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Radial position of single-site gamma-ray interactions from a parametric
pulse shape analysis of germanium detector signals: Pulse shape analysis of germanium gamma-ray spectrometer signals can yield
information on the radial position of individual gamma-ray interactions within
the germanium crystal. A parametric pulse shape analysis based on calculation
of moments of the reconstructed current pulses from a closed-ended coaxial
germanium detector is used to preferentially select single-site gamma-ray
interactions. The double escape peak events from the 2614.5 keV gamma-ray of
208-Tl are used as a training set to optimize the single-site event selection
region in the pulse shape parameter space. A collimated source of 320.1 keV
gamma-rays from 51-Cr is used to scan different radial positions of the same
semi-coaxial germanium detector. The previously trained single-site selection
region is used to preferentially identify the single-site photoelectric
absorption events from the 320.1 keV full-energy peak. From the identified
events, a comparison of the pulse shape parameter space distributions between
different scan positions allows radial interaction location information to be
collected. | nucl-ex |
Anisotropy Scaling Functions in Heavy-Ion Collisions: Insights into the
`Ultra-Central Flow Puzzle' and Constraints on Transport Coefficients and
Nuclear Deformation: Anisotropy scaling functions, derived from extensive measurements of
transverse momentum- and centrality-dependent anisotropy coefficients
$v_2(p_T,\text{cent})$ and $v_3(p_T,\text{cent})$ in Pb+Pb collisions at 5.02
and 2.76 TeV, and Xe+Xe collisions at 5.44 TeV at the LHC, shed light on the
'ultra-central flow puzzle'. These functions amalgamate diverse measurements
into a unified curve, elucidating anisotropy attenuation across the full $p_T$
and centrality range and unveiling dependencies on key factors including
initial-state eccentricities ($\varepsilon_{n}$), dimensionless size
($\mathbb{R}$), radial flow, viscous correction to the thermal distribution
function ($\delta_f$), the medium's stopping power ($\hat{q}$), and specific
shear viscosity ($\eta/s$). Their analysis provides distinct insights into
transport coefficients and nucleus deformation constraints. | nucl-ex |
Experimental summary on global observables, hadron spectra and ratios: This article summarizes results on global observables, hadron spectra, and
ratios of integrated hadron yields as presented at the Quark Matter 2002
Conference. | nucl-ex |
High $p_T$ correlations of $γ$ and charged hadrons at RHIC: Prompt photon production in ultra-relativistic heavy-ion collisions provides
a calibrated probe for the study of the properties of high energy density QCD
matter. Especially interesting are the measurements of $\gamma$-tagged jets
where the hard scattering scale is known and can be used to determine the
partonic energy loss in the dense matter. We discuss the potential of
$\gamma$-jet measurements at the Relativistic Heavy Ion Collider (RHIC) and
argue that the observed supression of the away-side correlations for di-jet
production in central Au+Au collisions at $\sqrt{s_{NN}}$=200 GeV should
significantly reduce the backgrounds for the $\gamma$-jet coincidence
measurements. | nucl-ex |
Resonance photoproduction of pionic atoms at the Gamma Factory: We present a possibility of direct resonance production of pionic atoms
(Coulomb bound states of a negative pion and a nucleus) with a rate of up to
$\sim10^{10}$ per second using the gamma-ray beams from the Gamma Factory. | nucl-ex |
Muonic atom spectroscopy with microgram target material: Muonic atom spectroscopy -- the measurement of the x rays emitted during the
formation process of a muonic atom -- has a long standing history in probing
the shape and size of nuclei. In fact, almost all stable elements have been
subject to muonic atom spectroscopy measurements and the absolute charge radii
extracted from these measurements typically offer the highest accuracy
available. However, so far only targets of at least a few hundred milligram
could be used as it required to stop a muon beam directly in the target to form
the muonic atom. We have developed a new method relying on repeated transfer
reactions taking place inside a 100-bar hydrogen gas cell with an admixture of
0.25% deuterium that allows us to drastically reduce the amount of target
material needed while still offering an adequate efficiency. Detailed
simulations of the transfer reactions match the measured data, suggesting good
understanding of the processes taking place inside the gas mixture. As a proof
of principle we demonstrate the method with a measurement of the 2p-1s muonic x
rays from a 5-{\mu}g gold target. | nucl-ex |
Measurement of the Transverse Polarization of Electrons Emitted in Free
Neutron Decay: Both components of the transverse polarization of electrons emitted in the
beta-decay of polarized, free neutrons have been measured. The T-odd, P-odd
correlation coefficient quantifying the component perpendicular to the decay
plane defined by neutron polarization and electron momentum, was found to be
R=0.008 +/- 0.015 +/-0.005. This value is consistent with time reversal
invariance, and significantly improves limits on the relative strength of
imaginary scalar couplings in the weak interaction. The value obtained for the
correlation coefficient associated with the electron polarization component
contained within the decay plane N=0.056 +/- 0.011 +/- 0.005, agrees with the
Standard Model expectation, providing an important sensitivity test of the
experimental setup. | nucl-ex |
Observation of a multiplicity dependence in the $p_{\rm T}$-differential
charm baryon-to-meson ratios in proton-proton collisions at $\sqrt{s} = 13$
TeV: The production of prompt $D^{0}$, $D^{+}_{\rm s}$, and $\Lambda_{\rm c}^{+}$
hadrons, and their ratios, $D^{+}_{\rm s}$/$D^{0}$ and $\Lambda_{\rm
c}^{+}$/$D^{0}$, are measured in proton-proton collisions at $\sqrt{s}$ = 13
TeV at midrapidity ($|y| <0.5$) with the ALICE detector at the LHC. The
measurements are performed as a function of the charm-hadron transverse
momentum ($p_{\rm T}$) in intervals of charged-particle multiplicity, measured
with two multiplicity estimators covering different pseudorapidity regions.
While the strange to non-strange $D^{+}_{\rm s}$/$D^{0}$ ratio indicates no
significant multiplicity dependence, the baryon-to-meson $p_{\rm
T}$-differential $\Lambda_{\rm c}^{+}$/$D^{0}$ ratio shows a
multiplicity-dependent enhancement, with a significance of 5.3$\sigma$ for $1<
p_{\rm T} < 12$ GeV/$c$, comparing the highest multiplicity interval with
respect to the lowest one. The measurements are compared with a theoretical
model that explains the multiplicity dependence by a canonical treatment of
quantum charges in the statistical hadronisation approach, and with predictions
from event generators that implement colour reconnection mechanisms beyond the
leading colour approximation to model the hadronisation process. The
$\Lambda_{\rm c}^{+}$/$D^{0}$ ratios as a function of $p_{\rm T}$ present a
similar shape and magnitude as the $\Lambda/K^{0}_{s}$ ratios in comparable
multiplicity intervals, suggesting a potential common mechanism for light- and
charm-hadron formation, with analogous multiplicity dependence. The $p_{\rm
T}$-integrated ratios, extrapolated down to $p_{\rm T}$=0, do not show a
significant dependence on multiplicity within the uncertainties. | nucl-ex |
Suppression of Upsilon(1S), Upsilon(2S), and Upsilon(3S) production in
PbPb collisions at sqrt(s[NN]) = 2.76 TeV: The production yields of Upsilon(1S), Upsilon(2S), and Upsilon(3S) quarkonium
states are measured through their decays into muon pairs in the CMS detector,
in PbPb and pp collisions at the centre-of-mass energy per nucleon pair of 2.76
TeV. The data correspond to integrated luminosities of 166 inverse microbarns
and 5.4 inverse picobarns for PbPb and pp collisions, respectively.
Differential production cross sections are reported as functions of Upsilon
rapidity y up to 2.4, and transverse momentum pT up to 20 GeV/c. A strong
centrality-dependent suppression is observed in PbPb relative to pp collisions,
by factors of up to approximately 2 and 8, for the Upsilon(1S) and Upsilon(2S)
states, respectively. No significant dependence of this suppression is observed
as a function of y or pT. The Upsilon(3S) state is not observed in PbPb
collisions, which corresponds to a suppression for the centrality-integrated
data by at least a factor of approximately 7 at a 95% confidence level. The
observed suppression is in agreement with theoretical scenarios modeling the
sequential melting of quarkonium states in a quark gluon plasma. | nucl-ex |
First limits on double beta decays in $^{\bf 232}$Th: As one of the primordial radioactive isotopes, $^{232}$Th mainly undergoes
$\alpha$-decay with a half-life of $1.402 \times 10^{10}$ yr. However, it is
also one of 35 double beta decay candidates in which the single $\beta$-decay
is forbidden or strongly suppressed. 181 mg of thorium contained in a gas
mantle was measured in an HPGe well-detector at the Gran Sasso Underground
Laboratory (LNGS) with a total exposure of 3.25 g $\times$ d. We obtain
half-life limits on all double beta decay modes of $^{232}$Th to excited states
of $^{232}$U on the order of $10^{11-15}$ yr. For the most likely transition
into the $0_1^+$ state we find a lower half-life limit of $6.3 \times 10^{14}$
yr (90% credibility). These are the first constraints on double beta decay
excited state transition in $^{232}$Th. | nucl-ex |
Ridges in p-A (and pp) collisions: Correlations between particles separated by several units of pseudorapidity
were discovered in high-multiplicity pp and p-Pb collisions at the LHC. These
long-range structures observed in two-particle correlation functions are
reminiscent of features seen in Pb-Pb collisions, where they are often viewed
as a signature of collective behavior and the formation of a quark-gluon plasma
(QGP). Therefore, the discovery of these `ridges' in small systems has
implications for the study of collectivity in small systems as well as in
heavy-ion collisions. The ridges in pp and p-Pb collisions have been studied in
the ALICE, ATLAS, CMS, and LHCb experiments to characterize the $p_{\rm{T}}$-,
$\eta$-, and multiplicity-dependences of the ridge yield, as well as its
particle composition. | nucl-ex |
The structure of 70Fe: Single-particle and collective degrees of freedom: Excited states in the neutron-rich \nuc{70}{Fe} nucleus were populated in a
one-proton removal reaction from \nuc{71}{Co} projectiles at 87~MeV/nucleon. A
new transition was observed with the $\gamma$-ray tracking array GRETINA and
shown to feed the previously assigned $4^+_1$ state. In comparison to reaction
theory calculations with shell-model spectroscopic factors, it is argued that
the new $\gamma$ ray possibly originates from the $6^+_1$ state. It is further
shown that the Doppler-reconstructed $\gamma$-ray spectra are sensitive to the
very different lifetimes of the $2^+$ and $4^+$ states, enabling their
approximate measurement. The emerging structure of \nuc{70}{Fe} is discussed in
comparison to LNPS-new large-scale shell-model calculations. | nucl-ex |
Combined Analysis of all Three Phases of Solar Neutrino Data from the
Sudbury Neutrino Observatory: We report results from a combined analysis of solar neutrino data from all
phases of the Sudbury Neutrino Observatory. By exploiting particle
identification information obtained from the proportional counters installed
during the third phase, this analysis improved background rejection in that
phase of the experiment. The combined analysis resulted in a total flux of
active neutrino flavors from 8B decays in the Sun of (5.25 \pm
0.16(stat.)+0.11-0.13(syst.))\times10^6 cm^{-2}s^{-1}. A two-flavor neutrino
oscillation analysis yielded \Deltam^2_{21} = (5.6^{+1.9}_{-1.4})\times10^{-5}
eV^2 and tan^2{\theta}_{12}= 0.427^{+0.033}_{-0.029}. A three-flavor neutrino
oscillation analysis combining this result with results of all other solar
neutrino experiments and the KamLAND experiment yielded \Deltam^2_{21} =
(7.41^{+0.21}_{-0.19})\times10^{-5} eV^2, tan^2{\theta}_{12} =
0.446^{+0.030}_{-0.029}, and sin^2{\theta}_{13} =
(2.5^{+1.8}_{-1.5})\times10^{-2}. This implied an upper bound of
sin^2{\theta}_{13} < 0.053 at the 95% confidence level (C.L.). | nucl-ex |
Improved Limit on Neutrinoless Double-Beta Decay in $^{130}$Te with
CUORE: We report new results from the search for neutrinoless double-beta decay in
$^{130}$Te with the CUORE detector. This search benefits from a four-fold
increase in exposure, lower trigger thresholds and analysis improvements
relative to our previous results. We observe a background of
$(1.38\pm0.07)\cdot10^{-2}$ counts$/($keV$\cdot$kg$\cdot$yr$)$ in the
$0\nu\beta\beta$ decay region of interest and, with a total exposure of 372.5
kg$\cdot$yr, we attain a median exclusion sensitivity of $1.7\cdot10^{25}$ yr.
