microstructures in all kind of materials 40, like for example: crystalline and amorphous diamond; crystalline and polycrystalline silicon; Oxides, in particular aluminium oxide Al2O3, (sapphire or ruby), zircon Zr2O3 and titanium oxide, and TiO2; glass; ceramic materials, for example TiO2 based ceramics; nitrides, in particular nitrides of aluminium, silicon, titanium and boron; carbides, notably carbides of silicon, boron and tungsten. The above list is given by way of example only and the present invention is by no means limited to the above substrates, but is to be construed as encompassing all the suitable substrate materials, as well as all their combinations and compounds. According to a further aspect, the invention deals with a process for creating a predetermined structure in a diamond substrate, the process comprising the steps of: directing a beam (818) of radiation to said diamond substrate, deposing energy by said beam (818) locally into said diamond substrate, according to a predetermined pattern, selectively removing those parts of the diamond substrate in which said energy has been deposited. More particularly this aspect of the invention involves the delivery of a radiation dose sufficient for locally altering the crystalline carbon-carbon bonds in the diamond. The delivered dose may be sufficient, in embodiments of the invention, to cause partial or total transformation of the original diamond structure into a graphite structure or into another crystalline structure. The selective removing of the irradiated parts of the diamond substrate may be carried out, in embodiments, by means of dry etching processes, for example an oxygen plasma etching, or by selective oxidation, or by a UV-induced ozone process, or eventually by a suitable wet etching product. The radiation beam may be for example a beam of charged ions belonging to one of the following species: H; He; Li; Be; B; C; N; O, and whose energy is comprised between 1 keV and 10 MeV. The local energy deposition in the diamond may be obtained by collimating the radiation beam on the diamond, by varying the direction and the point of incidence of the radiation beam with respect to the diamond substrate and/or by varying the penetration depth of the radiation by altering the beam energy, and may be done according to a predefined three-dimensional pattern at various penetration depths in the diamond. According to the necessity, the pattern of the local energy deposition may be defined by a mask, interposed in the radiation beam before it impinges on the diamond substrate. In the latter case, the mask used for the definition of the pattern of local energy deposition may be a three-dimensional mask of varying thickness or variable energy loss, like mask 810, providing a variable energy loss, and defining a three-dimensional microstructure or nanostructure pattern within the diamond substrate.
050248022	summary	FIELD OF THE INVENTION This invention relates to a method for water level measurement in a steam generator such as used in pressurized water reactors and, more particularly, water level measurements using differential-type transmitters for sensing water level in a steam generator in a nuclear power plant. The current steam water level measurement methodology is built around the use of differential-type transmitters for comparing the steam generator water level with a reference leg pressure input. The transmitter responds to a differential of water pressures inputted to it, and provides an output representative of the difference between a reference leg pressure and the pressure to the height of the liquid in the steam generator. This differential is a good correlation to water level when the lower pressure tap, for measuring the water level in the steam generator, is located in a relative low velocity region of the steam generator. However, if the lower pressure tap is moved to a higher velocity region, an error is introduced due to the effective velocity head of the moving water. In such circumstances, a level measurement penalty must be taken, meaning that the steam generator operating level margin, i.e., a range of permissible water levels, needs to be reduced. Present steam generator design calls for the lower level tap to be relocated in the high velocity region so as to minimize well known shrink/swell phenomenon. Accordingly, there is a need for an improved methodology to account for the velocity head effects in the transmitter calibration, so as to maximize the steam generator level operating margin. SUMMARY OF THE INVENTION It is an object of this invention to provide, in a steam generator used in a pressurized water reactor nuclear power system, an improved method of measuring the water level in the steam generator and taking into account a velocity head effect for determining the operating margin, i.e., the range of water levels within which operation is controlled. In accordance with this object, calibration of the differential pressure transmitter includes subtracting a bias factor from the differential pressure at maximum water level, the bias factor being said equal to the velocity head at 100% power level, or another determined fraction of maximum velocity head, thereby to adjust the transmitter reading at maximum water level (and minimum meter reading) to account for a velocity head. The high level trip setpoint is calculated by determining the net water level, e.g., corresponding to the top of the riser minus a bias, or adjustment for velocity head due to the calibration at the riser, which is some percentage of the span between the lower and upper taps.
	abstract	A radiation condenser system for an X-ray microscope allows for the efficient collection and relay of radiation from a source to the sample. It generates a converging hollow cone of radiation that can be used in the imaging of a sample or target using a zone plate lens. This system comprises a capillary tube for receiving and focusing radiation onto a sample. A center stop is provided for blocking radiation being transmitted along an axis of the capillary tube.
	description	This application is a continuation of PCT Application PCT/US2009/035847, filed Mar. 3, 2009, and published under the PCT Articles in English as WO 2009/111454 A1 on Sept. 11, 2009. This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/033,899, filed Mar. 5, 2008, and of U.S. Provisional Patent Application Ser. No. 61/039,220, filed Mar. 25, 2008, and of U.S. Provisional Patent Application Ser. No. 61/042,974, filed Apr. 7, 2008, each of which is hereby incorporated herein by reference in its entirety. The present invention relates generally to x-ray analysis systems, and more particularly, to x-ray source assemblies providing multiple excitation energies to improve detection and analysis of multiple elements in homogeneous and heterogeneous sample structures. There is an emerging need to provide manufactured products of all types in which the levels of toxins is minimized or completely eliminated. This need has a clear underlying medical basis and is accelerated by fear and pending legislation—the results of many recent well-publicized cases of toxins in manufactured products (e.g., lead in toys). The costs of unsafe products go well beyond the health impact to include significant loss of business, permanent damage to brands and corporate image, and increased levels of corporate and personal liability. In response to these problems, there is a growing trend of increasingly strict environmental and health regulations of consumer products around the world. The list of products regulated is rapidly increasing and the types and permitted levels of toxins are becoming more restrictive. Some industry players are going beyond the regulations for the products they distribute, by mandating even cleaner products in their supply chain. Regulations are effectively aimed at decreasing direct human exposure to toxins by reducing toxins in our environment. Several stricter standards can be traced to European environmental directives that began in the early 1990s, starting with regulations in packaging materials and batteries. In subsequent years, reductions on hazardous substances were introduced by the EU for automobiles (ELV) and two directives related to electronics (Restriction of Hazardous Substances or RoHS and Waste Electrical and Electronic Equipment or WEEE). Pending U.S. Federal legislation lowers allowable lead levels in paint on toys by a factor of six and threatens criminal prosecution for companies that violate with penalties ranging from $10 million to $100 million for a single violation. In addition, nine other known toxins are targeted for restriction, including: mercury, arsenic, cadmium, barium, and chromium. The spread of such human health and environmental initiatives are having profound global implications on the way products are designed, manufactured, and ultimately discarded or recycled. Current measurement methods for toxins in manufactured products do not meet the needs of the supply chain, from the factories to the ultimate consumers. Identification and measurement of toxins are needed at each step of the chain, from raw materials, to components, to finished goods. While raw-material measurements are most efficient for factories, distribution channels typically require measurements on the final product. New techniques are urgently needed to accurately, quickly, consistently, and cost-effectively measure toxins at each stage, with minimal interruptions in the flow of manufacturing and distribution of the goods. Because toys and other manufactured products often have small painted features (pigments are often the source of the toxins), it is necessary to measure small areas while differentiating the paint from the base material. Existing low-cost methods of toxin detection are generally ineffective, e.g., swab tests. Higher-cost methods that provide the requisite accuracy are expensive and time consuming. These sometimes involve: manually scraping samples, digesting them in acids at elevated temperature and pressure, introducing them into a combustion chamber, and analyzing the combustion product. One widely used method today is inductively coupled plasma optical emission spectroscopy (ICP-OES)—a method which is expensive, destructive, and slow. Alternatively, handheld x-ray fluorescence (XRF) guns are rapid and nondestructive, but are only reliable for higher than regulated concentrations, and are averaged across large sample areas, and cannot separately evaluate paint layers. As discussed further below, the present invention provides a measurement solution having fast, accurate results for toxins in manufactured products, enabled by sophisticated proprietary x-ray optics. Such proprietary optics typically provide 10-1,000× improvements in the ability to focus x-rays; and optic-enabled analyzers are especially suited for these targeted markets—moving measurements from the lab into the factory, field, and clinic. In x-ray analysis systems, high x-ray beam intensity and small beam spot sizes are important to reduce sample exposure times, increase spatial resolution, and consequently, improve the signal-to-background ratio and overall quality of x-ray analysis measurements. In the past, expensive and powerful x-ray sources, such as rotating anode x-ray tubes or synchrotrons, were the only options available to produce high-intensity x-ray beams, in the laboratory. Recently, the development of x-ray optic devices has made it possible to collect the diverging radiation from an x-ray source by focusing the x-rays. A combination of x-ray focusing optics and small, low-power x-ray sources can produce x-ray beams with intensities comparable to those achieved with more expensive devices. As a result, systems based on a combination of small, inexpensive x-ray sources, excitation optics, and collection optics have greatly expanded the availability and capabilities of x-ray analysis equipment in, for example, small laboratories and in the field, factory, or clinic, etc. Monochromatization of x-ray beams in the excitation and/or detection paths is also useful to excite and/or detect very precise portions of the x-ray energy spectrum corresponding to various elements of interest (lead, etc.). X-ray monochromatization technology is based on diffraction of x-rays on optical crystals, for example, germanium (Ge) or silicon (Si) crystals. Curved crystals can provide deflection of diverging radiation from an x-ray source onto a target, as well as providing monochromatization of photons reaching the target. Two common types of curved crystals are known as singly-curved crystals and doubly-curved crystals (DCCs). Using what is known in the art as Rowland circle geometry, singly-curved crystals provide focusing in two dimensions, leaving x-ray radiation unfocused in the third or orthogonal plane. Doubly-curved crystals provide focusing of x-rays from the source to a point target in all three dimensions. This three-dimensional focusing is referred to in the art as “point-to-point” focusing. Commonly-assigned U.S. Pat. Nos. 6,285,506 and 7,035,374 disclose various configurations of curved x-ray optics for x-ray focusing and monochromatization. In general, these patents disclose a flexible layer of crystalline material (e.g., Si) formed into curved optic elements. The monochromating function, and the transmission efficiency of the optic are determined by the crystal structure of the optic. The ability to focus x-ray radiation to smaller spots with higher intensities, using focusing and monochromating x-ray optics, has enabled reductions in the size and cost of x-ray tubes, and x-ray systems have therefore been proliferating beyond the laboratory to in-situ, field uses. Commonly-assigned U.S. Pat. Nos. 6,934,359 and 7,072,439, incorporated by reference herein in their entirety, disclose monochromatic wavelength dispersive x-ray fluorescence (MWD XRF) techniques and systems, using doubly curved crystal optics in the excitation and/or detection paths. The x-ray optic-enabled systems described in these patents have enjoyed widespread success beyond the laboratory, for measuring sulfur in petroleum fuels in a variety of refinery, terminal, and pipeline environments. In such systems, precise optic alignment along an axis defined by a source and sample spot may be required, as illustrated in above-incorporated U.S. Pat. No. 7,035,374, which proposes an arrangement of curved, monochromating optics around a central axis operating according to Bragg diffraction conditions. FIG. 1a is a representative isometric view of this x-ray optic arrangement 150 having a curved optic 152, an x-ray source location 154, and an x-ray target location 156. X-ray source location 154 and x-ray target location 156 define a source-to-target transmission axis 162. Optic 152 may include a plurality of individual optic crystals 164, all of which may be arranged symmetrically about axis 162. FIG. 1b is a cross-sectional view taken along section lines 1b-1b of FIG. 1a, wherein the surface of optic 152, x-ray source location 154, and x-ray target location 156 define one or more Rowland (or focal) circles 160 and 161 of radius R for optic 152. Those skilled in the art will recognize that the number and orientation of the Rowland circles associated with crystal optic 152, or individual crystals 164, will vary with the position of the surface of optic crystal 152, for example, the variation of the toroidal position on optic crystal 152. The internal atomic diffraction planes of optic crystal 152 also may not be parallel to its surface. For example, as shown in FIG. 1b, the atomic diffraction planes of crystal 152 make an angle γ1 with the surface upon which x-rays are directed, at the point of tangency 158 of the surface and its corresponding optic circle 160 or 161. θB is the Bragg angle for crystal optic 152 which determines its diffractive effect. Each individual optic crystal can in one example be fabricated according to the method disclosed in above-incorporated U.S. Pat. No. 6,285,506, entitled “Curved Optical Device and Method of Fabrication.” All individual crystals 164 should be aligned to the source-to-target axis 162, for proper Bragg conditions. Improvement in optic alignment, especially for such multiple-crystal optics, therefore remains an important area of interest. Another issue, which particularly affects volume manufacturing, is the need to align disparate components which may be purchased from different vendors. For example, the x-ray tubes, when purchased in quantities from a vendor, may have source x-ray spots which are not consistently centered relative to their own housings. Re-centering these x-ray tube spots is necessary, as an initial step in the alignment process for an entire x-ray source assembly. Various optic/source combinations have already been proposed to handle thermal stability, beam stability, and alignment issues, such as those disclosed in commonly assigned U.S. Pat. Nos. 7,110,506; 7,209,545; and 7,257,193. Each of these patents is also incorporated herein by reference in its entirety. In particular, U.S. Pat. Nos. 7,209,545 (entitled “X-Ray Source Assembly Having Enhanced Output Stability, and Fluid Stream Analysis Applications Thereof”) and 7,257,193 (entitled “X-Ray Source Assembly Having Enhanced Output Stability Using Tube Power Adjustments and Remote Calibration”) address certain tube/optic alignment problems during source operation with real-time, corrective feedback approaches for alignment between the tube focal spot, optic, and output focal spot. Sensors are used to detect various operating conditions, and mechanical and/or thermal adjustments are made to correct for instabilities, including misalignments. These types of systems are necessary and valuable for certain applications, but can also increase the cost and complexity of fielded systems. The above-described XRF technology and systems have been useful in single element analyzers for measuring generally homogeneous sample structure (e.g., sulfur in petroleum products). However, the measurement of toxins in manufactured products presents an additional level of challenges. First, an instrument should have the capability to measure more than one element simultaneously or near-simultaneously, from a relatively confined list of about 10 toxic elements, discussed above. Moreover, manufactured products are likely to be heterogeneous in nature, requiring small spot resolution, as well as the ability to detect toxins in one of a number of heterogeneous layers (e.g., the level of lead in a paint layer and a substrate layer beneath the paint). Improved x-ray analysis method and systems are required, therefore, to address the problems associated with measuring multiple toxins in potentially heterogeneous samples, to enable in-the-factory and/or in-the-field measurement of toxins in manufactured products. The shortcomings of the prior art are overcome and additional advantages are provided by the present invention, which in one aspect is an x-ray analysis apparatus for illuminating a sample spot with an x-ray beam. An x-ray tube is provided having a source spot from which a diverging x-ray beam is produced having a characteristic first energy, and bremsstrahlung energy. A first x-ray optic receives the diverging x-ray beam and directs the beam toward the sample spot, while monochromating the beam; and a second x-ray optic receives the diverging x-ray beam and directs the beam toward the sample spot, while monochromating the beam to a second energy. The first x-ray optic may monochromate characteristic energy from the source spot, and the second x-ray optic may monochromate bremsstrahlung energy from the source spot. The x-ray optics may be curved diffracting optics, for receiving the diverging x-ray beam from the x-ray tube and focusing the beam at the sample spot. Detection is also provided to detect and measure various toxins in, e.g., manufactured products including toys and electronics. The present inventors have developed these novel and effective techniques to address the growing market need to scrutinize toxins in manufactured goods. Optic-enabled, monochromatic-excited, micro-focus energy-dispersive XRF utilizes the above-discussed advanced x-ray optics together with a low-wattage x-ray tube, commercially available sensors, and proprietary software algorithms in a compact touch-and-shoot design. The optics greatly improve the signal-to-noise and concentrate the intensity in a small spot. The optic-enabled analyzer can nondestructively detect and quantify multiple toxic elements simultaneously in the small features typically found in products such as toys and electronics, regardless of the product's shape, size, or homogeneity. Its simple-to-use design enables the quantifiable measurement of toxin concentrations as low as 1 ppm. The system maintains secure records including clear time-stamped photographic identification of the toy and feature measured, ensuring auditable compliance. Doubly Curved Crystal (DCC) monochromating optics can be used to enhance measurement intensities by capturing x-rays from a divergent source and redirecting them into an intense focused beam on the surface of the product. Their small spot size allows the analyzer to inspect small features down to 1.5 mm in diameter with no reduction in speed or data quality. This unique capability will distinguish very small features commonly seen in toys and electronics. Regulations require that each material be evaluated separately; the limits are per material and color, not averaging across multiple features. The favorable signal-to-noise ratio enabled by the optics provides the analyzer with extremely low limits of detection. This high-performance limit-of-detection increases the reliability of results, hence dramatically reducing the number of false positives or negatives. The analyzer will remain effective even at lowest proposed regulatory limits of 40 ppm for lead. Paint coatings are of particular interest in the toy market so the toy analyzer has incorporated a dedicated coating optic with optimum energy levels and angles to isolate paint layers. Conventional XRF technologies without optics take an average of the coating and substrate layers that can mask high toxin levels in the paint layer. The toy analyzer can distinguish the composition of the paint coating layer from the substrate. The multi-element capability can simultaneously provide results on the most requested toxins in toys and other consumer products. At least 26 different elements can be detected simultaneously using the system, with emphasis on the 10 toxins of greatest interest to manufacturers including Cr, As, Br, Cd, Sb, Ba, Se, Hg, Cl & Pb. Further, additional features and advantages are realized through the techniques of the present invention. Other embodiments and aspects of the invention are described in detail herein and are considered a part of the claimed invention. Highly-Aligned X-Ray Source Assembly: In accordance with the present invention, FIGS. 2-4 depict in various views (using like numerals to refer to like elements) a highly-aligned x-ray optic and source assembly 200 in accordance with the present invention. Various aspects of this package have been disclosed in the commonly assigned, previously-filed U.S. Provisional Applications entitled X-RAY OPTIC AND SOURCE ASSEMBLY FOR PRECISION X-RAY ANALYSIS APPLICATIONS, filed Mar. 5, 2008 as Ser. No. 61/033,899 and HIGHLY ALIGNED X-RAY OPTIC AND SOURCE ASSEMBLY FOR PRECISION X-RAY ANALYSIS APPLICATIONS, filed Mar. 25, 2008 as Ser. No. 61/039,220, each of which is incorporated by reference herein in its entirety. As discussed in those Applications, the assembly includes a first section 210, second section 220, and third section 230, which together align an x-ray tube 240 to a sample spot 250, along a central transmission axis Z. Also aligned along this axis are multiple optic carriage assemblies 222, 224, and 226 which hold exemplary monochromating optics also requiring alignment to transmission axis Z (as discussed above with respect to FIGS. 1a-b). First housing section 210 may include adjustable tube-mounting features 212, 214 about its perimeter for adjustably mounting tube 240 thereby ensuring centering of tube x-ray spot 242 centrally along a central axis of section 210 (not shown). As discussed below, further attachment of assembly sections 210, 220, and 230 will ensure that each respective section's axis (not shown) is ultimately aligned to the transmission axis Z. Therefore, the present invention allows for incremental alignment of potentially disparate components along the central transmission axis Z. For x-ray tube 240, they may be shipped with slightly off-center tube spots from the manufacturer, and therefore are required to be re-centered along section 210's axis using adjustable mounting features 212 and 214 (e.g., set screws). The ability to provide an efficient, economical, portable analysis capability depends to a large extent upon x-ray tube and optic technology. In that regard, certain tube and optic technology can be combined for smaller, portable systems, e.g., a compact, electron-bombardment x-ray tube. One example of this type of x-ray tube is available from Oxford Instruments—model # 5011, which operates at less than 100 watts (i.e., 75 watts) at a cost of less than $1500 per tube, in contrast to higher-power, laboratory sources which can cost many thousands, or hundreds of thousands of dollars—which is cost prohibitive for many applications. Another example is the Varian VF-50J (similar to that depicted here), tubular in shape, and which operates at 50 watts or less, at a cost of several thousand dollars each, with a molybdenum material, as discussed further below. Second housing section 220 includes additional alignment features. First, complimentary mating surfaces 216 and 228 (FIG. 4) are provided to align the axes of sections 210 and 220 upon assembly, i.e., upon insertion of tube section 210 into section 220. Sections 210 and 220 are separately fabricated to guarantee alignment along their axes, and therefore to the central axis Z, when the mating surfaces are in contact. Sections 210, 220, and 230 are shown in a form of tubular shape. Specifically, the sections are shown in the approximate form of a cylinder, with a circular cross-section, which is one type of tubular shape. The cross-section of tubular sections 210 and 220 could also be square, rectangular, etc. The tubular shapes shown, with circular cross-sections, provide a section-section alignment technique using outer perimeter mating surface 216 of section 210 and inner perimeter mating surface 218 of section 220. The fully enclosed tubular sections also provide required x-ray shielding. Second, section 220 also accommodates the attachment of optic carriages 222, 224, and 226, which are fabricated to adjustably mount and align x-ray optics 223, 225, and 227 (not shown but implied within carriage 226) respectively, to section 220 and, ultimately, to transmission axis Z. X-ray beam focusing and/or monochromating can be accomplished using certain focusing and/or collimating optics, for example, curved crystal monochromating optics such as those disclosed in commonly assigned U.S. Pat. Nos. 6,285,506; 6,317,483; and 7,035,374; and/or multilayer optics; and/or polycapillary optics such as those disclosed in commonly assigned U.S. Pat. Nos. 5,192,869; 5,175,755; 5,497,008; 5,745,547; 5,570,408; and 5,604,353. Each of the above-noted patents is incorporated herein by reference in its entirety. Of particular interest are curved monochromating optics (discussed above with reference to FIGS. 1a-b), which require precise alignment along, and a certain distance from, the transmission axis to meet the appropriate Bragg conditions of interest. Also of particular interest is the requirement to align multiple such optics (e.g., 223, 225, 227) along a single Z axis. The exemplary curved crystal optics 223, 225, and 227 within the second housing section receive the diverging x-ray beam from x-ray tube spot 242, and focus diffracted beam(s) to sample spot 250. The carriages 222, 224, and 226 are mountable either directly or indirectly to the second housing section, such that an active surface of the optic is aligned along, and positioned a desired distance from, the transmission axis Z. The outer surface area (e.g., outer diameter) of the second housing section to which the carriage is mounted can be appropriately sized (e.g., by outer radius) and fabricated such that the at least one x-ray optic is positioned the desired distance from the transmission axis. Moreover, a shim 229, and/or other spacing adjusters (set screws, etc) can be employed to ensure proper optic alignment (FIGS. 3-4). Notably, these types of optics, to maintain their Bragg condition conditions, may be mounted along a surface of the second housing section, while separated from the transmission axis Z. Third housing section 230 includes an aperture at its point, which requires alignment to transmission axis Z for proper illumination of sample spot 250 with the focused x-ray beam(s) from the optic(s). A cone 231 within this section may also be included for additional shielding, rigidly or adjustably mounted to section 230. Section 230 may also have rigidly mounted thereon an exemplary energy-dispersive detector 260 which itself requires close alignment to transmission axis Z. To effect alignment of section 230 with sections 220 and 210 (thereby completing alignment of the entire source assembly along transmission axis Z), complimentary mating surfaces and/or adjustable mounting means (e.g., set screws) can be employed to align housing section 230 to section 220 and therefore to section 210. Section 230 and/or cone 231 can also be adjusted in directions orthogonal to the transmission axis Z. Other types of detectors (e.g., wavelength dispersive) may also be used with or without similar optics in the detection path. Additional issues should be considered regarding detector alignment. Energy dispersive detector 260 may also have its own focal spot in space, which also requires alignment to beam/sample focal spot 250 (e.g., FIGS. 2-3). (Sample spot 250 may be at the surface, or below the surface, of the sample; depending on the focal point of the x-ray beam.) As shown, detector is mounted to cone 31, which may have adjustable mounting means (shims, set screws, etc.), as well as a predetermined mating surface, which ensure alignment of the detector. Using this approach, end-to-end alignment of the x-ray tube, optic(s), sample spot, and detector is provided. Additional shims can be placed between each section (210, 220, 230) to control their respective spacings and therefore their longitudinal placement along transmission axis Z. Also shown is an automated shutter system having its own carriage 272, motor 274 and shutter plates 276. This shutter can be used for x-ray safety purposes (i.e., full blocking shutter), and also for selecting which x-ray beams (from the optics) should be applied to the sample, in any mix ranging from individual non-simultaneous excitation, to full simultaneous excitation, or any mix thereof. This is especially important for the multiple-energy excitation techniques discussed below. Other blocking slits 282 and 284 can also be provided along the beam path to tailor the beam striking the optics, and reduce other noise and/or scatter. The above approach provides a highly aligned x-ray optic and source assembly using various techniques to ensure alignment of disparate components (optics, x-ray tubes, detectors, etc) in a small, rugged, portable, analyzer for in-situ, on-line, measurements in industrial process, clinical, and field settings. Volume manufacturing is enabled, even when components of varying dimensional tolerances are introduced into the production. Moreover, the highly aligned assembly provides the precision alignment required by focusing, diffractive optics according to Bragg conditions. Any mis-alignment of the optics will directly impact the precision of the device. Monochromating Optics at Different Energies: The benefit of using a monochromatic excitation beam for XRF in such a package can be better understood with reference to the output spectrum of a typical x-ray molybdenum target tube shown in FIG. 5a-showing characteristic lines from the tube's target material at about 17 keV, and a broader bremsstrahlung radiation spectrum. When this x-ray beam impinges on a sample, the secondary x-rays emitted from the sample have two components: the fluorescent characteristic lines of the elements in the sample and scattered x-rays from the source as shown in FIG. 5b. An energy dispersive (ED) detector measures the sum of the two. Therefore, the fluorescence signals of trace elements in the sample can be obscured by the background. Using a point-focusing, monochromatic optic between the source and the sample, the optic only diffracts the tube's characteristic line from the source. Therefore the spectrum of the beam that impinges on the sample is much simpler, as shown in FIG. 6a. The spectrum that emerges from the sample now has a much lower background at all energies except at the Compton scattering region. FIG. 6b illustrates the scattering spectrum with the fluorescence signal from a sample. The trace element signals undetected in FIG. 5b are now clearly detectable. In accordance with another aspect of the present invention, multiple optics 223 and 225 (and others) of apparatus 200 may be different, i.e., may be tuned to different parts of the x-ray energy spectrum, to optimize element detection and quantification in respective areas of the x-ray energy band. In general, for an element to fluoresce and therefore be subject to detection and measurement, the excitation energy must be at or above the element's x-ray absorption edge. Causing all of the elements of interest to fluoresce therefore requires an excitation energy above the absorption edges of all of the elements of interest. With reference to the comparative graph of FIG. 7a, this graph shows initially that an optic producing monochromatic excitation improves elemental detection by orders of magnitude (trace 710) versus the conventional polychromatic excitation (trace 720). As discussed above, and with further reference to FIG. 7b, a characteristic energy line E1 from, e.g., a molybdenum target x-ray tube at approximately 17 keV, is focused to the sample using a point-focusing, monochromating optic as discussed above, generally causing all elements having fluorescent lines of interest lower that 17 keV to fluoresce (e.g., trace 710). Its excitation effect gradually diminishes, however, for elements having fluorescence lines much lower (e.g., less than 10 keV in this example). In accordance with the present invention, additional optic(s) can be employed to simultaneously capture the non-characteristic, broad bremsstrallung energy transmitted from the same x-ray tube, and provide additional lines of excitation energy, at e.g., energies E2, E3, E4, E5 . . . each line from a respective point-focusing, monochromating optic. Energies higher than 17 keV (not shown) can also be used. This technique can be used for efficient, low-background excitation of various ranges of elements in the periodic table. In the particular system embodiment 200 shown herein and with further reference to the x-ray path diagram of FIG. 8, three optics 223, 225, and 227 provide the 31 keV (from bremsstrallung), the 17 keV characteristic molybdenum line, along with the 7 keV line (also from bremsstrahlung), respectively. These lines provide optimized excitation of the following approximate ranges of elements of interest from the periodic table (listed along with their atomic numbers): 31 keV: From about Zr (40) to Te (52) 17 keV: From about Cl (17) to Br (35); Rb(37) to Sr(38); Zr(40); Cs(55) to Bi(83); Th(90); U(92) 7 keV: From about Al (13) to Co (27) By using different optics, different excitation angles and/or energies can be simultaneously (or sequentially, or any mix thereof using a shutter system) applied to the sample. Because different energies cause different fluorescence effects, more information can be determined in the detection path. For example, higher energies penetrate deeper depths and can be used to detect substrate (rather than painted) layers in the material. Moreover, even though lower energies may penetrate the paint levels, the resultant fluorescence may not, giving more insight into material makeup. Certain elements exist in the energy band at spacings that generally exceed a detector's ability to resolve (e.g., Cd and Sn), and in fact have overlapping K/L lines and absorption energies. And tin (Sn), a commonly used lead substitute, may mask the cadmium in the detection path. Therefore, excitation just below the absorption of the higher element (Sn), thereby not exciting the tin but effectively exciting all the cadmium, can be used to isolate the lower element (Cd). Ratios of fluorescence spectra caused by two different excitation energies can also be exploited for additional information about the sample. FIG. 9 shows an exemplary excitation of a sample toy with the proposed apparatus in accordance with the present invention, for measuring 10 elements of interest. Multi-element optics (e.g., 223) can be used in accordance with the above-incorporated U.S. Pat. No. 7,035,374. Moreover, layered optics can be used, in accordance with multilayer techniques, and/or multi-crystal-layer techniques as disclosed in U.S. patent application Ser. No. 11/941,377 filed on Nov. 16, 2007 entitled X-RAY FOCUSING OPTIC HAVING MULTIPLE LAYERS WITH RESPECTIVE CRYSTAL ORIENTATIONS, the entirety of which is incorporated by reference. Such DCCs are referred to herein as LDCCs. There are several unique features of LDCC optics. The rocking curve width of the optic can be designed to be 2 to 5 times higher than single layer DCC optics. This will increase the bandwidth and provide flux increase for slicing the bremsstrahlung spectrum. For a single layer Si or Ge DCC, the rocking curve can be narrow such that its efficiency is reduced by the finite size of a typical x-ray point source. The LDCC can be designed to match the source size and improve the transmitted flux for focusing characteristic lines as well. The LDCC optics may also work better for higher energy photons. A more layered structure can be built for high energy x-rays due to reduced absorption. The useful energy range for the LDCC is expected to be 6-50 keV. In one particular example, three LDCC optics can be used to provide a tri-chromatic focused beam from a small spot Cu target source. The first LDCC focuses Cu Kαl 8.04 keV characteristic x-rays to the sample spot. The spot size is approximately 50 μm to 75 μm. The Cu LDCC covers the excitation for elements from Silicon (Si) to Manganese (Mn) including Cr. The second LDCC selects and focuses a band of bremsstrahlung centered at 16 keV for Hg, Pb and Br excitation. The third LDCC selects and focuses a band of bremsstrahlung centered at 28 keV for Cd excitation. The two bremsstrahlung optics have focused spots of 100 μm to 300 μm. The bandwidth of the bremsstrahlung optics are designed to be about 1-2% of the focusing energy. A PIN diode detector is used for EDXRF spectrometry. A shutter scheme can be constructed between the x-ray source and the optics, or between the optics and the sample (as discussed above) to have the option to turn the beam from each optic on and off, in any combination. A camera and/or laser spot can be placed in the center of the three optics in order to visually locate the measurement spot. The camera will also be used to store the image along with the spectral data. A small laser-height gauge is used to aid in the positioning of the sample at the focal point. The trend toward increasing global regulation of toxins presents an opportunity for such highly aligned systems as a platform technology to address a number of currently important applications. The disclosed system provides several advantages over previous toxin detection technologies with the combined ability to non-destructively detect very low levels, isolate small features, and give reliable results across a wide range of toxic elements. Conventional XRF analyzers and more standard analytical chemistry techniques do not possess the needed combination of reliable results, some level of portability, and low cost per test needed in today's tightening regulatory environment. Areas that are in need of these attributes include consumer products, electronics, air quality monitoring, body fluids, food products, and pharmaceuticals. Many of these applications can, in principle, share a common hardware and software platform, to hasten new product introductions, lower manufacturing costs, and provide higher quantities of precision instruments. Although preferred embodiments have been depicted and described in detail herein, it will be apparent to those skilled in the relevant art that various modifications, additions, substitutions and the like can be made without departing from the spirit of the invention and these are therefore considered to be within the scope of the invention as defined in the following claims.
	claims	1. A radiation image conversion panel having a radiation conversion layer, formed on a substrate, for converting an incident radiation into light;wherein the radiation conversion layer has a reflective layer, on a side opposite from a light exit surface for emitting the light, for reflecting the light to the exit surface side; andwherein the reflective layer has a helical structure comprising helically stacked phosphor crystals. 2. A radiation image conversion panel according to claim 1, wherein the radiation conversion layer is constituted by a plurality of columnar crystals in which the phosphor crystals are stacked like columns;wherein each of the columnar crystals has the helical structure formed on a root side secured to the substrate and a columnar structure extending from the helical structure to the light exit surface side along a direction intersecting the substrate; andwherein the helical structure and the columnar, structure are constructed by continuously stacking the phosphor crystals. 3. A radiation image conversion panel according to claim 1, wherein the radiation conversion layer is constituted by a plurality of columnar crystals in which the phosphor crystals are stacked like columns, the helical structure is formed on a root side of the plurality of columnar crystals secured to the substrate, and helical structure parts forming the helical structures of first and second columnar crystals adjacent to each other in the plurality of columnar crystals have a nested structure in which the second columnar crystal is nested in voids of the first columnar crystal vertically separated from each other. 4. A radiation image conversion panel according to claim 3, wherein a portion on the second columnar crystal side in the helical structure part of the first columnar crystal and a portion on the first columnar crystal side in the helical structure part of the second columnar crystal overlap each other as seen in a direction intersecting the substrate; andwherein a gap between the helical structure part of the first columnar crystal and the helical structure part of the second columnar crystal is wavy as seen in a direction orthogonal to the direction intersecting the substrate. 5. A radiation image conversion panel according to claim 1, wherein, in the radiation conversion layer, a plurality of helical loops forming the helical structure are stacked in a direction intersecting the substrate. 6. A radiation image conversion panel according to claim 5, wherein, in the reflective layer, the phosphor crystals are bent laterally in a cross section in a direction intersecting a surface of the substrate. 7. A radiation image conversion panel according to claim 5, wherein, in the radiation conversion layer, the helical loops have an interval on the order of about 0.67 μm to about 5 μm in a direction intersecting the substrate. 8. A radiation image conversion panel according to claim 1, wherein, in the radiation conversion layer, a plurality of flat spherical parts forming the helical structure are stacked obliquely with respect to a direction orthogonal to the substrate. 9. A radiation image conversion panel according to claim 8, wherein the flat spherical part connected to the columnar structure in the flat spherical parts is not greater than the column diameter of the columnar structure. 10. A radiation image conversion panel according to claim 1, wherein the radiation conversion layer is constituted by a scintillator containing CsI. 11. A radiation image conversion panel according to claim 1, wherein the radiation conversion layer is constituted by a photostimulable phosphor containing CsBr. 12. A radiation image conversion panel according to claim 1, wherein the substrate is made of a material containing a carbon fiber. 13. A method for producing a radiation image conversion panel having a radiation conversion layer, formed on a substrate, for converting an incident radiation into light;the method comprising vapor-depositing a vapor deposition source to become the radiation conversion layer onto the substrate while rotating a mount table mounting the substrate and an aperture for evaporating therethrough the vapor deposition source from a vapor deposition container accommodating the vapor deposition source about an axis of rotation extending in a direction intersecting the substrate with such a rotational speed difference that the aperture moves relatively slower than the substrate, so as to form, on a side opposite from a light exit surface for emitting the light in the radiation conversion layer, a reflective layer for reflecting the light to the exit surface side. 14. A method for producing a radiation image conversion panel according to claim 13, wherein, when constructing the radiation conversion layer by a plurality of columnar crystals in which the phosphor crystals are continuously stacked like columns, the method comprises the steps of:vapor-depositing the vapor deposition source onto the substrate while rotating the aperture at a first rotational speed, so as to form a helical structure comprising helically stacked phosphor crystals as the reflective layer, andvapor-depositing the vapor deposition source onto the substrate while rotating the aperture at a second rotational speed slower than the first rotational speed, so as to form a columnar structure extending from the helical structure to the light exit surface side along a direction intersecting the substrate integrally with the helical structure. 15. A method for producing a radiation image conversion panel according to claim 13, wherein, when constructing the radiation conversion layer by a plurality of columnar crystals in which the phosphor crystals are continuously stacked like columns, the method comprises the steps of:vapor-depositing the vapor deposition source onto the substrate while rotating the substrate at a first rotational speed, so as to form a helical structure comprising helically stacked phosphor crystals as the reflective layer; andvapor-depositing the vapor deposition source onto the substrate while rotating the substrate at a second rotational speed faster than the first rotational speed, so as to form a columnar structure extending from the helical structure to the light exit surface side along a direction intersecting the substrate integrally with the helical structure.
