2,103 research outputs found
Observation of Thermodynamical Properties in the Dy, Er and Yb Nuclei
The density of accessible levels in the (He,) reaction has
been extracted for the Dy, Er and Yb nuclei. The
nuclear temperature is measured as a function of excitation energy in the
region of 0 -- 6 MeV. The temperature curves reveal structures indicating new
degrees of freedom. The heat capacity of the nuclear system is discussed within
the framework of a canonical ensemble.Comment: 12 pages, 4 figures include
Estimating the nuclear level density with the Monte Carlo shell model
A method for making realistic estimates of the density of levels in even-even
nuclei is presented making use of the Monte Carlo shell model (MCSM). The
procedure follows three basic steps: (1) computation of the thermal energy with
the MCSM, (2) evaluation of the partition function by integrating the thermal
energy, and (3) evaluating the level density by performing the inverse Laplace
transform of the partition function using Maximum Entropy reconstruction
techniques. It is found that results obtained with schematic interactions,
which do not have a sign problem in the MCSM, compare well with realistic
shell-model interactions provided an important isospin dependence is accounted
for.Comment: 14 pages, 3 postscript figures. Latex with RevTex. Submitted as a
rapid communication to Phys. Rev.
Level density and gamma strength function in 162-Dy from inelastic 3-He scattering
Complementary measurements have been performed for the level density and
gamma strength function in 162-Dy using inelastic 3-He scattering. Comparing
these results to previous measurements using the 163-Dy(3-He,alpha) reaction,
reveals that the measured quantities above 1.5 MeV do not depend significantly
on the nuclear reaction chosen.Comment: 15 pages, including 7 figure
Shell Model Monte Carlo Investigation of Rare Earth Nuclei
We utilize the Shell Model Monte Carlo (SMMC) method to study the structure
of rare earth nuclei. This work demonstrates the first systematic ``full
oscillator shell plus intruder'' calculations in such heavy nuclei. Exact
solutions of a pairing plus quadrupole hamiltonian are compared with mean field
and SPA approximations in several Dysprosium isotopes from A=152-162, including
the odd mass A=153. Basic properties of these nuclei at various temperatures
and spin are explored. These include energy, deformation, moments of inertia,
pairing channel strengths, band crossing, and evolution of shell model
occupation numbers. Exact level densities are also calculated and, in the case
of 162 Dy, compared with experimental data.Comment: 40 pages; 24 figures; 2 tables. Update includes correction of figure
labe
Thermal and electromagnetic properties of 166-Er and 167-Er
The primary gamma-ray spectra of 166-Er and 167-Er are deduced from the
(3-He,alpha gamma) and (3-He,3-He' gamma) reaction, respectively, enabling a
simultaneous extraction of the level density and the gamma-ray strength
function. Entropy, temperature and heat capacity are deduced from the level
density within the micro-canonical and the canonical ensemble, displaying
signals of a phase-like transition from the pair-correlated ground state to an
uncorrelated state at Tc=0.5 MeV. The gamma-ray strength function displays a
bump around E-gamma=3 MeV, interpreted as the pygmy resonance.Comment: 21 pages including 2 tables and 11 figure
Validity and reliability of the Norwegian version of the Musculoskeletal Health Questionnaire in people on sick leave.