We find no evidence for $0\nu\beta\beta$ decay and set a $90\%$ CI Bayesian
lower limit of $3.2\cdot10^{25}$ yr on the $^{130}$Te half-life for this
process. In the hypothesis that $0\nu\beta\beta$ decay is mediated by light
Majorana neutrinos, this results in an upper limit on the effective Majorana
mass of 75-350 meV, depending on the nuclear matrix elements used. | nucl-ex |
Ratios of 15N/12C and 4He/12C inclusive electroproduction cross sections
in the nucleon resonance region: The (W,Q2)-dependence of the ratio of inclusive electron scattering cross
sections for 15N/12C was determined in the kinematic range 0.8<W<2 GeV and
0.2<Q2<1 GeV2 using 2.285 GeV electrons and the CLAS detector at Jefferson Lab.
The ratios exhibit only slight resonance structure, in agreement with a simple
phenomenological model and an extrapolation of DIS ratios to low Q2. Ratios of
4He/12C using 1.6 to 2.5 GeV electrons were measured with very high statistical
precision, and were used to correct for He in the N and C targets. The (W,Q2)
dependence of the 4He/12C ratios is in good agreement with the phenomenological
model, and exhibit significant resonance structure centered at W=0.94, 1.23 and
1.5 GeV. | nucl-ex |
Double deeply virtual Compton scattering with positron beams at SoLID: Double Deeply Virtual Compton Scattering (DDVCS) is the only experimental
channel for the determination of the dependence of the Generalized Parton
Distributions (GPDs) on both the average and the transferred momentum
independently. The physics observables of the electron induced di-muon
production reaction $\vv{e}^{\pm}p \to e^{\pm}p\mu^+\mu^-$ off unpolarized
hydrogen are discussed. Their measurement with the high luminosity and large
acceptance SoLID spectrometer at the Thomas Jefferson National Accelerator
Facility, using polarized and unpolarized positron and electron beams at 11 GeV
is investigated. This experimental configuration is shown to provide
unprecedented access to the GPDs with the determination of the real and
imaginary parts of the Compton Form Factor ${\mathcal H}$ in an unexplored
phase space, and to enable an exploratory investigation of higher twist
effects. | nucl-ex |
Mass measurements of As, Se and Br nuclei and their implication on the
proton-neutron interaction strength towards the N=Z line: Mass measurements of the $^{69}$As, $^{70,71}$Se and $^{71}$Br isotopes,
produced via fragmentation of a $^{124}$Xe primary beam at the FRS at GSI, have
been performed with the multiple-reflection time-of-flight mass spectrometer
(MR-TOF-MS) of the FRS Ion Catcher with an unprecedented mass resolving power
of almost 1,000,000. For the $^{69}$As isotope, this is the first direct mass
measurement. A mass uncertainty of 22 keV was achieved with only 10 events. For
the $^{70}$Se isotope, a mass uncertainty of 2.6 keV was obtained,
corresponding to a relative accuracy of $\delta$m/m = 4.0$\times 10^{-8}$, with
less than 500 events. The masses of the $^{71}$Se and $^{71}$Br isotopes were
measured with an uncertainty of 23 and 16 keV, respectively. Our results for
the $^{70,71}$Se and $^{71}$Br isotopes agree with the 2016 Atomic Mass
Evaluation, and our result for the $^{69}$As isotope resolves the discrepancy
between previous indirect measurements. We measured also the mass of
$^{14}$N$^{15}$N$^{40}$Ar (A=69) with a relative accuracy of $\delta$m/m =
1.7$\times 10^{-8}$, the highest yet achieved with a MR-TOF-MS. Our results
show that the measured restrengthening of the proton-neutron interaction
($\delta$V$_{pn}$) for odd-odd nuclei at the N=Z line above Z=29 (recently
extended to Z=37) is hardly evident at N-Z=2, and not evident at N-Z=4.
Nevertheless, detailed structure of $\delta$V$_{pn}$ along the N-Z=2 and N-Z=4
lines, confirmed by our mass measurements, may provide a hint regarding the
ongoing $\approx$500 keV discrepancy in the mass value of the $^{70}$Br
isotope, which prevents including it in the world average of ${Ft}$-value for
superallowed 0$^+\rightarrow$ 0$^+$ $\beta$ decays. The reported work sets the
stage for mass measurements with the FRS Ion Catcher of nuclei at and beyond
the N=Z line in the same region of the nuclear chart, including the $^{70}$Br
isotope. | nucl-ex |
The Majorana Demonstrator Status and Preliminary Results: The Majorana Collaboration is using an array of high-purity Ge detectors to
search for neutrinoless double-beta decay in 76Ge. Searches for neutrinoless
double-beta decay are understood to be the only viable experimental method for
testing the Majorana nature of the neutrino. Observation of this decay would
imply violation of lepton number, that neutrinos are Majorana in nature, and
provide information on the neutrino mass. The Majorana Demonstrator comprises
44.1 kg of p-type point-contact Ge detectors (29.7 kg enriched in 76Ge)
surrounded by a low-background shield system. The experiment achieved a high
efficiency of converting raw Ge material to detectors and an unprecedented
detector energy resolution of 2.5 keV FWHM at Q$_{\beta\beta}$. The Majorana
collaboration began taking physics data in 2016. This paper summarizes key
construction aspects of the Demonstrator and shows preliminary results from
initial data. | nucl-ex |
Resolving the Axial Mass Anomaly in neutrino Scattering: We present a parametrization of the observed enhancement in the transverse
electron quasielastic (QE) response function for nucleons bound in carbon as a
function of the square of the four momentum transfer (Q2) in terms of a
correction to the magnetic form factors of bound nucleons. The parametrization
should also be applicable to the transverse cross section in neutrino
scattering. If the transverse enhancement originates from meson exchange
currents (MEC), then it is theoretically expected that any enhancement in the
longitudinal or axial contributions is small. We present the predictions of the
"Transverse Enhancement" model (which is based on electron scattering data
only) for the neutrino and anti-neutrino differential and total QE cross
sections for nucleons bound in carbon. The 2Q2 dependence of the transverse
enhancement is observed to resolve much of the long standing discrepancy
("Axial Mass Anomaly}) in the QE total cross sections and differential
distributions between low energy and high energy neutrino experiments on
nuclear targets. | nucl-ex |
Inclusive Pion Double Charge Exchange in 4He at Intermediate Energies: A systematic experimental study of inclusive pion double charge exchange in
4He has been undertaken. The reaction 4He(pi+,pi-)4p was observed at incident
energies 120, 150, 180, 240 and 270 MeV; the 4He(pi-,pi+)4n reaction was
observed at incident energies 180 and 240 MeV. At each incident energy, the
doubly differential cross section was measured at three to five outgoing pion
laboratory angles between 25 deg and 130 deg. At each angle, cross sections
were measured over the range of outgoing pion energies from 10 MeV up to the
kinematic limit for the reaction in which the final state consists of the
oppositely charged pion plus four free nucleons.
The spectra of outgoing pions are strikingly different from those observed
for the inclusive double charge exchange reaction in heavier nuclei, but
resemble those observed in the (pi-,pi+) reaction in 3He. The forward-angle
spectra in the 3He and 4He reactions exhibit a prominent peak at high outgoing
pion energies. Interpretation of the peaks in 3He (4He) as a three-
(four-)nucleon resonance is ruled out by kinematic analysis. The results of a
calculation, wherein the double charge exchange reaction is assumed to proceed
as two sequential single charge exchange interactions, suggest that the
high-energy peak is naturally explained by this double scattering mechanism.
Non-static treatment of the pi-N interactions and the inclusion of nuclear
binding effects appear to be important in reproducing the shape of the energy
spectra at forward angles. | nucl-ex |
Influence of secondary decay on odd-even staggering of fragment cross
sections: Odd-Even Staggering (OES) appears in many areas of nuclear physics, and is
generally associated with the pairing term in the nuclear binding energy. To
explore this effect, we use the Improved Statistical Multifragmentation Model
to populate an ensemble of hot primary fragments, which are then de-excited
using the Weisskopf-Ewing statistical emission formalism. The yields are then
compared to experimental data. Our results show that, before secondary decay,
OES appears only in the yields of even mass fragments and not in the yields of
odd mass fragments. De-excitation of the hot fragments must be taken into
account to describe the data, suggesting that the OES in fragment yields is a
useful criterion for validating or adjusting theoretical de-excitation models. | nucl-ex |
Results of experimental investigations of cobalt beta decay rate
variation: Results of long-term investigations of variation of cobalt beta decay rate
from 28.12.2010 till 08.02.2012 are presented. The scintillation spectrometer
with two LaBr3 detectors is used to register of gamma-quanta with energy 1.173
and 1.332 MeV accompanying cobalt beta decay. Counting rate of each detector
and their gamma-quanta coincidence are collected in successive time intervals
10 s. The statistical Kolmogorov-Smirnov method for data analysis is used.