	summary
061343013	summary	FIELD OF THE INVENTION This invention relates generally to computed tomography (CT) imaging and more particularly, to collimators and detectors for use in such systems. BACKGROUND OF THE INVENTION In at least one known CT system configuration, an x-ray source projects a fan-shaped beam which is collimated to lie within an X-Y plane of a Cartesian coordinate system and generally referred to as the "imaging plane". The x-ray beam passes through the object being imaged, such as a patient. The beam, after being attenuated by the object, impinges upon an array of radiation detectors. The intensity of the attenuated beam radiation received at the detector array is dependent upon the attenuation of the x-ray beam by the object. Each detector element of the array produces a separate electrical signal that is a measurement of the beam attenuation at the detector location. The attenuation measurements from all the detectors are acquired separately to produce a transmission profile of the object. In known third generation CT systems, the x-ray source and the detector array are rotated with a gantry within the imaging plane and around the object to be imaged so that the angle at which the x-ray beam intersects the object constantly changes. A group of x-ray attenuation measurements, i.e., projection data, from the detector array at one gantry angle is referred to as a "view". A "scan" of the object comprises a set of views made at different gantry angles during one revolution of the x-ray source and detector. In an axial scan, the projection data is processed to construct an image that corresponds to a two dimensional slice taken through the object. One method for reconstructing an image from a set of projection data is referred to in the art as the filtered backprojection technique. This process converts the attenuation measurements from a scan into integers called "CT numbers" or "Hounsfield units", which are used to control the brightness of a corresponding pixel on a cathode ray tube display. Detector elements are configured to perform optimally when impinged by x-rays travelling a straight path from the x-ray source to the detector elements. Particularly, detector elements typically include scintillation crystals which generate light events when impinged by an x-ray beam. These light events are output from each detector element and directed to photoelectrically responsive materials in order to produce an electrical signal representative of the attenuated beam radiation received at the detector element. Typically, the light events are output to photomultipliers or photodiodes which produce individual analog outputs. Detector elements thus output a strong signal in response to impact by a straight path x-ray beam. X-rays often scatter when passing through the object being imaged. Particularly, the object often causes some, but not all, x-rays to deviate from the straight path between the x-ray source and the detector. Therefore, detector elements are often impinged by x-ray beams at varying angles. System performance is degraded when detector elements are impinged by these scattered x-rays. When a detector element is subjected to multiple x-rays at varying angles, the scintillation crystal generates multiple light events. The light events corresponding to the scattered x-rays generate noise in the scintillation crystal output, and thus cause artifacts in the resulting image of the object. To reduce the effects of scattered x-rays, scatter collimators are often disposed between the object of interest and the detector array. Such collimators are constructed of x-ray absorbent material and positioned so that scattered x-rays are substantially absorbed before impinging upon the detector array. One known scatter collimator is described, for example, in U.S. Pat. No. 5,293,417, assigned to the present assignee. It is important for a scatter collimator to be properly aligned with both the x-ray source and the detector elements so that substantially only straight path x-rays impinge on the detector elements. It is also important that a scatter collimator shield radiation damage sensitive detector elements from x-rays at certain locations, such as the detector element edges. Known collimators are complicated and cumbersome to construct. In addition, it is difficult to satisfactorily align known collimators with the x-ray source and the detector elements to both absorb scattered x-rays and shield sensitive portions of the detector elements. Even when a scatter collimator is sufficiently aligned and positioned, detector elements may still generate artifacts. Particularly, detector elements are known to exhibit output gain loss after being subjected to accumulated exposure to x-ray dosage. The extent of output gain loss is directly related to the accuracy and usefulness of the detector element. After exhibiting excessive output gain loss, the detector element must be replaced. Replacing individual detector elements, as well as entire detector arrays, is a time consuming and cumbersome process. To reduce output gain loss, and thus extend the operational life of detector elements, detector arrays typically include reflectors. Particularly, detectors typically include detector elements forming either one-dimensional or two-dimensional arrays of scintillation crystals having interstitial reflectors. As explained above, when impinged by an x-ray beam, the scintillation crystals produce light events. The reflectors are used to prevent the light within each crystal from escaping the crystal, i.e., to eliminate output gain loss. The interstitial reflectors typically are constructed of foils, coatings or other cast-in-place reflective materials. However, the reflective materials used for the reflectors typically include organic materials which exhibit radiation damage effects over time. Such radiation damage reduces reflector reflectivity, which results in output gain loss. Accordingly, it is desirable to shield the reflectors with the scatter collimator. It would be desirable to provide a scatter collimator that is not complicated and cumbersome to construct, and that effectively absorbs scattered x-rays and substantially prevents such x-rays from impinging the detector array. It also would be desirable to further reduce detector element output gain loss without significantly increasing the costs of detector elements and detector arrays. SUMMARY OF THE INVENTION These and other objects may be attained by a system which, in one embodiment, includes an x-ray source, a scatter collimator and a detector array having a plurality of reflective scintillators. Particularly, and in accordance with one embodiment of the present invention, the scatter collimator includes a housing, and a plurality of substantially parallel attenuating blades and a plurality of substantially parallel attenuating wires are located in the housing. The attenuating blades, and thus the openings between adjacent attenuating blades, are oriented substantially on a radial line emanating from the x-ray source, i.e., each blade and opening is focally aligned. The blades also are radially aligned with the x-ray source, i.e, each blade is equidistant from the x-ray source. Accordingly, scattered x-rays, i.e., x-rays diverted from radial lines, are attenuated by the blades. The attenuating wires, however, are oriented substantially perpendicular to the blades. The wires and blades thus form a two-dimensional shielding grid for attenuating scattered x-rays and shielding the detector array. The detector array includes a plurality of detector elements, and is configured to attach to the housing. The detector elements, in one embodiment, include scintillation elements, or scintillators, which are coated with a light-retaining material. Particularly, the scintillators are coated with a dielectric coating to contain light events generated in the scintillators within the scintillators. The above-described system provides an uncomplicated scatter collimator. In addition, the scatter collimator is believed to effectively absorb scattered x-rays. The coated scintillators are believed to reduce detector element output gain loss without significantly increasing the costs of detector elements and detector arrays.
047180765	summary	BACKGROUND OF THE INVENTION The present invention relates to an X-ray imaging apparatus suitable for use in medical diagnosis. When medical radiography is carried out using the conventional X-ray imaging apparatus, the resolution and contrast of the reproduced image are likely to be degraded because of scattered X-rays generated from the object to be imaged. A demand for a high-speed X-ray imaging apparatus which enables a short exposure time has arisen these days. The amount of irradiated X-rays must be increased to achieve a high speed operation. However, there is a limitation on increasing the amount of X-rays, because an X-ray generator has a limited load. Accordingly, Japanese Patent Disclosure (KOKAI) No. 53/7190, for example, discloses an X-ray imaging apparatus including an X-ray generator of the electronic beam scanning type which serves to move the X-ray irradiating position of an X-ray generating target, which has a slit plate positioned between the X-ray generator and the object to be imaged, which has substantially a single slit through which X-rays are allowed to pass, and which has an X-ray image detector positioned behind the slit plate to reproduce the X-ray image which is formed after X-rays pass through the slits and the object. In the case of this type of X-ray imaging apparatus, however, it is difficult to obtain a sufficient amount of X-rays and thus high S/N (signal to noise ratio) because the X-ray generator is of the stationary target type. It is also difficult to achieve high resolution because the X-ray detecting characteristic is discontinuous. U.S. Pat. No. 4,179,100 discloses an apparatus wherein an X-ray image is reproduced in such a way that an X-ray beam which has passed through a single slit of a slit plate is further passed through an object to be imaged, and then is introduced into an X-ray detector such as a fluorescent screen or an X-ray image intensifier to be converted to an optical image. However, the object, slit plate, X-ray generator and the like are mechanically moved. In this case, it is necessary to move them over a wide range of length in order to image the whole area of the object. Thus, it is difficult to achieve a high speed operation or a short exposure time. In addition, blur is still left in the reproduced X-ray image because of scattered X-rays generated in the object and because of veiling glares generated in the image intensifier by the scattered rays and the discharging of undesired floating electrons, thereby making it difficult to achieve a satisfactory resolution and contrast. SUMMARY OF THE INVENTION The present invention is therefore intended to eliminate the above-mentioned drawbacks. The object of the present invention is to provide an X-ray imaging apparatus wherein a high speed operation is made possible, wherein scattered X-rays in an object can be controlled and, whereby images having high resolution, high S/N and contrast can be produced. According to the invention, there is provided an X-ray imaging apparatus comprising: an X-ray generator including an electron gun for emitting an electron beam, a rotating cylindrical target for receiving an electron beam emitted from the electron gun and irradiating X-rays, and a deflection means for moving an electron beam of said electron gun on the target along the axis thereof; a slit plate separated by a certain distance from the X-ray generator and having an elongated slit extending in a direction perpendicular to the direction in which an X-ray focal point moves following the movement of said electron beam, to allow X-rays to pass therethrough; an X-ray image detector means arranged opposite to the slit plate with an object to be imaged interposed between them and serving to convert X-ray images created by the X-ray beams which have passed through the slit of said slit plate and the object, to electrical signal images; a signal processing means for picking up those signals from the electrical signal images obtained through the X-ray image detector means which correspond to X-ray images entering into areas on said X-ray image detector means when the slit is projected from positions of the X-ray focal point on said target; and an X-ray image reproducing means for displaying image signals processed by said signal processing means and obtained corresponding to the X-ray images. According to the invention, there is further provided an X-ray imaging apparatus comprising: an X-ray generator including an electron gun for emitting electron beam, an anode target for receiving the electron beam emitted from the electron gun to irradiate X-rays, and a deflection means for moving the electron beam of said electron gun on the target along the axis thereof; a slit plate separated by a certain distance from the X-ray generator and having a plurality of elongated slits each extending in a direction perpendicular to the direction in which an X-ray focal point moves following the movement of said electron beam, to allow X-rays to pass therethrough; an X-ray detector means arranged opposite to the slit plate with an object to be imaged interposed between them and serving to convert X-ray images created by the X-ray beams which have passed through the slits of said slit plate and the object, to electrical signal images; a signal processing means for picking up those signals from the electrical signal images obtained through the X-ray image detector means which correspond to X-ray images entering into areas on said X-ray image detector means when the slits are projected from positions of the X-ray focal point on said target; and an X-ray image reproducing means for displaying image signals processed by said signal processing means and obtained corresponding to the X-ray images. There is still further provided an X-ray imaging apparatus comprising: an X-ray generator including an electron gun for emitting an electron beam and a stationary anode target for receiving the electron beam emitted from the electron gun to irradiate X-rays; a slit plate separated by a certain distance from the X-ray generator and having a plurality of elongated slits, the slit plate being moved in a direction perpendicular to the direction in which the plurality of slits extend; a X-ray detector means arranged opposite to the slit plate with a subject to be imaged interposed between them and serving to convert X-ray images created by the X-ray beams which have passed through the slits of said slit plate and the subject, to electrical signal images; a signal processing means for picking up those signals from the electrical signal images obtained through the X-ray image detector means which correspond to X-ray images entering into areas on said X-ray image detector means when the slits are projected from the position of the X-ray focal point on said target; and an X-ray image reproducing means for displaying image signals processed by said signal process means and obtained corresponding to the X-ray images.
	summary
053944461	summary	FIELD OF THE INVENTION This invention relates generally to maintenance of a control rod drive of a boiling water reactor. Specifically, the invention relates to tools for dismantling or assembling a control rod drive during a maintenance operation. BACKGROUND OF THE INVENTION Control rod drives (CRDs) are used to position control rods in boiling water reactors (BWRs) to control the fission rate and fission density, and to provide adequate excess negative reactivity to shutdown the reactor from any normal operating or accident condition at the most reactive time in core life. Referring to FIG. 1, each CRD is mounted vertically in a CRD housing 10 which is welded to a stub tube 8, which in turn is welded to the bottom head of the reactor pressure vessel 4. The CRD flange 6 is bolted and sealed to the flange 10a of the CRD housing 10, which contains ports for attaching the CRD hydraulic system lines 80, 81. Demineralized water supplied by the CRD hydraulic system serves as the hydraulic fluid for CRD operation. As shown schematically in FIG. 1, the CRD is a double-acting, mechanically latched hydraulic cylinder. The CRD is capable of inserting or withdrawing a control rod (not shown) at a slow controlled rate for normal reactor operation and of providing rapid control rod insertion (scram) in the event of an emergency requiring rapid shutdown of the reactor. A locking mechanism in the CRD permits the control rod to be positioned at 6-inch (152.4-mm) increments of stroke and to be held in these latched positions until the CRD is actuated for movement to a new position. A spud 46 at the top of the index tube 26 (the moving element) engages and locks into a socket at the bottom of the control rod. Once coupled, the CRD and control rod form an integral unit which must be manually uncoupled by specific procedures before a CRD or control rod may be removed from the reactor. When installed in the reactor, the CRD is wholly contained in housing 10. The CRD flange 6 contains an insert port 66, a withdraw port 70 and an integral two-way check valve (with a ball 20). For normal drive operation, drive water is supplied via an associated hydraulic control unit (HCU) to the insert port 66 for drive insertion and/or to withdraw port 70 for drive withdrawal. For rapid shutdown, reactor pressure is admitted to the two-way check valve from the annular space between the CRD and a thermal sleeve (not shown) through passages in the CRD flange, called scram vessel ports. The check valve directs reactor pressure or external hydraulic pressure to the underside of drive piston 24. Referring to FIGS. 2A and 2B, the CRD further comprises an inner cylinder 57 and an outer tube 56, which form an annulus through which water is applied to a collet piston 29b to unlock index tube 26. The internal diameter of inner cylinder 57 is honed to provide the surface required for expanding seals 65 on the drive piston 24. A collet housing 51 (which is part of outer tube 56) is provided with ports 73 to permit free passage of water from the clearance space between the outer diameter of index tube 26 and the inner diameter of inner cylinder 57 and the inner diameter of collet housing 51. The bottom of collet piston 29b normally rests against a spacer 52 in the upper portion of the annular space. Grooves in the spacer permit the passage of water between the bottom of the collet piston 29b and the passage area within the cylinder, tube and flange. Welded pipes 80 and 81, installed in the CRD housing, port water to the insert port 66 and the withdraw port 70 respectively. A port 69 below outer tube 56 connects to withdraw port 70 in CRD flange 6 so that water is applied through the annulus to collet piston 29b when a withdraw signal is given. The CRD is secured to the CRD housing flange 10a by eight mounting bolts (not shown). A pressure-tight seal is effected between the mated flanges by O-ring gaskets (not shown) mounted in a spacer 7 secured to the CRD flange face. Insert port 66 contains a ball check valve which consists of check-valve ball 20, ball retainer 21, and retainer O-ring 22. This valve directs HCU accumulator pressure or reactor pressure to the underside of drive piston 24 during scram operation. Port 66 is connected internally to the annulus and the bottom of drive piston 24 and serves as the inlet for water during normal insertion or scram. Water enters this port for a brief period in response to a withdraw signal to move the index tube 26 upward so that collet fingers 29a are cammed out. Following this brief unlocking period, water from below drive piston 24 is discharged through port 66 and through the under-piston hydraulic line for the duration of the withdraw signal. During the time the CRD remains stationary, cooling water passes through an annulus internal to flange 6 to the area between outer tube 56 and the inside of the thermal sleeve to cool the CRD. The withdraw port 70 serves as the inlet port for water during control rod withdrawal and as the outlet port for water during normal or scram insertion. It connects with internal porting and annuli to the area above drive piston 24. During a withdraw operation, water is supplied from port 70 through a small connecting port in CRD flange 6 to the annular space between outer tube 56 and inner cylinder 57 for application to the bottom of collet piston 29b. The locking mechanism consists of collet fingers 29a, collet piston 29b, barrel 35, guide cap 39, and collet spring 31. The mechanism is contained in the collet housing 51 portion of outer tube 56 and is the means by which index tube 26 is locked to hold the control rod at a selected position. The collet assembly consists of a collet piston 29b fitted with four piston seal rings, two outer 28 and two inner 27, six fingers 29a and a retainer (not shown) and is set into a bore in the collet housing 51. In addition, a spring 31, barrel 35 and guide cap 39 complete the components installed in the collet housing 51. Guide cap 39 is held in place above the collet by three plugs 37 which penetrate the upper end of collet housing 51, and which are held in place by fillister-head screws. It provides a fixed camming surface to guide collet fingers 29a upward and away from index tube 26 when unlocking pressure is applied to collet piston 29b. Barrel 35 is installed below guide cap 39 and serves as fixed seat for collet spring 31. The collet mechanism requires a hydraulic pressure greater than reactor pressure to unlock for CRD-withdraw movement. A preload is placed on collet spring 31 at assembly and must be overcome before the collet can be moved toward the unlocked position. For control rod withdrawal, a brief insert signal is applied to move index tube 26 upward to relieve the axial load on collet fingers 29a, camming them outward against the sloping lower surface of index tube locking notch 55. Immediately thereafter, withdraw pressure is applied. In addition to moving index tube 26 downward, this pressure is at the same time applied to the bottom of collet piston 29b to overcome the spring pressure and cam the fingers 29a outward against guide cap 39. When the withdraw signal ceases, the spring pressure forces the collet downward so that fingers 29a slip off guide cap 39. As index tube 26 settles downward, collet fingers 29a snap into the next higher notch and lock. When collet fingers 29a engage a locking notch 55, collet piston 29b transfers the control rod weight from index tube 26 to the outer tube 56. Unlocking is not required for CRD insertion. The collet fingers are cammed out of the locking notch as index tube 26 moves upward. The fingers 29a grip the outside wall of index tube 26 and snap into the next lower locking notch for single-notch insertion to hold index tube 26 in position. For scram insertion, index tube 26 moves continuously to its limit of travel during which the fingers snap into and cam out of each locking notch as index tube 26 moves upward. When the insert, withdraw or scram pressures are removed, index tube 26 settles back, from the limit of travel, and locks to hold the control rod in the required position. The drive piston 24 and index tube 26 are the primary subassembly in the CRD, providing the driving link with the control rod as well as the notches for the locking mechanism collet fingers. Drive piston 24 operates between positive end stops, with a hydraulic cushion provided at the upper end only. Index tube 26 is a nitrided stainless-steel tube threaded internally at both ends. The spud 46 is threaded to its upper end, while the head of the drive piston 24 is threaded to its lower end. Both connections are secured in place by means of bands 25, 25' with tab locks. There are 25 notches machined into the wall of index tube 26, all but one of which are locking notches 55 spaced at 6-inch intervals. The uppermost surfaces of these notches engage collet fingers 29a, providing 24 increments at which a control rod may be positioned and preventing inadvertent withdrawal of the rod from the core. The lower surfaces of the locking notches slope gradually so that the collet fingers cam outward for control rod insertion. Drive piston 24 is provided with internal (62, 71, 72) and external seal rings (65), and is operated in the annular space between piston tube 15 and inner cylinder 57. Internal (63) and external (64) bushings prevent metal-to-metal contact between drive piston 24 and the surface of piston tube 15 and the wall of inner cylinder 57 respectively. When a control rod is driven upward to its fully inserted position during normal operation or scram, the upper end of the piston head contacts the spring washers 30 which are installed below the stop piston 33. Washers 30 and stop piston 33 provide the upper limit of travel for drive piston 24. The spring washers, together with the series of buffer orifices 53 in the upper portion of piston tube 15, effectively cushion the moving drive piston 24 and reduce the shock of impact when the piston head contacts the stop piston. The magnet housing, which comprises the lower end of drive piston 24, contains a ring magnet 67 which actuates the switches of the position indicator probe (not shown) to provide remote electrical signals indicating control rod position. The piston tube assembly forms the innermost cylindrical wall of the CRD. It is a welded unit consisting of piston tube 15 and a position indicator tube 61. The piston tube assembly provides three basic functions for CRD operation: (a) position indicator tube 61 is a pressure-containing part which forms a drywell housing for a position indicator probe 12a (see FIG. 2A); (b) piston tube 15 provides for the porting of water to or from the upper end of the piston head portion of drive piston 24 during rod movement; and (c) during control rod scram insertion, buffer orifices 53 in piston tube 15 progressively shut off water flow to provide gradual deceleration of drive piston 24 and index tube 26. A stud 59 is welded to the upper end of tube piston 15. Stud 59 is threaded for mounting the stop piston 33. A shoulder on the stud, just below the threaded section, is machined to provide a recess for the spring washers 30 that cushion the upward movement of drive piston 24. The tube section 15a and head section 15b of piston tube 15 provide space for position indicator tube 61, which is welded to the inner diameter of the threaded end of head section 15b and extends upward through the length of tube section 15a, terminating in a watertight cap near the upper end of the tube section. Piston tube 15 is secured by a nut 16 at the lower end of the CRD. Two horizontal ports are provided in the head section 15b, 180.degree. apart, to transmit water between the withdraw porting in the CRD flange and the annulus between indicator tube 61 and tube section 15a of piston tube 15 for application to the top of drive piston 24. Three O-ring seals 18 are installed around head section 15b. Two seal the bottom of the CRD against water leakage and one seals the drive piston 24 under-piston pressure from the drive piston over-piston pressure. The position indicator probe 12a, which is slidably inserted into indicator tube 61, transmits electrical signals to provide remote indications of control rod position and CRD operating temperature. Probe 12a is welded to a plate 12b, which plate is in turn bolted to housing 12. Housing 12 is secured to the CRD ring flange 17 by screws 13. A cable clamp 11, located at the bottom of a plug 14, secures a connecting electrical cable (not shown) to plug 14. Ring flange 17 is in turn secured to the CRD housing by screws 9. Thus, probe 12a, housing 12 and cable clamp 11 (with the cables passing therethrough) can be removed as a unit. The stop piston 33 threads onto the stud 59 at the upper end of piston tube 15. This piston provides the seal between reactor pressure and the area above the drive piston. It also functions as a positive-end stop at the upper limit of drive piston travel. Six spring washers 30 below the stop piston help absorb the final mechanical shock at the end of travel. Seals 34 include an upper pair used to maintain pressure above the drive piston during CRD withdrawal and a lower pair used only during the cushioning of the drive piston at the upper end of the stroke. Two external bushings 32 prevent metal-to-metal contact between stop piston 33 and index tube 26. As seen in FIG. 3, spud 46, which connects the control rod 90 and the CRD, is threaded onto the upper end of index tube 26 and held in place by locking band 44. The coupling arrangement will accommodate a small amount of angular misalignment between the CRD and the control rod. Six spring fingers permit the spud to enter the mating socket 92 on the control rod. A lock plug 94 then enters spud 46 from socket 92 and prevents uncoupling. Two uncoupling means are provided. The lock plug 94 may be raised against the return force of a spring 95 by an actuating shaft 96 which extends through the center of the control rod velocity limiter to an unlocking handle 98. The control rod, with lock plug 94 raised, may then be lifted from the CRD. The lock plug may also be raised from below to uncouple the CRD from below the reactor vessel. To accomplish this, a special tool is attached to the bottom of the CRD and used to raise the piston tube 15 (see FIG. 2B). This raises the uncoupling rod 48, lifting lock plug 94 so that spud 46 disengages from the control rod coupling socket 92. The uncoupling rod consists of a rod 48 and a tube 43, supported in the base of the spud at the upper end of the CRD. The rod 48 is welded to the flared end of tube 43 such that a dimension of 1.125 inch exists between the top of rod 48 and the top end of spud 46. This is a critical dimension and must be maintained to ensure proper CRD and control-rod coupling. For this reason, uncoupling rods cannot be interchanged unless the critical dimension is verified. In addition to its function in uncoupling, rod 48 positions the control rod lock plug 92 such that it supports (i.e., opposes radially inward deflection of) the spud fingers when the control rod and CRD are coupled. An outer filter 45 and the inner filter 41 are installed near the upper end of the CRD. The outer filter is mounted on guide cap 39 using screws 40. A center lug 44 at the top of stop piston 33 is provided for mounting inner filter 41. The inner filter is held in place by a spring clip 42 which grips lug 44. Both filters are provided to filter reactor water flowing into the CRD, removing foreign particles or abrasive matter that could result in internal damage and excessive wear. Strainer 36, which is secured by screws 5, reduces the entry of coarse foreign particles from reactor water into the scram ports and ball-check valve in the CRD flange in the event such particles penetrate or bypass the outer filter 45. The inner filter is sealed by means of a seal ring 50 installed in a groove in the outer circumferential surface of the inner filter ring. During maintenance of a CRD, the uncoupling rod and spud are removed. During re-assembly of the control rod drive, the spud and uncoupling rod are re-installed. Incorrect installation of the uncoupling rod is a major cause of inadvertent control rod coupling/uncoupling problems. SUMMARY OF THE INVENTION The present invention is a gauge for ensuring that the uncoupling rod of the control rod drive of a nuclear reactor is properly inserted in the center hole of the spud and not in any of the outer lobes, i.e., spud flow holes, which communicate with the center hole. The uncoupling rod is inserted in the center hole of the spud. Then the gauge is placed on top of the spud with a centering ring protruding into the spud. The uncoupling rod is correctly installed if it is free to slide inside the gauge and the spud. The gauge is also provided with a ring to protect the spud during transfer, and to check the diameter of the spud fingers and their concentricity to assure the spud fingers have not been damaged.
	claims	1. A nuclear reactor comprising:a pressure vessel having an interior sidewall:a core barrel disposed within the pressure vessel for circumferentially surrounding a nuclear core, the core barrel and the pressure vessel sidewall defining a downcomer region; anda plurality of circumferentially spaced apart neutron panels disposed in the downcomer region, each panel having a concave surface facing the core barrel and a convex surface facing the pressure vessel sidewall, with each panel having a variable thickness from a center to a side between the concave surface and the convex surface, wherein the thickness of the neutron panels varies in the circumferential direction and is greatest at the center and tapers to the sides. 2. The nuclear reactor of claim 1 wherein the thickness is approximately 3 inch, or 7.62 cm, in the center and tapers to approximately 1 inch, or 2.54 cm, on the side. 3. The nuclear reactor of claim 1 wherein the neutron panels are constructed of stainless steel. 4. The nuclear reactor of claim 1 wherein a top of the neutron panels is chamfered. 5. The nuclear reactor of claim 1 wherein the core barrel has a central axis that extends in a vertical direction and the neutron panels are constructed from a plurality of separate segments that are stacked vertically. 6. The nuclear reactor of claim 5 wherein each of the segments are rectangular having two longer sides with the longer sides extending in the vertical direction. 7. The nuclear reactor of claim 5 wherein each of the segments are approximately the same size. 8. The nuclear reactor of claim 5 wherein the number of segments is three. 9. The nuclear reactor of claim 5 wherein each of the segments is bolted to the core barrel. 10. The nuclear reactor of claim 5 wherein at least a portion of the concave surface of the neutron panel is spaced from an outside diameter of the core barrel by a standoff. 11. The nuclear reactor of claim 10 wherein the standoff is a washer. 12. The nuclear reactor of claim 5 wherein each neutron panel segment has a sloped opposing edge that inversely matches the slope on the opposing edge of the adjacent segment wherein the opposing adjacent edges are spaced from each other to permit reactor coolant to pass there between to cool the neutron panel segments. 13. The nuclear reactor of claim 1 wherein the neutron panels have grooves in the concave surface facing the core barrel that promotes cooling.
048448613	summary	BACKGROUND OF THE INVENTION 1. FIELD OF THE INVENTION The invention relates to fuel assemblies for nuclear reactors of the type comprising a skeleton having two end pieces connected together by elongate elements such as guide tubes and grids spaced apart along the guide tubes and forming cells for holding a bundle of fuel elements in position at the nodes of a regular lattice. It is particularly suitable for use in spectral shift light water reactors in which the initial reactivity excess is compensated by undermoderating the reactor and hardening the neutron energy spectrum. An increase fraction of the neutrons is then absorbed by fertile material. In such a reactor, it is possible to increase the moderation rate for a predetermined fuel burn-up by removing rods which contain neutron transparent or fertile material (depleted uranium, for example) from guide tubes which are then invaded by water. 2. PRIOR ART In fuel assemblies of the above-defined type, the grids fulfill a number of separate functions. They guide and support the fuel elements containing fissile material. They provide resistance to transverse shocks which the assemblies may undergo during handling, accidents and, possibly, seisms. In most cases, the grids cause turbulence in the coolant flow and deflect coolant streams within the assembly to homogenize the temperature and avoid the formation of hot spots which could lead to local boiling and to sheath failure. A description of such fuel assemblies may be found in numerous reference, for instance European No. 54,236 (Westinghouse) and U.S. Pat. No. 4,059,483 (Anthony). The grids required for fulfilling all these functions impress on the flow of the coolant in the assembly a pressure drop which should be reduced as much as possible. But, concurrently, research work carried out for further increasing the thermal performances of nuclear reactors have led to increasing the coolant flow rate and, therefore, the forces exerted by the coolant on the components of the assemblies. The problem becomes more acute in spectral shift reactors since part of the cross-section should be reserved for guide tubes associated with water displacer rods and the lattice pitch should be decreased for locating the same amount of fissile material in the fuel assembly. As a result, the cross-sectional area available for coolant flow is reduced, which causes an increased pressure drop and a reduction of the protection margin before nucleated boiling in the top part (i.e., the downstream part) of the assemblies. SUMMARY OF THE INVENTION It is an object of the invention to provide a fuel assembly of the above-defined type having, compared with a conventional assembly, a reduced pressure drop while having a comparable mechanical strength. To this end, there is provided a fuel assembly in which the grids are of several different types and may be considered as comprising median grids, designed for withstanding the lateral shocks, and having fins for creating turbulences in the coolant flow along the assembly, bottom grids without fins and providing cross bracing of the elements, and top grids with fins and ensuring cross bracing of the elements, the top and bottom grids imposing on the coolant a lower pressure drop than the median grids. This arrangement considerably reduces the total pressure drop for a given flow rate since the median grids alone, which must have a high rigidity, impose a pressure drop comparable to that of the grids conventionally used in prior fuel assemblies (slightly smaller, however, if the usual fuel element supporting springs are omitted), while the top and bottom grids may impress a pressure loss much smaller than the median grids. In practice, the median grids will generally have a height greater than that of the top and bottom grids, and each will of a median grid cell will have two bosses for bearing on the corresponding fuel element, said bosses being offset in the flow direction. The top and bottom grids may have a single boss per wall. For increasing the rigidity of the median grids, they may be extended upstream (i.e., towards the bottom) by tongues having a bend in the longitudinal direction and playing the role of stiffener. Fuel assemblies have already been proposed in which the fuel elements are supported axially by the two end grids only, situated close to top and bottom end pieces (French No. 2,496,316). The two end grids may be made from a material different from the others, having a higher neutron absorption (for example, the "INCONEL" nickel-chrome base alloy) instead of a zirconium based alloy, because they are in end zones of the core. The purpose, however, is then only to improve the neutron balance by removing as much as possible materials having a considerable neutron absorption cross-section from the core. A comparable result may be attained, in a fuel assembly according to the invention, by providing an additional grid for supporting the elements above the top holding grids mentioned above and made from low neutron absorption material. Due to the reduction in the pressure drop imposed to the flow across each grid, the total number of grids may be increased in the fuel assembly; in addition, it will often be of advantage to space these grids not at equal intervals, but at progressively decreasing intervals in the direction of flow, so as to increase the turbulences in the downstream part and consequently to counter nucleate boiling.
041727614	summary	BACKGROUND OF THE INVENTION This invention relates to cellular grids for positioning nuclear fuel rods, or the like in close proximity to one another. As will be known a nuclear fuel element comprises an assembly of nuclear fuel rods held together in a cluster so that it may be handled as a unit and, in order to ensure correct spacing between adjacent rods over their length, cellular grids are employed. Generally these grids are usually one of two kinds. Those of one kind are constructed from metal strips which run parallel to one another in two directions at right angles so as to form cells between intersecting strips of adjacent rows. Those of a second kind are constituted by a group of co-joined cylindrical or tubular ferrules each ferrule being adapted to receive a nuclear fuel rod and having received it, to hold it in its correct position. The present invention is concerned with grids of the second kind and aims to provide an improved construction of the ferrule type grid. SUMMARY OF THE INVENTION According to the invention a cellular grid structure of the kind employing ferrules to define respective openings for nuclear fuel rods comprises a plurality of tubular ferrules grouped within an encircling band, with at least some of the adjacent openings framed by twin ferrules formed from one piece of metal strip and a bridge piece dividing means dividing the interior of the twin ferrule into two similar openings. The twin ferrules are preferably brazed together at their points of contact and also to the encircling band. Any suitable means may be provided for positively locating fuel rods in the grid openings but it is preferred to use a modification of a method proven in conventional ferrule type grids and to this end a bowspring or leaf spring would be associated with the bridge piece for urging a fuel rod in contact with a pair of co-planar dimples formed in an opposite face of the ferrule. As will be known ferrule type grids for locating nuclear fuel are especially suitable for fuel assemblies in which it is desired to incorporate auxiliary coolant tubes or sparge pipes which, when connected to a source of auxiliary coolant, can play a part in supplementing the flow of main coolant which passes through the fuel element cluster in a direction parallel to the axis of the tubular ferrules. The auxiliary coolant may also replace the main coolant on occasion. The grid according to the present invention is especially adaptable to receive and locate sparge pipes of substantially the same outer diameter as the fuel rods. It is preferred to fit the part of the ferrule wall which is to locate a sparge pipe with an inner lining.
