49 research outputs found
Consistent description of magnetic dipole properties in transitional nuclei
It is shown that a consistent description of magnetic dipole properties in
transitional nuclei can be obtained in the interacting boson model-2 by F-spin
breaking mechanism, which is associated with differences between the proton and
neutron deformations. In particular, the long standing anomalies observed in
the -factors of the Os-Pt isotopes are resolved by a proper inclusion of
F-spin breaking.Comment: Revtex, 10 pages, 4 figures (available from authors upon request
Impact of nuclear structure from shell model calculations on nuclear responses to WIMP elastic scattering for F and Xe targets
Non-relativistic effective field theory (NREFT) is one approach used for
describing the interaction of WIMPs with ordinary matter. Among other factors,
these interactions are expected to be affected by the structure of the atomic
nuclei in the target. The sensitivity of the nuclear response components of the
WIMP-nucleus scattering amplitude is investigated using shell model
calculations for F and Xe. Resulting integrated nuclear response
values are shown to be sensitive to some specifics of the nuclear structure
calculations.Comment: 7 pages, 3 figure
Impact of shell model interactions on nuclear responses to WIMP elastic scattering
Background: Nuclear recoil from scattering with weakly interacting massive
particles (WIMPs) is a signature searched for in direct detection of dark
matter. The underlying WIMP-nucleon interactions could be spin and/or orbital
angular momentum (in)dependent. Evaluation of nuclear recoil rates through
these interactions requires accounting for nuclear structure, e.g., through
shell model calculations.
Purpose: To evaluate nuclear response functions induced by these interactions
for F, Na, Si, Ar, Ge,
I, and Xe nuclei that are
relevant to current direct detection experiments, and to estimate their
sensitivity to shell model interactions.
Methods: Shell model calculations are performed with the NuShellX solver.
Nuclear response functions from non-relativistic effective field theory (NREFT)
are evaluated and integrated over transferred momentum for quantitative
comparisons.
Results: Although the standard spin independent response is barely sensitive
to the structure of the nuclei, large variations with the shell model
interaction are often observed for the other channels.
Conclusions: Significant uncertainties may arise from the nuclear components
of WIMP-nucleus scattering amplitudes due to nuclear structure theory and
modelling. These uncertainties should be accounted for in analyses of direct
detection experiments.Comment: 19 pages, 20 figures. Contains supplementary material at the en
Absorbed dose evaluation of Auger electron-emitting radionuclides: impact of input decay spectra on dose point kernels and S-values
The aim of this study was to investigate the impact of decay data provided by
the newly developed stochastic atomic relaxation model BrIccEmis on dose point
kernels (DPKs - radial dose distribution around a unit point source) and
S-values (absorbed dose per unit cumulated activity) of 14 Auger electron (AE)
emitting radionuclides, namely 67Ga, 80mBr, 89Zr, 90Nb, 99mTc, 111In, 117mSn,
119Sb, 123I, 124I, 125I, 135La, 195mPt and 201Tl. Radiation spectra were based
on the nuclear decay data from the medical internal radiation dose (MIRD)
RADTABS program and the BrIccEmis code, assuming both an isolated-atom and
condensed-phase approach. DPKs were simulated with the PENELOPE Monte Carlo
(MC) code using event-by-event electron and photon transport. S-values for
concentric spherical cells of various sizes were derived from these DPKS using
appropriate geometric reduction factors. The number of Auger and Coster-Kronig
(CK) electrons and x-ray photons released per nuclear decay (yield) from
MIRD-RADTABS were consistently higher than those calculated using BrIccEmis.
DPKs for the electron spectra from BrIccEmis were considerably different from
MIRD-RADTABS in the first few hundred nanometres from a point source where most
of the Auger electrons are stopped. S-values were, however, not significantly
impacted as the differences in DPKS in the sub-micrometre dimension were
quickly diminished in larger dimensions. Overestimation in the total AE energy
output by MIRD-RADTABS leads to higher predicted energy deposition by AE
emitting radionuclides, especially in the immediate vicinity of the decaying
radionuclides. This should be taken into account when MIRD-RADTABS data are
used to simulate biological damage at nanoscale dimensions.Comment: 27 pages, 4 figures, 3 table
Pushing the limits of excited-state -factor measurements
Current developments in excited-state -factor measurements are discussed
with an emphasis on cases where the experimental methodology is being extended
into new regimes. The transient-field technique, the recoil in vacuum method,
and moment measurements with LaBr detectors are discussed.Comment: 5 pages, 6 figure
Critical test of multi-{\it j} supersymmetries from magnetic moment measurements
Magnetic moment measurements in odd nuclei directly probe the distribution of
fermion states and hence provide one of the most critical tests for multi-
supersymmetries in collective nuclei. Due to complexity of calculations and
lack of data, such tests have not been performed in the past. Using the
Mathematica software, we derive analytic expressions for magnetic moments in
the limit of the supersymmetry and
compare the results with recent measurements in Pt.Comment: 10 pages with 1 figur
Emerging collectivity from the nuclear structure of Xe 132: Inelastic neutron scattering studies and shell-model calculations
Inelastic neutron scattering was used to study the low-lying nuclear structure of 132Xe. A comprehensive level scheme is presented, as well as new level lifetimes, multipole mixing ratios, branching ratios, and transition probabilities. Comparisons of these data as well as previously measured E2 strengths and g factors are made with new shell-model calculations for 132, 134, 136 Xe
to explore the emergence of collectivity in the Xe isotopes with N<82 near the closed shell.This material is based upon work supported by the US
National Science Foundation under Grant No. PHY-1606890.
This research was also sponsored in part by the Australian
Research Council under Grant No. DP17010167