Temperature influence on experimental results is also analyzed. Deviations of
beta decay counting rate from constant distribution during the days were
detected in those decades: from 11.03 to 21.03 with significance level a = 0.1;
from 22.04 to 02.05 with a=0.0125; from 24.06 to 04.07 with a=0.05; from 04.08
to 14.08 with a=0.05. | nucl-ex |
Measurement of the neutron $β$-asymmetry parameter $A_0$ with
ultracold neutrons: We present a detailed report of a measurement of the neutron
$\beta$-asymmetry parameter $A_0$, the parity-violating angular correlation
between the neutron spin and the decay electron momentum, performed with
polarized ultracold neutrons (UCN). UCN were extracted from a pulsed spallation
solid deuterium source and polarized via transport through a 7-T magnetic
field. The polarized UCN were then transported through an
adiabatic-fast-passage spin-flipper field region, prior to storage in a
cylindrical decay volume situated within a 1-T $2 \times 2\pi$ solenoidal
spectrometer. The asymmetry was extracted from measurements of the decay
electrons in multiwire proportional chamber and plastic scintillator detector
packages located on both ends of the spectrometer. From an analysis of data
acquired during runs in 2008 and 2009, we report $A_0 = -0.11966 \pm
0.00089_{-0.00140} ^{+0.00123}$, from which we extract a value for the ratio of
the weak axial-vector and vector coupling constants of the nucleon, $\lambda =
g_A/g_V = -1.27590 \pm 0.00239_{-0.00377}^{+0.00331}$. Complete details of the
analysis are presented. | nucl-ex |
Measurement of flow harmonics correlations with mean transverse momentum
in lead-lead and proton-lead collisions at $\sqrt{s_{NN}}=5.02$ TeV with the
ATLAS detector: To assess the properties of the quark-gluon plasma formed in heavy-ion
collisions, the ATLAS experiment at the LHC measures a correlation between the
mean transverse momentum and the magnitudes of the flow harmonics. The analysis
uses data samples of lead-lead and proton-lead collisions obtained at the
centre-of-mass energy per nucleon pair of 5.02 TeV, corresponding to total
integrated luminosities of $22 ~\mu b^{-1}$ and $28~nb^{-1}$, respectively. The
measurement is performed using a modified Pearson correlation coefficient with
the charged-particle tracks on an event-by-event basis. The modified Pearson
correlation coefficients for the $2^{nd}$-, 3$^{rd}$-, and 4$^{th}$-order
harmonics are measured as a function of event centrality quantified as the
number of charged particles or the number of nucleons participating in the
collision. The measurements are performed for several intervals of the
charged-particle transverse momentum. The correlation coefficients for all
studied harmonics exhibit a strong centrality evolution in the lead-lead
collisions, which only weakly depends on the charged-particle momentum range.
In the proton-lead collisions, the modified Pearson correlation coefficient
measured for the second harmonics shows only weak centrality dependence. The
data is qualitatively described by the predictions based on the hydrodynamical
model. | nucl-ex |
In-gas-cell laser spectroscopy for magnetic dipole moment of $^{199}$Pt
toward $N=$ 126: Magnetic dipole moment and mean-square charge radius of $^{199}$Pt
($I^{\pi}=$ 5/2$^-$) have been evaluated for the first time from the
investigation of the hyperfine splitting of the $\lambda_1=$ 248.792 nm
transition by in-gas-cell laser ionization spectroscopy. Neutron-rich nucleus
$^{199}$Pt was produced by multi-nucleon transfer reaction at the KISS where
the nuclear spectroscopy in the vicinity of $N=$ 126 is planed from the aspect
of an astrophysical interest as well as the nuclear structure. Measured
magnetic dipole moment $+$0.63(13)$\mu_{\rm N}$ is consistent with the
systematics of those of nuclei with $I^{\pi}=$ 5/2$^-$. The deformation
parameter $|<\beta_2^2>^{1/2}|$ evaluated from the isotope shift indicates the
gradual shape change to spherical shape of platinum isotopes with increasing
neutron number toward $N=$ 126. | nucl-ex |
Investigation of alpha-induced reactions on 130Ba and 132Ba and their
importance for the synthesis of heavy p nuclei: Captures of alpha particles on the proton-richest Barium isotope, 130Ba, have
been studied in order to provide cross section data for the modeling of the
astrophysical gamma process. The cross sections of the 130Ba(alpha,gamma)134Ce
and 130Ba(alpha,n)133Ce reactions have been measured with the activation
technique in the center-of mass energy range between 11.6 and 16 MeV, close
above the astrophysically relevant energies. As a side result, the cross
section of the 132Ba(alpha,n)135Ce reaction has also been measured. The results
are compared with the prediction of statistical model calculations, using
different input parameters such as alpha+nucleus optical potentials. It is
found that the (alpha,n) data can be reproduced employing the standard
alpha+nucleus optical potential widely used in astrophysical applications.
Assuming its validity also in the astrophysically relevant energy window, we
present new stellar reaction rates for 130Ba(alpha,gamma)134Ce and
132Ba(alpha,gamma)136Ce and their inverse reactions calculated with the SMARAGD
statistical model code. The highly increased 136Ce(gamma,alpha)132Ba rate
implies that the p nucleus 130Ba cannot directly receive contributions from the
Ce isotopic chain. Further measurements are required to better constrain this
result. | nucl-ex |
High-resolution (p,t) reaction measurements as spectroscopic tests of
{\it ab-initio} theory in the mid $pf$-shell: Detailed spectroscopic measurements of excited states in $^{50}$Cr and
$^{62}$Zn were performed using 24~MeV (p,t) transfer reactions on $^{52}$Cr and
$^{64}$Zn, respectively. In total, forty-five states in $^{50}$Cr and
sixty-seven states in $^{62}$Zn were observed up to excitation energies of
5.5~MeV, including several previously unobserved states. These experimental
results are compared to {\it ab-initio} shell-model calculations using chiral
effective field theory ($\chi$-EFT) with the valence-space in-medium similarity
renormalization group (VS-IMSRG) method. This comparison demonstrates good
agreement in the level orderings with these new theoretical methods, albeit
with a slight over binding in the calculations. This work is part of a
continued push to benchmark {\it ab-initio} theoretical techniques to nuclear
structure data in $0^+\rightarrow0^+$ superallowed Fermi $\beta$ decay systems. | nucl-ex |
Coulomb and nuclear excitations of $^{70}$Zn and $^{68}$Ni at
intermediate energy: The reduced transition probabilities $B(E2;
0^+_{g.s.}\rightarrow2_1^+,2^+_2)$ in $^{70}$Zn and the full $B(E2;
0^+_{g.s.}\rightarrow2^+)$ strength up to S$_n$=7.79 MeV in $^{68}$Ni have been
determined at the LISE/GANIL facility using the Coulomb-excitation technique at
intermediate beam energy on a $^{208}$Pb target. The $\gamma$ rays emitted
in-flight were detected with an array of 46 BaF$_2$ crystals. The angles of the
deflected nuclei were determined in order to disentangle and extract the
Coulomb and nuclear contributions to the excitation of the 2$^+$ states. The
measured $B(E2; 0^+_{g.s.}\rightarrow2_1^+)$ of 1432(124) e$^2$fm$^4$ for
$^{70}$Zn falls in the lower part of the published values which clustered
either around 1600 or above 2000 e$^2$fm$^4$, while the $B(E2;
0^+_{g.s.}\rightarrow2^+_2)$ of 53(7) e$^2$fm$^4$ agrees very well with the two
published values. The relatively low $B(E2; 0^+_{g.s.}\rightarrow2_1^+)$ of
301(38) e$^2$fm$^4$ for $^{68}$Ni agrees with previous studies and confirms a
local magicity at $Z=28, N=40$. Combining the results of the low-energy spectra
of $^{68}$Ni and $^{70}$Zn and their shell-model interpretations, it is
interesting to notice that four different shapes (spherical, oblate, prolate
and triaxial) are present. Finally, a summed $E2$ strength of only about 150
e$^2$fm$^4$ has been found experimentally at high excitation energy, likely due
to proton excitations across the $Z=28$ gap. The experimental distribution of
this high-energy $E2$ excitation agrees with SM calculations, but its strength
is about two times weaker. | nucl-ex |
Triangular flow of negative pions emitted in PbAu collisions at
$\sqrt{s_{NN}} = $ 17.3 GeV: Differential triangular flow, $v_3(p_T)$, of negative pions is measured at
$\sqrt{s_{NN}}$= 17.3 GeV around midrapidity by the CERES/NA45 experiment at
CERN in central PbAu collisions in the range 0-30\% with a mean centrality of
5.5\%. This is the first measurement as a function of transverse momentum of
the triangular flow at SPS energies. The $p_T$ range extends from about 0.05
GeV/c to more than 2 GeV/c. The triangular flow magnitude, corrected for the
HBT effects, is smaller by a factor of about 2 than the one measured by the
PHENIX experiment at RHIC and the ALICE experiment at the LHC. Within the
analyzed range of central collisions no significant centrality dependence is
observed. The data are found to be well described by a viscous hydrodynamic
calculation combined with an UrQMD cascade model for the late stages. | nucl-ex |
Does deuteron-induced fission on actinide nuclei prevails over the
breakup at low incident energies?: An analysis of the $^{231}$Pa$(d,3n)$$^{230}$U reaction excitation function
at energies around the Coulomb barrier has taken into account the
pre-equilibrium and compound-nucleus cross sections corrected for the
deuteron-breakup decrease of the total reaction cross section, as well as the
inelastic breakup enhancement. The analysis reveals the dominance of the
deuteron breakup mechanism unlike a former assessment in this respect of the
deuteron-induced fission process. | nucl-ex |
Beam Asymmetry $\mathbfΣ$ for the Photoproduction of
$\mathbfη$ and $\mathbf{η^{\prime}}$ Mesons at
$\mathbf{E_γ=8.8}$GeV: We report on the measurement of the beam asymmetry $\Sigma$ for the reactions
$\vec{\gamma}p\rightarrow p\eta$ and $\vec{\gamma}p \rightarrow p\eta^{\prime}$
from the GlueX experiment, using an 8.2--8.8 GeV linearly polarized tagged
photon beam incident on a liquid hydrogen target in Hall D at Jefferson Lab.
These measurements are made as a function of momentum transfer $-t$, with
significantly higher statistical precision than our earlier $\eta$
measurements, and are the first measurements of $\eta^{\prime}$ in this energy
range. We compare the results to theoretical predictions based on $t$--channel
quasi-particle exchange. We also compare the ratio of $\Sigma_{\eta}$ to
$\Sigma_{\eta^{\prime}}$ to these models, as this ratio is predicted to be
sensitive to the amount of $s\bar{s}$ exchange in the production. We find that
photoproduction of both $\eta$ and $\eta^{\prime}$ is dominated by natural
parity exchange with little dependence on $-t$. | nucl-ex |
Early onset of ground-state deformation in the neutron-deficient
polonium isotopes: In-source resonant ionization laser spectroscopy of the even-$A$ polonium
isotopes $^{192-210,216,218}$Po has been performed using the $6p^37s$ $^5S_2$
to $6p^37p$ $^5P_2$ ($\lambda=843.38$ nm) transition in the polonium atom
(Po-I) at the CERN ISOLDE facility. The comparison of the measured isotope
shifts in $^{200-210}$Po with a previous data set allows to test for the first
time recent large-scale atomic calculations that are essential to extract the
changes in the mean-square charge radius of the atomic nucleus. When going to
lighter masses, a surprisingly large and early departure from sphericity is
observed, which is only partly reproduced by Beyond Mean Field calculations. | nucl-ex |
Deeply virtual Compton scattering off nuclei: Deeply virtual Compton scattering (DVCS) is the golden exclusive channel for
the study of the partonic structure of hadrons, within the universal framework
of generalized parton distributions (GPDs). This paper presents the aim and
general ideas of the DVCS experimental program off nuclei at the Jefferson
Laboratory. The benefits of the study of the coherent and incoherent channels
to the understanding of the EMC (European Muon Collaboration) effect are
discussed, along with the case of nuclear targets to access neutron GPDs. | nucl-ex |
A Vision for the Science of Rare Isotopes: The field of nuclear science has considerably advanced since its beginning
just over a century ago. Today, the science of rare isotopes is on the cusp of
a new era with theoretical and computing advances complementing experimental
capabilities at new facilities internationally. In this article we present a
vision for the science of rare isotope beams (RIBs). We do not attempt to cover
the full breadth of the field, but rather provide a perspective and address a
selection of topics that reflect our own interests and expertise. We focus in
particular on systems near the drip lines, where one often finds nuclei that
are referred to as "exotic," and where the role of the "nuclear continuum" is
only just starting to be explored. An important aspect of this article is the
attempt to highlight the crucial connections between nuclear structure and
nuclear reactions required to fully interpret and leverage the rich data to be
collected in the next years at RIB facilities. Further, we connect the efforts
in structure and reactions to key questions of nuclear astrophysics. | nucl-ex |
Excited states in the neutron-rich nucleus 25F: The structure of the nucleus 25F was investigated through in-beam
{\gamma}-ray spectroscopy of the fragmentation of 26Ne and 27,28Na ion beams.