052346099	claims	1. An X-ray permeable membrane for an X-ray lithographic mask which is a membrane consisting of the elements of silicon, carbon and nitrogen and which has a chemical composition expressed by the formula SiC.sub.x N.sub.y, in which the subscript x is a number in the range from 0.25 to 0.86 and the subscript y is a number in the range from 0.18 to 1.0; and hydrogen in an amount not to exceed 1.0 atomic % of the membrane. 2. The membrane of claim 1 having a thickness of from 0.3 to 3.0 .mu.m. 3. The X-ray permeable membrane for X-ray lithographic mask as claimed in claim 1 in which the molar ratio of silicon to the total of carbon and nitrogen is in the range from 0.05 to 2.0 and the molar ratio of carbon to nitrogen is in the range from 0.2 to 5.0. 4. The X-ray permeable membrane for X-ray lithographic mask as claimed in claim 1 which is formed by the thermal chemical vapor-phase deposition method from a gaseous compound comprising the elements of silicon, carbon and nitrogen or a combination of gaseous compounds comprising, as a group, the elements of silicon, carbon and nitrogen.
056663960	description	DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows diagrammatically an X-ray examination apparatus 1 in accordance with the invention. The X-ray source 2 emits an X-ray beam 15 for irradiating an object 16. Due to differences in X-ray absorption within the object 16, for example a patient to be radiologically examined, an X-ray image is formed on an X-ray sensitive surface 17 of the X-ray detector 3, which is arranged opposite the X-ray source. The X-ray detector 3 of the present embodiment is formed by an image intensifier pick-up chain which includes an X-ray image intensifier 18 for converting the X-ray image into an optical image on an exit window 19 and a video camera 23 for picking up the optical image. The entrance screen 20 acts as the X-ray sensitive surface of the X-ray image intensifier which converts X-rays into an electron beam which is imaged on the exit window by means of an electron optical system 21. The incident electrons generate the optical image on a phosphor layer 22 of the exit window 19. The video camera 23 is coupled to the X-ray image intensifier 18 by way of an optical coupling 24, for example a lens system or a fiber-optical coupling. The video camera 23 extracts an electronic image signal from the optical image, which signal is applied to a monitor 25 for the display of the image information in the X-ray image. The electronic image signal may also be applied to an image processing unit 26 for further processing. Between the X-ray source 2 and the object 16 there is arranged the X-ray filter 4 for local attenuation of the X-ray beam. The X-ray filter 4 comprises a large number of filter elements 5 in the form of capillary tubes whose X-ray absorptivity can be adjusted by application of an electric voltage, referred to hereinafter as adjusting voltage, to the inner side of the capillary tubes by means of the adjusting unit 7. The adhesion of the X-ray absorbing liquid to the inner side of the capillary tubes can be adjusted by means of an electric voltage to be applied to an electrically conductive layer (36) on the inner side of the capillary tubes (5). One end of the capillary tubes communicates with a reservoir 30 for an X-ray absorbing liquid. The capillary tubes are fried with a given quantity of X-ray absorbing liquid as a function of the electric voltage applied to the individual tubes. Because the capillary tubes extend approximately parallel to the X-ray beam, the X-ray absorptivity of the individual capillary tubes is dependent on the relative quantity of X-ray absorbing liquid in such a capillary tube. The electric adjusting voltage applied to the individual filter elements is adjusted by means of the adjusting unit 7, for example on the basis of brightness values in the X-ray image and/or the setting of the X-ray source 2; to this end, the adjusting unit is coupled to the output terminal 10 of the video camera and to the power supply 11 of the X-ray source 2. The construction of an X-ray filter 4 of this kind and the composition of the X-ray absorbing liquid are described in detail in the International Patent Application No. 1B95/00874). FIG. 2 is a side elevation of an X-ray filter 4 of the X-ray examination apparatus of FIG. 1. The Figure shows seven capillary tubes by way of example, but a practical embodiment of an X-ray filter 4 of an X-ray examination apparatus in accordance with the invention may comprise a large number of capillary tubes, for example 40,000 tubes in a 200.times.200 matrix arrangement. Each of the capillary tubes 5 communicates with the X-ray absorbing liquid 6 via an end 31. The inner side of the capillary tubes is covered by an electrically conductive layer 37, for example of gold or platinum which layer 37 is coupled to a voltage line 34 via a switching element 33. For application of the electric adjusting voltage to an electrically conductive layer 37 of a capillary tube, the relevant switching element 33 is closed while the voltage line 34 which thus electrically contacts the capillary tube has been adjusted to the desired electric adjusting voltage. The switching elements are driven by a control line 35. When brief voltage pulses having a length of a few tens of microseconds are used, adjusting voltages in a range of from 0 V to 400 V can be used. In this voltage range switches in the form of .alpha.-Si thin-film transistors can be used. Preferably, an adjusting voltage in the range of from 30 V to 100 V is used. Because the voltage pulses are so brief, the application of the adjusting voltage does not cause any, or hardly any, electrolysis of the lead salt solution used as the X-ray absorbing liquid. The X-ray absorptivity of the individual capillary tubes can be controlled on the basis of the period of time during which the electric adjusting voltage is applied to the capillary tubes. Each of the capillary tubes, notably the conductive layer 37 and the X-ray absorbing liquid in the capillary tube, constitutes a capacitor. During the filling of such a capillary tube with the X-ray absorbing liquid, the capacitance of said capacitor varies as a function of the level of the liquid in the capillary tube or, in other words, as a function of the relative filling of said capillary tube. The charging of the capacitor produces electric energy for filling the capillary tube with the X-ray absorbing liquid. The longer the electric adjusting voltage remains applied, the further the capacitor is charged and the more the tube is filled with the X-ray absorbing liquid. On the electrically conductive layer there is preferably provided a dielectric layer of a thickness which suffices to ensure that the electric capacitance of the capillary tubes remains low enough to enable fast response to the application of the electric voltage. In order to ensure that the contact angle between the X-ray absorbing liquid and the inner side of the capillary tubes varies, as a function of the applied electric voltage, in a range of values which includes the contact angle value 90.degree., for example a coating layer having suitable hydrophilic/hydrophobic properties is provided on the dielectric layer. Use is preferably made of metal capillary tubes whose inner side is covered by successively the dielectric layer and the coating layer. The electric voltage can then be applied to the metal of the tubes. The manufacture of an embodiment of this kind is easier than providing glass capillary tubes with a metal coating. When a teflon layer is used as the dielectric layer covering the inner side of a metal tube, a separate coating layer can be dispensed with. FIG. 3 is a plan view of an X-ray filter 4 of the X-ray examination apparatus shown in FIG. 1. An X-ray filter 4 comprising 16 capillary tubes in a 4.times.4 matrix arrangement is shown by way of example; however, in practice the X-ray filter 4 may comprise a much larger number of capillary tubes, for example 200.times.200 tubes. Each of the capillary tubes is coupled, by way of the electrically conductive layer 37, to the drain contact 40 of a field effect transistor 33 which acts as a switching element and whose source contact 41 is coupled to a voltage line. For each row of capillary tubes there is provided a control line 35 which is coupled to the gate contacts of the field effect transistors in the relevant row in order to control the field effect transistors in this row. The control line 35 of the relevant row is energized by an electric control voltage pulse in order to apply an adjusting voltage to the electrically conductive inner side of the capillary tubes in the row, so that the field effect transistors in the relevant row are electrically turned on during the control voltage pulse. The adjusting unit 7 comprises a voltage generator 27 for applying an electric voltage to the timer unit 8 which applies the control voltage pulses having the desired duration to the individual control lines of the rows of capillary tubes. While the relevant field effect transistors are turned on, i.e. the switching elements are closed, the electric adjusting voltage of the relevant control lines 34 is applied to the capillary tubes. The periods of time during which the electric adjusting voltage is applied to individual capillary tubes in a row can be differentiated by application of the electric adjusting voltage to the respective voltage lines 34 of individual columns for different periods of time. To this end, the adjusting unit 7 comprises a column driver 36 which controls a period during which the electric adjusting voltage generated by the voltage generator 27 is applied to the individual voltage lines. The electric adjusting voltage is applied to a contact 43 via a switch 42. Each of the voltage lines 34 is coupled to a respective switching element, for example a transistor 44, by way of the contact 43. When the transistor 44 of the voltage line 34 is turned on by energizing the gate contact of the relevant transistor by means of a gate voltage, the adjusting voltage is applied to the voltage line. The gate contacts of the transistors 44 are coupled, via a bus 45, to the voltage generator 27 which supplies the gate voltage. The period of time during which the individual voltage lines are energized by the adjusting voltage is controlled by way of the period during which the gate voltages are applied to the gate contacts of the individual transistors 44. A large effective surface area with adhesion to the X-ray absorbing liquid is realized by providing filter elements with a plurality of capillary tubes. The quantities of X-ray absorbing liquid in capillary tubes of one and the same filter element, which may be coupled to one and the same transistor in their control line, of course, cannot be separately controlled. FIGS. 4 and 5 show diagrammatically, for two different ways of adjusting the X-ray Filter 4, the variation of control voltage pulses applied to the X-ray filter 4. As is shown in FIG. 4, first a control voltage pulse V.sub.1 of duration .tau..sub.1 is applied to the control line of the first row of capillary tubes; subsequently, control voltage pulses V.sub.2,V.sub.3 and V.sub.4 of a duration .tau..sub.2, .tau..sub.3 and .tau..sub.4, respectively, are applied to control lines of the second, the third and the fourth row of capillary tubes, respectively. The capillary tubes in the respective rows are thus successively filled with the X-ray absorbing liquid to a level which is dependent on the period of time during which the relevant voltage line is excited in the period in which a control voltage is supplied. The periods .tau..sub.i (i=1, 2, 3 . . . ) amount to approximately one millisecond, so that a few tenths of a second are required to adjust an X-ray filter 4 comprising a few hundred rows of capillary tubes; the adjusting time t.sub.f of the X-ray filter 4 thus mounts to a few tenths of a second. FIG. 4 also shows the X-ray absorptivity of capillary tubes in the respective rows .alpha..sub.x as a function of time. The X-ray absorptivity is related directly to the relative quantity of liquid in the capillary tubes. When the control voltage pulse V.sub.1 is applied to the first row, the capillary tubes become filled with the X-ray absorbing liquid and the X-ray absorptivity increases because the capillary tube is electrically charged. Filling takes place with some delay relative to the control voltage pulse, because some time is required for application of the electric charge (to charge the capacitance) and for the subsequent inflow of the X-ray absorbing liquid. Ultimately, the X-ray absorptivity in the first row reaches the value .alpha..sub.1, being the maximum value of the X-ray absorptivity that can be reached in the first row; lower values can be adjusted by applying the adjusting voltage to relevant columns for a period of time which is shorter than the duration of the control voltage pulse. After the voltage pulse V.sub.1, the second and subsequent rows receive successive control voltage pulses V.sub.2, V.sub.3, V.sub.4, having durations .tau..sub.2, .tau..sub.3, .tau..sub.4, respectively, so that in the second and subsequent rows maximum X-ray absorptivities .alpha..sub.2, .alpha..sub.3, .alpha..sub.4 can be reached. The X-ray absorptivities of filter elements in the rows are adjusted to different values by way of the period of time during which the voltage lines of the individual columns are energized. Because of the inertia of the inflow of the liquid, the durations of the control voltage pulses in this embodiment cannot be substantially shorter than a few milliseconds; however, the major advantage of this method of adjustment resides in the simplicity of the switching procedure which can be carried out by means of a simple timer unit. Because the adjusting time is shorter than one second, the filter setting, as it is controlled on the basis of the electronic image signal, follows movements in or of the object which have a duration of more than approximately one second. Such movements may be, for example movements of the patient or be caused by respiration, cardiac action or peristaltic movements of the patient. A particularly advantageous method of adjusting the X-ray filter 4 will be described in detail with reference to FIG. 5. According to this method all rows of the X-ray filter 4 are activated a number of times (n) in succession by control voltage pulses. A setting involving three repeats (n=3) will be described with reference to the Figure. During the first activation first a control voltage pulse V.sub.1.sup.1 of duration .tau..sub.1.sup.1 is applied to the control line of the first row; furthermore, control voltage pulses V.sup.1.sub.2, V.sup.1.sub.3, V.sub.4.sup.1, having a duration .tau..sub.2.sup.1, .tau..sub.3.sup.1, .tau..sub.4.sup.1, respectively, are applied to the second and subsequent rows. The control voltage pulses are successively applied to the respective rows, so that a control voltage pulse is applied to a row always after termination of a control voltage pulse for the preceding row. During this first activation period capillary tubes in the first and then in the second and subsequent rows become filled with the X-ray absorbing liquid, at least in as far and for as long as the relevant voltage lines carry an adjusting voltage. The periods .tau..sub.i.sup.j amount to approximately one pulse period t.sub.p =t.sub.f /Nn, where N denotes the number of rows. t.sub.p =25 .mu.s for N=200, n=20 and t.sub.f =0.1 s. Subsequently, during a second activation period control voltage pulses V.sup.2.sub.1, V.sup.2.sub.2, V.sup.2 .sub.3, V.sup.2.sub.4 having durations .tau..sup.2.sub.1, .tau..sup.2.sub.2, .tau..sup.2.sub.3, .tau..sup.2.sub.4, are applied to respective rows so that the filling of the capillary tubes continues. Finally, during the third activation period control voltage pulses V.sup.3.sub.1, V.sup.3.sub.2, V.sup.3.sub.3, V.sup.3.sub.4, having durations .tau..sub.1.sup.3, .tau..sub.2.sup.3, .tau..sub.3.sup.3, .tau..sub.4.sup.3, are applied. Because the control pulses are applied, the capillary tubes are filled with the X-ray absorbing liquid in a phased fashion and the X-ray absorptivity also increases in a phased fashion; the X-ray absorptivity remains approximately constant between the successive control voltage pulses. After termination of the control voltage pulse V.sup.j.sub.i, in the i.sup.th row an X-ray absorptivity .alpha..sub.i.sup.j is reached and the next control voltage pulse V.sub.i .sup.j+1 increases the X-ray absorptivity to .alpha..sub.1.sup.j+1 until ultimately, after the control voltage pulse V.sup.3 .sub.i,the value .alpha..sub.i is reached. The capillary tubes in the k.sup.th row are thus filled with a quantity of X-ray absorbing liquid which is controlled on the basis of the overall duration t.sub.k =.tau..sub.k.sup.1 +.tau..sub.k.sup.2 +.tau..sub.k.sup.2 +. . . +.tau..sub.k.sup.n of the control voltage pulses applied to the k.sup.th row. Because the capillary tubes in different rows are filled partly simultaneously, the adjusting time is reduced and, because the electric charges are delivered in fractions, the durations of the control voltage pulses can be reduced as the number of sampling periods is taken to be larger. A further advantage consists in that more time is available for the filling of the capillary tubes in the rows which are filled last. Furthermore, in comparison with the adjustment of the X-ray filter 4 of FIG. 4, a smaller time difference exists between the filling of the capillary tubes in the first rows and those in the last rows. The adjustment of the X-ray filter has been explained with reference to the FIGS. 4 and 5 for an X-ray filter comprising only four rows of capillary tubes and involving only three activation repeats by means of control voltage pulses. Evidently, to those skilled in the art it will be obvious that the method in accordance with the invention can be used equally well for an X-ray filter with a large number of rows, for example hundreds of rows, and with a large number of, for example from some tens to some hundreds of repeated activation periods. In FIG. 3 each capillary tube is coupled to a control line via a respective transistor; it is alternatively possible to couple a plurality of capillary tubes together to a control line via one transistor. In a contemporary X-ray examination apparatus the functions of the adjusting unit can also be executed by a suitably programmed computer or by a microprocessor designed for this purpose.
	summary
045171530	claims	1. In a fast neutron nuclear reactor comprising a core consisting of fuel assemblies arranged side by side with their lateral faces in contact in va vessel containing a reactor cooling fluid circulated by means of pumping, so as to traverse the core in the longitudinal direction of said assemblies, and a device incorporating means for detecting and localizing defective assemblies by detecting fission products in the cooling fluid, consisting of at least one localizing module and sampling conduits for abstracting the cooling fluid, each being associated with a fuel assembly, independently joining each of the zones situated at the exit of each of said assemblies to the localizing module and assuring the transport of said cooling fluid from the core exit as far as said modules, the improvement consisting of at least two completely independent localizing modules and an arrangement of the sampling conduits joining the exit of said assemblies to said modules such that, for each assembly of said core, there is at least one adjacent assembly in contact through the intermediary of one of its lateral faces, which is connected by its sampling conduit to a localizing module different from the module to which the first assembly is connected by its sampling conduit. 2. The improvement according to claim 1, wherein said core is divided into at least two parts, each comprising a set of assemblies, sampling conduits being associated with the assemblies of a set connected to one or the other of two localizing modules which are independent of the localizing modules to which the sampling conduit associated with the assemblies of the other sets are connected. 3. The improvement according to claim 2, wherein said core is divided into three parts, comprising three pairs of totally independent localizing modules, each associated to the set of assemblies in a part of said core, the sampling conduits of which are connected to either of the two localizing modules of the corresponding part of said core. 4. The improvement according to any one of claims 1 to 3, the sampling conduits of said assemblies being connected to one or the other of two independent localizing modules, respectively, arranged over rings coaxial with the axis of said core.
050154370	claims	1. In a reactor core for a gas-cooled reactor, which core is composed of a plurality of prismatic bodies of graphite, each body containing nuclear fuel and having a top wall, a bottom wall and a plurality of vertically extending side walls, and each graphite body being provided with a plurality of first coolant flow channels extending vertically between the top wall and the bottom wall, the improvement wherein each said body is further provided with a plurality of second coolant flow channels extending transversely to said first channels and each interconnecting a plurality of said first channels to provide alternate flow paths for the coolant. 2. A core as defined in claim wherein each of said second channels extends between two of said side walls. 3. A core as defined in claim 2 wherein the two side walls between which each said second channel extends are separated by at least one intervening side wall. 4. A core as defined in claim 2 wherein said second channels are divided into a plurality of groups and said groups are spaced apart in the vertical direction of said body. 5. A core as defined in claim 4 wherein said second channels of each said group extend parallel to one another. 6. A core as defined in claim 5 wherein said second channels of each said group extend in a direction which forms an angle, about a vertical axis, with the direction in which said second channels of each adjacent group extend. 7. A core as defined in claim 6 wherein said first channels are arranged in a pattern forming a plurality of rows extending in the direction in which said second channels of each said group extend and said second channels of each said group interconnect alternate rows of said first channels. 8. A core as defined in claim 7 wherein said second channels of each said group extend between two of said side walls which are separated by at least one intervening side wall.
062298682	description	DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a fuel assembly of a boiling water type comprising an upper handle 1, a lower end portion 2 and a plurality of fuel units 3 stacked one above the other. Each fuel unit 3 comprises a plurality of fuel rods 4 arranged in parallel and in spaced relationship to each other in a given lattice. Further, each fuel unit 3 comprises a top tie plate 16 and a bottom tie plate 17 for attachment of the fuel rods 4 in their respective positions in the lattice. The fuel units 3 are stacked on top of each other in the longitudinal direction of the fuel assembly and they are stacked in such a way that the top tie plate 17 in one fuel unit 3 is facing the bottom tie plate 16 in the next fuel unit 3 in the stack and such that the fuel rods 4 in all the fuel units 3 are parallel to one another. A fuel rod 4 contains fuel in the form of a stack of fuel pellets 7b of uranium arranged in a cladding tube 7a. A coolant is adapted to flow from below and up through the fuel assembly. FIG. 2 shows that the fuel assembly is enclosed in a fuel channel 8 with a substantially square cross section. The fuel channel 8 is provided with a hollow support member 9 of cruciform cross section, which is secured to the four walls of the fuel channel 8. In the central channel 14 formed of the support member 9, moderator water flows. The fuel channel 8 surrounds four vertical channel-formed parts 10, so-called sub-channels, with an at least substantially square cross section. The four sub-channels each comprises a stack of fuel units 3. Each fuel unit 3 comprises 24 fuel rods 4 arranged in a symmetrical 5.times.5 lattice. The fuel units 3 are kept in position by being fitted onto and fixed to the water channel 14 which surrounds the vertical channel. The fuel assembly in FIG. 2 comprises 10.times.10 fuel rod positions. By a fuel rod position is meant a position in the lattice. All the fuel rod positions in the lattice need not be occupied by fuel rods 4. In certain fuel assemblies, a number of fuel rods 4 are replace by one or a plurality of water channels. The introduction of a water channel changes the number of fuel rods 4 but not the number of fuel rod positions. FIG. 2a shows a fuel assembly which is provided with an internally arranged vertical channel 14a through which water is conducted in a vertical direction from below and upwards through the fuel assembly. The channel 14a is surrounded by a tube 9a with a substantially square cross section. The fuel units 3 are kept in position by being fitted onto the tube which surrounds the vertical channel. FIG. 2b shows a fuel assembly which is provided with two centrally arranged vertical water rods 14b through which water is conducted from below and upwards through the fuel assembly. The water rods 14b have a diameter which is somewhat larger than the diameter of the fuel rods 4 and are formed with a substantially circular cross section. The fuel units 3 are kept in position by being fitted onto the water rods 14b. FIG. 3 shows a pressurized-water fuel assembly. In the same way as the fuel assembly in FIG. 1, it comprises a plurality of fuel units 3 stacked on top of each other. Each fuel unit 3 comprises a plurality of fuel rods 4 arranged in parallel and in spaced relationship to each other in a given lattice. Each fuel unit 3 further comprises a top tie plate 17 and a bottom tie plate 16 for attachment of the fuel rods 4 in their respective positions in the lattice. The fuel units 3 are stacked on top of each other in the longitudinal direction of fuel assembly and they are stacked in such a way that the top tie plate 17 in one fuel unit 3 is facing the bottom tie plate 16 in the next fuel unit 3 in the stack, and such that the fuel rods 4 in all the fuel units 3 are parallel to each other. A fuel rod 4 contains fissionable material in the form of a stack of fuel pellets 7b of uranium arranged in a cladding tube 7a. A coolant is adapted to flow from below and upwards through the fuel assembly. A number of so-called control rod guide tubes 4a are arranged extending through the whole fuel assembly. The control rod guide tubes 4a are intended to receive finger-shaped control rods (not shown) which are, respectively, inserted into and withdrawn form the guide tubes 4a for the purpose of controlling the power of the nuclear reactor. The guide tubes extend between a top art 4b and a bottom part 4c. The top part 4b is arranged above the uppermost fuel unit 3 in the fuel assembly and the bottom part 4c is arranged below the lowermost fuel unit 3 in the fuel assembly. The fuel units 3 are kept in position by being fitted onto and fixed to the control rod guide tubes 4a. FIG. 4a shows a fuel unit 3 for a pressurized-water reactor according to FIG. 3, which is connected at top and bottom to fuel units 3. The fuel units 3 are interconnected by way of the guide tubes 4a extending through the whole fuel assembly. The fuel rods 4 extend between a bottom tie plate 16 and a top tie plate 17. In the bottom tie plate 16 and the top tie plate 17, sleeves 18 are arranged. To the left in FIG. 4a, the sleeves 18 and the guide tubes 4a are shown in a view from the side and to the right in FIG. 4a, the sleeves 18 and the guide tubes 4a are shown in a vertical section. The bottom tie plate 16 is fixed to the guide tube 4a by means of bulging (not shown) of the guide tube 4a when this is inserted into the sleeve 18. The top tie plates 17 are freely movable along the guide tubes 4a. The top tie plates 17 may, of course, be fixed to the guide tube 4a whereas the bottom tie plates 16 are arranged freely movable in relation thereto. Admittedly, FIG. 4a refers to a fuel assembly for a pressureized-water reactor, but in those cases where a boiling water reactor is intended, the fuel assembly is designed in a corresponding manner but in that case the bottom tie plates 16 and the top tie plates 17 are instead arranged to the water channels 14, 14a, 14b with axial gaps between the fuel units. FIG. 4b shows a fuel unit 3 of the same type as in FIG. 4a but with a spacer 19 arranged between the bottom tie plate 16 and the top tie plate 17. In an advantageous embodiment, the spacer 19 is made from sleeve-formed cells with elongated contact surfaces, for example of the type indicated in SE 9303583-0. The sleeves 19a which surround the control rod guide tubes 4a have been given a larger length in the axial direction for increased mechanical guiding of the control rod guide tubes. The sleeves in the sleeve spacer 19 may possibly be provided with conventional mixing vanes for mixing the coolant flowing upwards through the fuel assembly. The top tie plate 17 and the bottom tie plate 16 are provided with a plurality of flow openings 20 intended to be traversed by the coolant flowing upwards in the fuel assembly. These flow openings 20 are thus arranged substantially between the positions of the fuel rods 4. FIG. 5a shows a flow opening 20 in a top tie plate 17. In the flow opening 20, flow tongues 21 are arranged. Between the flow tongues, spaces 22 are arranged. FIG. 5b shows a flow opening 20 in a bottom tie plate 16. In the flow opening 20, flow tongues 23 are arranged. Between the flow tongues, spaces 24 are arranged. FIG. 5c shows the bottom tie plate 16 in FIG. 5b arranged above the top tie plate 17 in FIG. 5a. The flow tongues 23 in the bottom tie plate 16 are arranged above the spaces 22 in the top tie plate 17 and the flow tongues 21 in the top tie plate 17 are arranged below the spaces 24 in the bottom tie plate 16. In a new fuel assembly, the top tie plate 17 is arranged at a definite distance A1, of the order of size of a few millimeters, from the bottom tie plate 16 (see FIG. 5d). When, during operation of the reactor, the fuel rods 4 are extended, because of the radioactive irradiation, more than the control rod guide tubes 4a and the water channels 14, 14a, 14b, respectively, and when one of the top tie plate 17 or the bottom tie plate 16 is secured to the control rod guide tubes 4a and the water channels 14, 14a, 14b, respectively, whereas the other is freely movable around the guide tubes and water channels, the distance between the top tie plate 17 and the bottom tie plate 16 is reduced gradually during the service life of the fuel assembly (see A2 in FIG. 5e). In this way, burnup-dependent and automatic flow limitation, restriction, is obtained. The arrows in FIGS. 5d and 5e indicate the path of the coolant through the top tie plate 17 and the bottom tie plate 16. FIGS. 6a-6c show an alternative form of burnup-dependent flow limitation where the flow openings 20 in the top tie plate 17 and in the bottom tie plate 16 are given eccentrically displaced center axes. FIGS. 6d-6e show how the coolant flow is gradually restricted during the service life of the fuel assembly in that the fuel rods 4 grow more in the axial direction than the control rod guide tubes 4a and the water channels 14, 14a, 14b, respectively. FIG. 7a shows an embodiment of top tie plates 17 and bottom tie plates 16 provided with flow openings 20 with center axes displaced in relation to each other. In FIG. 7a, the center axes are displaced in relation to each other in such a way that a diagonal flow is created by a mixing cross section in the fuel assembly which, for example, may consist of two adjacently located fuel assemblies or four adjacently located sub-assemblies. FIG. 7b shows an alternative embodiment of the flow control in FIG. 7a. In FIG. 7b the center axes of the flow openings have been displaced such that, within the mixing cross section, the flow is deflected through substantially 90.degree..
042253896	description	DESCRIPTION OF THE PREFERRED EMBODIMENTS In the construction shown in FIG. 1 a nuclear reactor fuel assembly 1 is submerged in a pool of liquid sodium coolant 2 in a primary vessel 3 which is housed in a concrete vault 4. The fuel assembly is carried by a strongback 5 and is surrounded by a barrier 6 which defines inner and outer regions 7, 8 of the pool. There are eight coolant pumps 9 (only one being shown in FIG. 1) in the outer region 8 for circulating coolant through the fuel assembly by way of a diagrid 5a and thence to eight heat exchangers 10 (again only one being shown in FIG. 1) disposed in the inner region 7. The heat exchangers finally discharge the coolant into the outer region. The primary vessel 3, a leak jacket 11 for the primary vessel, the strongback 5, heat exchangers 10 and coolant pumps 9 are all suspended from the roof of the vault and the roof includes a double rotating shield 12 from which control rods 13 extend to the top of the core. A neutron shield 15 surrounds the fuel assembly within the barrier 6 and the internal wall surface of the barrier is clad with thermal insulation 16. A secondary liquid sodium coolant flowing through the heat exchangers conveys the heat energy derived from the fuel assembly to steam generating plant not shown in the drawings. In operation of the reactor, the coolant in the inner region of the pool is at temperature approximately 540.degree. C. and that in the outer region is at temperature approximately 370.degree. C. The pressure differential across the inlet and outlet ports of the pumps 9 causes a differential in the levels of the coolant in the regions the levels being designated L1 and L2. The thermal insulation 16 comprises a plurality of spaced layers of stainless steel sheet, each layer lying substantially parallel to the wall surface and comprising rectilinear panels secured to the wall surface in spaced array in vertical and horizontal rows. The spaces between adjacent panels are closed by members of cruciform shape the arms of the members being arranged to overlap opposed faces of adjacent panels. As shown in detail in FIGS. 2, 3, and 4 the rectilinear panels designated 24 are secured to the internal wall surface of the barrier 6 by central retaining studs 25. The spaces between the panels are closed by closure members 18 secured to the wall by further studs 25. The closure members 18 are of cruciform shape each comprising a cruciform spacer 27 intermediate a pair of cruciform sealing strips 26. The inner (relative to the wall surface) cruciform strip 26 of each member is welded to the spacer 27 whilst the outer is free for assembly after placing the complementing panels 24. The sealing strips 26 of each member 18 are disposed to overlap opposed faces of adjacent panels 24 and each arm of the cruciform member co-operates with an arm of a neighbouring cruciform member to extend along and overlap adjacent sides of adjacent panels. The combination of cruciform strips 26, spacer 27 and panel 24 form a labyrinth barrier serving to restrict flow of coolant through each layer of panels. The studs 25 are arranged in two lattices of square pitch, one lattice being displaced relative to the other by one half pitch in both horizontal and vertical directions and each stud carries alternately a panel 24 and a closure member 18 so that the vertical rows of panels in one layer are displaced relative to the vertical rows of panels in an adjacent layer, the displacement being one half of the pitch of the rows in both horizontal and vertical directions. By displacing the panels in one layer relative to the panels in an adjacent layer coolant flow across the insulation due to convection currents is reduced. The panels are 0.9 meters square and 0.55 mm thick, and are disposed on a 1 meter square lattice pitch. The cruciform strips of the sealing members are 0.55 mm thick and the cruciform spacing members are 0.70 mm thick. Stud spacers 29 10 mm thick serve to space to the closure members part. A clearance 32 is provided between the ends of the arms of the cruciform strips to provide for thermal expansion but the joints are closed to fluid flow by lapping strips 30 attached to selected arms of the cruciform strips. Two of the arms of each spacer 27 are longer than the other two, long and short arms of adjoining strips being assembled together and providing an expansion clearance 33 which is displaced from the expansion clearance 32 of the strips. Spacers 31 are also attached to selected arms of the cruciform strips to hold adjacent strips of adjacent membranes in place. In an alternative construction of liquid metal cooled fast breeder nuclear reactor generally similar to that described in respect of the first embodiment of the invention the panels 24 each comprise two opposed membranes of stainless steel sealed together along their edges to define a sachet which is charged with inert gas. As shown in FIG. 5, the panels 24 and closure members 18 are each adapted to engage a stud 25 by central bosses or hubs, designated 24a, 18a respectively, and the peripheral regions 24b of the panels 24 are extended by a single thickness of membrane to complement the closure members 18. One of the cruciform strips designated 18b of each closure member is also of sachet form so that, in effect, substantially the full area of each layer of insulation comprises a gas filled layer. The inert gas contained in the sachets is argon at sub-atmospheric pressure under external conditions of normal temperature and pressure and each sachet contains dimpled stainless steel foil 34 which serves as stiffening against collapse of the thin walls of the sachet. For this reason each sachet is also seam welded in quilt like manner to form a plurality of compartments. Thermal insulation of the described forms provides a substantial barrier to flow of coolant and accommodates superficial thermal expansion. The expansion is accommodated by the clearances between the panels and closure members and thereby substantially avoids distortion and complex stresses. The insulation is easily erected because the components are small and can be handled by an operator and components can be readily repaired or replaced on site.
