$^{145}$Ba and $^{145, 146}$La structure from lifetime measurements

TL;DR

This study measures excited-state lifetimes in specific Ba and La isotopes to explore their nuclear structure, revealing new spin and parity assignments but not conclusively confirming octupole deformation.

Contribution

It provides new lifetime measurements for odd-mass Ba and La isotopes, offering insights into their nuclear structure and highlighting the need for further research.

Findings

Different spin and parity assignments than previous works

Lifetimes measured in the 100 ps to few ns range

No conclusive evidence of octupole deformation

Abstract

The occurrence of octupole shapes in even-mass neutron-rich Ba isotopes has been well established. However, the situation with the odd-mass Ba and odd or odd-odd La nuclei around them is far from settled. In order to shed light on these less-studied isotopes, a fast-timing experiment was performed using GRIFFIN at TRIUMF-ISAC. A wealth of excited-state lifetimes in the 100~ps to few ns range have been measured in $^{144, 145, 146}$Ba and $^{145,146}$La populated in the $\beta^-$ and $\beta^--n$ decay of $^{145,146}$Cs. The results do not allow to draw firm conclusions on the possible octupole deformation of these nuclei but suggest different spin and parity assignments than previous works. This work highlights the need for more detailed study of the odd and odd-odd isotopes in this region to properly understand their structure.