Based on the particle-{\gamma} and particle-{\gamma}{\gamma} coincidence data,
a level scheme was constructed and compared with shell model and
coupled-cluster calculations. Some of the observed states were interpreted as
quasi single-particle states built on top of the closed-shell nucleus 24O,
while the others were described as states arising from coupling of a single
proton to the 2+ core excitation of 24O. | nucl-ex |
Multifractal analysis of charged particle multiplicity distribution in
the framework of Renyi entropy: A study of multifractality and multifractal specific heat has been carried
out for the produced shower particles in nuclear emulsion detector for
16O-AgBr, 28Si-AgBr and 32S-AgBr interactions at 4.5AGeV/c in the framework of
Renyi entropy. Experimental results have been compared with the prediction of
Ultra Relativistic Quantum Molecular Dynamics (UrQMD) model. Our analysis
reveals the presence of multifractality in the multiparticle production process
in high energy nucleus-nucleus interactions. Degree of multifractality is found
to be higher for the experimental data and it increases with the increase of
projectile mass. The investigation of quark-hadron phase transition in the
multiparticle production in 16O-AgBr, 28Si-AgBr and 32S-AgBr interactions at
4.5 AGeV/c in the framework of Ginzburg-Landau theory from the concept of
multifractality has also been presented. Evidence of constant multifractal
specific heat has been obtained for both experimental and UrQMD simulated data. | nucl-ex |
The performance of thin NaI(Tl) scintillator plate for dark matter
search: A thin (0.05cm) and wide area (5cmX5cm) NaI(Tl) scintillator was developed.
The performance of the thin NaI(Tl) plate, energy resolution, single
photoelectron energy and position sensitivity were tested. An excellent energy
resolution of 20% (FWHM) at 60keV was obtained. The single photoelectron energy
was calculated to be approximately 0.42 0.02keV. Position information in the
5cmx5cm area of the detector was also obtained by analyzing the ratio of the
number of photons collected at opposite ends of the detector. The position
resolution was obtained to be 1cm (FWHM) in the 5cmx5cm area. | nucl-ex |
Spin Sum Rules and the Strong Coupling Constant at large distance: We present recent results on the Bjorken and the generalized forward spin
polarizability sum rules from Jefferson Lab Hall A and CLAS experiments,
focusing on the low $Q^2$ part of the measurements. We then discuss the
comparison of these results with Chiral Perturbation theory calculations. In
the second part of this paper, we show how the Bjorken sum rule with its
connection to the Gerasimov-Drell-Hearn sum, allows us to conveniently define
an effective coupling for the strong force at all distances. | nucl-ex |
Photofission of heavy nuclei at energies up to 4 GeV: Total photofission cross sections for 238U, 235U, 233U, 237Np, 232Th, and
natPb have been measured simultaneously, using tagged photons in the energy
range Egamma=0.17-3.84 GeV. This was the first experiment performed using the
Photon Tagging Facility in Hall B at Jefferson Lab. Our results show that the
photofission cross section for 238U relative to that for 237Np is about 80%,
implying the presence of important processes that compete with fission. We also
observe that the relative photofission cross sections do not depend strongly on
the incident photon energy over this entire energy range. If we assume that for
237Np the photofission probability is equal to unity, we observe a significant
shadowing effect starting below 1.5 GeV. | nucl-ex |
Prospects for time reversal invariance studies with the use of five-fold
correlation: Advantages of investigation of time reversal invariance violation with the
use of three-fold (P,T-odd) and five-fold (P-even,T-odd) correlations in the
interaction of resonance neutrons with nuclei are briefly considered. Possible
enhancements of T-odd effects in both cases are discussed. It is shown that the
study of five-fold correlation is a perspective way to test time reversal
invariance. Prospects to realize dynamical nuclear alignment method for
measurements of five-fold correlation are described. | nucl-ex |
Nuclear Targets for a Precision Measurement of the Neutral Pion
Radiative Width: A technique is presented for precision measurements of the area densities,
density * T, of approximately 5% radiation length carbon and 208Pb targets used
in an experiment at Jefferson Laboratory to measure the neutral pion radiative
width. The precision obtained in the area density for the carbon target is +/-
0.050%, and that obtained for the lead target through an x-ray attenuation
technique is +/- 0.43%. | nucl-ex |
Mass Measurements of Neutron-Rich Gallium Isotopes Refine Production of
Nuclei of the First r-Process Abundance Peak in Neutron Star Merger
Calculations: We report mass measurements of neutron-rich Ga isotopes $^{80-85}$Ga with
TRIUMF's Ion Trap for Atomic and Nuclear science (TITAN). The measurements
determine the masses of $^{80-83}$Ga in good agreement with previous
measurements. The masses of $^{84}$Ga and $^{85}$Ga were measured for the first
time. Uncertainties between $25-48$ keV were reached. The new mass values
reduce the nuclear uncertainties associated with the production of A $\approx$
84 isotopes by the \emph{r}-process for astrophysical conditions that might be
consistent with a binary neutron star (BNS) merger producing a blue kilonova.
Our nucleosynthesis simulations confirm that BNS merger may contribute to the
first abundance peak under moderate neutron-rich conditions with electron
fractions $Y_e=0.35-0.38$. | nucl-ex |
Photoproduction of {\boldmath{$π^{0}$}} Mesons off Protons and
Neutrons in the Second and Third Nucleon Resonance Region: Photoproduction of mesons off quasi-free nucleons bound in the deuteron
allows to study the electromagnetic excitation spectrum of the neutron and the
isospin structure of the excitation of nucleon resonances. The database for
such reactions is much more sparse than for free proton targets. Single $\pi^0$
photoproduction off quasi-free nucleons from the deuteron was experimentally
studied. Nuclear effects were investigated by a comparison of the results for
free protons and quasi-free protons and used as a correction for the quasi-free
neutron data. The experiment was performed at the tagged photon beam of the
Mainz MAMI accelerator for photon energies between 0.45~GeV and 1.4~GeV, using
an almost $4\pi$ electromagnetic calorimeter composed of the Crystal Ball and
TAPS detectors. A complete kinematic reconstruction of the final state removed
the effects of Fermi motion. Reaction model predictions and PWA for $\gamma
n\rightarrow n\pi^{0}$, based on fits to data for the other isospin channels,
disagreed between themselves and no model provided a good description of the
new data. The results demonstrate clearly the importance of a measurement of
the fully neutral final state for the isospin decomposition of the cross
section. Model refits, for example from the Bonn-Gatchina analysis, show that
the new and the previous data for the other three isospin channels can be
simultaneously described when the contributions of several partial waves are
modified. The results are also relevant for the suppression of the higher
resonance bumps in total photoabsorption on nuclei, which are not well
understood. | nucl-ex |
Azimuthal anisotropy: the higher harmonics: We report the first observations of the fourth harmonic (v_4) in the
azimuthal distribution of particles at RHIC. The measurement was done taking
advantage of the large elliptic flow generated at RHIC. The integrated v_4 is
about a factor of 10 smaller than v_2. For the sixth (v_6) and eighth (v_8)
harmonics upper limits on the magnitudes are reported. | nucl-ex |
Collection of CERES Results: Plenary talk in Quark Matter 2005, Budapest. | nucl-ex |
Energy Dependence of Strangeness Production in Heavy-ion Collision: An experimental overview of the energy dependence of strangeness production
is presented. The strange hadrons are considered a good probe to study the QCD
matter created in relativistic nucleus-nucleus collisions. The heavy-ion
experiments at SPS, RHIC, and LHC have recorded a wealth of data in
proton-proton, proton-nucleus and nucleus-nucleus collisions at several beam
energies. In this proceeding, I discuss the invariant yield and azimuthal
anisotropy measurement of strange hadrons in nucleus-nucleus collisions at SPS,
RHIC, and LHC. | nucl-ex |
Isoscaling and the symmetry energy in spectator fragmentation: Isoscaling and its relation to the symmetry energy in the fragmentation of
excited residues produced at relativistic energies were studied in two
experiments conducted at the GSI laboratory. The INDRA multidetector has been
used to detect and identify light particles and fragments with Z <= 5 in
collisions of 12C on 112,124Sn at incident energies of 300 and 600 MeV per
nucleon. Isoscaling is observed, and the deduced parameters decrease with
increasing centrality. Symmetry term coefficients, deduced within the
statistical description of isotopic scaling, are near gamma = 25 MeV for
peripheral and gamma < 15 MeV for central collisions.
In a very recent experiment with the ALADIN spectrometer, the possibility of
using secondary beams for reaction studies at relativistic energies has been
explored. Beams of 107Sn, 124Sn, 124La, and 197Au were used to investigate the
mass and isospin dependence of projectile fragmentation at 600 MeV per nucleon.
