Studies of positive-parity low-spin states in the A = 150 region

Robert Bark,John Sharpey-Schafer,Zhipan Li,Shuangquan Zhang,Zhi Shi,Siyabonga Majola,Yang Sun

doi:10.1051/epjconf/201817802012

Abstract

A systematic investigation of low-lying levels of nuclides in the mass 150 region has been undertaken at iThemba LABS. An extensive set of data on the low-lying, positive-parity bands in the nuclides between N = 88 and 92 and Sm to Yb has been obtained from γ-γ coincidence measurements following fusion-evaporation reactions optimized of the population of low-spin states. The energies and electromagnetic properties of the so-called β- and γ-bands of nuclei in this region have been compared with the solutions of a five dimensional collective Hamiltonian for quadrupole vibrational and rotational degrees of freedom, with moments-of-inertia and mass parameters determined by constrained self-consistent relativistic mean-field calculations using the PC-F1 relativistic functional. Some of the results of this comparison are presented here.

Highlights

The Bohr Hamiltonian [1], one of the earliest models describing the lowest-lying excitations of deformed nuclei, predicted the existence of the so-called and vibrational bands, based on K=0 and K=2 excitations.While numerous examples of K=0 and K=2 bands have been identified, the identification of the lowest lying K=0 band with the -band of the Bohr Hamiltonian is under question [2]
To highlight the salient points of the work in these proceedings, we focus on the data and calculations of a subset of the region, along N=90
The same cannot be said for the 02+ bands, where only in the case of 156Dy does the 02+ band run parallel to the ground band

Summary

Introduction

The Bohr Hamiltonian [1], one of the earliest models describing the lowest-lying excitations of deformed nuclei, predicted the existence of the so-called and vibrational bands, based on K=0 and K=2 excitations.While numerous examples of K=0 and K=2 bands have been identified, the identification of the lowest lying K=0 band with the -band of the Bohr Hamiltonian is under question [2]. A more realistic “Bohr Hamiltonian” has been developed - a five-dimensional Hamiltonian for quadrupole vibrational and rotational degrees of freedom, with collective parameters determined by constrained self-consistent covariant density functional calculations for triaxial shapes [7,8].

Results

Conclusion