	description	This application claims the benefit of co-pending United States patent application entitled “SOLID TARGET SYSTEM AND METHOD FOR THE HANDLING OF A Cu-64 TARGET” filed Oct. 5, 2010 and assigned Ser. No. 12/898,120; co-pending United states patent application entitled “SOLID TARGET SYSTEM FOR THE HANDLING OF A Cu-64 TARGET” filed Jan. 30, 2006 and assigned Ser. No. 11/342,501; and United States provisional patent application filed Jan. 28, 2005 and assigned Ser. No. 60/648,147, which are incorporated by reference herein. 1. Field of the Invention The present invention relates to the field of positron emission tomography (PET). More particularly, this invention relates to a system and method for manually loading and remotely unloading a target disk into a proton beam. 2. Description of the Related Art Accelerators are commonly used to produce radionuclides for a variety of uses including Positron Emission Tomography (PET). PET is a noninvasive diagnostic imaging procedure that assesses the level of metabolic, biochemical, and functional activity and perfusion in various organ systems of the human body. PET provides information not available from traditional imaging technologies, such as Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) which depict changes in anatomy rather than changes in physiology. Physiological activity provides a much earlier detection measure for certain forms of disease, cancer in particular, than do anatomical changes over time. Typically, an accelerator produces radionuclides by accelerating a particle beam and bombarding a target material with the accelerated beam thereby producing radionuclides. The type of radionuclides produced are determined by the target material and particle beam used. Low or medium energy charged-particle accelerators typically produce radionuclides having a short half life. Radionuclides such as copper-64 or 64Cu have a longer half life than the conventional radionuclides typically used. Specifically, copper-64 is the cyclotron-produced PET isotope of copper. This isotope undergoes a special type of radioactive decay, whereby its nuclei emit positrons that travel only a few millimeters in tissue before colliding with electrons, converting their total mass into two photons of energy. The photons are displaced at 180 degrees from each other and can be detected simultaneously as “coincident” photons on opposite sides of the body. However, copper-64 is not easily producible as is shown in U.S. Pat. No. 6,011,825 which is incorporated herein in its entirety by reference. The production of copper-64 requires the irradiation of a solid target rather than a liquid or gaseous target that conventional accelerators are capable of handling. The combination of gold with plated enriched nickel can be used to produce copper-64. Other combinations of metals can also be used to provide copper-64. In addition, the combination of metals can take the form of pellets, foil or coin. There is a need for a target holder for loading and unloading a solid target to produce a radionuclide. There is also a need for a target holder that can accommodate a solid as well as a liquid and gas target cost effectively. There is a further need for a target holder that has a service position and an irradiation position An object of the present invention is to provide a solid target handling system for manually loading and remotely unloading a target disk into a proton beam. Another object of the present invention is to provide a target handling system that can efficiently and cost effectively accommodate a solid target, a liquid target and a gas target. An aspect of the present invention provides a system and method for a system for accommodating a solid target in an accelerator. The system and method includes a target changer having at least one port for accommodating the solid target, an insert for receiving the solid target in the target changer, a piston for providing a vacuum and a cooling system for the solid target, a cylinder for displacing the piston in one of three positions; and a bracket for securing the insert, piston and cylinder to the target changer. Another aspect of the present invention also provides a system and method for accommodating a solid target, a liquid target and a gaseous target mounted on an accelerator. The system and method provide a target changer having four ports, two of which are service positions, an insert for receiving the solid target in the target changer, a piston for providing a vacuum and a cooling system for the solid target, a cylinder for displacing the piston in one of three positions; and a bracket for securing the insert, piston and cylinder to the target changer in one of the ports. A further aspect of the present invention provides for the target changer being rotated from a first position to a second position, wherein the first position comprises a service/removal position and the second position comprises a beam position for irraditiating the solid target. Throughout the figures, like symbols and numbers are used throughout. The solid target handling system 10 is configured with several criteria. First, the system 10 is received and operates in a conventional shield envelope (not shown). The system 10 is mounted to a conventional exiting target changer hub 24 as shown and described in U.S. Pat. No. 5,608,224 which is incorporated herein by reference in its entirety, and interfaces to an existing cooling arrangement. The hub 24 also mounts to an adjustable back plate for alignment to a beam. The beam has a range of about 5 MeV to about 25 MeV. Preferably, the beam has energies at about 11 MeV. FIGS. 1-4 show the above described components and assembly. More specifically, FIG. 1 illustrates a target changing system in accordance with an embodiment of the present invention. FIG. 2 illustrates an elevation view, in section, of the target assembly in accordance with an embodiment of the present invention. FIG. 3 illustrates the target changer 2 having four ports in accordance with an embodiment of the present invention. FIG. 4 illustrates various components of the target system in accordance with an embodiment of the present invention. The basic operation of the target changer interfaces with a conventional accelerator control system (not shown). The unloading of the system 10 is controlled by a remote controller (not shown), positioned outside the shield, with operational logic. The system 10 accommodates all conventional eclipse style targets in two ports, and accommodates a solid target in another two ports. The system 10 comprises a target changer 2, an insert 4, a piston 6, a shaft 22, a cylinder 8, a bracket 12 and a feed slot 14 as shown in FIG. 1. The insert 4 has an o-ring 16, a first opening 7, a second opening 9 and a cavity (not shown) providing a pass through between the first opening 7 and the second opening 9. The first and second openings of the insert 4 can be the same size; the first opening can be larger than the second opening or vice versa. The insert 4 also includes a slot 3. The slot 3 is positioned and arranged to allow a target to fall through from the feed slot 14. The piston 6 has a tab 5 and an o-ring 20. The feed slot 14 is located within the target changer 2. FIGS. 1, 2 and 3 together further show target changer 2 having a first port 26 for accommodating the insert 4, the piston 6, the shaft 22, the cylinder 8, and the bracket 12 all of which comprise subsystem 11. Target changer 2 also includes a third port 28 disposed about 180 degrees from the first port 26. It should be appreciated by those skilled in the art that the positions of the first port 26 and third position port 28 can vary from 180 degrees without departing from the scope of the present invention. For example, the first port 26 and the third port 28 can be 90 degrees apart without varying from the scope of the present invention. As shown in the combination of FIBS 1-5, first port 26 is in the service/removal position. Third port 28 is in the beam position. The target changer 2 is rotated so that the first port 26 is displaced from a service position to a beam position. Second port 30 and fourth port 32 can accommodate conventional liquid and gas targets. In an embodiment of the present invention, target changer 2 comprises only first port 26 and third port 28. In another embodiment of the present invention, target changer 2 comprises a plurality of first ports 26 and a plurality of third ports 28. This will enable a plurality of solid targets to be accommodated and produce substantial amounts of radionuclides in a short amount of time. In operation, the solid target is manually loaded in the first port 26 or the service position of the target changer 2. The target extraction mechanism is then attached to the target via computer control. The target is then rotated into the beam position and bombarded for the desired time and current. The target is then rotated back to the service port and unloaded. The unloading process includes the following steps. First, the solid target is rotated to the service/removal position. The first port 26 vacuum line 40 is then vented. The cooling water valve 36 is closed, and then opened to drain. An air flush valve 42 is opened to remove all trapped water from the cooling lines. The target removal mechanism is initialized and the target is extracted from the insert 4. The target falls out of the device and to the floor of the accelerator pit aided by gravity. The fall is within a track (not shown) to control speed and location. The target changer 2 is then available to manually load another solid target. FIG. 4 illustrates an exemplary target 34. Target 34 is a solid target and preferably comprises a combination of enriched nickel and gold sufficient to provide copper-64. The piston 6 fits within the insert 4 and channels cooling water to the solid target via perforations 44 (See FIGS. 1, 4 and 6). The insert serves as the vacuum seal between the target and the accelerator. The piston has three positions within the insert. A load, extended and extraction position. The load position is such that the tab 5 on the piston extends into the slot 3 of the insert 4 preventing the target from continuing to fall out of the feed slot 14 where it exits the target changer. Specifically, the tab 5 (see mark up to FIG. 4) stops the target disk as it falls into the target changer 2 and positions the target in the center of the beam. In the extraction position the piston 6 is extracted in the insert 4. It should be appreciated by those skilled in the art that the extraction position can comprise a location where the piston 6 is still in the insert 4 but the tab 5 is not blocking feed slot 14. The three positions of the piston are controlled by a pneumatic cylinder 8 manufactured by Bimba. The cylinder is held in position by the bracket 12, which is connected to first port 26 via screws and precisely positions the cylinder 8 so that the stroke lengths are as needed. The displacement of shaft 22 which is connected to cylinder 8 at one end and piston 6 at a distant end causes piston 6 to move in a lateral direction. In an embodiment of the present invention, the system 10 is configured to accommodate a solid target having a range between 0.5 mm to 5 mm thickness and 10 mm to 35 mm in diameter. Preferably the target disk has 2 mm thickness and 25 mm diameter. The solid target preferably has a thermal conductivity greater than 2200 BTU-in/hr-Ft2-° F. In accordance with an embodiment of the present invention, system 10 operates in the following manner. When first port 26 is in the service position, the target 34 is dropped either manually or remotely into the feed slot 14 of the target changer 2. The feed slot 14 was formed via a rectangular slot that was burned into the target changer 2 via EDM. The feed slot 14 allows the target disk to fall by gravity into the insert 4. The target enters the insert 4 via the insert slot 3 and is prevented from passing through the insert 4 by the piston tab 5 because the piston 6 is in the load position. Air is removed via air inlet 40 compressing the target against the o-ring 16 of insert 4. The piston is placed in an extended position compressing the target against O-ring 20 of the piston 6. The port 26 is rotated by the hub 24 from a service position to a beam position where the target is irradiated for a predetermined period by a beam having a predetermined energy. An exemplary predetermined time period can be 2 hours of 40 uA operation for the accelerator. In an embodiment of the present invention, the rotation can be clockwise. In another embodiment of the present invention, the rotation can be counter clockwise. Water is input via inlet 36 and the perforations 44 of the piston 6 to maintain the temperature of the target below a predetermined threshold temperature so that the target does not melt. Water is removed via outlet 38. The target changer 2 is rotated clockwise so that first port 26 is positioned to be in a removal position. In another embodiment of the present invention rather than continuing forward in a clockwise direction, the target changer 2 is rotated in a counter clockwise position. In the removal position, air is provided to port 26 via inlet 42, the piston 6 is placed in an extracted position causing the target to fall through slot 3 of the insert 4 via gravity out of the target changer 2 where the target is automatically unloaded and interfaces with a customer supplied transport system. The insert is designed to fit within the target changer. It functions to position the 25 mm diameter solid target in the larger target slot. It provides cooling water and vacuum seals. It also has integral tabs to strip the target disk from the piston during extraction. The beam position compresses the target disk between two face seal O-rings for vacuum seal. The extract position pulls the piston back within the insert and allows the target disk to fall into the exit feed slot. The operation of the target assembly of the present invention is illustrated in FIG. 5. Target Cooling: The target disk is cooled by water jets normal to its non-beam side surface. The water is routed through the insert as indicated in FIG. 6. The target disk is cooled by conduction through the disk and convection from the disk into the cooling water. Conduction is calculated by Fouriers Law: q = KA ⁢ ⅆ t ⅆ l . Since the heat transmission is steady and the K and L are constant, this becomes: q = KA ⁢ ⁢ Δ ⁢ ⁢ T L ,where: q=heat input; K thermal conductivity of material; A=area of heat conduction; ΔT=(T2−T1); and L=thickness of target disk. In the instant case, where: q=10.5 MeV×60 uA=630 W 2150 btu/hr; K=2200 btu-in/hr-ft2-° F. (for gold); A=0.00136 ft2; and L=2 mm=0.079 in,then: ΔT=57° F. To estimate the value for “h”, the coefficient of heat transfer used in the following equations are used:H=Nu(Kwater)/L;Nu=0.228Re0.731Pr33 Re=VLρ/μ; andPr=CDμ/Kwater,where: Nμ=Nusselt number; Re=Reynolds number; Pr=Prandlt number; Kwater=thermal conductivity of water=0.58 W/m K; L=length of flow=0.019 m; P=density of water=1000 kg/m3; M=viscosity of water=0.00114 kg/m-s; Cp=specific heat of water=4180 KJ/kg-K; and V=velocity of flow=4.3 m/s. From this, the results yield: Pr=8.2; Re=7.2×104; Nu=1627; and H=49,667 W/k=8741 btu/hr-ft2-° F. Convection is calculated by Newton's Law of Cooling for forced convection.q=hAΔTwhere: q=heat input; h=coefficient of heat transfer; A=area of heat convection; and ΔT=Twatt−Twater). In the instant case, where: q=10.5 MeV×60 uA=630 W=2150 btu/hr; h=8741 btu/hr-ft2° F.; and A=0.00136 ft2,then: ΔT=180° F. The results show that where the temperature of the cooling water is 45° F., the temperature of the wall on the cooling water side is 225° F. and the temperature of the wall on the beam side is 282° F. While the present invention has been illustrated by description of several embodiments and while the illustrative embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant's general inventive concept.
	claims	1. A method for producing x-ray-optical gratings for x-ray dark field imaging and for x-ray phase contrast imaging, comprising the steps of:applying an x-ray-sensitive layer with an electrically conductive cover layer on a base plate;transferring a grating structure into the x-ray-sensitive layer with a lithographic method, creating exposed and unexposed regions;dissolving the exposed regions of the x-ray-sensitive layer so that a grating structure remains;introducing a metal into the grating interstices by electroplating;removing the x-ray-sensitive material and the base plate so a negative impression of a grating made of metal remains;producing a grating made of a first material with this negative impression that has a plurality of periodically arranged grating webs and grating openings; andfilling the grating openings with a second material by electroplating, by continuing the electroplating until a cohesive layer of the second material is created over the grating webs. 2. A method as claimed in claim 1, comprising employing a first material having an x-ray absorption coefficient that is lower than the x-ray absorption coefficient of the second material. 3. A method as claimed in claim 1 comprising producing the layer of the second material to a uniform height by polishing. 4. A method as claimed in claim 1 comprising implementing the electroplating to give the second material a layer thickness of at least 5 μm. 5. A method as claimed in claim 1 comprising implementing the electroplating to give the second material a layer thickness of at least 10 μm. 6. A method as claimed in claim 1 comprising employing a plastic as a first material. 7. A method as claimed in claim 6 comprising employing a polymethacrylate as the first material. 8. A method as claimed in claim 1 comprising employing an epoxy resin as the first material. 9. A method as claimed in claim 1 comprising employing a metal as the second material. 10. A method as claimed in claim 9 comprising employing gold as the second material. 11. A method as claimed in claim 9 comprising employing nickel as the second material. 12. A method as claimed in claim 1 comprising producing the grating with an aspect ratio of at least 50.
061538094	summary	TECHNICAL FIELD This invention relates to the use of chemically bonded phosphate ceramics (CBPCs) for immobilizing large volumes of low-level mixed waste material, and, in particular, to a polymeric coating that increases the leach resistance in CBPCs encapsulating waste containing salt anions. BACKGROUND OF INVENTION Low-level mixed waste streams are composed of aqueous liquids, heterogeneous debris, inorganic sludge and particulates, organic liquids, and soils. Of particular concern are low-level mixed waste streams that are high in salt content, especially those salt waste streams generated as sludge and solid effluents in nuclear processing applications. For example, the extraction of plutonium and uranium from their ore matrices by the use of strong acids or precipitation techniques produces nitrate salt and heavy metal waste. Chemical compositions typically found in salt waste streams, either high in chloride or high in nitrate, include aluminum trihydroxide, sodium phosphate, MicroCel E (CaSiO.sub.3), water, sodium chloride, trichloroethylene, calcium sulfate, sodium nitrate, and oxides of lead, chromium, mercury, iron, cadmium, and nickel, among other compounds. Stabilization of salt waste requires that the contaminants and soluble salt anions are effectively immobilized. No single stabilization and solidification technology is known to successfully treat and dispose of salt waste, due to the physical and chemical diversity of salt waste streams. Generally, stabilization refers to the conversion of the waste into a less soluble form, while solidification refers to the micro-encapsulation of the waste in a monolithic solid of high structure integrity. Conventional thermal waste treatment methods, such as incineration or vitrification, are expensive and largely unsuitable for the treatment of salt waste streams because of their reliance on high temperature steps that risk the release of volatile contaminants and the generation of undesirable (e.g., pyrophoric) secondary waste streams. In addition, thermal treatments produce hot spots that affect the quality of a solidified final waste form. A low-temperature approach is to stabilize hazardous waste by using inorganic (e.g., pozzolanic) binders, such as cement, lime, kiln dust, and/or fly ash. Disadvantages of this approach include a high sensitivity to the presence of impurities, high porosity, and low waste loading volume. Organic binders (e.g., thermosetting polymers) are used even less frequently, because of cost and greater complexity of application. Organic binders are not compatible with water-based wastes, unless the waste is first pre-treated and converted to an emulsion or solid, and organic binders are subject to deterioration from environmental factors, including biological action and exposure to ultraviolet light. Recently, an alternative non-thermal, low-temperature approach has been developed at Argonne National Laboratory for stabilizing and solidifying low-level mixed waste by incorporating or loading the waste into a phosphate ceramic waste form having a high structural integrity. This technique immobilizes the waste by solidification, such that the waste is physically micro-encapsulated within the dense matrix of the phosphate ceramic waste form, and/or stabilizes the waste by converting the waste into their insoluble phosphate forms. Ceramic encapsulation systems are particularly attractive given that the bonds formed in these systems are ether ionic or covalent, and hence stronger than the hydration bonds in cement systems. Also, the ceramic formulation process is exothermic and economical. Phosphates are particularly good candidates for stabilization of radioactive and hazardous waste, because phosphates of radio nuclides and hazardous metals are essentially insoluble in groundwater. A salient feature of the low-temperature ceramic phosphate formulation process is an acid-base reaction. For example, magnesium phosphate ceramic waste forms have been produced by reacting magnesium oxide (MgO) with phosphoric acid to form a phosphate of magnesium oxide, Newberyite, as represented in the chemical equation (1), below. EQU MgO+H.sub.3 PO.sub.4 +2H.sub.2 O.fwdarw.MgHPO.sub.4.3H.sub.2 O(1) The acid-base reaction results in the reaction of the waste components with the acid or acid-phosphates, leading to chemical stabilization of the waste. In addition, encapsulation of the waste in the phosphate ceramic results in physical containment of the waste components. The reaction represented above in Equation (1) occurs rapidly and generates heat, and upon evaporation of the water, a porous ceramic product results. U.S. Pat. No. 5,645,518 issued to Wagh, et al., incorporated herein by reference, describes in detail the process steps for setting liquid or solid waste in CBPC products using acid-base reactions. Accordingly, the process involves mixing ground solid waste, including salt waste spiked with heavy metals, with a starter powder of oxide and hydroxide powders of various elements; slowly adding the waste-powder mixture to an acid solution of phosphoric acid or soluble acid phosphates; thoroughly mixing the waste-powder-acid mixture for about a half hour to an hour at ambient temperatures (less than 100.degree. C.), such that the components of the mixture chemically react to form stable phases and a reacted viscous slurry or paste results; and allowing the slurry or paste to set for a few hours into the final CBPC product. Liquid waste is similarly stabilized by mixing the liquid waste with the acid solution (preferably 50:50), and then reacting the waste-acid mixture with the starting powders. The maximum temperature for the process is about 80.degree. C. The CBPC products attain full strength in about three weeks, and exhibit a complex structure, including a major crystalline phase, e.g., Newberyite (MgHPO.sub.4.3H.sub.2 O), and an insoluble, stable phase. The waste components are generally homogeneously distributed within the phosphate ceramic matrix. Unfortunately, however, the porous product (Newberyite) is unsuitable for waste treatment on a large scale. U.S. Pat. No. 5,830,815 issued to Wagh, et al., incorporated herein by reference, describes improving the CBPC fabrication process by incorporating two temperature control processes for both reducing heat generation during the encapsulation (reaction) steps and moderating pH conditions (some wastes are unstable at a low pH). The first temperature control process involves pre-treating the phosphoric acid with a carbonate, bicarbonate or hydroxide of a monovalent metal (e.g., K, Na, Li, Rb) prior to mixing with an oxide or hydroxide powder so as to buffer the acid. In particular, potassium containing alkali compounds (e.g., K.sub.2, KHCO.sub.3, KOH) result in a more crystalline waste form, and the higher the concentration of potassium in the potassium containing compound, the more crystalline the final product, resulting in a higher compression strength, lower porosity, and greater resistance to weathering, compressive forces, and leaching. The second temperature control process involves bypassing the use of the acid and mixing the oxide powder with dihydrogen phosphates of potassium, sodium, lithium, or other monovalent alkali metal, to form a ceramic at a higher pH. Neutralizing the phosphoric acid solution in equation (1) by adding potassium hydroxide (KOH), as represented in the chemical equation (2) below, reduces the reaction rate and heat generation, and results in the formation of a superior magnesium potassium phosphate (MKP) mineral product, MgKPO.sub.4.6H.sub.2 O (magnesium potassium phosphate hexahydrate), as represented in chemical equation (3) below. EQU H.sub.3 PO.sub.4 +KOH.fwdarw.KH.sub.2 PO.sub.4.H.sub.2 O (2) EQU MgO+KH.sub.3 PO.sub.4 +5H.sub.2 O.fwdarw.MgKPO.sub.4.6H.sub.2 O(3) The chemically bonded ceramic phosphate (CBPC) waste form (e.g, MgKPO.sub.4.6H.sub.2 O) is a dense, hard material with excellent durability and a high resistance to fire, chemicals, humidity, and weather. The low-temperature (e.g., room-temperature) process encapsulates chloride and nitrate salts, along with hazardous metals, in magnesium potassium phosphate (MKP) ceramics, with salt waste loadings of up to between approximately 70 weight percent and approximately 80 weight percent. This durable MKP ceramic product has been extensively developed and used in U.S. Department of Energy waste treatment projects. Phosphates in general are able to bind with hazardous metals in insoluble complexes over a relatively wide pH range and most metal hydroxides have a higher solubility than their corresponding phosphate forms. In addition to the magnesium and magnesium-potassium phosphate waste products discussed above, known waste encapsulating phosphate systems include, but not limited to, phosphates of magnesium-ammonium, magnesium-sodium, aluminum, calcium, iron, zinc, and zirconium (zirconium is preferred for cesium encapsulation). A non-exclusive summary of known phosphate systems and processing details is provided in Table I below, selected according to ready availability of materials and literature about the materials, in addition to low cost. TABLE I ______________________________________ Phosphate Systems and Processing Details Curing System Starting Materials Solution Time ______________________________________ MKP Ground MgO, ground K Water 1 hour dihydrophosphate crystals Mg phosphate Calcined MgO Phosphoric >8 days acid-water (50/50) Mg--NH.sub.4 phosphate Crushed dibasic NH.sub.4 Water 21 days phosphate crystals mixed w. calcined MgO Mg--Na phosphate Crushed dibasic Na Water 21 days phosphate crystals mixed w. calcined MgO Al phosphate Al(OH).sub.3 powder Phosphoric Reacted acid powder, (.apprxeq.60.degree. C.) pressed Zr phosphate Zr(OH).sub.4 Phosphoric 21 days acid ______________________________________ Appropriate oxide powders include, but are not limited to, MgO, Al(OH).sub.3, CaO, FeO, Fe.sub.2 O.sub.3, Fe.sub.3 O.sub.4, Zr(OH).sub.4, ZrO, and TiO.sub.2, and combinations thereof. The oxide powders may be pre-treated (e.g., heated, calcined, washed) for better reactions with the acids. While no pressure is typically applied to the reacted paste, about 1,000 to 2,000 pounds per square inch may be applied when zirconium-based powders are used. The acid component may be dilute or concentrated phosphoric acid or acid phosphate solutions, such as dibasic or tribasic sodium, potassium, or aluminum phosphates, and the paste-setting reactions are controllable either by the addition of boric acid to reduce the reaction rate, or by adding powder to the acid while concomitantly controlling the temperature. Representative bulk constituents for salt waste include, but are not limited to, activated carbon, Na.sub.2 (CO.sub.3).sub.2, widely used cation or anion exchange resins, water, NaCl, Na(NO.sub.3).sub.2, Na.sub.3 PO.sub.4, and Na.sub.2 SO.sub.4. The salt waste may be reacted with phosphoric acid to any consume carbon dioxide (CO.sub.2) present, prior to mixing the salt waste with the oxide powders or binding powders, as the evolution of CO.sub.2 results in very porous final ceramic products. Unfortunately, however, encapsulation of low-level mixed waste into CBPC products is currently of limited practical use for waste that is predominantly comprised of salts, such as chlorides, nitrates, and sulfates. Efforts to encapsulate salt waste in phosphate ceramic products are hampered by low maximum waste loading capacities, because of interference of the salt anions with ceramic-setting reactions, leaching of soluble salt anions from the resulting highly porous ceramic product (especially in aqueous environments), and rapid structural degradation of the ceramic product caused by the high leach rates. Also, environmental stresses degrade the integrity of known CBPC waste forms over time. For example, exposure to repeated cycles of wetting, drying and/or freezing, or acidic or other conditions conducive to leaching may affect the long term effectiveness of waste encapsulated CBPC waste forms. A need in the art exists for a method for disposing of salt waste that involves a low-temperature stabilization process and improves resistance to leaching, without degrading the integrity of the ceramic phosphate product. The present invention is a process and product for safely containing radioactive and/or hazardous waste comprised of salt anions in a phosphate ceramic product, involving a new and surprisingly effective immobilization technique. The invented process and product involves the application of a specific polymer coating to the exterior surface of a phosphate ceramic composite encapsulating waste, such that the polymer coating infiltrates the surface structure and adheres to and/or bonds to the phosphate ceramic composite matrix, effectively isolating the waste from the environment and improving the leach resistance of the phosphate ceramic composite. The polymer coating contains at least one inorganic metal compound, preferably an inorganic metal oxide of magnesium or silicon. Therefore, in view of the above, a basic object of the present invention is to provide an improved process and product for immobilizing hazardous, radioactive, and/or mixed salt waste in phosphate ceramic composites. Another object of the invention is to provide a safe, low temperature, economical process and product for immobilizing salt waste in a phosphate ceramic product that increases the loading capacity and improves the leach resistance of the salt waste within the phosphate ceramic product. A further object of the invention is to provide process and product for immobilizing large volumes of salt waste in a durable, long term storage phosphate ceramic product. Additional objects, advantages, and novel features of the invention are set forth in the description below and/or will become apparent to those skilled in the art upon examination of the description below and/or by practice of the invention. The objects, advantages, and novel features of the invention may be realized and attained by means of instrumentation and combinations particularly pointed out in the appended claims. BRIEF SUMMARY OF THE INVENTION Briefly, the present invention is a surprisingly effective process and product for immobilizing waste having a high concentration of salt in chemically bonded phosphate ceramic (CBPC) products. The invention involves a new coating step, wherein a select polymer coating is applied to the surface of a fabricated salt waste loaded CBPC product, such that the coating infiltrates the surface structure of the CBPC product and adheres to the phosphate ceramic matrix, thereby isolating soluble salt anions from the environment and ensuring long-term integrity of the phosphate ceramic system. The fabricated salt waste loaded CBPC product is formulated by methods known in the art. A critical feature of the invention is the selection of the polymer coating, which contains at least one inorganic metal compound. Preferably, the polymer coating is a polymer resin comprised of fine powders of magnesium oxide and/or silicon oxide. The powders of the coating material act as wetting agents that apparently cause mechanical and/or chemical bonding between the phosphate ester in the surface structure of the CBPC product and the polymer coating composition. The polymer coating infiltrates and macro-encapsulates the CBPC product to improve durability and leach resistance.
	description	A seal arrangement and method for sealing an ICI housing according to the present invention will now be explained in detail with reference to FIGS. 1 to 8 of the drawings. FIG. 1 shows a portion of a nuclear reactor system 10 having a reactor 12 including a substantially upright cylindrical vessel 14 and a substantially hemispherical head 16. The vessel has an upper flange 18, and the head 16 has a lower flange 20. The flanges 18 and 20 are bolted together in a known manner for normal operation of the reactor system 10. As is well known in the field of nuclear engineering, the operating conditions within the reactor 12 can be monitored by ICIs, such as thermocouples and so forth. This is typically accomplished by a plurality of ICIs 23 that pass through respective nozzles 22 into the reactor 12. For the purpose of simplifying the present description, only one of the reactor vessel nozzles 22 on the head 16 is shown, but it should be appreciated that normally there are several nozzles 22 positioned in an organized array across the head 16. Each ICI 23 is housed in an ICI housing 24 connected to a respective one of the nozzles 22. The ICI 23, ICI housing 24, and other components shown in FIG. 1 are conventional. As explained above, the ICIs 23 must be partially withdrawn at every refueling outage to allow for movement of the fuel. The process of withdrawing the ICIs 23 often results in damage to the sealing surfaces of the O-rings installed in the grooves 25 (FIG. 2) of the ICIs 23 and/or to the ICI seal housing 24. The present invention provides seal arrangements for resealing the interface between the ICI 23 and the ICI housing 24 after the ICIs 23 are reinserted following the refueling. Three embodiments of seal arrangements according to the present invention are described herein and shown in FIGS. 2 to 8 of the drawings. All three embodiments utilize external seal rings, preferably made of a graphite material, on the external surfaces of the existing ICI 23 and ICI housing 24. To effect a seal against full system design pressure of up to 2500 psi, the seal rings must be compressed under very high loads to prevent leakage. The sealing principle is the same in each of the three embodiments. The method used to compress the seal rings differs. As shown in FIGS. 2 to 4, a seal arrangement 30 according to the first embodiment of the present invention includes a first lower seal assembly 31 surrounding an outer portion 32 of the ICI housing 24, and a second upper seal assembly 33 surrounding an outer portion of an ICI 23 contained within the ICI housing 24. The lower seal assembly 31 includes a first pair of seal rings 34, 35 positioned in abutting relationship with each other. The upper seal assembly 33 includes a second pair of seal rings 36, 37 positioned in abutting relationship with each other. The seal rings 34, 35 of the lower seal assembly 31 have an inside diameter that fits closely to the external surface of the ICI housing 24. The seal rings 36, 37 of the upper seal assembly 33 have an inside diameter that fits closely to the external surface of the ICI 23. The seal rings 34-37 are preferably fabricated of a graphite material. A seal housing 38 is provided which spans the interface between the ICI 23 and the ICI housing 24. The seal housing 38 has a first recess 39 formed in a first lower end 40 and a second recess 41 formed in a second upper end 42. The lower seat assembly 31 is positioned in the first recess 39 so as to be enclosed by the lower end 40 of the seal housing 38. The upper seal assembly 33 is positioned in the second recess 41 so as to be enclosed by the upper end 42 of the seal housing 38. The seal housing 38 has a housing portion 43 and an integral retainer portion 44. The retainer portion 44 has an inner diameter 45 that fits closely around the external surface of the ICI 23, and an outer diameter having external male threads 46. The retainer portion 44 is secured to the ICI housing 24 by threadably engaging the external threads 46 of the retainer portion 44 to corresponding internal threads 47 formed in the upper end of the ICI housing 24. The retainer portion 44 has an abutment seat 48 at the top of the external threads 46 that engages and seats against an upper end surface 49 of the ICI housing 24. A lower end of the retainer portion 44 has an abutment surface 50 against which the existing spacers 51 surrounding the ICI 23 can be engaged. A lower end 52 of the lowest spacer 53 is engaged by an annular shoulder 54 formed on the ICI 23. Thus, the retainer portion 44 provides positive retention against slipping of the ICI 23 and other parts relative to the ICI housing 24 when system pressure is applied. The housing portion 43 of the seal housing 38 is molded together with the retainer portion 44 in a single, integral piece. The housing portion 43 has external male threads 55 on each end, which threads may extend along the entire length of the housing portion 43, as shown in FIG. 2. The seal housing 38 is preferably fabricated from a stainless steel alloy that resists galling and seizing of threads, such as NITRONIC 60(trademark) Stainless Steel. A first lower compression assembly 56 and a second upper compression assembly 57 are positioned on the lower and upper ends 40, 42 of the seal housing 38, respectively. The lower compression assembly 56 includes a first lower drive nut 58 and a first lower compression collar 59. The lower drive nut 58 has internal threads 60 threadably engaged on the external threads 55 of the housing portion 43, and a flange 61 that extends inwardly at a lower end. The lower compression collar 59 has a first annular portion 62 engageable by the flange 61 of the lower drive nut 58, a second annular portion 63 which extends through the flange 61 and protrudes from a lower end of the lower drive nut 58, and a third annular portion 64 facing the lower seal assembly 31. A first lower spacer ring 65 is positioned between the third annular portion 64 and the seal rings 34, 35 of the lower seal assembly 31. The lower compression collar 59 is axially movable against the lower spacer ring 65 using a compression tool, which will be described below, to compress the lower seal assembly 31 to form a seal between the ICI housing 24 and the seal housing 38. The lower drive nut 58 is threaded onto the housing portion 43 of the seal housing 38 until the flange 61 is engaged snugly against the first annular portion 62 of the lower compression collar 59 to maintain the compressed seal between the ICI housing 24 and the seal housing 38. The upper compression assembly 57 includes a second upper drive nut 66 and a second upper compression collar 67. The upper drive nut 66 has internal threads 68 threadably engaged on the external threads 55 at the upper end of the housing portion 43, and a flange 69 that extends inwardly at an upper end of the upper drive nut 66. The upper compression collar 67 has a first annular portion 70 engageable by the flange 69 of the upper drive nut 66, a second annular portion 71 which extends through the flange 69 and protrudes from an upper end of the upper drive nut 66, and a third annular portion 72 facing the upper seal assembly 33. A second upper spacer ring 73 is positioned between the third annular portion 72 of the upper compression collar 67 and the seal rings 36, 37 of the upper seal assembly 33. The upper compression collar 67 is axially movable against the upper spacer ring 73 using a compression tool, which will be described below, to compress the upper seal assembly 33 to form a seal between the ICI 23 and the seal housing 24. The upper drive nut 66 is threaded onto the housing portion 43 of the seal housing 38 until the flange 69 is engaged snugly against the first annular portion 70 of the upper compression collar 67 to maintain the compressed seal between the ICI 23 and the seal housing 38. As shown in FIG. 2, the diameters of the threaded portions 60, 68 of the lower and upper drive nuts 58, 66 are the same. The inner diameter of the flange 69 of the upper drive nut 66 and the corresponding portions of the upper compression collar 67 are smaller than the inner diameter of the flange 61 of the lower drive nut 58 and the corresponding portions of the lower compression collar 59. An installation tool 74 for installing the seal arrangement 30 shown in FIG. 2 over the existing ICI 23 and ICI housing 24 during a refueling outage is shown in FIG. 3. The installation tool 74 includes a pair of leg assemblies 75, 76 each having a lower end 77 with a gripping portion 78 protruding inwardly toward the ICI housing 24, and an upper end 79 supporting a hydraulic cylinder 80. The gripping portions 78 at the lower end 77 of the leg assemblies 75, 76 engage the protruding second annular portion 63 of the lower compression collar 59. The pair of leg assemblies 75, 76 can be easily positioned over and removed from the seal arrangement 30 after the compression assemblies 56, 57 are installed with the drive nuts 58, 66 threaded hand tight. The installation tool 74 also includes an upper compression plate 81 surrounding the ICI 23 above the upper compression collar 67. A lower surface 82 of the compression plate 81 engages the protruding second annular portion 71 of the upper compression collar 67. A piston 83 protrudes from each of the hydraulic cylinders 80 into engagement with the upper compression plate 81. When the tool 74 is placed over the seal arrangement 30, as shown in FIG. 3, a predetermined pressure can be introduced into the hydraulic cylinders 80 to force the respective pistons 83 against the upper compression plate 81, which in turn pushes the upper compression collar 67 against the upper seal assembly 33. At the same time, a corresponding force is transmitted through the leg assemblies 75, 76 to force the gripping portions 78 against the lower compression collar 59 to compress the lower seal assembly 31. The tool 74 is thus operable to provide a compression load to the lower and upper seal assemblies 31, 33 simultaneously. While the tool 74 is installed and a compression preload is applied to the seal assemblies 31, 33, the lower and upper drive nuts 58, 66 can be threaded further along the seal housing 38 until the flanges 61, 69 of the drive nuts 58, 66 are engaged snugly against the respective lower and upper compression collars 59, 67. For example, the drive nuts 58, 66 can be seated hand tight while the seal assemblies 31, 33 are under compression from the installation tool 74. When the hydraulic pressure is released from the tool 74, the drive nuts 58, 66 pick up the load and maintain the compression preload on the seal assemblies 31, 33. Having explained the construction of the seal arrangement 30 according to a first embodiment of the present invention, a method of installing the seal arrangement 30 during a nuclear reactor refueling outage will now be described. After the seal welds have been cut (where applicable) and the surfaces cleaned, the existing retainer nut (not shown) is removed and discarded. The ICI 23 is partially withdrawn in accordance with existing procedures. The existing ICI O-rings in the grooves 25 can be discarded because they are not required with the seal arrangement 30 of the present invention. The refueling is then completed in accordance with existing procedures. The ICI 23 is then reinserted to the proper depth. The reinsertion can be done by hand without using an insertion tool because the grooves 25 do not have O-rings causing a friction drag during reinsertion. Spacers 51 are added according to the existing procedure to a defined height so that the seal housing 38 will seat properly. The lower drive nut 58, lower compression collar 59, lower spacer ring 65, and lower seal assembly 31 are lowered over the outside of the ICI housing 24. The retainer portion 44 of the seal housing 38 is threaded (e.g., hand tight) into the internal threads 47 of the ICI housing 24 until the seal housing 38 is seated on the ICI housing 24. After the seal housing 38 is installed, the ICI 23 is pulled up slightly by hand to close any gaps with the spacers 51. The lower seal assembly 31, lower spacer ring 65, lower compression collar 59 and lower drive nut 58 are then installed to the lower end 40 of the seal housing 38 (e.g., hand tight), as shown in FIG. 2. The upper seal assembly 33 and upper spacer ring 73 are installed in the upper end 42 of the seal housing 38. The upper compression collar 67 and upper drive nut 66 are then installed (e.g., hand tight), as shown in FIG. 2. The installation tool 74 shown in FIG. 3 is used to seat the lower and upper seal assemblies 31, 33, preload the seal arrangement 30 during installation, and unload the seal arrangement 30 for removal. Because the tool 74 loads both seal assemblies 31, 33 simultaneously, the number of operations required to install or remove the seal arrangement 30 is reduced, thereby saving installation and removal time. The upper and lower compression collars 59, 67 are axially loaded simultaneously by the hydraulic tool 74 to compress the lower and upper seal assemblies 31, 33 to the desired preload. While under compression with the hydraulic tool 74, both drive nuts 58, 66 are seated (e.g., hand tight). When the hydraulic pressure is released from the tool 74, the drive nuts 58, 66 pick up the load and maintain the preload on the seal assemblies 31, 33. The tool 74 can then be removed. A seal arrangement 85 according to a second embodiment of the invention will now be described with reference to FIG. 5. The seal arrangement 85 shown in FIG. 5 is similar in most respects to the seal arrangement 30 shown in FIGS. 2 to 4. The main difference is that the seal arrangement 85 of FIG. 5 includes a retainer nut 86 as a separate component from the seal housing 87. The retainer nut 86 has external threads 88 which are threaded into the internal threads 47 of the ICI housing 24 until the retainer nut 86 is seated against the upper end of the ICI housing 24. The seal housing 87 is installed over the retainer nut 86 after the retainer nut 86 is seated in the ICI housing 24. An inwardly directed flange 89 at the upper end of the seal housing 87 engages an upper surface of the retainer nut 86 to maintain the vertical positioning of the seal housing 87. The seal housing 87 and retainer nut 86 are both preferably fabricated from a stainless steel alloy that resists galling and seizing of threads, such as NITRONIC(trademark) 60 Stainless Steel. The installation tool 74 shown in FIG. 3 is used for installing and removing the seal arrangement 85 of FIG. 5 in the same manner described above. A seal arrangement 90 according to a third embodiment of the invention will now be described with reference to FIGS. 6 to 8. The seal arrangement 90 shown in FIGS. 6 to 8 is similar in many respects to the seal arrangement 85 shown in FIG. 5. The main difference is that the seal arrangement 90 of FIGS. 6 to 8 relies upon the torque applied to the lower and upper drive nuts 91, 92 to compress and load the lower and upper seal assemblies 93, 94 during installation, rather than a hydraulic installation tool. The seal arrangement 90 of FIGS. 6 to 8 includes a first lower seal assembly 93 enclosed by a lower end of a seal housing 95, and a second upper seal assembly 94 enclosed by an upper end of the seal housing 95. A first lower compression collar 96 and a second upper compression collar 97 are installed against the respective lower and upper seal assemblies 93, 94. The lower and upper compression collars 96, 97 each have anti-rotation keys 98, 99 protruding radially outwardly, as shown in FIG. 8, for example. The lower and upper ends of the seal housing 95 have mating keyways 100, 101 formed therein into which the anti-rotation keys 98, 99 of the compression collars 96, 97 are received. The compression collars 96, 97 act as a bearing surface for the applied thrust loads and prevent rotational loads on the seal rings of the respective seal assemblies 93, 94. Thrust bearing rings 102, 103 are installed between each of the drive nuts 104, 105 and the respective compression collars 96, 97. The thrust bearing rings 102, 103 reduce the rotational frictional drag as the drive nuts 104, 105 are tightened. The thrust bearing rings 102, 103 can be eliminated if the compression collars 96, 97 are fabricated of a good bearing material. The seal housing 95 has at least a pair of flat surfaces 106, 107 formed intermediate its ends on an external perimeter for engagement by a wrench (not shown) to prevent rotation during torquing of the upper and lower drive nuts 104, 105. For example, the external perimeter of the seal housing 95 can be hexagonal shaped. As shown in FIG. 6, the diameter of the threaded portion of the lower drive nut 104 is larger than the diameter of the threaded portion of the upper drive nut 105. The inner diameter of the flange 108 of the lower drive nut 104 and the corresponding portions of the lower compression collar 96 are also larger than the inner diameter of the flange 109 of the upper drive nut 105 and the corresponding portions of the upper compression collar 97. A method of installing the seal arrangement 90 of FIGS. 6 to 8 will now be described. As in the embodiments described above, the existing O-rings in the grooves 25 on the ICI 23 can be removed and discarded because they are not required with the seal arrangement 90 of the present invention. After the refueling is completed, the ICI 23 is reinserted to a proper depth. Spacers 51 are added according to the existing procedure to a defined height. The retainer nut 86 is then seated in the upper end of the ICI housing 24. The lower drive nut 104, lower thrust bearing ring 102, lower compression collar 96, and seal rings of the lower seal assembly 93 are lowered over the outside of the ICI housing 24. The seal housing 95 is then placed over the retainer nut 86 with its upper flange 110 seated against the upper surface of the retainer nut 86. The lower seal assembly 93, lower compression collar 96, lower thrust bearing ring 102, and lower drive nut 104 are then installed to the lower end of the seal housing 95. The lower drive nut 104 is torqued using a wrench (not shown) until a sufficient load is placed on the lower seal assembly 93 to prevent leakage under full system pressure. A second wrench (not shown) is used to engage the flat surfaces 106, 107 on the seal housing 95 to prevent rotation of the seal housing 95 when the lower drive nut 104 is being torqued. The upper seal assembly 94, upper compression collar 97, and upper thrust bearing ring 103 are then installed over the ICI 23 and seated into the upper end of the seal housing 95. While pulling the ICI 23 up slightly by hand to close any gaps with the spacers 51, the upper drive nut 105 is threaded onto the upper end of the seal housing 95 and torqued using a wrench until a sufficient load is placed on the upper seal assembly 94 to prevent leakage under full system pressure. The seal arrangements 30, 85, 90 described above provide the following advantages over the existing technology: (1) no field cutting or welding are required; (2) the existing ICIs and ICI housings can be reused, even with damaged O-ring sealing surfaces; (3) the seal assemblies will seal the expected pressure without machining or polishing the existing parts; (4) the seal arrangements can be assembled quickly and easily by hand; (5) the ICIs do not need to be withdrawn any further than normal to install the seal arrangements; (6) the existing O-rings can be eliminated making the ICI removal and insertion process easier; (7) the seal arrangements can be fit and installed into smaller areas of access; and (8) the seal arrangements can be reused throughout the life of the plant. While the invention has been specifically described in connection with specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation, and the scope of the appended claims should be construed as broadly as the prior art will permit.
