Study of high spin phenomena in even-even dysprosium isotopes by using projected shell model

Abstract

Back-bending phenomenon which occurs at high spin states of some heavy mass nuclei has been studied, for the first time, by using the ratio of electromagnetic reduced transition probabilities B(M1) / B(E2) within the Projected Shell Model (PSM). In this model, all angular momenta are projected on the symmetry axis of the deformed nucleus, which makes shell model calculations much easier. The electric quadrupole transition probability B(E2) and the magnetic dipole transition probability B(M1) are sensitive to the nuclear shape deformation and nuclear charge distribution, respectively. As a result, any change in the nuclear rotation speed can change the transition probability ratios at high spins. Our ratio findings at high state spins in even - even 152-164Dy isotopes confirm the previous back-bendings seen in these isotopes, in good agreement wth the experimental data. Increasing spectroscopic quadrupole moments with spin is another high spin phenomenon in heavy mass nuclei studied in this paper. While intrinsic quadrupole moments are constant for each Dy isotope, this study shows that spectroscopic (observed) quadrupole moments are increasing with spin.

Keywords

• projected shell model
• high spins phenomena
• dysprosium isotopes
• electromagnetic reduced transition probability ratio
• spectroscopic quadrupole moments