The decrease of the isoscaling parameters is confirmed and extended over the
full fragmentation regime covered in these reactions. | nucl-ex |
Non-Gaussian elliptic-flow fluctuations in PbPb collisions at
$\sqrt{\smash[b]{s_{_\text{NN}}}} =$ 5.02 TeV: Event-by-event fluctuations in the elliptic-flow coefficient $v_2$ are
studied in PbPb collisions at $\sqrt{s_{_\text{NN}}} =$ 5.02 TeV using the CMS
detector at the CERN LHC. Elliptic-flow probability distributions ${p}(v_2)$
for charged particles with transverse momentum 0.3 $< p_\mathrm{T} <$ 3.0 GeV
and pseudorapidity $| \eta | <$ 1.0 are determined for different collision
centrality classes. The moments of the ${p}(v_2)$ distributions are used to
calculate the $v_{2}$ coefficients based on cumulant orders 2, 4, 6, and 8. A
rank ordering of the higher-order cumulant results and nonzero standardized
skewness values obtained for the ${p}(v_2)$ distributions indicate non-Gaussian
initial-state fluctuation behavior. Bessel-Gaussian and elliptic power fits to
the flow distributions are studied to characterize the initial-state spatial
anisotropy. | nucl-ex |
Neutral $s$ States in Loosely Bound Nuclei: In reviewing the data that has accumulated in light nuclei we find that the
binding energy plays a critical role in describing the variation in energy of
$s$ states relative to other states. The behavior of states with zero angular
momentum within a few MeV of threshold is qualitatively different from that of
neutron states with any other $\ell$ value or of any proton state. This
observation is explored for simple Woods-Saxon potentials and is remarkably
successful in describing a wealth of experimental data for nuclei with neutron
numbers between 5 and 10. The lingering of neutron $s$ states just below
threshold is associated with the increases in radii of the neutron density
distributions, the neutron halos, and leads to speculations about possible
halos in heavier nuclei. | nucl-ex |
Measurement of the neutron capture cross-section on argon: The use of argon as a detection and shielding medium for neutrino and dark
matter experiments has made the precise knowledge of the cross section for
neutron capture on argon an important design and operational parameter. Since
previous measurements were averaged over thermal spectra and have significant
disagreements, a differential measurement has been performed using a
Time-Of-Flight neutron beam and a $\sim$4$\pi$ gamma spectrometer. A fit to the
differential cross section from $0.015-0.15$\,eV, assuming a $1/v$ energy
dependence, yields $\sigma^{2200} = 673 \pm 26 \text{ (stat.)} \pm 59 \text{
(sys.)}$\,mb. | nucl-ex |
Nuclear symmetry energy: An experimental overview: The nuclear symmetry energy is a fundamental quantity important for studying
the structure of systems as diverse as the atomic nucleus and the neutron star.
Considerable efforts are being made to experimentally extract the symmetry
energy and its dependence on nuclear density and temperature. In this article,
we review experimental studies carried out up-to-date and their current status. | nucl-ex |
Light neutral meson production in the era of precision physics at the
LHC: The production of light neutral mesons in different collision systems is
interesting for a variety of reasons: In nucleus-nucleus (AA) collisions the
measurements provide important information on the energy loss of partons
traversing the Quark-Gluon Plasma (QGP) which is formed in heavy-ion collisions
at the LHC. In proton--proton (pp) collisions, neutral mesons allow us to test
with high precision the predictions of perturbative QCD and other model
calculations, and also serve as a reference for pA and AA collisions. In pA
collisions, cold nuclear matter effects are studied. In the ALICE experiment,
which is dedicated to the study of the QGP, neutral mesons can be detected via
their decay to two photons. The latter can be reconstructed using the two
calorimeters EMCal and PHOS or via conversions in the detector material.
Combining state-of-the-art reconstruction techniques with the large data sample
delivered by the LHC in Run 2 gives us the opportunity to enhance the precision
of our measurements. In these proceedings, an overview of neutral meson
production in pp, p--Pb and Pb--Pb collisions at LHC energies, as measured with
the ALICE detector is presented. | nucl-ex |
The $Q_{weak}$ Experiment: First Determination of the Weak Charge of the
Proton: The $Q_{weak}$ Collaboration has completed a challenging measurement of the
parity-violating asymmetry in elastic electron-proton ($\vec{e}$p) scattering
at the Thomas Jefferson National Accelerator Facility (Jefferson Lab). The
initial result reported here is extracted from the commissioning part of the
experiment, constituting about 4% of the full data set. The parity-violating
asymmetry at a low momentum transfer $Q^2$=0.025 GeV$^2$ is $A_{ep}$ = -279
$\pm$ 35 (stat) $\pm$ 31 (syst) ppb, which is the smallest and most precise
asymmetry ever measured in $\vec{e}$p scattering. This result allowed the first
determination of the weak charge of the proton $Q_W^p$ from a global fit of
parity-violating elastic scattering (PVES) results from nuclear targets, where
earlier data at higher $Q^2$ constrain uncertainties of hadronic structure. The
value extracted from the global fit is $Q_W^p$ (PVES) = 0.064 $\pm$ 0.012, in
agreement with the standard model prediction $Q_W^p$ (SM) = 0.0710 $\pm$
0.0007. The neutral weak charges of up and down quarks are extracted from a
combined fit of the PVES results with a previous atomic parity violation (APV)
measurement on $^{133}$Cs. The analysis of the full $Q_{weak}$ data is ongoing
and expected to yield a value for the asymmetry within 10 ppb of precision.
Because of the suppression of $Q_W^p$, such a high precision measurement will
place significant constraints to models of physics beyond the standard model. | nucl-ex |
Experiments with polarized 3He at MAMI: Experiments with polarized 3He at MAMI have already a long tradition. The A3
collaboration started in 1993 with the aim to measure the electric form factor
of the neutron. At this time MAMI was the second accelerator where experiments
with 3He were possible. Some years before this pilot experiment the development
of the apparatus to polarize 3He in Mainz started. There are two techniques
which allow to polarize sufficient large quantities of 3He. Both techniques
will be compared and the benefit of 3He for nuclear physics will be discussed.
An review of the experiments done so far with 3He at MAMI will be given and the
progress in the target development, the detector setup and the electron beam
performance will be pointed out. | nucl-ex |
Activation cross sections of proton and deuteron induced nuclear
reactions on holmium and erbium, related to the production of $^{161}$Er and
$^{160}$Er medical isotopes: Experimental excitation functions for long-lived products in proton induced
reactions were measured with the activation method in the 37-65 MeV energy
range on natural holmium. Stacked foil irradiation technique and high
resolution gamma spectrometry were used in order to measure cross-section data
for the production of $^{161}$Er, $^{160}$Er and $^{159,157}$Dy. For comparison
of the production routes of medically related $^{161}$Er and $^{160}$Er
radioisotopes new experimental cross section data were deduced for the
$^{162}$Er(p,x)$^{161,160}$Er and $^{162}$Er(d,x)$^{161,160}$Er reactions by
re-evaluating gamma-ray spectra from earlier measurements. No earlier data were
found in the literature for these reactions. The experimental data are compared
with results of TALYS theoretical code reported in TENDL-2015. | nucl-ex |
Study of $φ$-meson production in $p$$+$Al, $p$$+$Au, $d$$+$Au, and
$^3$He$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV: Small nuclear collisions are mainly sensitive to cold-nuclear-matter effects;
however, the collective behavior observed in these collisions shows a hint of
hot-nuclear-matter effects. The identified-particle spectra, especially the
$\phi$ mesons which contain strange and antistrange quarks and have a
relatively small hadronic-interaction cross section, are a good tool to study
these effects. The PHENIX experiment has measured $\phi$ mesons in a specific
set of small collision systems $p$$+$Al, $p$$+$Au, and $^3$He$+$Au, as well as
$d$$+$Au [Phys. Rev. C {\bf 83}, 024909 (2011)], at $\sqrt{s_{_{NN}}}=200$ GeV.
The transverse-momentum spectra and nuclear-modification factors are presented
and compared to theoretical-model predictions. The comparisons with different
calculations suggest that quark-gluon plasma may be formed in these small
collision systems at $\sqrt{s_{_{NN}}}=200$ GeV. However, the volume and the
lifetime of the produced medium may be insufficient for observing
strangeness-enhancement and jet-quenching effects. Comparison with calculations
suggests that the main production mechanisms of $\phi$ mesons at midrapidity
may be different in $p$$+$Al versus $p/d/$$^3$He$+$Au collisions at
$\sqrt{s_{_{NN}}}=200$ GeV. While thermal quark recombination seems to dominate
in $p/d/$$^3$He$+$Au collisions, fragmentation seems to be the main production
mechanism in $p$$+$Al collisions. | nucl-ex |
The $2_1^+ \to 3_1^+$ gamma width in $^{22}$Na and second class currents: A previous measurement of the $\beta-\gamma$ directional coefficient in
$^{22}$Na $\beta$ decay was used to extract recoil-order form factors. The data
indicate the requirement of a significant induced-tensor matrix element for the
decay.This conclusion largely relies on a Standard-Model-allowed weak magnetism
form factor which was determined using an unpublished value of the analog
$2_1^+\to3_1^+$ $\gamma$ branch in $^{22}$Na, with the further assumption that
the transition is dominated by its isovector $M1$ component. We obtain for the
first time an unambiguous determination of the $2_1^+ \to 3_1^+$ branch in
$^{22}$Na to be $0.45(8)\%$. Using the Conserved Vector Current (CVC)
hypothesis, our branch determines the weak magnetism form factor for $^{22}$Na
$\beta$ decay to be $|b/Ac_1| = 8.7(1.1)$. Together with the $\beta-\gamma$
angular correlation coefficient, we obtain a large induced-tensor form factor
for the decay that continues to disagree with theoretical predictions. Two
plausible explanations are suggested. | nucl-ex |
New nuclear structure features in transactinide nuclei: The structural evolution of the heavy nuclei, with Z > 82, is investigated by
looking at the differential variation of the two-neutron separation energies.