	claims	1. A dynamic pattern generator for reflection electron beam lithography comprising:conductive pixel pads;an insulative border surrounding each conductive pixel pad so as to electrically isolate the conductive pixel pads from each other; andconductive elements coupled to the conductive pixel pads for controllably applying voltages to the conductive pixel pads,wherein the conductive pixel pads are cup shaped with a bottom portion, a sidewall portion, and an open cavity. 2. The dynamic pattern generator of claim 1, wherein the cup-shaped pixel pads provide high contrast between reflective and absorptive pixels by reducing backscattering of low energy electrons. 3. The dynamic pattern generator of claim 1, wherein a height of the sidewall portion is greater than a width of the bottom portion. 4. A pattern generating apparatus comprising:conductive pixel pads;conductive elements coupled to the conductive pixel pads for controllably applying voltages to the conductive pixel pads;an insulative border surrounding each conductive pixel pad so as to electrically isolate the conductive pixel pads from each other; anda well structure with sidewalls and a cavity configured above each conductive pixel pad. 5. The apparatus of claim 4, wherein the sidewalls comprise alternating layers of conductive and insulative materials. 6. The apparatus of claim 5, wherein the sidewalls comprise at least three layers of insulative material alternating with at least three layers of conductive material. 7. The apparatus of claim 6, wherein voltages are applied to three layers of conductive material in the sidewalls. 8. The apparatus of claim 7, wherein a first voltage applied to an upper conductive layer away from the pixel pad is a small positive voltage, a second voltage applied to a middle conductive layer in a middle region of the sidewalls is a large positive voltage, a third voltage applied to a lower conductive layer close to the pixel pad is a negative voltage. 9. The apparatus of claim 8, wherein a zero voltage is applied to a pixel pad to be in an absorptive state, and a positive voltage between the first and second voltages is applied to a pixel pad to be in a reflective state. 10. The apparatus of claim 6, wherein a voltage applied to at least one of the conductive layers is adjusted to change a numerical aperture of a reflected beam of electrons when a pixel pad is in a reflective state. 11. The apparatus of claim 4, wherein a height of the sidewalls is greater than a width of the conductive pixel pads. 12. A method of reflective electron beam lithography, the method comprising:forming an incident electron beam;directing the incident electron beam to a dynamically patterned structure having conductive pixel pads with a sidewall surrounding each pixel pad;reflecting electrons from a first set of pixel pads of the dynamically patterned structure having a lower voltage level applied thereto;absorbing electrons from a second set of pixel pads of the dynamically patterned structure having a higher voltage level applied thereto; anddirecting the reflected electrons towards a target substrate to imprint a lithographic pattern. 13. The method of claim 12, wherein the lithographic pattern of reflected electrons comprises an on/off pattern. 14. The method of claim 12, wherein the lithographic pattern of reflected electrons comprises a gray scale pattern. 15. The method of claim 12, wherein each pixel pad and surrounding sidewall comprises a cup-shaped conductive structure. 16. The method of claim 12, wherein the surrounding sidewall comprises alternating layers of insulative and conductive material, and wherein voltages are applied to the layers of conductive material.
	summary
	abstract	An efficient turbine system that preferably utilizes nuclear thermal energy in a unique combined Carnot cycle and Rankine cycle in a closed cogenerative and regenerative cycle with a condensible working fluid heated by the nuclear thermal energy and delivered to each stage of a multiple-stage gas turbine for isothermal expansion with a portion of the spent working fluid condensed and injected onto stators before and between the turbine blade stages and onto the turbine blades for a regenerative cogeneration expansion that supplements and combines with the primary working fluid in the staged gas turbine and in a final adiabatic expansion in a staged recovery turbine with work extracted by electric generators.
	abstract	Systems and methods for refueling a nuclear reactor that has a reactor core in a reactor pool having a plurality of elongated reactor core components, a fuel pool for storing core components, and a transfer channel connecting the fuel pool to the reactor pool. The method includes retrieving a replacement core component from the fuel pool, and securing the replacement core component in a first compartment of a handover assembly in a vertical position. The method also includes retrieving a spent core component from the reactor core, and securing the spent core component in a second compartment of the handover assembly in a vertical position. The replacement core component is retrieved from the first compartment and installed into the reactor core. The spent core component is retrieved from the second compartment and stored in a storage rack in the fuel pool.
	description	This application claims priority to U.S. Provisional Application Ser. No. 61/045,997, titled IDENTIFYING NUCLEAR MATERIAL and filed on Apr. 18, 2008, and U.S. Provisional Application Ser. No. 61/052,072, titled IMAGING SYSTEM and filed on May 9, 2008 both of which are herein incorporated by reference in their entirety. This disclosure relates to identifying fissionable material. Characteristics of a material may be determined based on the interaction of the material with radiation and neutral particles. In one general aspect, a system for detecting the presence of fissionable material includes a source of radiation that is switchable between a screening mode and a verification mode. The source of radiation is configured to produce, in the screening mode, a first type of radiation having a first energy and a second type of radiation having a second energy, the second energy being higher than the first energy, and to direct the first type of radiation and the second type radiation toward a physical region. In the verification mode, the system is configured to produce a third type of radiation, and to direct the third type of radiation toward the physical region, the third type of radiation being sufficient to induce fission in a fissionable material. The system also includes a sensor system that is configured to sense radiation having the first energy and the second energy from the physical region, and a sensor configured to sense a fission product. The system also includes a processor coupled to a computer-readable storage medium storing instructions that, when executed, capture data from the sensor configured to sense radiation having the first energy and the second energy, determine, for the physical region represented by the captured data, an absorption of the first type of radiation and the second type of radiation, determine whether the physical region is a region of interest based on the absorption, and cause the source of radiation to switch from the screening mode to the verification mode when the physical region is a region of interest. Implementations may include one or more of the following features. The first type of radiation may be x-ray radiation, and the second type of radiation may be x-ray radiation. To determine whether the physical region is a region of interest based on the absorption, the processor may be operable to determine an effective atomic number of the physical region. The third type of radiation may be x-ray radiation having an energy that is lower than the energy of the first energy. The first type of x-ray radiation may have an energy spectrum with a maximum energy of 6 MeV, the second type of x-ray radiation may have an energy spectrum with a maximum energy of 9 MeV, and the third type of x-ray radiation may have an energy spectrum with a maximum energy of 10 MeV. The first type of radiation, the second type of radiation, and the third type of radiation may be the same type of radiation. The first type of radiation, the second type of radiation, and the third type of radiation may be different types of radiation. The system also may include a track configured to support the source, and enable the source to move along the track with respect to the physical region. The source and the sensor system may move concurrently with respect to the physical region. The physical region may a region within a larger region, the source may moves with respect to the larger region during the screening mode, and the physical region may be determined to be a region of interest. The source may be moved to the physical region during the verification mode. The system also may include a photo-neutron conversion target configured to produce, in response to interaction with the third type of radiation, a neutron of sufficient energy to cause fission in a fissionable material. The photo-neutron conversion target may be made of beryllium, deuterium, or lithium. The conversion target may be between the source and the physical region. The conversion target may be coupled to the source. The source of radiation may include a first source of radiation and a second source of radiation that is separate from the first source of radiation. The first source of radiation may produce the first type of radiation and the second type of radiation in the screening mode, and the second source of radiation may produce the third type of radiation in the verification mode. The first type of radiation, the second type of radiation, and the third type of radiation may be produced by a single source of radiation that is configured to operate in multiple modes, including the screening mode and the verification mode. In another general aspect, the presence of fissionable material may be detected. A first type of radiation may be directed, from an imaging system in a screening mode, towards a physical region. The first type of radiation has a first energy. A second type of radiation may be directed, from the imaging system in the screening mode, towards the physical region. The second type of radiation has a second energy that is higher than the first energy. An absorption characteristic of the physical region may be determined based on an absorption of the first type of radiation and the second type of radiation by the physical region. Whether the physical region is a region of interest is determined from the absorption characteristic. The imaging system switches from the screening mode to a verification mode in response to determining that the physical region is a region of interest. In the verification mode, a third type of radiation is directed toward the physical region. The third type of radiation is sufficient to induce fission in a fissionable material. Whether a fissionable material is present in the physical region is determined based on an interaction between the third radiation and the physical region. Implementations may include one or more of the following features. The first type of radiation may be x-ray radiation, the second type of radiation may be x-ray radiation, and the third type of radiation may be a photon or a neutron. Radiation from a fission product emitted from the physical region may be detected after the source of the third type of radiation is turned off. The absorption characteristic may be an effective atomic number. The physical region may be a region of interest. The imaging system may be moved during the screening mode, and the imaging system may be moved to the physical region at the beginning of the verification mode. Fissionable material may be identified. In another general aspect, an imaging system for discriminating fissionable materials from other high-effective atomic number materials includes a source configured to produce dual-energy x-ray radiation sufficient to cause fission in fissionable materials, and to direct the dual-energy x-ray radiation sufficient to cause fission in fissionable materials towards a physical region. The system also includes a sensor configured to sense x-ray radiation and a product of fission from the physical region, and a processor operable to determine an absorption of the dual-energy x-ray radiation by the physical region based on the sensed x-ray radiation, and to determine whether the physical region includes fissionable material based on the presence of a product of fission. Implementations of any of the techniques described above may include a method, a process, a system, a device, an apparatus, or instructions stored on a computer-readable medium. The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims. Techniques are described for discriminating fissionable materials from materials that, because they have a relatively high effective atomic number, are of interest but are not fissionable. Many fissionable materials may be weaponizable (e.g., made into a weapon) or pose other types of hazards not necessarily posed by materials having a high effective atomic number. Using a dual-energy x-ray imaging system, a portion of a physical region is determined to be a region of interest if the portion is associated with a high effective atomic number. The region of interest is further examined to determine whether the region of interest includes a fissionable material by exposing the region of interest to a type of radiation that is sufficient to induce fission in a fissionable material. The type of radiation is associated with a particular type of particle (e.g., a neutron or a photon) and an energy spectrum that has a maximum energy. The type of radiation that the region of interest is exposed to may be, for example, a neutron or a photon that has an energy sufficient to cause fission in fissionable materials. In some examples, the type of radiation that is sufficient to induce fission may be x-ray radiation that is produced by the dual-energy x-ray imaging system. The techniques discussed below may be used, for example, to screen large cargos and/or cargo containers at a seaport, a boarder checkpoint, a rail yard, and/or an airport or to screen smaller cargos that are hand-portable by passengers at a rail station, airport, seaport, and/or bus depot. Thus, the physical region may be all or a portion of such a container or cargo. In particular, a dual-energy detection system and delayed gamma/neutron nuclear detection techniques are used to identity fissionable material, including, for example, shielded nuclear material. The absorption of x-ray radiation by a material may be used to determine an effective atomic number of the material. High-Z materials (e.g., materials that have a relatively high effective atomic number) are typically materials of interest because high-Z materials (such as lead) may be used to shield hazardous nuclear material or the materials themselves (such as uranium) may be weaponizable. Systems that determine regions of interest based on effective atomic number may produce an alarm and/or an representation of a location of a region of interest when a material having an effective atomic number over a pre-determined threshold is detected. However, in applications that look for fissionable materials, alarms generated for materials that have a high-Z but are not fissionable should be distinguished from alarms generated for materials that are fissionable in order to more accurately and quickly identify fissionable materials. The techniques discussed below may be used to discriminate between fissionable materials, some of which may be used to make weapons or other hazardous products, and non-fissionable materials that have a high effective atomic number. FIGS. 1A-1C illustrate a plan view of an example system 100 for discriminating fissionable materials from non-fissionable materials that have a relatively high effective atomic number. In the example of FIG. 1A, the system 100 is operating in a screening mode at a time “t1” and, in FIGS. 1B and 1C, the system 100 is operating in a verification mode at times “t2” and “t3.” As discussed in more detail below, in the screening mode, the system 100 determines whether a physical region 105 includes a region of interest by scanning the physical region 105, or a portion of the physical region 105, with dual-energy x-ray radiation from a source 110 to determine whether the physical region 105, or the portion of the physical region 105, includes a region that has a high effective atomic number (e.g., a region having a Z of seventy-two or greater). In the verification mode, the system 100 scans one or more regions of interest identified in the screening mode with a type of radiation that causes fission in fissionable materials. For example, the type of radiation may be a beam of neutral particles sufficient to first cause fission and then the production of delayed fission product radiation in a fissionable material. The type of radiation may be the same as the energy used in the scanning mode. The system 100 determines whether the regions of interest include a fissionable material. As discussed in greater detail with respect to FIG. 2, the effective atomic number of materials in the physical region 105 may be determined based on the absorption of the x-ray radiation by the materials. A portion of the physical region 105 may be identified as a region of interest if the portion is associated with a relatively high effective atomic number (Z). For example, materials having a high effective atomic number (e.g., materials having a “Z” of 72 or above), such as lead and uranium, tend to be materials of interest because such materials may be used for shielding of hazardous materials or may themselves pose a threat. However, a high effective atomic number does not definitively indicate whether the material is a fissionable material that may be used to make a weapon or otherwise pose a significant threat. For example, both lead and uranium have high effective atomic numbers (Z=82 and Z=92, respectively). However, lead is not weaponizable, whereas some forms of uranium are weaponizable. Thus, by performing a second scan of the identified region of interest with radiation capable of inducing fission in fissionable materials, the presence of fissionable material in the region of interest may be determined. For example, after the region of interest is identified in the screening mode, a type of radiation sufficient to cause fission in fissionable materials may be directed toward the region of interest. For example, the type of radiation may be neutrons that are produced using a photo-neutron conversion target. In this example, interactions between the incident neutrons and materials in the region of interest causes fission and the production of delayed fission products if fissionable materials are present in the region of interest. In another example, the type of radiation may be the same as that used during the screening mode. In these examples, one of the two x-ray beams generated by the dual-energy x-ray system may be switched to a higher energy level (such as 10 MeV) and directed toward the region of interest. Fission is an exothermic reaction in which the nucleus of an atom splits into smaller parts. Fission may release energy as both electromagnetic radiation in the form of gamma rays and as kinetic energy in the form of free neutrons that are released from the fission reaction. Detection of delayed fission products (e.g., gamma rays and/or neutrons) from the region of interest indicates the presence of a fissionable material. The delayed fission products may be fission products that are emitted from the region of interest after the incident neutral particles provided by the source have been extinguished. Accordingly, fissionable materials may be distinguished from among other materials in the physical region that have a high effective atomic number. In some implementations, the region of interest also may be exposed to neutrons of different energies, a “slow” neutron that only induces fission in weaponizable materials and a “fast” neutron that induces fission in all, or almost all, fissionable materials. In these implementations, the fissionable materials in the region of interest may be further separated into weaponizable materials and non-weaponizable materials. The weaponizable material may be a special nuclear material (SNM). In the example shown in FIGS. 1A-1C, the physical region includes objects 106, 107, and 108. The object 106 is an innocuous object that does not have a high effective atomic number and is not fissionable. The object 106 may be, for example, a cardboard box full of foam peanuts that protect a set of glassware. The object 107 is uranium and the object 108 is lead. Thus, the objects 107 and 108 have high effective atomic numbers, and the system 100 identifies a region 103 in the vicinity of the object 107 and a region 104 in the vicinity of the object 108 as regions of interest during the screening mode. However, during the verification mode, only the uranium object 107 is identified as a fissionable material. The system 100 includes a source 110 and a sensor 120. The source 110 is switchable between the screening mode and the verification mode. During the screening mode, the source 110 emits x-ray radiation at two different energies. The two different energies used in the screening mode may be x-rays having an energy spectrum with a maximum energy of between, for example, four Mega-electron volts (MeV) and ten MeV. In other examples, and in the verification mode, the source may produce radiation having an energy spectrum with a maximum energy above 10 MeV and/or below 4 MeV. The x-ray radiation at the two different energies may be referred to as a dual-energy x-ray 115. The source 110 may include two x-ray sources, each of which produce radiation at a fixed energy level, or the source 110 may include one x-ray source that operates at one of a few selectable energies. The sensor 120 is a sensor that is sensitive to x-ray radiation (e.g., the sensor 120 produces an electrical or light signal to indicate detection of x-ray radiation) and to products of fission. In some implementations, the sensor 120 includes more than one detector and/or sensor. The sensor 120 may be considered to be a sensor system that includes detectors that are sensitive to x-ray radiation and detectors that are sensitive to fission products. In the screening mode, the source 110 directs the dual-energy x-ray 115 toward to the physical region 105, the dual-energy x-ray 115 passes through the physical region 105 while being attenuated by materials within the physical region 105, and exits the physical region 105 toward the sensor 120. If the physical region 105 is partially or completely enclosed by a container (not shown), the dual-energy x-ray 115 has sufficient energy to penetrate the container and enter the space within the container. The sensor 120 detects the attenuated dual-energy x-ray radiation and creates two images of the physical region 105 based on the attenuated dual-energy x-ray radiation. One of the images is an image that represents the absorption of x-ray radiation at the first energy level by the physical region 105, and the second image represents the absorption of x-ray radiation at the second energy level by the physical region 105. The absorption characteristics of the physical region 105, such as the effective atomic number of the region 105, may be determined from the sensed attenuated x-ray radiation. The uranium object 107 and the lead object 108 are identified as being or including materials of a high effective atomic number and are respectively flagged as the regions of interest 103 and 104. Referring to FIG. 1A, the source 110 and the sensor 120 move with respect to the physical region 105 in a direction “d,” which allows the entire physical region 105 to be imaged during the screening mode. In other implementations, the source 110 and the sensor 120 may be fixed and the physical region 105 may move with respect to the source 110 and the sensor 120. A portion of the physical region 105, rather than the entire physical region 105, may be imaged in the screening mode. The source 110 also emits radiation sufficient to cause fission in fissionable materials, and the fission produces fission products (e.g., free neutrons and/or gamma rays). In the screening mode, the regions of interest 103 and 104, which respectively include the object 107 and the object 108, were identified. Upon receiving an indication that a region of interest is present, the source 110 switches from the screening mode to the verification mode and the source 110 moves to the a location corresponding to the region of interest that was identified in the screening mode. The source 110 and the sensor 120 may move concurrently and in tandem together. In some implementations, the physical region 105 moves such that an identified region of interest is positioned in front of the source 110. Referring to FIG. 1B, in the verification mode, the source 110 emits radiation 125 toward the region of interest 103, which includes the uranium object 107. The radiation 125 is a type of radiation that is sufficient to cause fission in fissionable materials. The type of radiation 125 is defined by a particle type and an energy spectrum. For example, the radiation 125 may be a beam of neutral particles (e.g., a beam of neutrons or photons) that have an energy sufficient to cause fission in fissionable materials. As discussed in more detail with respect to FIGS. 2 and 6, in examples in which the radiation is a beam of neutrons, the radiation 125 may be created by switching the energy level of one of the x-rays to a lower energy level and causing the emitted x-ray to interact with a photo-neutron conversion target (not shown). The photo-neutron conversion target emits neutrons in response to being struck by photons having sufficient energy to eject a neutron from a nucleus of the material that makes up the photo-conversion target. The photo-neutron conversion target also may be referred to as the conversion target. The photons that strike the conversion target are produced by striking a bremsstrahlung target with a beam of electrons. The generated photons then strike the conversion target. Because the eventual conversion to neutrons involves the used of both the tungsten target and the photo-neutron conversion target, the conversion target also may be considered a secondary target, and the bremsstrahlung target may be considered a primary target. In some implementations, the energy from the source 110 may be increased to ten MeV or greater to create the radiation 125 without the use of a conversion target. At the time “t2,” the radiation 125 travels into the physical region 105 and strikes the object 107. Because uranium is a fissionable material, fission begins and fission products 130, in addition to neutrons that may be present in the radiation 125, are released from the physical region 125 and sensed by the sensor 120. The fission reaction causes prompt fission products and delayed fission products. The delayed fission products may be daughter neutrons that are released from the fission reaction with the uranium object 107, and the delayed fission products may be present even after the radiation 125 is extinguished (e.g., after the source 110 is turned off or directed away from the physical region 105). For example, the delayed fission products may be present 10 milliseconds (ms) after the radiation 125 is extinguished. The presence of the delayed fission products indicates that, in addition to being a high-Z material, the object 107 is also a fissionable material. In some implementations, the prompt fission products also may be detected. Referring to FIG. 1C, at a time “t3,” the source 110 is still operating in the verification mode, and the source 110 and the detector 120 move to a location corresponding to the region of interest 104. The region of interest 104 includes the lead object 108. The source 110 emits the radiation 125 toward the region of interest 104. In contrast to the uranium object 107, the lead object 108 is not a fissionable material, and, thus, fission products are not created from the interaction between the radiation 125 and the lead object 108. Although, in examples where the radiation 125 is a type of radiation having neutron particles, the sensor 120 may detect the presence of neutrons while the radiation 125 illuminates the region of interest 104, no delayed fission products are detected at the sensor 120. Accordingly, the lead object 108 is not identified as a fissionable material. Thus, the system 100 may be used to distinguish between high-Z materials that are fissionable and those that are non-fissionable. In the example shown in FIGS. 1A-1C, the physical region 105 is scanned in the screening mode and regions of interest 103 and 104 are identified. The regions of interest 103 and 104 are scanned again in the verification mode, which occurs after the scanning of the physical region 105. However, in other examples, the verification of each region of interest may occur immediately, or soon after, the region of interest is identified. Thus, in some implementations, the sensor 110 may switch from the screening mode to the verification mode before the entire physical region 105 is screened. Additionally, the sensor 110 may switch from the verification mode back to the screening mode. FIG. 2 illustrates a plan view of an example system 200 in which two separate imaging systems 210 and 220 generate and detect x-rays 270 and 275 that have two different energies. The two different energies may be, for example two energies between 4 MeV and 10 MeV. The example system 200 may be referred to as a dual energy system and represents only an example configuration of a dual energy system. The example system 200 also includes a post-screener linac that may be used to expose regions of interest identified by the dual-energy system to radiation sufficient to cause fission in fissionable materials. In the example shown in FIG. 2, the post-screener linac is part of the dual-energy system. In particular, either or both the sources 212 and 224 includes a source that has an adjustable energy level, and the source may be set to emit an energy that is sufficient to cause fission in fissionable materials. In some implementations, the post-screener linac may be a separate from the imaging systems 210 and 220. Referring to FIG. 2, the x-rays 270 and 275 interact with objects 230A-230D after passing through a surface of a container 240 in which the objects 230-230D are located. X-ray radiation that is not absorbed by the objects 230A-230D or the container 240 are sensed by detectors 212 and 222. Detection of the x-ray radiation that is not absorbed by the objects 230A-230D allows determination of characteristics of the materials that make up the objects 230A-230D. For example, and as described below, a characteristic related to the effective atomic number of the materials that make up the objects 230A-230D may be determined based on the absorption of x-ray radiation by the materials. The effective atomic number may be used to determine whether the objects 230A-230D may include contraband or hazardous items, such as nuclear material. For example, items having a relatively high effective atomic number (e.g., a Z of 72 or greater), may be an item of interest. An alarm, alert, or other indicator may be provided in response to a determination that the objects 230A-230D include a high-Z material. The indicator includes a location corresponding to the material such that the post-screener linac may be moved to the region of interest (or the container 240 moved relative to the dual-energy system) to scan the region of interest and determine whether the region of interest includes fissionable materials. In the example shown, the container 240 is a truck. However, the container 240 may be any type of vessel. In some cases, the container 240 is a large container used in the transportation system, such as, for example, a shipping container, a rail car, or an automobile. In other examples, the container 240 also may be a smaller container, such as a suitcase, a package, a trunk or even a smaller item. The imaging systems 210 and 220 each include a source that generates X-rays having a particular energy and a detector that senses X-rays having that particular energy level. In particular, the imaging system 210 includes a detector 212 and a source 214, and the imaging system 220 includes a detector 222 and a source 224. The sources 214 and 224 may be, for example, Varian Linatron M9 X-ray® sources available from Varian Medical Systems of Las Vegas, Nev. The sources 214 and 224 may operate at either a fixed energy level or at one of a few, selectable energy levels. In the example shown in FIG. 2, the imaging systems 210 and 220 are mounted on a gantry and the imaging systems 210 and 220 move concurrently along rails 250 and 260. The imaging systems 210 and 220 scan the container with x-rays 270 and 275 as the imaging systems 210 and 220 move along the rails 250 and 260 in a direction 280. In the example shown, the imaging systems 210 and 220 are physically connected such that they move in tandem. However, in some implementations the imaging systems 210 and 220 may move independently of each other. In these implementations, the imaging systems 210 and 220 may be configured to be connected to each other and disconnected from each other as required. The detectors 212 and 222 sense radiation that is not absorbed by the objects 230A-230D such that images of the objects 230A-230D may be created. X-rays 270 generated by the source 214 pass through the container 240 and interact With the objects 230A-230D. X-rays that are not absorbed by the objects 230A-230D reach the detector 212. Similarly, x-rays 275 generated by the source 224 that are not absorbed by the objects 230A-230D reach the detector 222. In general, the efficiency of a material in absorbing X-ray radiation provides an indication of the effective atomic number (“Z”) of the material. Thus, the amount of X-ray radiation reaching the detectors 212 and 222 provides an indication of how the materials that make up the objects 230A-230D absorb radiation, which also provides an indication of the effective atomic number of the materials. The rate at which materials absorb x-rays depends on the energy and the material. Thus, by comparing the amount of absorption by a material exposed to a lower-energy x-ray to the amount of absorption by the material when the material is exposed to a higher-energy x-ray, an indication of the effective atomic number of the material may be determined. If one material is present, the effective atomic number of the material may be determined from the comparison. When more than one material is present, various processing techniques may be applied to determine the effective atomic number of a particular material. Also, when more than one material is present, the average effective atomic number of the materials present may be determined from the comparison. At both lower energies and higher energies, high-Z materials, such as lead, are more attenuating (e.g., absorb more x-rays) than low-Z materials, such as concrete and organic goods. At lower energies, the increased absorption is due to the Compton effect. At higher energies, the increased absorption is due to pair-production. Thus, images of the low-Z material formed from the radiation detected as a result of exposure of the low-Z material to the higher-energy x-ray are distinguishable from images formed from the radiation detected as a result of exposure of the low-Z material to the lower-energy x-ray. In particular, the images of the low-Z material formed from exposure to the higher-energy x-ray may appear lighter as a result in a change in the amount of signal that passes through the material (e.g., the images formed from exposure to the higher-energy x-rays have a lower relative intensity as compared to the images formed from exposure to the lower-energy x-rays). The relative change in intensity of the signal is dependent on material and the energies used. For example, low-Z and high-Z materials both absorb the lower-energy x-ray; however, only high-Z materials absorb the higher-energy x-ray. Thus, the images of the low-Z materials and the high-Z materials formed from exposure to the lower-energy x-ray are similar, but the images formed from exposure to the higher-energy x-ray are not (the high-Z material appears dark while the low-Z material appears lighter). Accordingly, comparison of an image of an object formed from interaction between a lower-energy x-ray and the object with an image of the object formed from the interaction between a higher-energy x-ray allows a determination of whether the material that compose the object is a high-Z material. In this example, the higher-energy x-ray may have a peak energy of 9 MeV, and the lower-energy x-ray may have a peak energy of 6 MeV. The system 200 may be used to perform such a comparison. For example, the source 214 may generate a lower-energy x-ray that interacts with the objects 230A-230D. The radiation from the source 214 that is not absorbed by the objects 230A-230D is sensed by the detector 212. An image of the lower-energy x-ray interaction may be formed based on the sensed radiation. Similarly, the source 224 may generate a higher-energy x-ray that interacts with the objects 230A-230D. The radiation from the source 224 that is not absorbed by the objects 230A-230D is sensed by the detector 222. An image of the higher-energy x-ray interaction may be formed from the sensed radiation. The image of the lower-energy x-ray interaction and the image of the higher-energy x-ray interaction are aligned (or registered with each other) such that the corresponding portions of the objects 230A-230D in the images may be compared. More particularly, these images are aligned to account for the displacement of the imaging systems 210 and 220 along the direction 280 and are compared to determine if high-Z materials are present in the image. Because the imaging systems 210 and 220 are distinct imaging systems, the detectors 212 and 222 may be individually optimized for the sources 214 and 224, respectively. For example, use of the separate imaging systems 210 and 220 allows the detector 222, which is associated with the lower-energy source 224 in this example, to be larger than the detector 212. Because the photons in the lower-energy x-ray are less energetic than the photons in the higher-energy x-ray, the lower-energy beam is less penetrating. Thus, having the detector 222 be larger than the detector 212 may increase the number of lower-energy photons that are detected by the detector 222. Increasing the number of lower-energy photons may improve the image formed from the interaction with the lower-energy x-ray, which also may improve the comparison of the lower-energy image and the higher-energy image. Moreover, the use of the imaging systems 210 and 220 also may allow the sources 214 and 224 to be individually optimized to generate x-rays having a particular peak energy. The peak energy may be considered the maximum energy. For example, the sources 214 and 224 may be separately filtered to more precisely achieve generation of a particular energy, or band of energies, or to remove certain energies from the generated x-ray radiation. Such filtering may improve the quality of both the lower-energy image and the higher-energy image, which may improve the results of the comparison. Additionally, because the imaging systems 210 and 220 each have a source that generates x-rays, the overall number of photons available to interact with the objects 230A-230D is increased as compared to a system that has one x-ray source. Thus, using the sources 212 and 222 may improve the images generated by the imaging systems 210 and 220 by increasing the signal received by the detectors 212 and 222. Thus, the dual-energy system discussed above, which may be referred to as a pre-screening linac is used to identify regions of high-Z materials, and these regions may be referred to as regions of interest. In some implementations, a dual energy system at the MeV level (such as the dual-energy system discussed above) and a post-screener linac may be used to determined whether the regions of high Z material(s), which may be referred to as region(s) of interest, also include fissionable materials. Once a region of interest is identified, the energy of the pre-screener linac is changed to 10 MeV, the linac is moved to the region of interest, the region of interest is exposed to the 10 MeV beam, and specific material in the region of interest (or object or cargo) is identified by counting gammas and neutrons some time after the post-screener linac pulse has ended. Presence of a delayed neutron/gamma signal indicates a material of interest, which may be, for example, a nuclear material. Stated differently, shielded nuclear material detection may be based on detected delayed neutron/gamma signals from the region of interest (or object or cargo) that is consistent with photon or neutron induced fission. For example, photon detection for above 3 MeV and below 1 MeV neutrons may be made with high specificity. These techniques may help detect special nuclear material at the Z and isotopic level. In one example implementation, the dual energy system 200 of FIG. 2 with additional neutron/photon detectors and electronics may be used. In other implementations, the dual-energy system may use one of the sources 214 or 224 to generate high-energy photons from, for example, a pulsed laser integrated with one the sources 214 or 224. In other implementations, the energy of one of the sources 214 or 224 may be changed and the radiation produces by the source may interact with a photo-neutron conversion target such as deuterium, beryllium, or lithium. The photo-neutron conversion target creates neutrons from photo-neutron production. In particular, an electron beam strikes a tungsten target to produce photons. The photons interact with the conversion target and, if the photons have sufficient energy, the interactions between the photons and the conversion target produces neutrons by ejecting a neutron from the nucleus of an atom of the material from which the target is made. In some implementations, the type of radiation sufficient to cause fission may be considered a neutron or photon probes, and the probe may be based on the background Z determined. Neutron or photon probes may work best in different backgrounds. In some implementations, the predetermination of a region of high Z material may reduce the dose of neutron or photon probe needed. Some implementations may uniquely identify 100 cm3 of highly enriched uranium (HEU) and weapons-grade plutonium (WGPu), with or without shielding. In another example, some implementations may distinguish uranian-235 (U235) from uranium-238 (U238), which may require measurement beyond Z or fission. Some implementations may be configured to detect an enhanced fission rate or to detect relatively low energy neutron fission (e.g., fission that occurs as a result of radiation by a 1 MeV neutron). In these implementations, a “fast” neutron (e.g., a neutron having an energy greater than about 1.5 MeV) and a “slow” neutron (e.g., a neutron having an energy less than 1.5 MeV) are both directed toward the region of interest. The “slow” neutron causes fission in weaponizable materials (which may be special