Structure of the doublet bands in doubly odd nuclei: The case of $^{128}Cs$

TL;DR

This paper investigates the structure of doublet bands in $^{128}Cs$ using the Interacting Vector Boson Fermion Model, providing a collective interpretation and successfully reproducing energy levels, transition probabilities, and staggering effects.

Contribution

It introduces a new collective interpretation of doublet bands in odd-odd nuclei within the IVBFM framework, highlighting the role of dynamical symmetry and supersymmetry in their formation.

Findings

Energy levels and transition probabilities are well described.

Odd-even staggering of transition strengths is reproduced.

Doublet bands may result from larger dynamical symmetry realization.

Abstract

The structure of the $\Delta J = 1$ doublet bands in $^{128}Cs$ is investigated within the framework of the Interacting Vector Boson Fermion Model (IVBFM). A new, purely collective interpretation of these bands is given on the basis of the used boson-fermion dynamical symmetry of the model. The energy levels of the doublet bands as well as the absolute $B(E2)$ and $B(M1)$ transition probabilities between the states of both yrast and yrare bands are described quite well. The observed odd-even staggering of both $B(M1)$ and $B(E2)$ values is reproduced by the introduction of an appropriate interaction term of quadrupole type, which produces such a staggering effect in the transition strengths. The calculations show that the appearance of doublet bands in certain odd-odd nuclei could be a consequence of the realization of a larger dynamical symmetry based on the non-compact supersymmetry group $OSp(2\Omega /12, R)$.