It indicates, by non-monotonous behavior at certain neutron numbers, structure
phenomena such as major shell (N = 126) and deformed subshell (N = 152)
closures. Another interesting effect is observed at N ~ 142, which is very well
correlated with a previously observed, intriguing behavior of quantities
measured in alpha decay, such as relative branching ratios and hindrance
factors of excited states from the ground state band of deformed nuclei in this
region. Corroboration of the existing experimental data indicates another
possible deformed subshell closure. | nucl-ex |
Neutron knockout of 12Be populating neutron-unbound states in 11Be: Neutron-unbound resonant states of 11Be were populated in neutron knock-out
reactions from 12Be and identified by 10Be-n coincidence measurements. A
resonance in the decay-energy spectrum at 80(2) keV was attributed to a highly
excited unbound state in 11Be at 3.949(2) MeV decaying to the 2+ excited state
in 10Be. A knockout cross section of 15(3) mb was inferred for this 3.949(2)
MeV state suggesting a spectroscopic factor near unity for this 0p3/2- level,
consistent with the detailed shell model calculations. | nucl-ex |
Light Baryon Spectroscopy using the CLAS Spectrometer at Jefferson
Laboratory: Baryons are complex systems of confined quarks and gluons and exhibit the
characteristic spectra of excited states. The systematics of the baryon
excitation spectrum is important to our understanding of the effective degrees
of freedom underlying nucleon matter. High-energy electrons and photons are a
remarkably clean probe of hadronic matter, providing a microscope for examining
the nucleon and the strong nuclear force. Current experimental efforts with the
CLAS spectrometer at Jefferson Laboratory utilize highly-polarized frozen-spin
targets in combination with polarized photon beams. The status of the recent
double-polarization experiments and some preliminary results are discussed in
this contribution. | nucl-ex |
Isoscalar Giant Resonance Strengths in $^{32}$S and possible excitations
of superdeformed and $^{28}$Si + $α$ cluster bandheads: Isoscalar giant resonances and low spin states in $^{32}$S have been measured
with inelastic $\alpha$ scattering at extremely forward angles including zero
degrees at E$_{\alpha}$ = 386 MeV. By applying the multipole decomposition
analysis, various excited states are classified according to their spin and
parities (J$^{\pi}$), and are discussed in relation to the super deformed and
$^{28}$Si + $\alpha$ cluster bands. | nucl-ex |
Formation of dense partonic matter in relativistic nucleus-nucleus
collisions at RHIC: Experimental evaluation by the PHENIX collaboration: Extensive experimental data from high-energy nucleus-nucleus collisions were
recorded using the PHENIX detector at the Relativistic Heavy Ion Collider
(RHIC). The comprehensive set of measurements from the first three years of
RHIC operation includes charged particle multiplicities, transverse energy,
yield ratios and spectra of identified hadrons in a wide range of transverse
momenta (p_T), elliptic flow, two-particle correlations, non-statistical
fluctuations, and suppression of particle production at high p_T. The results
are examined with an emphasis on implications for the formation of a new state
of dense matter. We find that the state of matter created at RHIC cannot be
described in terms of ordinary color neutral hadrons. | nucl-ex |
Tensor interaction constraints from beta decay recoil spin asymmetry of
trapped atoms: We have measured the angular distribution of recoiling daughter nuclei
emitted from the Gamow-Teller $\beta$ decay of spin-polarized $^{80}$Rb. The
asymmetry of this distribution vanishes to lowest order in the Standard Model
(SM) in pure Gamow-Teller decays, producing an observable very sensitive to new
interactions. We measure the non-SM contribution to the asymmetry to be
$A_{T}$= 0.015 $\pm$ 0.029 (stat) $\pm$ 0.019 (syst), consistent with the SM
prediction. We constrain higher-order SM corrections using the measured
momentum dependence of the asymmetry, and their remaining uncertainty dominates
the systematic error. Future progress in determining the weak magnetism term
theoretically or experimentally would reduce the final errors. We describe the
resulting constraints on fundamental 4-Fermi tensor interactions. | nucl-ex |
Proton-cluster femtoscopy with the HADES experiment: The matter created in Ag+Ag collisions at $\sqrt{s_{NN}}$ = 2.55 GeV, as
measured with the HADES experiment, can be characterized by similar
thermodynamic quantities as Neutron Star Mergers, thus becoming an essential
reference for the understanding of these compact stellar objects. One of the
methods applied to investigate heavy-ion collisions are femtoscopic
correlations. They are a unique tool for the determination of the interactions
between hadrons and allow to search for possible exited or unbound states of
nuclear matter. We performed precise experimental studies of the correlations
between protons and different clusters and compared them with the existing
theoretical descriptions. | nucl-ex |
Neutron Transfer Studied with a Radioactive beam of 24Ne, using TIARA at
SPIRAL: A general experimental technique for high resolution studies of nucleon
transfer reactions using radioactive beams is briefly described, together with
the first new physics results that have been obtained with the new TIARA array.
These first results from TIARA are for the reaction 24Ne(d,p)25Ne, studied in
inverse kinematics with a pure radioactive beam of 100,000 pps from the SPIRAL
facility at GANIL. The reaction probes the energies of neutron orbitals
relevant to very neutron rich nuclei in this mass region and the results
highlight the emergence of the N=16 magic number for neutrons and the
associated disappearance of the N=20 neutron magic number for the very neutron
rich neon isotopes. | nucl-ex |
Cosmic ray measurements using the ISMRAN setup in a non-reactor
environment: The cosmic rays data collected using a large area plastic scintillator array
ISMRAN (Indian Scintillator Matrix for Reactor AntiNeutrino) are presented. The
data collected serve as a useful benchmark of cosmogenic background in a
non-reactor environment for the future measurements of electron-antineutrinos
to be performed using the ISMRAN setup. The zenith angle distribution of the
atmospheric muons has been measured and compared with Monte Carlo expectations.
The detector setup was further used to measure the lifetime distribution of
stopped muons and extract their rates inside the detector matrix. The measured
spectra of decaying muons and associated electrons show a good agreement with
the MC simulations performed through GEANT4 simulation. | nucl-ex |
A luminosity monitor for the A4 parity violation experiment at MAMI: A water Cherenkov luminosity monitor system with associated electronics has
been developed for the A4 parity violation experiment at MAMI. The detector
system measures the luminosity of the hydrogen target hit by the MAMI electron
beam and monitors the stability of the liquid hydrogen target. Both is required
for the precise study of the count rate asymmetries in the scattering of
longitudinally polarized electrons on unpolarized protons. Any helicity
correlated fluctuation of the target density leads to false asymmetries. The
performance of the luminosity monitor, investigated in about 2000 hours with
electron beam, and the results of its application in the A4 experiment are
presented. | nucl-ex |
Reply to Comment on "High-Precision Determination of the Electric and
Magnetic Form Factors of the Proton": In arXiv:1108.3058v1 [nucl-ex], Arrington criticizes the Coulomb corrections
we applied in the analysis of high precision form factor data (see
Phys.Rev.Lett.105:242001, 2010, arXiv:1007.5076v3 [nucl-ex]). We show, by
comparing different calculations cited in the Comment, that the criticism of
the Comment neglects the large uncertainty of "more modern" TPE corrections.
This uncertainty has also been seen in recent polarized measurements. We rerun
our analysis using one of these calculations. The results show that the Comment
exaggerates the quantitative effect at small Q^2. | nucl-ex |
Cross-sections for the ${^{27}\!\rm{Al}}(γ,\textit{x})^{24}\rm{Na}$
multiparticle reaction at $E_{\rm{γmax}}$ = 40 $÷$ 95 MeV: The bremsstrahlung flux-averaged cross-sections $\langle{\sigma(E_{\rm{\gamma
max}})}\rangle$ and the cross-sections per equivalent photon
$\langle{\sigma(E_{\rm{\gamma max}})_{\rm{Q}}}\rangle$ were measured for the
photonuclear multiparticle reaction $^{27}\!\rm{Al}(\gamma,\textit{x};
\textit{x} = {^{3}\rm{He}} + pd + 2pn)^{24}\rm{Na}$ at bremsstrahlung end-point
energies ranging from 40 MeV to 95 MeV. The experiments were performed using
the beam from the NSC KIPT electron linear accelerator LUE-40 with the use of
the $\gamma$-activation technique. The bremsstrahlung quantum flux was
calculated with the program GEANT4 and, in addition, was monitored by means of
the $^{100}\rm{Mo}(\gamma,n)^{99}\rm{Mo}$ reaction. The cross-sections
$\sigma(E)$ were computed using the TALYS1.9 code with the default options. The
measured average cross-sections $\langle{\sigma(E_{\rm{\gamma max}})}\rangle$
and $\langle{\sigma(E_{\rm{\gamma max}})_{\rm{Q}}}\rangle$ have appeared to be
higher by factors of 2.0 to 2.4 than the theoretical results. The experimental
results have been found to be in good agreement with the data of other
laboratories. Consideration is given to special features of calculation of
$\langle{\sigma(E_{\rm{\gamma max}})}\rangle$ and $\langle{\sigma(E_{\rm{\gamma
max}})_{\rm{Q}}}\rangle$ for the
$^{27}\!\rm{Al}(\gamma,\textit{x})^{24}\rm{Na}$ reaction, with occurrence of
three $^{27}\!\rm{Al}$ photodisintegration channels. The paper also discusses
the possibility of using the $^{27}\!\rm{Al}(\gamma,\textit{x})^{24}\rm{Na}$
reaction for monitoring the bremsstrahlung $\gamma$-quantum flux in the photon
energy region above 30 MeV. | nucl-ex |
Scaling properties of the $Δγ$ correlator and their
implication for detection of the chiral magnetic effect in heavy-ion
collisions: The scaling properties of the $\Delta\gamma$ correlator, inferred from the
Anomalous Viscous Fluid Dynamics (AVFD) model, are used to investigate a
possible chiral-magnetically-driven (CME) charge separation in $p$+Au, $d$+Au,
Ru+Ru, Zr+Zr, and Au+Au collisions at $\sqrt s_{\mathrm{NN}}=200$ GeV, and in
$p$+Pb ($\sqrt s_{\mathrm{NN}}=5.02$ TeV) and Pb+Pb collisions at $\sqrt
s_{\mathrm{NN}}=5.02$ and $2.76$ TeV. The results indicate that the values of
the quotient $\Delta\gamma/v_2$ with the elliptic flow coefficient $v_2$ for
$p$+Au, $d$+Au, $p$+Pb, and Pb+Pb collisions, scale as $1/{\rm N_{ch}}$
consistent with background-driven charge separation. By contrast, the
$\Delta\gamma/v_2$ values for Ru+Ru, Zr+Zr, and Au+Au collisions show scaling
violations consistent with the presence of background plus a CME-driven
contribution. Quantifying this CME-driven component indicates that in
mid-central collisions, the fraction of the measured $\Delta\gamma/v_2$
attributable to the CME is approximately 27\% for Au+Au and roughly a factor of
two smaller for Ru+Ru and Zr+Zr, which show similar magnitudes. | nucl-ex |
Energy dependence of particle ratio fluctuations in central Pb+Pb
collisions from $\sqrt{s_{_{NN}}} =$~6.3 to 17.3 GeV: We present measurements of the energy dependence of event-by-event
fluctuations in the K/pi and (p + \bar{p})/pi multiplicity ratios in heavy ion
collisions at the CERN SPS. The particle ratio fluctuations were obtained for
central Pb+Pb collisions at five collision energies, \sqrt{s_{_{NN}}}, between
6.3 and 17.3 GeV. After accounting for the effects of finite-number statistics
and detector resolution, we extract the strength of non-statistical
fluctuations at each energy. For the K/pi ratio, larger fluctuations than
expected for independent particle production are found at all collision
energies. The fluctuations in the (p + \bar{p})/pi ratio are smaller than
expectations from independent particle production, indicating correlated pion
and proton production from resonance decays. For both ratios, the deviation
from purely statistical fluctuations shows an increase towards lower collision
energies. The results are compared to transport model calculations, which fail
to describe the energy dependence of the K/pi ratio fluctuations. | nucl-ex |
Elliptic flow fluctuations in Au+Au collisions at $\sqrt{s_{NN}}=200$
GeV: Please note that after these results were reported at Quark Matter 2006 and
posted on the preprint server it was found that what is reported here as