nuclear materials) but not in other fissionable materials. Thus, use of both the “slow” and “fast” neutrons may allow special nuclear materials to be distinguished from other fissionable materials. As discussed in more detail below with respect to FIG. 6, in implementations that use two separate sources (such as the sources 214 and 224), the radiation from the two sources may be used to interact with two separate targets made from different materials to produce neutrons of different energies (e.g., a “slow” neutron and a “fast” neutron). FIG. 3 presents an example process 300 that may be implemented by a dual energy detection system that uses delayed gamma/neutron nuclear detection techniques. The process 300 may be performed using a system such as the system 100 or the system 200 discussed above with respect to FIGS. 1A-1C and 2. A physical region (such as the physical region 105 or the truck 240) is scanned with a dual-energy source (310). The physical region may be scanned with x-ray radiation of two different energy levels during a screening mode. For example, the physical region may be scanned with two sources (such as the sources 214 and 224 discussed above with respect to FIG. 2) that are mounted on a gantry and that move concurrently with each other and with respect to the physical region such that the physical region is irradiated with radiation from the first source and then with radiation from the second source. In some implementations, the physical region moves with respect to the sources. The x-rays of both energy levels travel through the physical region and are attenuated. The attenuated x-rays are sensed with sensors (such as the sensors 212 and 222), and the sensed radiation is used to produce images of the absorption of the lower energy x-ray radiation and the higher energy x-ray radiation by the physical region. The images are compared as discussed above to determine an estimation of the effective atomic number of various portions of the physical region. Based on the estimated effective atomic number, it is determined whether a high-Z material is present in the physical region (320). A portion of the physical region having an estimated effective atomic number of seventy-two or more may be determined to include a high-Z material. Materials having a relatively high effective atomic number may be of interest because such materials may be used as shields for nuclear materials or such materials may be nuclear materials. To determine whether a high-Z material is present in the physical region, the estimated Z may be compared to a pre-determined threshold value. The pre-determined threshold value may be stored in an electronic storage, and the pre-determined threshold value may be adjustable by an operator of the system. If high-Z regions are present, the regions of high-Z are considered to be regions of interest, and the location of the high-Z regions of interest is determined based on the images produced by the detectors. If the physical region does not include any portions that have a high-Z, an “all-clear” indicator is presented (325). The “all-clear” indicator may be, for example, an alarm, message, or signal that indicates that the physical region does not include a high-Z material. Once the “all-clear” indicator is produced, the another physical region may be screened. If high-Z portions are present, the source (such as the source 110 or one or more of the sources 214 and 224) are moved, in a verification mode, to a location that corresponds to a location of a region of interest (330). In some implementations, the physical region is moved with respect to the source such that the region of interest is positioned to receive radiation from the source. In some implementations, a source that is separate from the source that produces the dual-energy x-rays is moved to the location corresponding to the region of interest. The region of interest is scanned using a technique that is based on characteristics of the background of the physical region (340). The region of interest is exposed to neutral particles (e.g., photons or neutrons) of sufficient energy to cause fission in fissionable materials. Scanning the region of interest with neutral particles and then detecting for the presence of delayed fission products allows high-Z materials that are also fissionable materials to be separated from high-Z materials that are not fissionable. The characteristics of the background may indicate the type of photon or neutron probes to use to probe the region of interest for the presence of fissionable materials. For example, if the region of interest has a relatively high effective atomic number, a lower-dose (e.g., lower energy) photon or neutron radiation may be used to cause fission as compared to the photon or neutron radiation energy needed to cause fission in a material having a lower effective atomic number. In some implementations, the neutral particles used to probe the region of interest for fissionable materials is produced by switching the source from the higher-energy level used in the dual-energy scan to a mode in which the source produces a 10 MeV beam of radiation (e.g., a beam of radiation having an energy spectrum with a maximum energy of 10 MeV), and the 10 MeV beam of radiation is directed toward the region of interest. In some implementations, the source includes two separate sources of x-ray radiation (such as the sources 214 and 224), and each of the sources is switched to a different energy level (e.g., switched to produce energy having a different energy spectrum and a different maximum energy). For example, in the screening mode, the source 214 may produce x-ray radiation of 6 MeV and the source 224 may produce radiation of 9 MeV. In the verification mode, the source 214 may be switched to produce 4 MeV radiation, and the source 224 may be switched to produce 9 MeV radiation. The radiation from the source 214 may be directed toward a conversion target that produces neutrons in response to being struck by photons having energy sufficient to eject a neutron from a nucleus of an atom of the material from which the conversion target is made. Thus, in this example, the neutral particles used to probe the region of interest for the presence of fissionable materials are the neutrons produced by the interaction between the 4 MeV radiation and the conversion target. The conversion target may be, for example, beryllium, lithium, or deuterium. The presence of delayed fission products is determined (350). The presence of delayed fission products (e.g., gamma rays or neutrons emitted from the region of interest after the probe that exposes the region of interest to neutral particles is removed) indicates that the region of interest includes a fissionable material. The delayed fission products may be, for example, daughter neutrons that are produced as the nuclei of fissionable materials in the region of interest split apart. These daughter neutrons are detected (at a detector such as the sensor 120) at a time after the incident neutral particles are removed and the daughter neutrons indicate the presence of a fissionable material. If no delayed fission products are detected, the “all-clear” indicator is presented (325). If delayed fission products are detector, fissionable material is present (360) and an alarm is produced (370). The alarm may be, for example, a sound, a message displayed to an operator of the system, a visual but non-audio warning, or an automated alert (such as an e-mail or text message sent to an operator of the system or to an automated process). FIG. 4 shows a block diagram of a system 400 used to identify fissionable materials. The system 400 includes a source system 410 and sensor system 450. Together, the source system 410 and the sensor system 450 determine whether a physical region 405 includes materials having a high effective atomic number and determine whether any such materials are fissionable materials. The source system 410 includes a dual-energy x-ray source 415 that produces a lower-energy x-ray (e.g., an x-ray of 6 MeV) and a higher-energy x-ray (e.g., an x-ray of 9 MeV) in order to determine an effective atomic number of a physical region 405. The source system 410 may include a photo-neutron conversion target 420 made of a material that produces neutrons in response to being struck with photons. The photo-neutron conversion target 420 may be made from beryllium, lithium, or deuterium. The source system 410 also may include a switch 425 that switches the source system 410 from a screening mode in which the source system 410 produces dual-energy x-ray radiation to a verification mode in which the source system 410 produces a type of radiation that is sufficient to cause fission in fissionable materials. The type of radiation may be the same type of radiation as radiation produced by the dual-energy x-ray system. The switch 425 may be activated upon receipt of a location, or other indication, of a region of interest identified in the screening mode. The verification mode is used to determine whether the region of interest includes fissionable materials. The source system 410 also includes a processor 430, an electronic storage 435, source electronics 440, and an input/output module 445. The electronic storage 435 stores instructions, that when executed, cause the switch 425 to transition the source system 410 from the screening mode to the verification mode in response to receiving an indication of the presence of one or more regions of interest from the sensor system 450, from the electronic storage 435, or from an operator of the system 400. The processor also may cause the source system 410 to switch from the verification mode to the screening mode. The electronic storage 435 is an electronic memory module, and the electronic storage 435 may be a non-volatile or persistent memory. The processor 430 may be a processor suitable for the execution of a computer program such as a general or special purpose microprocessor, and any one or more processors of any kind of digital computer. Generally, a processor receives instructions and data from a read-only memory or a random access memory or both. The processor 430 receives instruction and data from the components of the source system 410 and/or the sensor system 450, such as, for example, a location and/or other indication of the presence of a region of interest that causes the source system 410 to switch from the screening mode to the verification mode. In some implementations, the source system 410 includes more than one processor. The input/output module 445 may be any device able to transmit data to, and receive data from, the source system 410. For example, the input/output device 445 may be a mouse, a touch screen, a stylus, a keyboard, or any other device that enables a user to interact with the source system 410. In some implementations, the input/output device 445 may be configured to receive an input from an automated process or a machine and/or configured to provide an output to an automated process or a machine. The system 400 also includes the sensor system 450. The sensor system 450 senses attenuated dual-energy x-ray radiation and fission products that emanates from the physical region 405 due to the irradiation of the physical region 405 by the source system 410. The sensor system 450 includes a dual-energy sensor 455, a fission product sensor 460, an absorption analyzer 465, a materials identifier 470, a processor 475, an electronic storage 480, and an input/output module 485. The dual-energy sensor 455 includes a sensor that is sensitive to the energy spectra present in the x-ray radiation produced by the dual-energy source 415. The dual-energy sensor 455 may be a scintillator that senses x-ray radiation emitted from the physical region 405 and produces a visible light signal in response. The intensity of the visible light signal is proportional to the intensity of the sensed x-ray radiation. The dual-energy sensor 455 also includes a photodetector, or other detector that is sensitive to visible light, that senses the visible light signal from the scintillator and produces an electrical signal in response. The current of the electrical signal is proportional to the intensity of the detected visible light, thus, the value of the electrical signal provides an indication of the intensity of the detected x-ray radiation. The electrical signal may be digitized by an analog-to-digital converter, and the digitized signal may be used to generate an image of the physical region 405 that represents the attenuation of the x-ray radiation by the physical region 405. Two such images may be generated, one representing the attenuation of the lower-energy x-ray from the dual-energy source 415 and the other representing the attenuation of the higher-energy x-ray from the dual-energy source 415. These images may be used to determine the effective atomic number of various portions of the physical region 405. The sensor system 460 also includes a fission product sensor 460 that is sensitive to fission products emitted from the physical region 405 in response to being irradiated with neutral particles from the neutral particle source 420. The fission product sensor 460 may be an array of scintillators that detect freed neutrons and/or gamma rays. For example, the fission product sensor 460 may be liquid or plastic scintillators and/or germanium (Ge) or high-performance germanium (HPGe) detectors. The sensor system 450 also includes the absorption analyzer 465 that determines absorption characteristics of the region of interest based on the radiation sensed by the dual-energy sensor 455. The absorption analyzer 465 determines the effective atomic number of various portions of the physical region 405, compares the effective atomic number to a pre-set threshold value to determine whether any of the various portions are regions of interest, and identifies locations corresponding to any regions of interest. The materials identifier 470 determines whether a fissionable material is present based on data from the fission product sensor 460. The sensor system 450 also includes a processor 475, an electronic storage 480, and an input/output module 485. The electronic storage 480 stores instructions, that when executed, cause the processor 475 to determine absorption characteristics (such as effective atomic number) of the physical region 405 that is scanned by the dual-energy x-rays produced by the dual-energy source 415 and imaged by detecting attenuated x-ray radiation at the sensor system 450. The electronic storage 480 may store a pre-determined threshold value for an effective atomic number above which a region is considered a region of interest. The electronic storage 435 also includes instructions that, when executed, cause the processor 475 and the materials identifier 470 to determine whether fissionable materials are present in the physical region 405. The electronic storage 435 also includes instructions, that when executed, cause the processor 475 to determine a location corresponding to an identified region of interest and to provide the location to the source system 410. The electronic storage 480 is an electronic memory module, and the electronic storage 480 may be a non-volatile or persistent memory. The processor 475 may be a processor suitable for the execution of a computer program such as a general or special purpose microprocessor, and any one or more processors of any kind of digital computer. Generally, a processor receives instructions and data from a read-only memory or a random access memory or both. In some implementations, the sensor system 450 includes more than one processor. The input/output module 485 may be any device able to transmit data to, and receive data from, the sensor system 450. For example, the input/output module 485 may be a mouse, a touch screen, a stylus, a keyboard, or any other device that enables a user to interact with the sensor system 450. In some implementations, the input/output module 485 may be configured to receive an input from an automated process or a machine and/or configured to provide an output to an automated process or a machine. Referring to FIG. 5, a plan view of another example system 500 for discriminating fissionable materials from non-fissionable materials that have a relatively high effective atomic number. Like the system 100 discussed above with respect to FIGS. 1A-1C, the system 500 may operate in a screening mode and a verification mode. In the screening mode, the source 110 emits dual-energy x-ray radiation, and in the verification mode, the source 110 emits neutral particles having energy sufficient to cause fission in fissionable materials. The system 500 includes a sensor system 510 having multiple detectors 511, 512, 513, and 514 that are placed along the physical region 105 to capture and sense the fission product 130 emitted from the region of interest 103 during the verification mode. Because fission products may be emitted equally in all directions (e.g., fission products are isotropically radiated), the sensor system 510 may be able to collect more fission products and produce a higher signal-to-noise ratio, thus improving the accuracy of the system 500 in detecting fissionable materials. A plain view of the system is shown in FIG. 5, which illustrates that the detectors 511, 512, 513, and 514 are placed equidistant from the physical region 105, the sensor system 510 also may include additional detectors (not shown) that are vertically above or below the detectors 511, 512, 513, and 514 and are equidistant from the physical region 105. Additionally, the sensor system 510 may include more or fewer detectors. In some implementations, the detectors included in the sensor system 510 may be arranged such that they are not equally spaced with respect to each other and/or the detectors included in the sensor system 510 may not be equidistant to the physical region 105. Referring to FIG. 6, a plan view of another example system 600 for discriminating fissionable materials from non-fissionable materials that have a relatively high effective atomic number. The system 600 also may be used to determine whether a fissionable material is also a weaponizable material. Like the system 100 discussed above with respect to FIGS. 1A-1C, the system 600 may operate in a screening mode and a verification mode. In the screening mode, the source 610 emits dual-energy x-ray radiation, and in the verification mode, the source 610 emits neutral particles having energy sufficient to cause fission in fissionable materials. The source 610 includes sources 615 and 620, each of which produce x-ray radiation. The source 615 produces lower-energy x-ray radiation, and the source 620 produces higher-energy x-ray radiation. For example, in the screening mode, the source 615 may produce x-ray radiation having an energy of 6 MeV, and in the verification mode, the source 615 may produce x-ray radiation having an energy of 4 MeV. In the screening mode, the source 620 may produce x-ray radiation having an energy of 9 MeV, and in the verification mode, the source 620 may produce x-ray radiation having an energy of 10 MeV. In the verification mode, the radiation emitted from the sources 615 and 620 interacts with photo-neutron conversion targets 625 and 630, respectively. The conversion targets 625 may be made of different materials. For example, the conversion target 625 may be made of beryllium and the conversion target 630 may be made of deuterium. The interactions between the radiation from the sources 615 and 620 and the conversion targets 625 and 630 result in the production of neutrons 635 and 640. The neutron 635 may be a “slow” neutron having an energy of less than 1 MeV, and the neutron 640 may be a “fast” neutron having an energy greater than 2 MeV. The “slow” neutron 635 causes fission only in certain fissionable materials, such as special nuclear materials and other weaponizable materials. In contrast, the “fast” neutron 640 may cause fission in almost all fissionable materials. Thus, by irradiating the region of interest 103 (which was identified as including a fissionable material) with both the “fast” neutron 640 and the “slow” neutron 635, the region of interest 103 may be examined to determine whether the region of interest 103 includes weaponizable materials. As shown in the example, the region of interest 103 emits fission product 650 in response to being irradiated with the “slow” neutron 635. Thus, the region of interest includes a special nuclear material or another type of weaponizable material. In some implementations, the techniques discussed above may provide advantages including, for example, increased throughput of cargo and automatic detection of nuclear material. For example, because a dual-energy x-ray system is used to first identify regions of interest based on effective atomic number, only portions of the physical region under examination are further probed with neutral particles to determine the presence of fissionable materials. A number of implementations have been described. Nonetheless, it is understood that other implementations are within the scope of the claims.
	abstract	A high-temperature nuclear reactor, cooled by a liquid fluoride salt, is described. The reactor uses an annular fuel pebble comprised of an inert graphite center kernel, a TRISO fuel particles region, and a graphite outer shell, with an average pebble density lower than the density of the liquid salt so the pebbles float. The pebbles are introduced into a coolant entering the reactor and are carried into the bottom of the reactor core, where they form a pebble bed inside a plurality of vertical channels inside one or more replaceable Pebble Channel Assemblies (PCAs). Pebbles are removed through defueling chutes located at the top of each PCA. Each PCA also includes channels for insertion of neutron control and shutdown elements, and channels for insertion of core flux mapping and other instrumentation.
050948083	abstract	The invention relates to an apparatus for detecting and measuring water production in oil and gas wells and in injection wells, involving a neutron source for activating oxygen atoms in any water produced or injected in the well, and a plurality of detectors, at least three (3) but preferably four (4), longitudinally spaced within the housing for detecting and counting gamma ray emissions resulting from the oxygen activation.
	description	The present disclosure relates generally to particle accelerators. More particularly, the present disclosure relates to a particle accelerator system and method for irradiating a product. Irradiation of products, whether they are food products or medical devices, is known in the art. The delivery of a sufficient minimum radiation dose is required to ensure efficacy of the process and compliance with regulations. The ability to maintain the radiation dose below a maximum value is required to avoid damage to the processed product and/or to remain below prescribed regulatory maxima for radiation doses. Irradiation of products with an irradiation dose that is uniform, to a certain degree, on and within surfaces of a given product is also known. The ratio of maximum dose to minimum dose is referred to as the dose uniformity ratio (DUR). In some prior art uniform dose irradiation systems, steel shutters and an x-ray beam are used to irradiate, one after the other, the surfaces of a product that is conveyed across the x-ray beam multiple times for each of the surfaces. The steel shutters are used to attenuate different widths of the x-ray beam each time the product is conveyed across the x-ray beam in order to obtain a final irradiated product that has received a uniform irradiation dose of x-rays. This is done to achieve a constant DUR for each portion of each surface of the product. Such prior art systems require multiple passes of the product across the x-ray beam and are inefficient in that they waste a considerable amount of x-ray radiation through the irradiation of the steel shutters during the multiple passes of the product across the x-ray beam. Therefore, improvements in systems and methods for the irradiation of products are desirable. It is an object of the present disclosure to obviate or mitigate at least one disadvantage of previous prior art systems. In a first aspect, the present disclosure provides a system for irradiating a product. The system comprises a radiation source to generate a radiation beam; a conveyor to move the product across the radiation beam to expose a surface of the product to the radiation beam in order to irradiate the surface; and a controller to control a speed at which the conveyor moves the product across the radiation beam. The speed is a function of a distance between a position at which the surface of the product is irradiated and a reference position. In a further embodiment, there is provided a method of irradiating a product. The method comprises: conveying a product across a radiation beam to expose a surface of the product to the radiation beam; and controlling a speed at which the product is conveyed across the radiation beam. The speed is a function of a distance between a position at which the surface of the product is irradiated and a reference position. Other aspects and features of the present disclosure will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments in conjunction with the accompanying figures. Generally, the present disclosure provides a system and method to irradiate a product with a substantially uniform irradiation dose, which reduces the DUR value of the irradiated product. The substantially uniform irradiation dose is attained by conveying the product across the path of a radiation beam (e.g., an electron beam or an x-ray beam) at a conveyor speed that varies as function of the position of the product with respect to the radiation beam. As an example, the conveyor speed function can be a quadratic function of the position of the product with respect to the radiation beam. Multiple faces or sides of the product can be exposed, in sequence (i.e., one after the other), to the radiation beam. For each surface, the product is conveyed across the radiation beam at a conveyor speed that varies as a function of the position of the product with respect to the x-ray beam. The conveyor speed function effectively modulates or controls the dose of radiation delivered to the product. Any suitable type of product can be irradiated. Examples of such product include food, e.g., produce, and medical devices. The present disclosure improves the efficiency, accuracy, and throughput of radiation processing of products by reducing the wasted ionizing energy delivered to the surfaces of products and by improving the DUR. FIG. 1 shows a block diagram representation of an embodiment of a system for multi-sided, intensity modulated irradiation of a product in accordance with the present disclosure. The system includes a radiation source 100 providing a radiation beam 102 to a product 104. The radiation beam 102 can be an electron beam, and x-ray beam, or any other suitable type of radiation beam. The radiation beam 102 is spread over an angle 2Ø, shown at reference numeral 103. The radiation beam is typically scanned in the z-direction i.e., perpendicularly to the x and y directions, along a height of the product being irradiated. The scanning in the z-direction can be controlled to deliver a substantially constant radiation dose to the product along the z-direction. As will be understood by the skilled worker, to enable x-ray irradiation, an electron source can be selected as the radiation source 100 to generate an electron beam and, an electron to x-ray converter (a bremsstrahlung converter) plate 107 can be placed between the radiation source 100 and the product 104. The output side 101 of the converter plate 107 radiates x-rays in a characteristic pattern along the same direction as the impinging electrons on the input side 109 of the converter plate 107. To irradiate the product 104, a conveyor 99 moves (conveys) the product 107 across the path of the radiation beam 102, along the x-direction 106, which is perpendicular to the central axis of 105 of the radiation beam 102. In a first pass across the radiation beam 102, the surface 108 of the product is irradiated. Subsequently, the product 104 is rotated by 90 degrees clockwise and the product is again conveyed along the x-direction 106 to irradiate the surface 110 of the product. Following irradiation of the surface 110, the product is again rotated by 90 degrees and conveyed in the x-direction 106 to irradiate the surface 112. Finally, the product is further rotated by 90 degrees and is conveyed in the x-direction 106 to irradiate the surface 114. As will be understood by the skilled worker, additional surfaces or fewer surfaces of the product can be irradiated without departing from the scope of the present disclosure. The y-direction is shown at reference numeral 111. A conveyor controller system 98 controls the speed of the conveyor 99. The conveyor 99 can include any suitable type of motor or actuator or any other type of displacement mechanism that can act to move the product 104 along a linear direction; the conveyor can include elements to allow the conveyor to rotate, lift, or rotate and lift, the product 104. The conveyor controller system 98 can include a processor and a computer-readable medium that has recorded thereon instructions to be carried out by the processor to control the motor or actuator or any other type of displacement mechanism to move the product 104. With reference to FIG. 2, for irradiation stemming directly from a radiation source, for example, the aforementioned radiation source 100, when the conveyor speed along the x-direction 106 is constant, the resulting irradiation dose (Dosed) at point ‘R’, which is at a depth ‘d’ from a surface (surface 108, 110, 112, or 114) and at an angle θ from the radiation source can be calculated using the following equation: Dose d = Dose 0 × 1 ( a + b ) 2 × e - 100 ⁢ μ ⁢ ⁢ b ⁢ ⁢ ρ ( equation ⁢ ⁢ 1 ) where Dose0 is the irradiation dose received directly at the point ‘R0’ on the surface 1000, θ = tan - 1 ⁡ ( h D + d ) , a = D cos ⁢ ⁢ θ , and ⁢ ⁢ b = d cos ⁢ ⁢ θ . ‘D’ is the distance between the irradiation source 100 and the surface 1000, ‘d’ is the depth for which the dose is calculated, and ‘h’ is the vertical distance from the irradiation source 100 to the point ‘R’. Further, μ is the mean mass attenuation coefficient of the product being irradiated by the radiation stemming from the irradiation source and ρ is the mean density of the product 104 being irradiated. In another example, FIG. 3 shows the product 104 being irradiated not directly from the irradiation source 100 but is instead from an x-ray converter plate 107 that is itself irradiated directly from the irradiation source 100. In this case, the resulting irradiation dose (xDosed) at point ‘R’, which is at a depth ‘d’ from the surface 1000 and at an angle θ from the radiation source can be calculated using the following equation: x ⁢ Dose d = x ⁢ Dose 0 × 1 ( a + b ) 2 × e - 100 ⁢ μ ⁢ ⁢ b ⁢ ⁢ ρ ( equation ⁢ ⁢ 2 ) where xDose0 is the irradiation dose received directly at the point ‘R0’ on the surface 1000, θ = tan - 1 ⁡ ( h L + t + D + d ) , a = D cos ⁢ ⁢ θ , and ⁢ ⁢ b = d cos ⁢ ⁢ θ . ‘L’ is the distance between the irradiation source 100 and the x-ray converter plate 107, ‘t’ is the thickness of the x-ray converter plate 107, ‘D’ is the distance between the x-ray converter plate and the surface 1000, ‘d’ is the depth for which the dose is calculated, and ‘h’ is the vertical distance from the irradiation source 100 to the point ‘R’. Further, μ is the mean mass attenuation coefficient of the product being irradiated by the x-rays stemming from the x-ray converter plate 107 and ρ is the mean density of the product 104 being irradiated. FIG. 4 shows an example of an irradiation dose profile for the product 104 when the product 104 (shown in FIG. 1) is moved a constant speed across the beam 102 (shown in FIG. 1). In this figure, side 1 can be considered to be surface 108 (shown at FIG. 1) and side 2 can be considered to be surface 110 (shown at FIG. 1). As evidenced by FIG. 4 there is a higher dose at the edges of the product than at the center. In this example, the dose uniformity ratio (DUR) is about 6.3:1. The inventors have discovered that by varying the speed at which the product 104 is conveyed across the beam, that an improved DUR can be obtained. As an example, instead of the product 104 being conveyed across the beam 102 at constant speed, conveying the product 104 at a speed that is a quadratic function of the distance between the beam and the center of the product 104 can produce an improved DUR. As an example of such a quadratic function, the speed of conveying the product 104 across the radiation beam 102 can be set in accordance with the speed function (SF):SF(x)=2.45x2−2.7x+0.905 (equation 3)where ‘x’ is equal to the difference between the x-coordinate at which the product is being irradiated and ‘xc’, which is the center of the side of the product being irradiated. This is represented at FIG. 5 where ‘x1’ is at one edge of the product and ‘x2’ is at the opposite edge. In this embodiment, the conveyor controller system 98 is configured to move the product in accordance with the speed function of equation 3. That is, the computer-readable medium of the conveyor controller system 98 has recorded thereon instructions to be carried out by the processor of the conveyor controller system 98 to control the motor or actuator or any other type of displacement mechanism to move the product 104 in accordance with the speed function of equation 3. FIG. 6 shows a plot of the speed at which product 104 is conveyed across the radiation beam 102 as a function of ‘x-xc’. The speed is greater when the product 104 is irradiated near ‘x1’ or ‘x2’ than when the product is irradiated at position ‘xc’. Essentially, the conveyor speed is reduced as the product 105 goes from being irradiated at the edge ‘x1’ to being irradiated at the center ‘xc’ and then, the conveyor speed is increased as the product is conveyed to be irradiated at the edge ‘x2’. By irradiating each side of the product 105 in accordance with the conveyor speed function of equation 3, the uniformity of the irradiation dose delivered and, the DUR is improved as evidenced by FIG. 7 where the DUR, in this example, is about 1.22:1. In the example of FIG. 7, the mean product density is 0.8 g/cm3. Even though equation 3 is a quadratic speed function, any other type of speed function is to be considered within the scope of the present disclosure. For example, the polynomial speed function of equation 4 below is also within the scope of the present disclosure.SF(x)=anxn+an-1xn-1+ . . . +a2x2+a1x+a0 (equation 4)with ‘n’ being a positive integer and ‘ai’ being the polynomial coefficients. As will be understood by the skilled worker, the polynomial coefficients ‘ai’ can be obtained by radiation simulations. FIGS. 8, 9 and 10 show examples of quadratic coefficients of the speed control function for different speed function and mean product densities. In these examples, x-ray radiation is used to irradiate the product. In the example of FIG. 8, the mean product density is 0.2 g/cm3 and the speed function is:SF(x)=x2−1.5x+0.905 (equation 5)This produces a DUR=1.265. In the example of FIG. 9, the mean product density is 0.4 g/cm3 and the speed function is:SF(x)=1.9x2−2.2x+0.905 (equation 6)This produces a DUR=1.248. In the example of FIG. 10, the mean product density is 0.8 0.6 g/cm3 and the speed function is:SF(x)=1.97x2−2.4*x+0.905 (equation 7)This produces a DUR=1.284. Even though the examples above are for products having flat surfaces, the irradiation of products having arbitrarily shaped surfaces is to be considered within the scope of the present disclosure. Further, in the aforementioned examples, only four of the six sides of the product are irradiated. This need not be the case. The irradiation of any number of total number of surfaces is to be considered within the scope of the present disclosure. FIG. 11 shows a flowchart of an embodiment of a method in accordance with the present disclosure. At action 200, a product secured to a conveyor is conveyed across a radiation beam to irradiate a surface of the product. At action 202, the speed of the conveyor to which the product is secured is varied in accordance with a position of the product with respect to the radiation beam. As will be understood by the skilled worker, any suitable known technique can be used to detect the edges of the product to be irradiated. Further, any suitable type of conveyor can be used to maintain a proper orientation of the product during irradiation. In the preceding description, for purposes of explanation, numerous details are set forth in order to provide a thorough understanding of the embodiments. However, it will be apparent to one skilled in the art that these specific details are not required. In other instances, well-known electrical structures and circuits are shown in block diagram form in order not to obscure the understanding. For example, specific details are not provided as to whether the embodiments described herein are implemented as a software routine, hardware circuit, firmware, or a combination thereof. Embodiments of the disclosure can be represented as a computer program product stored in a machine-readable medium (also referred to as a computer-readable medium, a processor-readable medium, or a computer usable medium having a computer-readable program code embodied therein). The machine-readable medium can be any suitable tangible, non-transitory medium, including magnetic, optical, or electrical storage medium including a diskette, compact disk read only memory (CD-ROM), memory device (volatile or non-volatile), or similar storage mechanism. The machine-readable medium can contain various sets of instructions, code sequences, configuration information, or other data, which, when executed, cause a processor to perform steps in a method according to an embodiment of the disclosure. Those of ordinary skill in the art will appreciate that other instructions and operations necessary to implement the described implementations can also be stored on the machine-readable medium. The instructions stored on the machine-readable medium can be executed by a processor or other suitable processing device, and can interface with circuitry to perform the described tasks. The above-described embodiments are intended to be examples only. Alterations, modifications and variations can be effected to the particular embodiments by those of skill in the art. The scope of the claims should not be limited by the particular embodiments set forth herein, but should be construed in a manner consistent with the specification as a whole.
	claims	1. An apparatus for generating extreme ultraviolet light by exciting a target material to turn the target material into plasma, the apparatus comprising:a frame;a chamber in which the extreme ultraviolet light is generated and in which a through-hole is formed;a target supply unit inserted through the through-hole and configured for supplying the target material into the chamber;a first connection member configured for connecting the frame and the chamber flexibly;a mechanism configured for fixing the target supply unit to the frame; anda second connection member for flexibly connecting the chamber, at the periphery of the through-hole, and the target supply unit, to seal the chamber, the second connection member being a flexible pipe. 2. The apparatus according to claim 1, wherein a coefficient of thermal expansion of at least one member of the frame is smaller than a coefficient of thermal expansion of at least one member of the chamber. 3. The apparatus according to claim 1, wherein the first connection member is an elastic member. 4. The apparatus according to claim 1, wherein at least a part of the frame is disposed outside the chamber. 5. The apparatus according to claim 1, further comprising a vacuum pump connected to the chamber via a fourth connection member, the fourth connection member being a flexible pipe. 6. An apparatus for generating extreme ultraviolet light by exciting a target material to turn the target material into plasma, the apparatus comprising:a frame to which a window is fixed;a chamber in which the extreme ultraviolet light is generated and in which a through-hole is formed;a target sensor for detecting, through the window, a trajectory of the target material supplied into the chamber;a first connection member configured for connecting the frame and the chamber flexibly;a mechanism configured for fixing the target sensor to the frame; anda second connection member for flexibly connecting the chamber, at the periphery of the through-hole, and the frame, at the periphery of the window, to seal the chamber, the second connection member being a flexible pipe. 7. An apparatus for generating extreme ultraviolet light by exciting a target material to turn the target material into plasma, the apparatus comprising:a frame a chamber in which the extreme ultraviolet light is generated and in which a through-hole is formed;a collector mirror, disposed inside the chamber, for collecting the extreme ultraviolet light generated inside the chamber;a first connection member configure for connecting the frame and the chamber flexibly;a fixing member, inserted through the through-hole, for fixing the collector mirror to the frame; anda second connection member for flexibly connecting the chamber, at the periphery of the through-hole, and the fixing member, to seal the chamber, the second connection member being a flexible pipe. 8. An apparatus for generating extreme ultraviolet light by exciting a target material to turn the target material into plasma, the apparatus comprising:a frame to which a window is fixed;a chamber in which the extreme ultraviolet light is generated and in which a through-hole is formed;an extreme ultraviolet light emission position sensor for detecting, through the window, energy of the extreme ultraviolet light generated inside the chamber;a first connection member configured for connecting the frame and the chamber flexibly;a mechanism configured for fixing the extreme ultraviolet light emission position sensor to the frame; anda second connection member for flexibly connecting the chamber, at the periphery of the through-hole, and the frame, at the periphery of the window, to seal the chamber, the second connection member being a flexible pipe. 9. A system for generating extreme ultraviolet light by exciting a target material to turn the target material into plasma, the system comprising:a frame;a chamber in which the extreme ultraviolet light is generated and in which a through-hole is formed;a target supply unit configured for supplying the target material into the chamber;a first connection member configured for connecting the frame and the chamber flexibly;a driver laser configured to output a laser beam, with which the target material supplied into the chamber from the target supply unit is irradiated;a mirror, disposed inside the chamber, for reflecting the laser beam in the chamber;a beam dump positioned to absorb the laser beam reflected by the mirror;a fixing member, inserted through the through-hole, for fixing the mirror to the frame; anda second connection member for flexibly connecting the chamber, at the periphery of the through-hole, and the fixing member, to seal the chamber, the second connection member being a flexible pipe.
