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

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.

arXiv comment16 pages, 7 figures

References in corpus (6)

• Tables of E2 Transition Probabilities from the first $2^{+}$ States in Even-Even Nuclei
• Direct Evidence of Octupole Deformation in Neutron-Rich ${}^{144}$Ba
• Direct Evidence for Octupole Deformation in ${}^{146}$Ba and the Origin of Large $E1$ Moment Variations in Reflection-Asymmetric Nuclei
• The GRIFFIN Facility for Decay-Spectroscopy Studies at TRIUMF-ISAC
• The GRIFFIN Data Acquisition System
• Shape coexistence in the neutron-deficient lead region: A systematic study of lifetimes in the even-even ${}^{188-200}$Hg with GRIFFIN