Microscopic structure of deformed and superdeformed collective bands in rotating nuclei

Abstract

We investigate in self-consistent cranked Nilsson plus quasiparticle random-phase approximation the structure of 190,192,194Hg in their evolution from normal to superdeformation and from low to high rotational frequencies. The analysis of the energy levels suggests a splitting of few normally deformed bands into two or more branches. The investigation of the dynamical moments of inertia supports the octupole character of the low-lying negative parity superdeformed bands, in agreement with previous theoretical predictions and experimental findings. As a more direct confirm of their octupole nature, we obtain strong E1 transitions linking those bands to the yrast superdeformed band, in agreement with experiments. A similar result is shown to hold also for 152Dy. Like in 152Dy, the collectivity of the low-lying scissors mode gets enhanced with the onset of superdeformation

Rotation and shape changes inTb151andPb196: Probe

“…In fact, as reported in the case of 152 Dy [51], 196 Pb [52], and 190 Hg [53], strongly enhanced E1 transitions are experimentally observed, linking the excited SD bands to yrast. In all cases, the B(E1) values are of the order of 10 −4 W.u., namely, 1 to 2 orders of magnitude larger than expected from the tail of the GDR, in agreement with various theoretical models [54][55][56]. We have therefore performed simulation calculations for 151 Tb ( 196 Pb) adding a new Lorentzian component f oct to the E1 strength, with a peak energy E oct = 1.5(1.0) MeV and a FWHM oct = 1.0 (0.5) MeV, as shown by solid lines in Figs.…”

Investigation of high-Kstates in252No

“…It would also be a valuable task to challenge predictions based on quasiparticle random phase approximation (QRPA) calculations [58], provided that the theory is extended to the rotating frame. Such an approach proved successful previously for the interpretation of back-bending phenomena observed in π = − superdeformed bands of Hg isotopes [59,60]. Running QRPA calculations in the rotating frame with the D1S force as sole input would be a formidable task that most likely is manageable with the availability of algorithms and computers of the next generation.…”

Polarized electric dipole moment of well-deformed reflection asymmetric nuclei

“…The left-right asymmetry of fission induced by polarized neutrons can be also linked to the PEDM [30]. The E1 transitions possibly linked to octupole vibrations around super-deformed shape can be also enhanced by the PEDM [31,32,33,34,35]. Strong E1 transitions related to the low-energy shape oscillations of negative parity in the first and second (isomeric) minima in actinides are also connected to the PEDM [36].…”