050362054	description	According to the invention, and as is shown more particularly by way of example in FIG. 1 of the accompanying drawings, the apparatus for the transfer and in-situ reactions under a controlled atmosphere, of specimens for transmissive electron microscopy, which is essentially constituted by a cylindrical rod 1 of slight diameter comprising near one end, two grid-holders 2 and mounted slidably in a cover 3 of greater diameter provided with a sealed chamber 4 for housing the grid-holders 2 in transport position, by a traction bar 5 integrated with the end of the rod 1 of slight diameter opposite the grid-holders 2, guided in the cover 3 of greater diameter and provided at its other end with a manipulating button 6, the grid-holders 2 being advantageously arranged in a flat 8 of the end of the rod 1 and the cover 3 being advantageously formed in two parts and having a front part 3' of lesser diameter intended to penetrate into the gate of the microscope and provided with a longitudinal opening 9 corresponding at least to the section of the grid holders of the rod 1 in analysis position of this latter, is characterized in that it is provided, in addition, with a means 7 for guiding and locking in transport and analysis positions the rod 1 provided with grid holders 2, the said rod 1 being advantageously integrated by screwing with the corresponding end of the traction bar 5 which is guided in the cover 3, of which the opening 9 of the front part 3' of lesser diameter is extended, over a portion of the length of this front part 3', on both sides, by longitudinal grooves 10, the said front part 3' being connected to the rest of the cover 3 by screwing of a shouldered portion 11, a gasket 13' effecting the sealing at the level of the screwed assembly (FIGS. 1 and 3). The provision of the longitudinal grooves 10 permits a progressive placing under vacuum of the samples mounted on the grid holders 2 at the time of the sliding to analysis position of the rod 1 in the gate of the microscope. According to a characteristic of the invention, the rear part of the cover 3, near the manipulating button 6, is advantageously surrounded by a sleeve 22 delimiting a sealed chamber connected to the chamber 4 through the intermediary of a hole 19 provided in the said rear part of the cover 3, the said chamber being itself connected, through the intermediary of a tube 20, to a multi-position valve 21. The cover 3 is additionally provided, on the one hand, near its shouldered portion 11, with an external sealing gasket 12 housed in a channel 12' and intended to cooperate with the opening for passage of the gate of the microscope and, on the other hand, with an internal gasket 13 delimiting, with a gasket 14 provided at the opposite end of the cover 3, for sealing and guidance of the opposite end of the bar 5, the gasket 13' and the multi-position valve 21, situated at the end of the tube 20, perpendicular to the sleeve 22, the sealed chamber 4 (FIG. 1). The traction bar 5 is provided with the means 7 for guiding and locking in positions of transport, reaction and analysis of the rod 1, which is constituted by a guiding projection 15 cooperating with a longitudinal guiding groove 16 provided in the cover 3, this groove 16 having a right angled porotion at its ends and an intermediate portion 16' and permitting locking of the projection 15 in the position of analysis, transport and reaction of the rod 1. The intermediate portion 16' permits stopping the bar 5 in a position where it is possible to effect an evacuation of the chamber 4 through the intermediary of the gate of the microscope. The sample positioned on the grid holders 2 of the rod 1 under a controlled atmosphere in the sterile gas circulation chamber is then protected from the exterior atmosphere by retraction of the rod 1 interiorly of the sealed chamber 4 of the cover 3 by means of the traction bar 5. The apparatus is thus in a closed position permitting transport of a sample on the grids. Thanks to the multi-position valve 21, it is possible to effect, as a first step, evacuation of the sealed chamber 4 and replacement of the initial atmosphere by another atmosphere, whose nature, composition, pressure and temperature may be controlled so as to effect a reaction of this atmosphere with the sample. Such an operation may be repeated several times, so as to establish, for example, kinetics of the reaction. It is possible to cause reactive gas to circulate in the chamber 4 by maintaining the cover 3 in "pumping in the gate" position. If the reactive atmosphere is capable of attacking the gate or the pumping assembly of the microscope, it is necessary, at the end of the operation, to evacuate the chamber 4 through the intermediary of the valve 21. Locking in closed or reaction position is assured by a slight rotation of the rod 1 and thus of the bar 5 by means of the manipulating button 6, for example by 10.degree., bringing the projection 15 to the base of the right angle part of the corresponding end of the groove 16, as shown in FIG. 1A or of the intermediary portion 16'. According to another characteristic of the invention, the front part 3' of the cover 3 is provided, at its free end, with a ruby intended to cooperate with a conical female guiding part provided in the examination chamber of the microscope. Thus, the end of the of the cover 3 may be perfectly positioned in the said chamber of the microscope, in the analysis positions of the grid holders 2. According to a variant of the invention, the ruby 17 may be fixedly mounted on the conical female guiding part provided in the examination chamber of the microscope, only the rod 1 being manipulated and its centering being assured, on the one hand, by the exterior cone of the front part of the cover 3 and, on the other hand, by the cone 18 of the free end of the rod 1 cooperating with the corresponding exterior cone 18' of the cover. Thus, it is possible to effect a perfect repositioning of the sample after reaction and examination of the evolution of a given particle after variable exposure times to a reactive gas. In the case where a reaction study is not contemplated, the apparatus may thus be introduced by the front part of the cover 3 into the stage of the microscope, effecting the sealing by means of the external gasket 12. After attaining the usual degree of vacuum in the stage, the rod 1 is partially slid interiorly of the cover 3, outside of the sealed chamber 4, so as to obtain the same degree of vacuum at the level of the grid holders 2. Such an opening is effected in an intermediate position of the projection 15 in the groove 16. Thereafter, the grid holders 2 with the sample or samples are conducted into the analysis position of the rod 1 with locking in this position by slight rotation of the right angle part of the corresponding end of the groove 16, the interior door of the gate of the microscope is opened, and the assembly is lowered into the examination chamber of the microscope. Thanks to the invention, it is possible to maintain a correct vacuum, not only dynamic in the body of the microscope, but also static in the gate, permitting obtaining good working conditions. In addition, the apparatus according to the invention does not require any modification of the electron microscope itself or of the exterior dimensions of the sample holder. Finally, the sealing of the chamber housing the samples during transport and reaction being assured by internal gaskets of the apparatus, not coming in contact with the elements of the microscope, degradation of these gaskets is prevented and guiding of the apparatus interiorly of the examination chamber of the microscope may be effected without hindrance, and thus in a more precise manner. Finally, the invention permits obtaining an apparatus for transfer and in-situ reactions under a controlled atmosphere of specimens for examination by a transmissive electron microscope having a lateral inlet permitting, on the one hand, to maintain the said samples under a controlled atmosphere outside of the periods of examination in the microscope and, on the other hand, to effect in-situ reactions between a sample and a gas whose nature, composition, pressure and temperature may be controlled, the said apparatus being adaptable to all types of electron microscopes having lateral inlet without requiring any modification of the microscope or its inlets. It will be understood that the invention is not limited to the embodiment described and shown in the accompanying drawing. Modifications remain possible, especially from the point of view of the constitution of the various elements or by substitution of equivalent techniques, without departing whatsoever from the scope of protection of the invention.
050376055	claims	1. In a nuclear fuel assembly having a plurality of fuel rods held in a spaced array by grid assemblies, guide tubes extending through the grid assemblies and attached at their upper and lower ends to an upper end fitting and a lower end fitting, the end fittings having openings therethrough for coolant flow, and a debris filter, the debris filter comprising: a. a plate attached to the bottom periphery of and spanning the lower end fitting; and b. said plate having a plurality of substantially triangular-shaped flow holes therethrough that each measure approximately 0.181 inch from the base to the apex with the majority of said triangular-shaped flow holes arranged in groups of four to define square clusters that each measure approximately 0.405 inch on each side whereby the portions of said plate between said flow holes in each cluster are diagonally oriented relative to the sides of the plate.
044407157	claims	1. A method of controlling an output of a nuclear power plant including a boiling water reactor having first and second coolant loops, a plurality of feed water pumps in the first loop selectively driven for feeding water into the reactor, and a recirculating control system in the second loop for controlling a flow rate of steam generated in the first loop by the reactor by controlling a recirculating water flow rate in the second loop of the reactor, the method comprising the step of controlling the recirculating water flow rate in response to the tripping of at least one of the plurality of feed water pumps, the control of the recirculating water flow rate being effected in accordance with an available water feeding capacity provided by the remaining feed water pumps wich are not tripped, and thereby controlling the flow rate of steam produced by the reactor. 2. A method according to claim 1, further comprising the step of determining the tripping of at least one of the plurality of feed water pumps, and controlling the recirculating water flow rate in response to the tripping determination. 3. A method according to claim 2, further comprising the step of determining the available water feeding capacity provided by the remaining feed water pumps which are not tripped, and controlling the recirculating water flow rate in accordance therewith. 4. A method of controlling an output of a nuclear power plant including a boiling water reactor having first and second coolant loops, a water feed pipe system in the first loop connected to the reactor and having a plurality of water feed pumps for feeding water into the reactor, a steam pipe system connected to the reactor for feeding steam produced by the reactor from the reactor, and a recirculating control system in the second loop for controlling a recirculating water flow rate in the second loop of the reactor to thereby control the flow rate of steam produced in the first loop by the reactor, the method comprising the step of controlling the recirculating water flow rate in response to the tripping of at least one of the plurality of water feed pumps, the recirculating water flow rate being controlled for a predetermined period of time so as to cause the flow rate of steam produced by the reactor to be less than the flow rate of the feed water supplied to the reactor. 5. A method according to claim 4, further comprising the step of controlling the recirculating flow rate in accordance with an available water feeding capacity provided by the remaining water feed pumps which are not tripped in response to the lapse of the predetermined period of time, and thereby controlling the flow rate of steam produced by the reactor. 6. A method according to claim 5, further comprising the step of determining the tripping of at least one of the plurality of feed water pumps, and controlling the recirculating water flow rate in response to the tripping determination. 7. A method according to claim 6, further comprising the step of determining the available water feeding capacity provided by the remaining water feed pumps which are not tripped, and controlling the recirculating flow rate in accordance therewith.
	description	This application claims the benefit under 35 USC 119(e) of U.S. Provisional Application No. 61/233,375, filed on Aug. 12, 2009, which is incorporated herein by reference in its entirety. Lens-based high-resolution x-ray microscopy largely resulted from research work at synchrotron radiation facilities in Germany and United States starting in the 1980's. While projection-type x-ray imaging systems with up to micrometer resolution have been widely used since the discovery of x-ray radiation, ones using x-ray lens with sub-100 nanometer (nm) resolution began to enter the market only this century. These high-resolution microscopes are configured similarly to visible-light microscopes with an optical train typically including an x-ray source, condenser, objective lens, and detector. Because x rays do not refract significantly in most materials, nearly all such x-ray microscopes use diffractive objective lenses, called Fresnel zone plates. As illustrated in FIG. 1, they are essentially circular diffraction gratings, with the grating spacing decreasing with increasing distance from the center in order to increase the diffraction angle and thus produce the focusing effect. By year 2009, x-ray microscopes using synchrotron x-ray sources have achieved 30 nm resolution and commercial systems using laboratory x-ray sources have achieved 50 nm resolution. Compared with the widely used visible light and electron microscopy techniques, x-ray microscopy combines properties that make it favorable for a large number of applications: (1) high energy x rays have very large penetration length to image internal structures of a thick samples without deprocessing; (2) the absorption and fluorescence emission depends strongly on the elemental composition of the sample, allowing high-sensitivity material analysis; and (3) x-ray imaging causes little structural damage to integrated circuit samples without a charging effect. The key component of an x-ray microscope is the zone plate lens that focuses the x-rays and magnifies the x-ray images. From FIG. 2, the diffraction-limited resolution of the zone plate lens z is δ=1.22Δrn, the focal length is f=2 rn/(λΔrn), and the numerical aperture is NA=λ/(2Δrn). Zone plates with zones intended primarily to block x-ray radiation are called amplitude zone plate. They can provide up to 9% efficiency. Zone plate with zones intended to produce an ideally π phase shift are called phase zone plates. They can provide up to 40% efficiency. In practice, a zone plate will both absorb and phase shift the x-ray beam impinging on it, and will behave as a combination of amplitude and phase zone plates. Even higher theoretical efficiency can be achieved when the zones approximate the profile of a Fresnel lens. This type of “blazed” zone plates can achieve nearly 100% theoretical efficiency. The efficiency depends primarily on the wavelength and the thickness of the zones. An amplitude zone plate reaches its maximum efficiency when each zone completely absorbs the x-ray beam; and a phase zone plate reaches its maximum efficiency when each zone shifts the phase of x-ray beam by π, with no absorption. For example, with higher x-ray energy, the zone thickness must be increased to maintain absorption or phase shift. Thinner zone plates are generally acceptable when using soft x-ray energies within the range of 200-500 eV. However, in order to image inorganic materials such as that used in material science research or semiconductors industries, the x-ray energy must be increased to multi-keV range in order to penetrate samples without excessive deprocessing. FIG. 3 is a plot of efficiency as a function of x-ray energy for different gold zone plate thicknesses. With higher energy x-ray radiation, thicker zone plates are required to achieve its optimal efficiency. For example, a zone plate having a thickness of 1650 nanometers (nm) reaches a maximum efficiency at just below 10 keV. At this same energy, a 350 nm thick zone plate has an efficiency below 5%. Therefore, the challenge of making high resolution and high efficiency zone plate lenses becomes the challenge of making structures with high thickness-to-width aspect ratio, especially with increasing x-ray energy. For zone plates with 50 nm outer zone width, this would require an aspect ratio of 33. Such a high aspect ratio often poses significant difficulty for fabricating a single optic element. The criticality in fabricating thicker zone plates comes in the fabrication and the mechanical stabilization of the outer zones. It is here that the aspect ratios become extreme since the outer zones are the narrowest zones, yet have to be the same height as the other, inner, wider zones. Fabricating these zones challenges existing fabrication processes such as plating technology due to the narrowness of the zones. And then, once fabricated, those high aspect ratio zones can be easily toppled by mechanical stress or other stresses due to charging effects. Some have proposed to fabricate effectively thick zone plates by aligning and stacking separate zone plates to create a compound optic. One specific example relies on the formation of a zone plate doublet by fabricating two zone plates on either side of a common substrate. This approach is problematic, however, because it necessitates thin substrates and front side and backside alignment and fabrication. Moreover, the first fabricated zone plate must survive the fabrication process for the second zone plate. Another approach relies on the fabrication of a series of zone plates successively, one on top of the other. In such approach, however, tolerances stacked up. It further requires effective planarization prior to forming the next zone plate along with techniques for stabilizing the zones sufficiently to survive multiple planarization processes. Nevertheless, compound x-ray optical elements have been developed. U.S. Pat. No. 6,917,472 B1 describes an Achromatic Fresnel Optic (AFO). This is typically a two element compound optic that is comprised of a diffractive Fresnel zone plate and a one or more refractive Fresnel lenses. Generally, AFO's have been proposed for imaging short wavelength radiation including extreme ultraviolet (EUV) and x-ray radiation. The diffractive element is the primary focusing element, and the refractive element typically provides no or very little net focusing effect. It serves to correct the chromatic aberration of the zone plate. This invention pertains to methods to fabricate compound x-ray lenses including two or more zone plate lenses. In these compound lenses, the individual zone plates are placed in proximity along the longitudinal direction and aligned preferably to an accuracy better than the outer most zone width Δrn. The resulting compound lens maintains the resolution of individual zone plates but lead to greatly increased focusing efficiency. In general, according to one aspect, the invention features a compound zone plate comprising a first zone plate frame including a first zone plate, a second zone plate frame including a second zone plate, and a base frame to which the first zone plate frame and the second zone plate frame are bonded. In embodiments, a spacer is used between the first zone plate frame and the base frame. Further, the second zone plate frame comprises a membrane, the second zone plate fabricated on the membrane, and an optical port to the membrane, in which the first zone plate is positioned laterally within the optical port. A third zone plate frame comprising a third zone plate and possibly a fourth zone plate can be further bonded to the assembly. In general, according to another aspect, the invention features compound zone plate comprising a first zone plate frame including a first zone plate, a second zone plate frame including a second zone plate, and a spacer between the first zone plate frame and the second zone plate frame including microbeads and possibly an adhesive. In the assembly process, the microbeads are used to ensure the parallelism, dial in the distance precisely between the zone plates by selecting the microbead size, possibly in response to the width of the frames, and ensure low friction lateral movement enabling nanometer precision alignment of the zone plates with respect to each other prior to being fixed by the adhesive. That is, when the frames are pressed together to ensure parallelism, it is still possible to align them to each other since the microbead layer facilitates the inplane movement of the alignment process. In one embodiment, a third zone plate frame including a third zone plate is bonded to the second zone plate frame via a base frame. In general, according to another aspect, the invention features a method for fabricating a compound zone plate comprising placing a first zone plate frame comprising a first zone plate over a second zone plate frame comprising a second zone plate, placing microbeads and an adhesive mechanically between the first zone plate frame and the second zone plate frame, and aligning the first zone plate to the second zone plate prior to hardening of the adhesive. In the current embodiment, the step of aligning the first zone plate to the second zone plate comprises transmitting x-rays through the first zone plate and the second zone plate and detecting the x-rays and positioning the first zone plate relative to the second zone plate in response to the detected x-rays. Preferably the x-rays are detected with a spatially resolved detector. The position is performed to optimize a Moiré pattern on the detector. Also additional zone plates are attached at similarly actively aligned, in one example. In general, according to still another aspect, the invention features full-field x-ray imaging system including an x-ray source that generates an x-ray beam, a sample stage for holding a sample in the x-ray beam, a compound zone plate optic including a first zone plate frame comprising a first zone plate, a second zone plate frame comprising a second zone plate that is bonded to the first zone plate frame, and a spatially resolved detector system that detects the x-ray beam from the sample and the compound zone plate optic. The above and other features of the invention including various novel details of construction and combinations of parts, and other advantages, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular method and device embodying the invention are shown by way of illustration and not as a limitation of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention. FIG. 4 shows an x-ray imaging system that has been constructed according to the principles of the present invention. The system has an x-ray source 110 that generates an x-ray beam 112 along the optical axis 122. In the current embodiment, the source is a beamline of a synchrotron x-ray generation facility. In other embodiments, lower power sources are used, such as laboratory sources. Such sources often generate x-rays by bombarding a solid target anode with energetic electrons. Specific examples include microfocus x-ray sources and rotating anode sources. The x-ray beam 112 is preferably a hard x-ray beam. In one embodiment, its energy is about 10 keV. Generally, the beam's energy is between about 2 keV and 25 keV. These higher energies ensure good penetration through any intervening coating, e.g. fluid layer, on the sample 10. The condenser 114 collects and focuses the x-ray beam 112 from the source 110. For the full field imaging setup, a suitable illumination of the sample 10 is required. This is most conveniently achieved by the use of a zone plate condenser optic 114. A sample holder 120 is used to hold the sample 10 in the x-ray beam 112. The stage 116 scans the sample holder 120 in both the x and y axis directions, i.e., in a plane that is perpendicular to the axis 122 of the x-ray beam 112. In other examples, the stage 116 further rotates the sample 10 to obtain projections at different angles, which are often used for tomographic reconstruction in an image processor 118. An x-ray objective 124 collects transmitted x-rays 128. The x-ray beam 128 from the sample 10 is focused onto a detector system 126. In a current embodiment, the objective 124 is a Fresnel zone plate. The detector system 126 is preferably a high-resolution, high-efficiency scintillator-coupled CCD (charge coupled device) camera system for detecting x-rays from the sample 10. But other x-ray detectors, such as optical taper-based systems can also be used. In one example, a camera system as described in U.S. Pat. No. 7,057,187, which is incorporated herein by this reference in its entirety, is used. The following specific parameters ensure good performance: Quantum detection efficiency >70% at 10 keV; Pixel resolution element on scintillator 0.65 μm; Spatially resolved (1 k×1 k elements in an two dimensional array) CCD detector, Peltier-cooled. According to embodiments of the invention either the condenser 114 or the x-ray objective 124, or both, is a compound zone plate. In a current embodiment, however, the condenser 114 is a reflective capillary optic and only the objective is a compound zone plate. FIG. 5A illustrates the construction of the compound zone plate of the condenser 114 and/or objective 124 according to the preferred embodiment of the present invention. The compound zone plate 114, 124 is held on a holder 302. The holder 302 as an annular shape with a center optical port 350. In the typical implementation, this center optical port 350 has a circular shape when observed looking along the direction of the optical axis 122. A bottom base frame 304 is secured on to the holder 302. The bottom base frame 304 similarly has a center optical port 352 that is aligned over the optical port 350 of the holder 302. The optical port 352 of the bottom base frame 304 is preferably square shaped when observed along the direction of the optical axis 122. It also has, preferably, obliquely angled sidewalls 354 such that the port 352 has a frusto-pyramidal profile. In the preferred embodiment, the bottom base frame 304 is constructed from silicon wafer material and has a isosceles trapezoidal cross sectional profile. The angled sidewalls 354 are fabricated by silicon anisotropic etching of the wafer material. A first small frame zone plate 310 is secured to the bottom base frame 304. The small frame zone plate 310 comprises an outer frame 358 that has an isosceles trapezoidal cross sectional profile. A frusto-pyramidal center optical port 356 is formed in the outer frame 358 and aligned on the optical axis 122. Preferably the outer frame 356 is fabricated from silicon wafer material. Preferred thicknesses range from 100 to 500 micrometers. It is currently approximately 180 micrometers thick. Extending over the center optical port is a membrane 360, which currently constructed from silicon nitride. In other embodiments, the membrane 360 is constructed from silicon carbide, silicon, silicon oxide, or diamond (carbon). Its thickness is typically between 0.05 to 2 micrometers. It is currently about 0.1 to 0.3 micrometers thick. A zone plate structure 312a is disposed on the membrane 360 and centered along the optical axis 122. The first small frame zone plate 310 is secured to the bottom base frame 304 via an adhesive layer 308. Small microbeads 306 in the adhesive layer 308 separate the outer frame 358 from the top surface of the bottom base frame 304 providing a controlled the spacing between these two elements. In the current embodiment, the microbeads are silicon oxide because of the hardness, quality of available beads, and close thermal matching to the silicon frames. A first large frame zone plate 316 is also secured to the top surface of the bottom base frame 304. Similar to the small frame zone plate 310, the large frame zone plate 316 comprises an outer frame 358 having an isosceles trapezoidal cross sectional profile with a frusto-pyramidal center optical port 356. This center optical port 356, however, is sized to accommodate, i.e., be larger than, the overall diameter of the first small frame zone plate 310 such that the first small frame zone plate 310 fits entirely, laterally, within the center optical port 356 of the large frame zone plate 316. The first large frame zone plate 316 includes a membrane 360 that extends over its center optical port 356 and the width of the small frame zone plate 310. A second zone plate 312b is formed on the top of the membrane 360 of the large frame zone plate 316. The outer frame 358 of the first large frame zone plate 316 is secured to the top surface of the base frame 304 via an adhesive layer 308. Large spherical microbeads 314 mixed in the adhesive layer 308 are located between the bottom surface of the outer frame 358 of the first large frame zone plate 316 and the top surface of base frame 304 to provide a controlled distance between these two elements. The large bead 314 ensure adequate clearance between the underside of the membrane 360 of the first large frame zone plate 316 and the top of zone plate 312a. A second large frame zone plate 318 is installed on the first large frame zone plate 316. It is an orientation, however, is inverted such that zone plate 312c formed on the membrane of the second large frame zone plate 318 is directly opposite the zone plate 312b of the first large frame zone plate 316. The second large frame zone plate 318 is secured to the first large frame zone plate 316 via an adhesive layer 308. Medium spherical microbeads 319 in layer 308 to define a standoff distance between the top surface of the first large frame zone plate 316 and the bottom surface of the second large frame zone plate 318. The medium microbeads 319 ensure that zone plate 312b is separated from zone plate 312c to prevent damage. A subassembly is constructed from a top base frame 320 and a second small frame zone plate 322. In more detail, the top base frame 320, similar to the bottom base frame 304, includes a center frusto-pyramidal optical port 352. It further has an isosceles trapezoidal cross sectional profile. A second small frame zone plate 322 is secured over this optical port 352. The second small frame zone plate 322 is constructed in a similar fashion to the first small frame zone plate 358. It includes a center frusto-pyramidal optical port 356 that is formed in a outer frame 358. A membrane 360 extends over the optical port 356. A zone plate 312d is fabricated on this membrane 360. The second small frame zone plate 322 is secured to the top base frame 320 such that their respective optical ports are aligned with each other. They are bonded together using an adhesive layer 308. Small spherical microbeads 306 are used to define the standoff distance between the top base frame 320 and the second small frame zone plate 322. The subassembly comprising the top base frame 320 and the second small frame zone plate 322 is inverted and bonded onto the top surface of the second large frame zone plate 318. They are secured by an adhesive layer 308. Large microbeads 314 in the layer 308 are used to set the distance between the bottom surface of the top base frame 320 and the top surface of the second large frame zone plate 318. In the preferred embodiments, the construction and sizing of the large frame zone plates 316, 318 and the small frame zone plates 310, 322 are similar. That is, preferably they are all constructed from silicon wafer material with a thickness ranging from 100 to 500 micrometers, currently approximately 180 micrometers thick. The membranes 360 are currently silicon nitride, but silicon carbide, silicon, silicon oxide, or diamond are other examples. The membrane thickness is typically between 0.05 to 2 micrometers. It is currently about 0.1 to 0.3 micrometers thick. The total overall distance 324 of the four zone plates 312a, 312b, 312c, 312d measured along the optical axis 122 is critical to high performance operation and should be minimized, to preferably less than the depth of focus of the zone plates 312a, 312b, 312c, 312d. Using typical numerical apertures (NA) in the range from 0.5 mrad to 8 mrad and for wavelengths from 0.05 nm to 0.25 nm. The DOF maximally ranges from 0.8 um to 250 um. Thus the distance 324 should be between 0.8 micrometers to 250 micrometers depending on the wavelength used. Currently, the DOF is more restricted from 10-100 micrometers, thus, in the current embodiment distance 324 is between 10-100 micrometers. In one embodiment, where the four zone plates 312a, 312b, 312c, 312d nominally have identical geometry, including diameter and outer zone width. That is, they have the same geometry, including diameter and outer zone width within manufacturing tolerances. In other embodiments, the four zone plates 312a, 312b, 312c, 312d form two four-step blazed zone plates or one 16-step blazed zone plate as described below. FIG. 5A illustrates the construction of the compound zone plate of the condenser 114 and/or objective 124 according to another embodiment. This example includes only to zone plates 312a, 312b. It is fabricated attaching two zone plate frames 310, 322 to each other. A layer of adhesive 308 is used to bond the zone plate frames 310, 322. A layer of microbeads 319 in the adhesive defines the standoff distance and prevents damage to the zone plates 312a, 312b due to contact. FIGS. 6A through 6F illustrate the process for fabricating the zone plates 312a-d on the frames 310, 316, 318, and 322. The method for fabricating the framed zone plates is essentially similar for the large frames 316, 318 and the small frames 310, 322. The only difference is the lateral overall size of the frames and their center frusto-pyramidal optical ports 352. As shown in FIG. 6A, the process begins with silicon wafer material 202 with an <100> crystalline orientation. A top silicon nitride membrane layer 360 is deposited on the wafer material 202. In FIG. 6B, a bottom silicon nitride layer 206 is deposited on the opposite side of the wafer material 202. This second silicon nitride layer 206 has typically the same thickness as the top layer. As shown in FIGS. 6C and 6D, a photoresist is then deposited on the bottom silicon nitride layer 206 and then patterned to the approximate desired size of the optical port. The exposed portions of the bottom silicon nitride layer 206 are then removed. An anisotropic etch process is then performed on the exposed wafer material 202 as shown in FIG. 6E. In a preferred embodiment, a KOH wet etch process is used. This preferentially etches the <100> crystalline lattice. It thus forms sloped side walls corresponding to the <111> plane of the wafer material 202. The etch is performed to the depth of the top silicon nitride layer 204 to form the membrane 360. FIG. 6F illustrates the conventional processing performed on the front side. In more detail, a thin metal seed layer 210 is deposited on the top silicon nitride membrane layer 360. A photoresist layer 212 is deposited on the metal layer. This is patterned 214 with the reverse pattern for the zone plate. And for embodiment, this patterning is performed by an electron beam writer. The pattern typically gets transferred to a thin metal layer, not shown, and then deep transferred into the polymer resist. Into this reverse pattern, the structure of the zone plate is plated beginning at the seed layer 210. As illustrated in FIG. 6G, after the plating step, the photoresist layer 212 is stripped leaving the plated structure of the zone plate 312. It should be noted that material stress control is important. Generally, when moving to a thicker membrane layer 360, from 0.3 micrometers to 1.0 micrometers, the stress in the membrane distorted the zone plates 312 on the large frames, so that the zone plates could not be aligned to each other. Thus, material stress in the membrane layer should be reduced or thinner membranes used. FIG. 7A through 7E illustrate the process for assembling the zone plate frames 310, 316, 318, 322 into the compound zone plate 114, 124. The general process includes the assembly of a zone plate doublet. Typically, two zone plate frames are then bonded successively to make the compound zone plate comprising the four separate zone plates. In the assembly process, a combination an adhesive and microbeads or microspheres are used between zone plate frames and based frames. These microspheres or microbeads (1) ensure the parallelism (2) dial in the distance precisely between the zone plates (3) ensure low friction lateral movement enabling nm-precision alignment of the zone plates with respect to each other prior to being fixed by the adhesive. That is, when the frames are pressed together to ensure parallelism, it is still possible to align them to each other since the microbead layer facilitates the inplane movement of the alignment process. In general, three different size classes of microbeads are used in the process described below. In other examples, one a single size is used. In any event, and in general, the microbeads in the size range of 0.5 to 10 micrometers. Currently, microbeads in the range of 1.6 to 10 micrometers are being used. FIG. 7A shows the bonding of the small frame zone plate 310 onto the bottom base frame 304 to create assembly 710. As described previously, they bonded together using an adhesive layer 308. Small spherical microbeads 306 used to precisely control the standoff distance between the top surface of the bottom base frame 304 and the bottom surface of the small frame zone plate 310, in some implementations. The alignment between the bottom base frame 304 and the small frame zone plate 310 is a relatively coarse alignment. That is, the zone plate 312 need only be generally centered on the center optical port 352 of the bottom base frame 304. Typically this alignment is performed using a standard stereo microscope. The adhesive 308 is applied between the bottom base frame 304 and the small zone plate 310. A precision x, y axis positioner 418 is used to first position and then hold the small frame zone plate 310 in position while the adhesive 308 cures. The x, y axis positioner 418 also provides a downward force by a spring mechanism to push the first small frame zone plate 310 against the bottom base frame 304 to ensure good contact and maintain planarity. A compound lens assembly is sensitive to angular deviations. For example, a 3-degree tilt will cause 50 nm lateral shift in the relative zone position. For a zone plate element with 50 nm outer zone width, this shift will be the same as the zone width—thus render the compound zone plate unusable. The downward force applied by the positioner 418 ensures parallelism and spacing. FIG. 7B illustrates the attachment of the first large frame zone plate 316 to the bottom base frame 304. Again, adhesive 308 is applied between the bottom surface of the first large frame zone plate 316 and the bottom base frame 304. Large spherical microbeads 314 are deposited between the large frame zone plate 316 and the bottom base frame 304 to ensure a precision standoff distance. The lateral alignment between zone plate 312b and a zone plate 312a must be as accurate as possible. In the preferred embodiment, an active alignment process is used. Ideally, the alignment is performed using feedback from the transmission of x-rays through the zone plates 312a and 312b. In more detail, a microfocus x-ray source 410 generates an x-ray beam that illuminates the zone plates 312a and 312b. Preferably, the x-ray source 410 generates x-rays having an energy of a system in which the compound zone plate 114, 124 will be deployed. The x-rays are transmitted through the zone plates 312a and 312b and converted into the optical frequencies by a scintillator 414, if required. A spatially resolved CCD detector 416, comprising a two dimensional array of pixels, detects the two dimensional pattern produced by the zone plates 312a and 312b. The x, y axis positioner 418 is then controlled to position the large frame zone plate 316 relative to the small frame zone plate 310 in the x and y axes based on the x-ray focus intensity or interference pattern detected by the detector 416. Currently the alignment is performed based on the Moire pattern formed on the detector 416. The microbeads 314 facilitate this positioning process by providing a low stiction mechanical interface. Once the optimal position is discovered the x, y axis positioner 418 holds that position while pushing down on the first large frame zone plate 316 to ensure good mechanical contact, parallelism and planarity relative to the bottom base frame 304, which is functioning as the mechanical reference, until the adhesive 308 cures. Currently a two part slow curing epoxy is used to facilitate the alignment process. FIG. 7C shows the x-ray system used for alignment. The x-ray source 410 generates a beam that is transmitted through the assembly 710. The positioning urges the next frame into engagement with the assembly while position that frame in the plane of the assembly. This positioning is performed in response to the pattern formed on the CCD detector 416. To improve that clarity of the Moire pattern detected by the CCD 416, both the source 410 and the detector assembly are moved on an optical bench relative to the positioner 418, see arrows 712, 714. As shown in FIG. 7D, the process is repeated for the attachment of the second large frame zone plate 318 to the top of the first large frame zone plate 316. Again, the x-ray focus intensity or interference pattern detected by the detector 416 is used to align zone plate 312c to the zone plate doublet comprising zone plates 312a and 312b. The microbeads 319 facilitate this positioning process by providing a low stiction interface to allow the x, y axis positioner 418 to move the second large frame zone plate 318. Note: when fabricating the dual zone plate compound zone plate shown in FIG. 5B, the bonding step as described in FIG. 7D is performed. The main difference is that in the fabrication of this embodiment, the first small frame zone plate 310 is not used. Further, the microbeads between the first large frame zone plate 316 and the bottom base frame 304 are not always used. Finally, as shown in FIG. 7E, the process is repeated for the attachment of a sub assembly comprising the top base frame 320 and the second small frame zone plate 322 to the top surface of the second large frame zone plate 318. The x-ray focus intensity or interference pattern produced by the detector 416 is used to align zone plate 312d to the zone plate series comprising zone plates 312a, 312b, 312c. The microbeads 314 facilitate this positioning process, allowing the x, y axis positioner 418 to move the sub assembly comprising the top base frame 320 and the second small frame zone plate 322 for the alignment in a low stiction environment. In the assembly process, up to three size classes of microbeads may be used: small, medium and large. Finer sized gradations are used in some instances to compensate for variations in the silicon frame thicknesses. In one embodiment, a blazed zone plate with stepped profile is fabricated by stacking two zone plates with different zone spacing as shown in FIG. 8. In this example, one zone plate 312a has double the spacing of zones 150 with respect to the zones 152 of the other zone plate 312b. When they are stacked in to a compound lens, a stepped profile approximating a Fresnel lens shape is created as shown in FIG. 9. Furthermore, additional zone plates can be used to produce better approximation of the Fresnel lens shape. In general 2n steps can be created by stacking n zone plates elements. A compound lens assembly as shown in FIGS. 5A and 5B can be very sensitive to angular deviations during use. For example, if a spacer is 1 um thick, a 3-degree tilt will cause 50 nm lateral shift in the relative zone position. For a zone plate element with 50 nm outer zone width, this shift will be the same as the zone width—thus render the compound zone plate unusable. Therefore a compound lens assembly is preferably integrated with an angular adjustment device, such as a tip-tilt stage. While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims. For example, while the description illustrate the fabrication of compound zone plates with 2 and 4 zone plate elements, the principles and technology described here is extendable to compound zone plates with 3 and more than four zone plate elements.