\textit{elliptic flow fluctuations}, should rather be taken as an upper limit
on the fluctuations. Further analysis has shown that fitting the multiplicity
dependence of the q-distribution does not enable one to disentangle non-flow
and fluctuations. The data from the q-vector distrubution does not, therefore,
exclude the case of zero fluctuations. The remainder of these proceedings we
leave as they were originally reported. | nucl-ex |
K$^-$ multi-nucleon absorption cross sections and branching ratios in
$Λ$p and $Σ^0$p final states: The determination of low-energy cross sections and branching ratios of the
K$^-$ multi-nucleon absorption processes in $\Lambda$p and $\Sigma^0$p final
states performed by the AMADEUS collaboration is presented. Low momentum K$^-$
($p_\mathrm{K} \simeq$ 127 MeV/c) produced at the DA$\Phi$NE collider are
impinged on a Carbon target within the KLOE detector and the two and three
nucleon absorption processes are disentangled by comparing the experimental
data to phenomenological calculations. The $\Lambda$p spectra are interpreted
in terms of K$^-$ multi-nucleon absorption processes; the possible contribution
of a K$^-$pp bound state is demonstrated to overlap with the two nucleon
capture process, its absolute yield thus resulting indistinguishable. | nucl-ex |
Activation cross sections of deuteron induced reactions on niobium in
the 30-50 MeV energy range: Activation cross-sections of deuterons induced reactions on Nb targets were
determined with the aim of different applications and comparison with
theoretical models. | nucl-ex |
Momentum dependence of the phi-meson nuclear transparency: The production of phi mesons in proton collisions with C, Cu, Ag, and Au
targets has been studied via the phi -> K+K- decay at an incident beam energy
of 2.83 GeV using the ANKE detector system at COSY. For the first time, the
momentum dependence of the nuclear transparency ratio, the in-medium phi width,
and the differential cross section for phi meson production at forward angles
have been determined for these targets over the momentum range of 0.6 - 1.6
GeV/c. There are indications of a significant momentum dependence in the value
of the extracted phi width, which corresponds to an effective phi-N absorption
cross section in the range of 14 - 21 mb. | nucl-ex |
Measurement of jet fragmentation in PbPb and pp collisions at
sqrt(s[NN]) = 2.76 TeV: The jet fragmentation function of inclusive jets with transverse momentum pt
above 100 GeV in PbPb collisions has been measured using reconstructed charged
particles with pt above 1 GeV in a cone of radius 0.3 around the jet axis. A
data sample of PbPb collisions collected in 2011 at a nucleon-nucleon
center-of-mass energy of sqrt(s[NN]) = 2.76 TeV corresponding to an integrated
luminosity of 150 inverse microbarns is used. The results for PbPb collisions
as a function of collision centrality and jet transverse momentum are compared
to reference distributions based on pp data collected at the same
center-of-mass energy in 2013, with an integrated luminosity of 5.3 inverse
picobarns. A centrality-dependent modification of the fragmentation function is
found. For the most central collisions, a significant enhancement is observed
in the PbPb / pp fragmentation function ratio for charged particles with pt
less than 3 GeV. This enhancement is observed for all jet pt bins studied. | nucl-ex |
Fission involves a new state of nuclear matter: The rearrangement step of nuclear fission occurs within 0.17 yoctosecond, in
a new state of nuclear matter characterized by the formation of closed shells
of nucleons. The determination of its lifetime is now based on the prompt
neutron emission law. The width of isotopic distributions measures the
uncertainty in the neutron number of the fragments. Magic mass numbers, 82 and
126, play a major role in the mass distributions. Arguments are presented in
favour of an all-neutron state. The boson field responsible for the new
collective interaction has to be searched for. | nucl-ex |
Direct photon elliptic flow in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ =
2.76 TeV: The elliptic flow of inclusive and direct photons was measured at
mid-rapidity in two centrality classes 0-20% and 20-40% in Pb-Pb collisions at
$\sqrt{s_{\rm NN}}$ = 2.76 TeV by ALICE. Photons were detected with the highly
segmented electromagnetic calorimeter PHOS and via conversions in the detector
material with the $e^{+}e^{-}$ pairs reconstructed in the central tracking
system. The results of the two methods were combined and the direct photon
elliptic flow was extracted in the transverse momentum range $0.9 < p_{\rm T} <
6.2$ GeV/$c$. A comparison to RHIC data shows a similar magnitude of the
measured direct-photon elliptic flow. Hydrodynamic and transport model
calculations are systematically lower than the data, but are found to be
compatible. | nucl-ex |
STAR results on medium properties and response of the medium to
energetic partons: We report new STAR results on the consequences of highly energetic partons
propagating through the medium formed in heavy ion collisions using
correlations as an experimental probe. The recent results providing insights
about color factor effects and path length dependence of parton energy loss,
system size dependence of di-hadron fragmentation functions, conical emission
and ridge formation in heavy ion collisions are presented. | nucl-ex |
Schottky mass measurements of heavy neutron-rich nuclides in the element
range $70\leZ \le79$ at the ESR: Storage-ring mass spectrometry was applied to neutron-rich $^{197}$Au
projectile fragments. Masses of $^{181,183}$Lu, $^{185,186}$Hf, $^{187,188}$Ta,
$^{191}$W, and $^{192,193}$Re nuclei were measured for the first time. The
uncertainty of previously known masses of $^{189,190}$W and $^{195}$Os nuclei
was improved. Observed irregularities on the smooth two-neutron separation
energies for Hf and W isotopes are linked to the collectivity phenomena in the
corresponding nuclei. | nucl-ex |
N=90 region: The decays of {152m,g}Eu to 152Sm: The decays of {152m,g}Eu to 152Sm have been studied by gamma-ray spectroscopy
using the 8pi Spectrometer, an array of 20 Compton-suppressed Ge detectors.
Very weak gamma-decay branches in 152Sm were investigated through gamma-gamma
coincidence spectroscopy. All possible E2 transitions between states below 1550
keV with transition energies > 130 keV are observed, including the previously
unobserved 2^+_3 to 0^+_2 401 keV transition. The results, combined with
existing lifetime data, provide a number of new or revised E2 transition
strengths which are critical for clarifying the collective structure of 152Sm
and the N=90 isotones. | nucl-ex |
Shallow and diffuse spin-orbit potential for proton elastic scattering
from neutron-rich helium isotopes at 71 MeV/nucleon: Vector analyzing powers for proton elastic scattering from 8He at 71
MeV/nucleon have been measured using a solid polarized proton target operated
in a low magnetic field of 0.1 T. The spin-orbit potential obtained from a
phenomenological optical model analysis is found to be significantly shallower
and more diffuse than the global systematics of stable nuclei, which is an
indication that the spin-orbit potential is modified for scattering involving
neutron-rich nuclei. A close similarity between the matter radius and the
root-mean-square radius of the spin-orbit potential is also identified. | nucl-ex |
Neutron occupancy of the 0d5/2 orbital and the N=16 shell closure in 24O: One-neutron knockout from 24O leading to the first excited state in 23O has
been measured for a proton target at a beam energy of 62 MeV/nucleon. The decay
energy spectrum of the neutron unbound state of 23O was reconstructed from the
measured four momenta of the 22O fragment and emitted neutron. A sharp peak was
found at Edecay=50$\pm$3 keV, corresponding to an excited state in 23O at
2.78$\pm$0.11 MeV, as observed in previous measurements. The longitudinal
momentum distribution for this state was consistent with d -wave neutron
knockout, providing support for a J{\pi} assignment of 5/2+. The associated
spectroscopic factor was deduced to be C2S(0d5/2)=4.1$\pm$0.4 by comparing the
measured cross section (View the MathML source) with a distorted wave impulse
approximation calculation. Such a large occupancy for the neutron 0d5/2 orbital
is in line with the N=16 shell closure in 24O. | nucl-ex |
Experiments for the absolute neutrino mass measurement: Experimental results and perspectives of different methods to measure the
absolute mass scale of neutrinos are briefly reviewed. The mass sensitivities
from cosmological observations, double beta decay searches and single beta
decay spectroscopy differ in sensitivity and model dependance. Next generation
experiments in the three fields reach the sensitivity for the lightest mass
eigenstate of $m_1<0.2eV$, which will finally answer the question if neutrino
mass eigenstates are degenerate. This sensitivity is also reached by the only
model-independent approach of single beta decay (KATRIN experiment). For higher
sensitivities on cost of model-dependance the neutrinoless double beta decay
search and cosmological observation have to be applied. Here, in the next
decade sensitivities are approached with the potential to test inverted
hierarchy models. | nucl-ex |
ALICE results on quarkonium production in pp, p-Pb and Pb-Pb collisions: The study of quarkonia, bound states of heavy (charm or bottom)
quark-antiquark pairs such as the J/psi or the Upsilon?, provides insight into
the earliest and hottest stages of high-energy nucleus-nucleus collisions where
the formation of a Quark-Gluon Plasma is expected. High-precision data from
proton-proton collisions represent an essential baseline for the measurement of
nuclear modifications in nucleus-nucleus collisions and serve also as a crucial
test for models of quarkonium hadroproduction. Another fundamental tool to
understand the quarkonium production in nucleus-nucleus collisions is the the
study of proton-nucleus interactions, which allows one to investigate cold
nuclear matter effects, such as parton shadowing or gluon saturation. The ALICE
detector provides excellent capabilities to study quarkonium production at the
Large Hadron Collider at both central and forward rapidity. An overview on
ALICE results on quarkonium production in pp, p-Pb and Pb-Pb collisions is
presented. Results are compared to theoretical model predictions. | nucl-ex |
Reexamining the half-lives of 195Os and 195Ir: Currently the half-life of 195Os is listed as unknown in most databases
because the value of the only available measurement had been reassigned. We
argue that the original assignment is correct and re-evaluate the half-life of
195Os to be 6.5(11)min, consistent with the original measurement. We also
suggest to reassign the half-life of 195Ir to 2.29(17)h. | nucl-ex |
Completing the nuclear reaction puzzle of the nucleosynthesis of 92Mo: One of the greatest questions for modern physics to address is how elements
heavier than iron are created in extreme, astrophysical environments. A
particularly challenging part of that question is the creation of the so-called
p-nuclei, which are believed to be mainly produced in some types of supernovae.
The lack of needed nuclear data presents an obstacle in nailing down the
precise site and astrophysical conditions. In this work, we present for the
first time measurements on the nuclear level density and average strength
function of $^{92}$Mo. State-of-the-art p-process calculations systematically
underestimate the observed solar abundance of this isotope. Our data provide
stringent constraints on the $^{91}$Nb$(p,{\gamma})^{92}$Mo reaction rate,
which is the last unmeasured reaction in the nucleosynthesis puzzle of
$^{92}$Mo. Based on our results, we conclude that the $^{92}$Mo abundance
anomaly is not due to the nuclear physics input to astrophysical model
calculations. | nucl-ex |
Electromagnetic Dissociation of 8B and the Rate of the 7Be(p,gamma)8B
Reaction in the Sun: In an effort to better determine the 7Be(p,gamma)8B reaction rate, we have
performed inclusive and exclusive measurements of the Coulomb dissociation of
8B. The former was a study of longitudinal momentum distributions of 7Be
fragments emitted in the Coulomb breakup of intermediate energy 8B beams on Pb
and Ag targets. Analysis of these data yielded the E2 contribution to the
breakup cross section. In the exclusive measurement, we determined the cross
section for the Coulomb breakup of 8B on Pb at low relative energies in order
to infer the astrophysical S factor for the 7Be(p,gamma)8B reaction.
