Microscopic Structure of the Yrast Bands in Even Xe Isotopes

Abstract

The interaction between collective states consisting mainly of the lowest-energy quadrupole phonons is considered along with that of noncollective states, including high-spin phonons in even Xe isotopes. Calculations are performed for yrast states with spins of up to ${{I}^{\pi }} = {{18}^{ + }}$ in the boson approximation. Collective states are gradually substituted for noncollective ones in isotopes with $A \leqslant 120$, leading to a smooth change in values of $B(E2)$ as spin increases. In contrast, there is a sharp transition from the collective to the noncollective band in isotopes with $A \geqslant 122$: the bands intersect and the corresponding $B(E2)$ value falls substantially.