	claims	1. A confinement system comprising:an enclosure comprising:a first end and a second end that is opposite from the first end; anda midpoint that is substantially equidistant between the first and second ends of the enclosure;two internal magnetic coils suspended within an interior of the enclosure and co-axial with a center axis of the enclosure, the two internal magnetic coils each having a toroidal shape;a plurality of encapsulating magnetic coils co-axial with the center axis of the enclosure, the encapsulating magnetic coils having a larger diameter than the internal magnetic coils;a center magnetic coil co-axial with the center axis of the enclosure and located proximate to the midpoint of the enclosure;one or more electromagnetic wave generators coupled to the enclosure; andtwo mirror magnetic coils co-axial with the center axis of the enclosure;wherein the magnetic coils are operable, when supplied with electrical currents, to form magnetic fields for confining plasma within a magnetic sheath inside the enclosure, the magnetic sheath configured to allow recirculation of plasma between edges of adjacent cusps formed within the enclosure;wherein each of the one or more electromagnetic wave generators is operable to inject a beam of electromagnetic waves into the enclosure; andwherein the center magnetic coil is disposed outside the interior of the enclosure. 2. The confinement system of claim 1, wherein at least one of the one or more electromagnetic wave generators is aligned with the center axis of the enclosure. 3. The confinement system of claim 1, wherein the electromagnetic wave generator comprises a helical antenna. 4. The confinement system of claim 1, wherein at least one of the one or more electromagnetic wave generators is operable to generate a beam of right-hand circularly polarized waves. 5. The confinement system of claim 1, wherein at least one of the one or more electromagnetic wave generators is operable to generate electromagnetic waves that, when injected within the enclosure, produce one or more of Alfven mode waves and Whistler mode waves. 6. The confinement system of claim 1, wherein at least one of the one or more electromagnetic wave generators is operable to generate linear rectangularly polarized waves, and the at least one of the one or more electromagnetic wave generators operable to generate linear rectangularly polarized waves is coupled to circuitry that converts the linear rectangularly polarized waves into right-hand circularly polarized waves. 7. The confinement system of claim 1, wherein settings of the electromagnetic wave generator are selected to maximize Landau damping of the confined plasma in the enclosure, wherein the settings comprise the size of a helical antenna of the electromagnetic wave generator. 8. A confinement system comprising:two internal magnetic coils suspended within an interior of an enclosure;a center magnetic coil coaxial with the two internal magnetic coils and located proximate to a midpoint of the enclosure;a plurality of encapsulating magnetic coils coaxial with the internal magnetic coils, the encapsulating magnetic coils being operable to preserve the magnetohydrodynamic (MHD) stability of the fusion reactor by maintaining a magnetic sheath that prevents plasma within the enclosure from expanding, wherein the magnetic sheath is configured to allow recirculation of plasma between edges of adjacent cusps formed within the enclosure;two mirror magnetic coil coaxial with the internal magnetic coils; andone or more electromagnetic wave generators operable to inject a beam of electromagnetic waves into the enclosure;wherein the center magnetic coil is disposed outside the interior of the enclosure. 9. The confinement system of claim 8, wherein at least one of the one or more electromagnetic wave generators is aligned with a center axis of the enclosure. 10. The confinement system of claim 8, wherein the electromagnetic wave generator comprises a helical antenna. 11. The confinement system of claim 8, wherein at least one of the one or more electromagnetic wave generators is operable to generate a beam of right-hand circularly polarized waves. 12. The confinement system of claim 8, wherein at least one of the one or more electromagnetic wave generators is operable to generate electromagnetic waves that, when injected within the enclosure, produce one or more of Alfven mode waves and Whistler mode waves. 13. The confinement system of claim 8, wherein settings of the electromagnetic wave generator are selected to maximize Landau damping of the confined plasma in the enclosure, wherein the settings comprise the size of a helical antenna of the electromagnetic wave generator. 14. A method comprising:energizing two internal magnetic coils suspended within an interior of an enclosure;energizing a center magnetic coil coaxial with the two internal magnetic coils and located proximate to a midpoint of the enclosure;energizing a plurality of encapsulating magnetic coils coaxial with the internal magnetic coils, the encapsulating magnetic coils being operable, when energized, to preserve the magnetohydrodynamic (MHD) stability of the fusion reactor by maintaining a magnetic sheath that prevents plasma within the enclosure from expanding, wherein maintaining the magnetic sheath comprises recirculating plasma between edges of adjacent cusps formed within the enclosure;energizing two mirror magnetic coil coaxial with the internal magnetic coils; andinjecting a beam of electromagnetic waves toward the center of the enclosure;wherein the center magnetic coil is disposed outside the interior of the enclosure. 15. The method of claim 14, wherein injecting the beam of electromagnetic waves comprises injecting right-hand circularly polarized waves into the enclosure. 16. The method of claim 14, wherein injecting the beam of electromagnetic waves comprises injecting electromagnetic waves that, when coupled to the electromagnetic fields inside the enclosure, produce one or more of Alfven mode waves and Whistler mode waves. 17. The confinement system of claim 1, wherein the one or more electromagnetic wave generators are configured to inject energy proximate wells formed within the enclosure based on at least a frequency and a polarization of the injected beam of electromagnetic waves. 18. The confinement system of claim 1, wherein the two mirror magnetic coils comprise a first mirror magnetic coil and a second mirror magnetic coil disposed on opposite sides of the center magnetic coil. 19. The confinement system of claim 1, further comprising:a center coil system configured to supply first electrical currents flowing in a first direction through the center magnetic coil;an internal coil system configured to supply second electrical currents flowing in a second direction through each of the two internal magnetic coils;an encapsulating coil system configured to supply third electrical currents flowing in the first direction through each of the plurality of encapsulating magnetic coils; anda mirror coil system configured to supply fourth electrical currents flowing in the first direction through each of the two mirror magnetic coils. 20. The confinement system of claim 1, wherein each of the two internal magnetic coils comprises at least a first shielding surrounding the internal magnetic coil and each of the two internal magnetic coils is suspended within the enclosure by at least one support.
042253900	claims	1. A nuclear reactor control system comprising: a nuclear reactor having a coolant containing a neutron absorber circulating therethrough, at least one ion exchanger flow-coupled with said nuclear reactor; said ion exchanger having basic anion exchange resins therein capable of chemically storing a material having the property of capturing neutrons, said ion exchange resins being temperature dependent with respect to their storage capacity of neutron capturing material; at least one heat exchanger flow-coupled to the ion exchanger and the reactor for varying the temperature of the coolant influent to said ion exchanger; means selectively connecting the outlet of said ion exchanger with said reactor for supplying coolant effluent therefrom to the reactor to accommodate reactor load follow operations; and at least one evaporator capable of concentrating a solution of said neutron capturing material flow-coupled to the ion exchanger for selectively receiving the coolant effluent from said ion exchanger, means connecting said evaporator with a high concentration tank and a low concentration tank to thereby provide separate solutions having a high concentration of neutron capturing material and a low concentration of neutron capturing material; and means separately connected to said high and low concentration tanks for separately supplying the effluent therefrom to said reactor to accommodate major changes in reactor load. means for determining the concentration of neutron capturing material in the effluent of said ion exchangers; and means responsive to said determining means for selectively and sequentially flow-coupling each of the ion-exchangers to the nuclear reactor. diverting a predetermined quantity of fluid containing a neutron-capturing material from the primary cooling system of a nuclear reactor; selectively heating or cooling said fluid quantity dependent upon whether the amount of homogeneously dispersed neutron-capturing material within the reactor is to be, respectively, increased or decreased; conveying said fluid quantity through an ion exchanger having a temperature dependent absorption capacity for the neutron-capturing material to either remove or release neutron-capturing material; periodically returning at least portions of said fluid quantity from the ion exchanger to said reactor cooling system for load follow purposes; periodically conveying at least a portion of said fluid quantity from the ion exchanger to evaporating means to provide separate solutions of neutron-capturing material of high and low concentrations; and selectively supplying each of said solutions to said reactor to accommodate major changes in reactor load. diverting a predetermined quantity of fluid containing a neutron-capturing material from the primary cooling system of a nuclear reactor; selectively heating or cooling said fluid quantity of fluid dependent upon whether the amount of homogeneously dispersed neutron-capturing material within the reactor is to be, respectively, increased or decreased; conveying said fluid quantity through an ion exchanger having a temperature dependent absorption capacity for neutron-capturing material to either remove or release neutron-capturing material; testing the effluent from said ion exchanger to determine the amount of neutron-capturing material in solution; and periodically and sequentially diverting the fluid to other ion exchangers, each diversion being indicated by the step of testing; returning a portion of the effluent from said ion exchangers to said cooling system to accommodate reactor load follow operations; periodically conveying at least a portion of said effluent from said ion exchangers to evaporating means to provide separate solutions of neutron-capturing material of high and low concentrations; and selectively supplying each of said solutions to said reactor to accommodate major changes in reactor load. a nuclear reactor having a primary coolant system containing a coolant having a neutron absorber therein; means for varying the quantity of neutron absorber in said coolant; said means comprising multiple parallel connected ion exchangers having basic an ion exchange resins therein capable of chemically storing a material having the property of capturing neutrons, said ion exchanger resins being temperature dependent with respect to their storage capacity of neutron capturing material; heat exchange means flow-coupled with said reactor coolant system and said ion exchanger for varying the temperature of a portion of coolant withdrawn from the reactor prior to supplying it to said ion exchangers, said coolant selectively being heated or cooled depending on whether the amount of neutron absorber in the coolant is to be increased or decreased; a volume control tank and liquid evaporator means connected to the outlet of said ion exchangers to receive the effluent therefrom, separate valve means between said ion exchangers outlet and the volume control tank and between the ion exchangers outlet and said evaporator means, said valve means being selectively operable to discharge the effluent from the ion exchangers into said volume control tank for return to the reactor coolant system or into said evaporator means depending on the amount of neutron absorber to remain in said coolant; a primary water storage tank connected through valve means directly with said reactor coolant system for selectively furnishing water thereto as coolant is withdrawn from the system; and means connecting the discharge side of said evaporator means with the primary water storage tank; whereby upon closing the valve means to said evaporator means and to said primary water storage tank, the portion of coolant from the reactor coolant system is circulated through said ion exchangers to effect slight changes in neutron absorber in said coolant, and to effect large changes in the neutron absorber in said coolant, the valve means to the primary water storage tank is opened and to the volume control tank closed, and the valve means to said evaporator means opened, thereby permitting circulation of reactor coolant through said ion exchangers and evaporator means for changing the neutron absorber content therein while simultaneously supplying water from the primary storage tank to the coolant system to replace the amount of coolant withdrawn therefrom. means in the inlet to each of said ion exchangers responsive to said test means for selectively and sequentially diverting said coolant from one ion exchanger to another when the resins in said one ion exchanger have absorbed a maximum amount of neutron absorber or when the neutron absorber on said resins have been completely depleted. means connecting said hold up tanks with an evaporator tank which separates the neutron absorber from the coolant prior to returning the coolant effluent to the primary water storage tank; and means connecting the evaporator tank with a concentrate holding tank which serves as storage for the separated neutron absorber. means connecting said primary water storage tank with said mixing tank wherein coolant from the storage tank is mixed with the neutron absorber concentrate; and means connecting said mixing tank with the reactor coolant system for supplying the neutron absorber-water mixture thereto for reactor control purposes. 2. The reactor control system of claim 1 including a plurality of said ion exchangers, 3. A process for controlling the amount of neutron-capturing material in reactor coolant, which comprises: 4. A process for controlling the amount of neutron-capturing material in reactor coolant, which comprises; 5. A nuclear reactor control system comprising: 6. The system according to claim 5 wherein coolant flow control means is located between the ion exchangers and the volume control tank for controlling the amount of coolant flowing through said ion exchangers thereby to control the rate of dilution of neutron absorber in said coolant. 7. The system according to claim 5 wherein test means connected in the outlet of said ion exchangers determines the amount of neutron absorber in the ion exchanger effluent; and 8. The system according to claim 5 wherein said heat exchanger means includes a let down chiller heat exchanger serially connected with a let down reheat heat exchanger. 9. The system according to claim 5 wherein said evaporator means includes hold up tanks for receiving effluent from said ion exchangers; and 10. The system according to claim 9 wherein effluent from the hold up tanks is supplied to an evaporator feed ion exchanger which removes gas from the coolant prior to discharge into said evaporator tank. 11. The system according to claim 9 wherein the concentrate holding tank is connected with a neutron absorber mixing tank for supplying concentrated neutron absorber thereto,
	description	The present disclosure relates to lithography methods and devices, intended to etch a pattern on a wafer. Generally, a lithography method is a method where a so-called photosensitive or thermosensitive layer having its properties modified by irradiation is deposited on a material to be etched. For example, the irradiation causes in the sensitive layer a chemical transformation which makes this layer selectively etchable by an etch product. Then, the layer affected by the radiation (or conversely, the unaffected portion of the layer) is removed and the remaining portions are used as mask to etch the substrate supporting the sensitive layer. There are many variations of such methods. For example, often, an intermediate layer is deposited between the substrate and the sensitive layer and the etching of the sensitive layer is followed by an etching of the intermediate layer and then only by an etching of the substrate. The layer may be literally photosensitive, that is, the photons interact with the material of the photosensitive layer to modify its state, or thermosensitive, that is, the sensitive layer is modified by the heat generated by the irradiation. Certain thermosensitive layers react to irradiation by becoming volatizable or pulverulent, whereby it is no longer necessary to perform an etching with a chemical etch product, and the irradiated portions may be simply removed by blowing or rubbing of the areas which have been made pulverulent. In other words, the properties of bonding of the thermosensitive layer to the underlying layer are modified. Generally, to irradiate selected locations of the sensitive layer, a laser beam scanning is performed. There is an increasing tendency to use laser beams in close ultraviolet, to decrease the spot size on the sensitive layer. Wavelengths on the order of 400 nm or less will for example be used. During the scanning of the photo- or thermosensitive layer, the distance between the irradiation laser beam optical focusing system and the surface of the photosensitive layer must be very accurately maintained. To set this distance, the actual irradiation laser beam cannot be used since this beam is intermittent, in order to only irradiate the selected areas. A probe beam which crosses the optical focusing system of the main irradiation beam and reflects on the layer to be irradiated to permanently detect the distance between the optical focusing system and the layer to be irradiated (or more exactly to detect any variation of this distance) is thus used and the data collected by this probe beam are used to control the distance between the optical focusing system and the layer to be irradiated. There however is a difficulty in the case where the surface to be irradiated exhibits abrupt thickness variations or perforations, since the control signal is then lost. Thus, such conventionally-used probe beam methods enable to perform a position control on even surfaces only. This is a first problem that the present invention aims at solving. Further, in the specific case where the material sensitive to an irradiation is a material where the variation of the properties of the sensitive layer reflects as a variation of the bonding of the irradiated portions, such being for example the case for a PtOx-type material, which, after an irradiation, turns into pulverulent platinum, another issue, described in relation with FIGS. 1A to 1C, arises. FIGS. 1A to 1C show a substrate 1, for example, made of glass, sapphire, or other, coated with a layer 2 of a thermosensitive material having its bonding properties varying according to an irradiation. It is desired to form on substrate 1, on the one hand, an opening 4 of minimum size, and on the other hand, an opening 6 having a size much greater than the minimum size. FIG. 1A shows the result of the irradiation in an optimal case: the irradiated area is regularly modified, after which the portion of the PtOx layer turned into platinum can be removed in the region of opening 6 by brushing or blowing, the bonding of this layer portion to substrate 1 then being very low. Unfortunately, after the irradiation, or during the irradiation, layer 2 is actually modified in irradiated region 6′ as illustrated in FIG. 1B. The layer is partially turned into powder during the irradiation, which results in the forming of chips which, as illustrated in FIG. 1C, remain on portions 6″ of the opening. Such chips may be projected on the optical irradiation system, and may disturb the writing by masking the irradiation beam or the probe beam. Known lithography methods thus need to be improved. An embodiment provides overcoming at least some of the disadvantages of known lithography methods. Another embodiment avoids the disadvantages associated with the forming of chips in a thermosensitive layer. Another embodiment provides a lithography installation adapted to substrates having surface discontinuities. Thus, an embodiment provides an installation for etching at least one wafer coated with a blank photosensitive layer, ready to be etched, this wafer having thickness irregularities, wherein the wafer is arranged to be able to be submitted to the scanning of an irradiation beam, a sheet transparent to the radiation to which the photosensitive layer is sensitive covers the wafer, and a probe beam intended to reflect on the upper portion of said sheet perpendicularly to the irradiation beam spot on the photosensitive layer is provided. According to an embodiment, an installation for etching a plurality of wafers is provided, where each wafer is arranged in a receptacle of a support plate submitted to the scanning of an irradiation beam, and the sheet covers all the wafers and the support plate. An embodiment provides an installation for etching a plurality of wafers coated with a blank photosensitive layer, ready to be etched, thickness irregularities being formed between the wafers, wherein the wafers are arranged to be able to be submitted to the scanning of an irradiation beam, a sheet transparent to the radiation to which the photosensitive layer is sensitive covers the wafers, and a probe beam intended to reflect on the upper portion of said sheet perpendicularly to the irradiation beam spot on the photosensitive layer is provided. According to an embodiment, the sheet is glued. According to an embodiment, the sheet has a 100-μm thickness. According to an embodiment, the sheet is an added element having a substantially planar upper portion. According to an embodiment, the photosensitive layer is a layer of a thermosensitive material having its bonding to the wafer modified after a heating. According to an embodiment, the thermosensitive layer is a platinum oxide layer. An embodiment provides a method for preparing a wafer or a plurality of wafers to be locally etched arranged in receptacles of a support plate comprising the steps of coating the wafer or the plurality of wafers with a photosensitive layer, and of coating the wafer or the plurality of wafers with a sheet transparent to the radiation to which the photosensitive layer is sensitive. The foregoing and other features, and advantages will be discussed in detail in the following non-limiting description of specific embodiments in connection with the accompanying drawings. In FIG. 2A, on a substrate 1 which is desired to be etched, a layer 2 of a thermosensitive material which has the property of becoming pulverulent or in any case little bonding to the substrate supporting it once it has been submitted to a heating radiation, has been deposited. Above thermosensitive layer 2, a sheet 11 has been glued via an adhesive 12. Layer 11 is made of a material transparent to the wavelength at which photosensitive material layer 2 is desired to be irradiated. The thermosensitive material for example is PtOx, which turns into platinum once it has been submitted to a heating radiation. At the step illustrated in FIG. 2B, an irradiation is performed with a light beam 14 crossing sheet 11. Beam 14 is concentrated to form spot 16 on the surface of the thermosensitive material, which leads to modifying portion 18 of the photosensitive material which has been irradiated. In the shown example, the case where the light spot is displaced to form a groove of minimum width in thermosensitive material 2 has been considered. As very schematically illustrated in FIG. 2C, if separations and a forming of chips 19 tends to occur in irradiated area 18, these chips are trapped by sheet 11 glued to the thermosensitive layer and thus cannot contaminate the installation. At the next step illustrated in FIG. 2D, protection sheet 11 is removed. This removal may be performed by simple tearing off or by submitting the structure to a product dissolving glue 12. Then, a portion at least of irradiated material 18 goes away with sheet 11 and the possible remaining portions are removed by conventional means, for example, by blowing with a pressurized fluid jet or by brushing. The structure shown in FIG. 2E where a groove 18 has been formed in the thermosensitive layer is thus obtained. At next steps, not shown, the mask formed by the etched thermosensitive layer is used to etch substrate 1. This may be directly performed. An intermediate layer, or hard mask, which is etched and is used as a mask for etching the substrate, may also be used. Many variations of this process will occur to those skilled in the art. For example, the intermediate layer capable of being used as a hard mask may be provided to be made of a good thermal insulator, so that the irradiation of the thermosensitive layer effectively cause a temperature rise at the level of this layer and to avoid for the heat to diffuse into the substrate if this substrate is relatively thermally conductive. Another generic advantage of the above-described protection sheet to improve the tracking of a focusing device on a photosensitive material (currently called resist), whether this material is thermosensitive with a bonding variation or not, should also be noted. FIG. 3 shows an example of a lithography installation of the type used to etch optical disks. A disk 21, coated with a photosensitive layer, receives the radiation of a laser 23. An optical device 25 or write head projects the beam of laser 23 in a quasi-point spot 24 on the disk which is rotated while the write head is shifted perpendicularly to the disk so that the spot follows a spiral path on the disk. A modulation device 26 is associated with laser 23 to provide intense light beams at selected locations. A focusing control device 28 is also provided to control a device for displacing write head 25 orthogonally to the disk to permanently maintain focused light on the disk. This control device comprises a probe beam or control beam which reflects on the disk at the same point as the irradiation spot. A variation of the distance between the write head and the disk translates as a displacement of the reflected probe beam. Such a lithography installation is intended to operate at very high speed to have the shortest possible write time. Thus, the device for controlling the vertical position of the write head is particularly sensitive. If the disk surface comprises abrupt irregularities, this results in a loss of control and the entire write process is to be started over. In practice, in certain cases, the disk on which the lithography is desired to be performed has discontinuities, for example, holes. Thus, a method enabling to ensure the tracking of the write head even if the disk has discontinuities is here provided. FIG. 4 shows a device for controlling the height of the write head with respect to the disk. A portion of the disk is shown at the bottom of the drawing under reference numeral 30. Disk 31 is coated with a photosensitive layer 32. Further, a sheet 33 transparent to the irradiation modifying the resin is glued to the entire disk above resist 32. A laser beam 40 is focused on a point 41 of the resist via an optical system comprising a light concentration device 43, a reflective plate 44, and lenses 45. The assembly formed of optical concentration system 43 and of lenses 45 is set so that the beam light focuses on point 41. A probe beam 51 emitted by a laser 52 which, by means of reflectors 53 and 54, is sent into optical concentration system 43 and returned to a detector 55, is further provided. The optical concentration system has been set so that light beam 51, instead of reflecting, as it usually does, on photosensitive layer 32, reflects on the upper surface of sheet 33 above spot 41. The wavelength of the probe beam is selected so that it crosses plate 44 with practically no attenuation, this plate, as it should be reminded, being reflective for irradiation beam 40. Thus, due to the fact that, instead of reflecting on photosensitive layer 32 which reproduces possible surface defects of support 31 which is desired to be etched, the light reflects on the upper surface of sheet 33, the possible thickness discontinuities of the support are smoothed out by the sheet having a surface with, at most, light irregularities. By means of receiver 55 and of a conventional control system, optical concentration system 43 can thus have its height controlled so that laser beam 40 remains focused on the surface of photosensitive layer 32. Of course, this optical system is likely to have various alterations, modifications, and improvements which will readily occur to those skilled in the art, the important point being that optical concentration system 43 forms a point image of the laser beam on the surface of photosensitive layer 32 and deviates the probe beam so that it reflects on the upper surface of sheet 33. FIGS. 5A and 5B are cross-section views of an installation capable of using the system described in relation with FIG. 4. In this case, several wafers to be etched, for example, clock glasses 60, are arranged in receptacles of a support disk 62 so that the upper surface of the wafers is at the level of the upper surface of the support disk. This system replaces the disk shown in FIG. 3. Of course, thickness irregularities (deep grooves 64) will appear at the limits between wafers 60 and support 62. Each wafer being coated with a photosensitive layer 66, the entire structure shown in top view in FIG. 5A is coated with a transparent layer 68 and the system will be used as described in relation with FIG. 4. As an example of embodiment, the write laser will have a 405-μm wavelength, the probe beam will have a 650-μm wavelength, and the sheet will have a thickness on the order of 100 μm. This sheet will be made of a material or of stack of materials capable of being transparent at 405 nm and of being substantially reflective at 650 nm. This sheet may be a thin glass plate or a polycarbonate sheet. Of course, the present invention is likely to have various alterations, modifications, and improvements which will readily occur to those skilled in the art. Especially, a specific scan system, of spiral type associated with a rotating disk, has been previously described. Any other scan system, for example, an XY scanning, may be provided. Further, various embodiments with different variations have been described hereabove. Those skilled in the art may combine various elements of these various embodiments and variations without showing any inventive step. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and the scope of the present invention. Accordingly, the foregoing description is by way of example only and is not intended to be limiting. The present invention is limited only as defined in the following claims and the equivalents thereto.
	summary
	claims	1. An optical hollow waveguide assembly, comprising:an optical hollow waveguide configured to guide illumination light, comprising:a tubular main body with a continuous waveguide cavity having an illumination light inlet and an illumination light outlet,wherein a cavity inner wall of the waveguide cavity is configured to reflect the illumination light under grazing incidence,a gas source that has a fluid connection to the waveguide cavity,wherein the gas source is configured to introduce gas into the waveguide cavity, anda chemically reducing environment over the cavity inner wall,wherein the chemically reducing environment comprises radicals produced in the gas under action of the illumination light, and the atmosphere is selected to decontaminate the waveguide cavity. 2. The waveguide assembly according to claim 1, wherein the gas source has a fluid connection to the waveguide cavity at the illumination light inlet and/or at the illumination light outlet. 3. The waveguide assembly according to claim 1, wherein the gas source has a fluid connection to the waveguide cavity via at least one gas inlet that opens into the waveguide cavity between the illumination light inlet and the illumination light outlet. 4. The waveguide assembly according to claim 3, wherein an opening of the at least one gas inlet tapers conically toward the waveguide cavity. 5. The waveguide assembly according to claim 3 wherein an opening cross section of the gas inlet into the waveguide cavity is less than 1 mm2. 6. The waveguide assembly according to claim 1, further comprising at least one positive pressure portion of the waveguide cavity, into which at least one gas inlet of the fluid connection to the gas source opens, wherein the at least one positive pressure portion is connected to a space surrounding the hollow waveguide through at least one pressure reduction opening such that, when gas is supplied via the gas source to the at least one positive pressure portion, a pressure (p1, p2) in the pressure reduction opening is greater than a pressure (pext) of the surrounding space. 7. The waveguide assembly according to claim 6, further comprising a further positive pressure portion, wherein the one positive pressure portion is arranged in proximity to the illumination light inlet and the further positive pressure portion is arranged in proximity to the illumination light outlet. 8. An illumination optical unit comprising a hollow waveguide assembly as claimed in claim 1. 9. An illumination system comprising an illumination optical unit as claimed in claim 8 and a light source. 10. An inspection apparatus comprising an illumination system according to claim 9 and configured to receive an object for inspection. 11. The optical hollow waveguide assembly of claim 1, wherein the gas comprises molecular hydrogen. 12. The optical hollow waveguide assembly of claim 1, wherein the illumination light comprises Extreme Ultraviolet (EUV) illumination. 13. The optical hollow waveguide assembly of claim 1, wherein the radicals comprise hydrogen radicals. 14. The optical hollow waveguide assembly of claim 1, wherein the atmosphere comprises a positive pressure atmosphere. 15. A method comprising:introducing a gas into an optical hollow waveguide comprising a cavity inner wall of the waveguide cavity configured to reflect illumination light under grazing incidence to guide the illumination light, wherein introducing the gas comprises introducing gas into the cavity from a gas source having a fluid connection with the cavity;transmitting the illumination light through the cavity;forming a reducing atmosphere including radicals in the cavity, wherein forming the reducing atmosphere comprises causing the illumination light to act on the gas to form the radicals; anddecontaminating the cavity under action of the reducing atmosphere. 16. The method of claim 15, wherein transmitting the illumination light through the cavity comprises transmitting Extreme Ultraviolet (EUV) illumination. 17. The method of claim 15, wherein causing the illumination light to act on the gas to form the radicals comprises causing EUV light to act on a gas comprising molecular hydrogen to form hydrogen radicals. 18. The method of claim 15, wherein decontaminating the cavity under action of the reducing atmosphere comprises:reacting the radicals with carbon particles on the inner walls of the cavity to form hydrocarbons; andblowing the hydrocarbons out of the cavity by positive pressure of the reducing atmosphere. 19. The method of claim 15, wherein introducing the gas into the optical hollow waveguide comprises introducing the gas via at least one gas inlet that opens into the waveguide cavity between an illumination light inlet and an illumination light outlet. 20. The method of claim 19, wherein introducing the gas via the at least one gas inlet comprises introducing the gas via an opening of the at least one gas inlet that tapers conically toward the waveguide cavity.
	abstract	A system for analyzing fabrication processes, such as analyzing device yield on a substrate. An input accesses fabrication information, where the fabrication information includes at least one of an dependent variable that is associated with substrate location information, and at least one independent variable that is associated with at least one of the fabrication processes. Desired portions of the substrate information are selected, based on at least one of the independent variable and the dependent variable. A substrate profile is produced, based on the desired portions of the fabrication information.
043550010	summary	FIELD OF THE INVENTION The present invention relates mainly to a reactor unit and to an installation of the type which forms a nuclear boiler, for example, and uses such a reactor unit. The invention also relates to a method of fitting up such an installation. BACKGROUND OF THE INVENTION Up till now, the various components which constitute a nuclear boiler have been manufactured in situ, i.e. at the chosen operation site. However, this has very numerous disadvantages. Indeed, when an installation is to be set up at a remote site or in a developing country, problems arise which relate to ground, labour, etc. and do not facilitate such manufacture or even make it impossible. One of the main aims of the present invention is to overcome the above-mentioned disadvantages by providing a complete prefabricated nuclear installation which can be transported to the operation site. In this connection, it must be stated that there are at present transport means such as barges, for example, which enable a complete prefabricated nuclear installation such as a boiler to be transported. However, the conditions of access to the boiler installation site are often difficult and further, the total weight and bulk of such a boiler are considerable and make it difficult to prefabricate, handle and transport it in a single piece. Therefore, the invention also aims to remedy the above drawbacks by providing in particular a nuclear installation constituted by prefabricated modular components which are separated and can be fitted together. SUMMARY OF THE INVENTION For this purpose, firstly, the invention provides a reactor unit of the type which includes a nuclear reactor installed on a support, wherein said reactor unit constitutes a module which can be shifted and/or transported and said support is constituted by a stand which also ensures stability of the reactor during operation. It should also be noted that means for shifting are associated with the above-mentioned stand. The invention also provides a nuclear installation which includes a reactor unit which has the above-mentioned characteristics, said installation constituting a complete nuclear boiler. According to another feature of the invention, said complete nuclear boiler itself constitutes a transportable module. According to yet another feature of the invention, the above-mentioned nuclear boiler is constituted by a plurality of modular components which can be fitted together. According to yet another feature of the invention, the above-mentioned nuclear boiler consists of at least two modular components constituted by the above-mentioned reactor unit and a container unit which is designed to accomodate it and can be closed by a detachable closing component. The invention further relates to a method of fitting up an installation such as defined hereinabove wherein the installation is in a prefabricated modular form and its modular components are previously checked and tested at the works before being transported to the operation site and assembled in situ. It will therefore be understood that a nuclear boiler according to the invention can be divided into several components which can be transported separately and be assembled subsequently at the chosen operation site. Further, in the method according to the invention the modules are assembled by successive insertion of the various modules in situ or, even, at the works. Further, in the method according to the invention, the modules are assembled and loaded onto transport means and unloaded therefrom by horizontal handling methods. Other features and advantages of the invention become more apparent from the following detailed description which refers to the accompanying drawings given only by way of example.

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