BACKGROUND: The Musculoskeletal Health Questionnaire (MSK-HQ) is a recently developed generic questionnaire that consists of 14 items assessing health status in people with musculoskeletal disorders. The objective was to translate and cross-culturally adapt the MSK-HQ into Norwegian and to examine its construct validity and reliability in people on sick leave with musculoskeletal disorders. METHODS: A prospective cohort study was carried out in Norway on people between 18 and 67 years of age and sick leave due to a musculoskeletal disorder. The participants were recruited through the Norwegian Labour and Welfare Administration during November 2018-January 2019 and responded to the MSK-HQ at inclusion and after four weeks. Internal consistency was assessed by Cronbach's alpha, and structural validity with a factor analysis. Construct validity was assessed by eight "a priori" defined hypotheses regarding correlations between the MSK-HQ and other reference scales. Correlations were analyzed by Spearman's- or Pearson's correlation coefficient and interpreted as high with values ≥ 0.50, moderate between 0.30-0.49, and low < 0.29. Reliability was tested with test-retest, standard error of measurement (SEM) and smallest detectable change (SDC). RESULTS: A total of 549 patients, mean age (SD) 48.6 (10.7), 309 women (56.3%), were included. The mean (SD) MSK-HQ sum scores (min-max 3-56) were 27.7 (8.2). Internal consistency was 0.86 and a three-factor structure was determined by factor analysis. Construct validity was supported by the confirmation of all hypotheses; high correlation with HRQOL, psychosocial risk profile, and self-perceived health; moderate correlation with physical activity, self-perceived work ability, and work presenteeism; and low correlation with the number of sick days. The test-retest reliability was good with an intraclass correlation coefficient of 0.83 (95% CI, 0.74-0.89), SEM was 2.3 and SDC 6.5. CONCLUSIONS: The Norwegian version of the MSK-HQ demonstrated high internal consistency, a three-factor structure, good construct validity and good test-retest reliability when used among people on sick leave due to musculoskeletal disorders
Pseudorapidity distributions of charged particles from Au+Au collisions at the maximum RHIC energy, Sqrt(s_NN) = 200 GeV
We present charged particle densities as a function of pseudorapidity and
collision centrality for the 197Au+197Au reaction at Sqrt{s_NN}=200 GeV. For
the 5% most central events we obtain dN_ch/deta(eta=0) = 625 +/- 55 and
N_ch(-4.7<= eta <= 4.7) = 4630+-370, i.e. 14% and 21% increases, respectively,
relative to Sqrt{s_NN}=130 GeV collisions. Charged-particle production per pair
of participant nucleons is found to increase from peripheral to central
collisions around mid-rapidity. These results constrain current models of
particle production at the highest RHIC energy.Comment: 4 pages, 5 figures; fixed fig. 5 caption; revised text and figures to
show corrected calculation of and ; final version accepted for
publicatio
Rapidity and centrality dependence of particle production for identified hadrons in Cu+Cu collisions at GeV
The BRAHMS collaboration has measured transverse momentum spectra of pions,
kaons, protons and antiprotons at rapidities 0 and 3 for Cu+Cu collisions at
GeV. As the collisions become more central the collective
radial flow increases while the temperature of kinetic freeze-out decreases.
The temperature is lower and the radial flow weaker at forward rapidity. Pion
and kaon yields with transverse momenta between 1.5 and 2.5 GeV/c are
suppressed for central collisions relative to scaled collisions. This
suppression, which increases as the collisions become more central is
consistent with jet quenching models and is also present with comparable
magnitude at forward rapidity. At such rapidities initial state effects may
also be present and persistence of the meson suppression to high rapidity may
reflect a combination of jet quenching and nuclear shadowing. The ratio of
protons to mesons increases as the collisions become more central and is
largest at forward rapidities.Comment: 19 pages, 11 figures and 6 table
Rapidity dependence of deuteron production in Au+Au collisions at = 200 GeV
We have measured the distributions of protons and deuterons produced in high
energy heavy ion Au+Au collisions at RHIC over a very wide range of transverse
and longitudinal momentum. Near mid-rapidity we have also measured the
distribution of anti-protons and anti-deuterons. We present our results in the
context of coalescence models. In particular we extract the "volume of
homogeneity" and the average phase-space density for protons and anti-protons.
Near central rapidity the coalescence parameter and the space
averaged phase-space density are very similar for both protons and
anti-protons. For protons we see little variation of either or the
space averaged phase-space density as the rapidity increases from 0 to 3.
However both these quantities depend strongly on at all rapidities. These
results are in contrast to lower energy data where the proton and anti-proton
phase-space densities are different at =0 and both and depend
strongly on rapidity.Comment: Document updated after proofs received from PR
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