248 research outputs found
Intermediate energy Coulomb excitation as a probe of nuclear structure at radioactive beam facilities
The effects of retardation in the Coulomb excitation of radioactive nuclei in
intermediate energy collisions (Elab ~100 MeV/nucleon) are investigated. We
show that the excitation cross sections of low-lying states in 11Be,
{38,40,42}S and {44,46}Ar projectiles incident on gold and lead targets are
modified by as much as 20% due to these effects. The angular distributions of
decaying gamma-rays are also appreciably modified.Comment: 21 pages, 3 figures, Phys. Rev. C, in pres
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
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
Probing the subshell closure: factor of the Mg(2) state
The first-excited state ~factor of Mg has been measured relative to
the factor of the Mg() state using the high-velocity
transient-field technique, giving . This new measurement is in
strong disagreement with the currently adopted value, but in agreement with the
-shell model using the USDB interaction. The newly measured factor,
along with and systematics, signal the closure of the subshell at . The possibility that precise -factor
measurements may indicate the onset of neutron admixtures in first-excited
state even-even magnesium isotopes below Mg is discussed and the
importance of precise excited-state -factor measurements on ~shell
nuclei with to test shell-model wavefunctions is noted.Comment: 8 pages, 5 figure
Conversion coefficients for superheavy elements
In this paper we report on internal conversion coefficients for Z = 111 to Z
= 126 superheavy elements obtained from relativistic Dirac-Fock (DF)
calculations. The effect of the atomic vacancy created during the conversion
process has been taken into account using the so called "Frozen Orbital"
approximation. The selection of this atomic model is supported by our recent
comparison of experimental and theoretical conversion coefficients across a
wide range of nuclei. The atomic masses, valence shell electron configurations,
and theoretical atomic binding energies required for the calculations were
adopted from a critical evaluation of the published data. The new conversion
coefficient data tables presented here cover all atomic shells, transition
energies from 1 keV up to 6000 keV, and multipole orders of 1 to 5. A similar
approach was used in our previous calculations [1] for Z = 5 - 110.Comment: Accepted for publication in Atomic Data and Nuclear Data Table
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