Interpreting the measurements with 1st-order perturbation theory, we obtained
SE2/SE1 = 4.7 (+ 2.0,- 1.3) times 10^-4 at Erel = 0.6 MeV, and S17(0) = 17.8 (+
1.4,- 1.2) eV b. Semiclassical 1st-order perturbation theory and fully quantum
mechanical continuum-discretized coupled channels analyses yield nearly
identical results for the E1 strength relevant to solar neutrino flux
calculations, suggesting that theoretical reaction mechanism uncertainties need
not limit the precision of Coulomb breakup determinations of the 7Be(p,gamma)8B
S factor. A recommended value of S17(0) based on a weighted average of this and
other measurements is presented. | nucl-ex |
Measurement of the Vector and Tensor Asymmetries at Large Missing
Momentum in Quasielastic $(\vec{e}, e^{\prime}p)$ Electron Scattering from
Deuterium: We report the measurement of the beam-vector and tensor asymmetries
$A^V_{ed}$ and $A^T_d$ in quasielastic $(\vec{e}, e^{\prime}p)$
electrodisintegration of the deuteron at the MIT-Bates Linear Accelerator
Center up to missing momentum of 500~MeV/c. Data were collected simultaneously
over a momentum transfer range $0.1< Q^2<0.5$~(GeV/c)$^2$ with the Bates Large
Acceptance Spectrometer Toroid using an internal deuterium gas target,
polarized sequentially in both vector and tensor states. The data are compared
with calculations. The beam-vector asymmetry $A^V_{ed}$ is found to be directly
sensitive to the $D$-wave component of the deuteron and have a zero-crossing at
a missing momentum of about 320~MeV/c, as predicted. The tensor asymmetry
$A^T_d$ at large missing momentum is found to be dominated by the influence of
the tensor force in the neutron-proton final-state interaction. The new data
provide a strong constraint on theoretical models. | nucl-ex |
Production cross section and decay study of $^{243}$Es and $^{249}$Md: In the study of the odd-$Z$, even-$N$ nuclei $^{243}$Es and $^{249}$Md,
performed at the University of Jyv\"askyl\"a, the fusion-evaporation reactions
$^{197}$Au($^{48}$Ca,2$n$)$^{243}$Es and $^{203}$Tl($^{48}$Ca,2$n$)$^{249}$Md
have been used for the first time. Fusion-evaporation residues were selected
and detected using the RITU gas-filled separator coupled with the focal-plane
spectrometer GREAT. For $^{243}$Es, the recoil decay correlation analysis
yielded a half-life of $24 \pm 3$s, and a maximum production cross section of
$37 \pm 10$ nb. In the same way, a half-life of $26 \pm 1$ s, an $\alpha$
branching ratio of 75 $\pm$ 5%, and a maximum production cross section of 300
$\pm$ 80 nb were determined for $^{249}$Md. The decay properties of $^{245}$Es,
the daughter of $^{249}$Md, were also measured: an $\alpha$ branching ratio of
54 $\pm$ 7% and a half-life of 65 $\pm$ 6 s. Experimental cross sections were
compared to the results of calculations performed using the KEWPIE2 statistical
fusion-evaporation code. | nucl-ex |
Beam energy dependent two-pion interferometry and the freeze-out
eccentricity of pions in heavy ion collisions at STAR: We present results of analyses of two-pion interferometry in Au+Au collisions
at $\sqrt{s_{NN}}$ = 7.7, 11.5, 19.6, 27, 39, 62.4 and 200 GeV measured in the
STAR detector as part of the RHIC Beam Energy Scan program. The extracted
correlation lengths (HBT radii) are studied as a function of beam energy,
azimuthal angle relative to the reaction plane, centrality, and transverse mass
($m_{T}$) of the particles. The azimuthal analysis allows extraction of the
eccentricity of the entire fireball at kinetic freeze-out. The energy
dependence of this observable is expected to be sensitive to changes in the
equation of state. A new global fit method is studied as an alternate method to
directly measure the parameters in the azimuthal analysis. The eccentricity
shows a monotonic decrease with beam energy that is qualitatively consistent
with the trend from all model predictions and quantitatively consistent with a
hadronic transport model. | nucl-ex |
Hypernuclear spectroscopy with K$^-$ at rest on $^7$Li, $^9$Be, $^{13}$C
and $^{16}$O: The FINUDA experiment collected data to study the production of hypernuclei
on different nuclear targets. The hypernucleus formation occurred through the
strangeness-exchange reaction $K^-_{stop} + \; ^AZ \rightarrow \; ^A_{\Lambda}Z
+ \pi^-$. From the analysis of the momentum of the emerging $\pi^-$, binding
energies and formation probabilities of $^7_{\Lambda}$Li, $^9_{\Lambda}$Be,
$^{13}_{\Lambda}$C and $^{16}_{\Lambda}$O have been measured and are here
presented. The behavior of the formation probability as a function of the
atomic mass number A is also discussed. | nucl-ex |
Studying the QGP with Jets at the LHC and RHIC: We review the current status of jet measurements in heavy-ion collisions at
the Large Hadron Collider (LHC) and the Relativistic Heavy Ion Collider (RHIC).
We discuss how the current measurements provide information about the
quark-gluon plasma and discuss near future opportunities at both RHIC and the
LHC. | nucl-ex |
Anomaly in the K^0_S Sigma^+ photoproduction cross section off the
proton at the K* threshold: The $\gamma + p \rightarrow K^0 + \Sigma^+$ photoproduction reaction is
investigated in the energy region from threshold to $E_\gamma = 2250$\,MeV. The
differential cross section exhibits increasing forward-peaking with energy, but
only up to the $K^*$ threshold. Beyond, it suddenly returns to a flat
distribution with the forward cross section dropping by a factor of four. In
the total cross section a pronounced structure is observed between the
$K^*\Lambda$ and $K^*\Sigma$ thresholds. It is speculated whether this signals
the turnover of the reaction mechanism from t-channel exchange below the $K^*$
production threshold to an s-channel mechanism associated with the formation of
a dynamically generated $K^*$-hyperon intermediate state. | nucl-ex |
Fragmentation of relativistic nuclei in peripheral interactions in
nuclear track emulsion: The technique of nuclear track emulsions is used to explore the fragmentation
of light relativistic nuclei down to the most peripheral interactions - nuclear
"white" stars. A complete pattern of therelativistic dissociation of a $^8$B
nucleus with target fragment accompaniment is presented. Relativistic
dissociation $^{9}$Be$\to2\alpha$ is explored using significant statistics and
a relative contribution of $^{8}$Be decays from 0$^+$ and 2$^+$ states is
established. Target fragment accompaniments are shown for relativistic
fragmentation $^{14}$N$\to$3He+H and $^{22}$Ne$\to$5He. The leading role of the
electromagnetic dissociation on heavy nuclei with respect to break-ups on
target protons is demonstrated in all these cases. It is possible to conclude
that the peripheral dissociation of relativistic nuclei in nuclear track
emulsion is a unique tool to study many-body systems composed of lightest
nuclei and nucleons in the energy scale relevant for nuclear astrophysics. | nucl-ex |
First Measurement of $Ξ^-$ Polarization in Photoproduction: Despite decades of studies of the photoproduction of hyperons, both their
production mechanisms and their spectra of excited states are still largely
unknown. While the parity-violating weak decay of hyperons offers a means of
measuring their polarization, which could help discern their production
mechanisms and identify their excitation spectra, no such study has been
possible for doubly strange baryons in photoproduction, due to low production
cross sections. However, by making use of the reaction $\gamma p \to K^+ K^+
\Xi^-$, we have measured, for the first time, the induced polarization, $P$,
and the transferred polarization from circularly polarized real photons,
characterized by $C_x$ and $C_z$, to recoiling $\Xi^-$s. The data were obtained
using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab for
photon energies from just over threshold (2.4 GeV) to 5.45 GeV. These
first-time measurements are compared, and are shown to broadly agree, with
model predictions in which cascade photoproduction proceeds through the decay
of intermediate hyperon resonances that are produced via relativistic meson
exchange, offering a new step forward in the understanding of the production
and polarization of doubly-strange baryons. | nucl-ex |
The 16N Calibration Source for the Sudbury Neutrino Observatory: A calibration source using gamma-rays from 16N (t_1/2 = 7.13 s) beta-decay
has been developed for the Sudbury Neutrino Observatory (SNO) for the purpose
of energy and other calibrations. The 16N is produced via the (n,p) reaction on
16O in the form of CO2 gas using 14-MeV neutrons from a commercially available
Deuterium-Tritium (DT) generator. The 16N is produced in a shielding pit in a
utility room near the SNO cavity and transferred to the water volumes (D2O or
H2O) in a CO2 gas stream via small diameter capillary tubing. The bulk of the
activity decays in a decay/trigger chamber designed to block the energetic
beta-particles yet permit the primary branch 6.13 MeV gamma-rays to exit.
Detection of the coincident beta-particles with plastic scintillator lining the
walls of the decay chamber volume provides a tag for the SNO electronics. This
paper gives details of the production, transfer, and triggering systems for
this source along with a discussion of the source gamma-ray output and
performance. | nucl-ex |
J/$ψ$ suppression in In-In collisions at 158 GeV/nucleon: The NA60 experiment has studied J/$\psi$ production in Indium-Indium
collisions at 158 A$\cdot$GeV. In this paper we present an updated set of
results obtained with the complete set of available statistics and an improved
alignment of the vertex tracker. The centrality dependence of the J/$\psi$
production, obtained with an analysis technique based only on the J/$\psi$
sample, indicates that a suppression beyond that induced by nuclear absorption
is present in In-In collisions, setting in at $\sim$80 participant nucleons. A
first study of the systematic errors related with this measurement is
discussed. We also present preliminary results on the J/$\psi$ azimuthal
distributions. | nucl-ex |
Experimental activities in few-body physics: Understanding the few-nucleon system remains one of the challenges in modern
nuclear and hadron physics. Observables in few-nucleon scattering processes are
sensitive probes to study the two and many-body interactions between nucleons
in nuclei. In the past decades, several facilities provided a large data base
to study in detail the three-nucleon interactions below the pion-production
threshold by exploiting polarized proton and deuteron beams and
large-acceptance detectors. Only since recently, the four-nucleon scattering
process at intermediate energies has been explored. In addition, there is a
focus to collect data in the hyperon-nucleon sector, thereby providing access
to understand the more general baryon-baryon interaction. In this contribution,
some recent results in the few-nucleon sector are discussed together with some
of the preliminary results from a pioneering and exclusive study of the
four-nucleon scattering process. Furthermore, this paper discusses the
experimental activities in the hyperon sector, in particular, the perspectives
of the hyperon program of PANDA. | nucl-ex |
Tensor Ayy and vector Ay analyzing powers in the H(d,d')X and
^{12}C(d,d')X reactons at initial deuteron momenta of 9 GeV/c in the region
of baryonic resonances excitation: The angular dependence of the tensor Ayy and vector Ay analyzing powers in
the inelastic scattering of deuterons with a momentum of 9.0 GeV/c on hydrogen
and carbon have been measured. The range of measurements corresponds to the
baryonic resonance excitation with masses 2.2--2.6 GeV/c^2. The Ayy data being
in good agreement with the previous results demonstrate an approximate $t$
scaling up to -1.5 (GeV/c)^2. The large values of A_y show a significant role
of the spin-dependent part of the elementary amplitude of the NN->NN* reaction.
The results of the experiment are compared with model predictions of the
plane-wave impulse approximation. | nucl-ex |
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