19 research outputs found
Semi-classical and anharmonic quantum models of nuclear wobbling motion
A semi-classical model for wobbling motion is presented as an extension to
the Bohr-Mottelson model of wobbling motion. Using the resultant wobbling
potential, a quantum mechanical equation is derived for anharmonic wobbling
motion. We then attempt to explain the anharmonicity observed in the excited
bands of two wobbling phonons in the A=160 region.Comment: 5 pages, 2 figures, accepted in Phys. Lett.
Evidence for particle-hole excitations in the triaxial strongly-deformed well of ^{163}Tm
Two interacting, strongly-deformed triaxial (TSD) bands have been identified
in the Z = 69 nucleus ^{163}Tm. This is the first time that interacting TSD
bands have been observed in an element other than the Z = 71 Lu nuclei, where
wobbling bands have been previously identified. The observed TSD bands in
^{163}Tm appear to be associated with particle-hole excitations, rather than
wobbling. Tilted-Axis Cranking (TAC) calculations reproduce all experimental
observables of these bands reasonably well and also provide an explanation for
the presence of wobbling bands in the Lu nuclei, and their absence in the Tm
isotopes.Comment: 13 pages, 7 figure
-factor and static quadrupole moment for the wobbling mode in La
The -factor and static quadrupole moment for the wobbling mode in the
nuclide La are investigated as functions of the spin by employing
the particle rotor model. The model can reproduce the available experimental
data of -factor and static quadrupole moment. The properties of the
-factor and static quadrupole moment as functions of are interpreted by
analyzing the angular momentum geometry of the collective rotor,
proton-particle, and total nuclear system. It is demonstrated that the
experimental value of the -factor at the bandhead of the yrast band leads to
the conclusion that the rotor angular momentum is . Furthermore, the
variation of the -factor with the spin yields the information that the
angular momenta of the proton-particle and total nuclear system are oriented
parallel to each other. The negative values of the static quadrupole moment
over the entire spin region are caused by an alignment of the total angular
momentum mainly along the short axis. Static quadrupole moment differences
between the wobbling and yrast band originate from a wobbling excitation with
respect to the short axis.Comment: 6 pages, 4 figure
Lifetimes of triaxial superdeformed states in \chem{^{163}Lu} and \chem{^{164}Lu}
Lifetimes of states in the yrast superdeformed bands of
Lu and Lu were determined in a Doppler-shift
attenuation-method experiment. From fractional Doppler shifts and line
shapes, average transition quadrupole moments, b and b, were deduced for one
of the bands in Lu and Lu,
respectively. These values are much larger than the quadrupole moment
of the normal-deformed yrast band in Yb, b, that was also determined in this experiment.
Comparison to cranking calculations indicates that both superdeformed
bands correspond to a local potential energy minimum with a pronounced
triaxiality,
Comparative quadrupole moments of triaxial superdeformed states in \chem{^{163,164,165}Lu}
Average transition quadrupole moments in the yrast triaxial
superdeformed bands of Lu, Lu and Lu were
determined in a Doppler-shift attenuation-method
experiment. Fractional Doppler shifts were determined in -ray
coincidence spectra measured with the Gammasphere array. The
transition quadrupole moments derived from these data show a decrease
from Lu to Lu which is not predicted by total-energy
surface calculations
First evidence for triaxial superdeformation in \chem{^{161}Lu} and \chem{^{162}Lu}
High-spin states in Lu and Lu have been investigated using the
GASP -ray spectrometer array. Excited states in these nuclei have
been populated through the
Mo(Cu, n) reaction at a beam energy of 260 MeV. Four presumably
triaxial superdeformed bands, three in Lu and one in Lu, have
been observed. This is the first evidence for triaxial superdeformation in
the two isotopes