Shell model analysis of the $ B(E2,2^+ \rightarrow 0^+)$'s in the A=70 T=1 triplet

TL;DR

This study uses advanced shell model calculations to analyze the B(E2) transition strengths in the A=70 T=1 triplet, providing insights into nuclear structure and potential anomalies in $^{70}$Br.

Contribution

It applies large scale shell model calculations with JUN45 and LNPS interactions to interpret recent experimental data on A=70 triplet nuclei, suggesting possible new nuclear states.

Findings

Calculations align with experimental data within uncertainties depending on effective charges.

An anomaly in $^{70}$Br may be due to an undetected 1+ T=0 state.

No evidence of shape change in $^{70}$Kr compared to its isobaric partners.

Abstract

he $B(E2,2^+ \rightarrow 0^+)$ transition strengths of the T=1 isobaric triplet $^{70}$Kr, $^{70}$Br, $^{70}$Se, recently measured at RIKEN/RIBF, are discussed in terms of state of the art large scale shell model calculations using the JUN45 and JUN45+LNPS plus Coulomb interactions. In this letter we argue that, depending on the effective charges used, the calculations are either in line with the experimental data within statistical uncertainties, or the anomaly happens in $^{70}$Br, rather than $^{70}$Kr. In the latter case, we suggest that it can be due to the presence of a hitherto undetected 1$^+$ T=0 state below the yrast 2$^+$ T=1 state. Our results do not support a shape change of $^{70}$Kr with respect to the other members of the isobaric multiplet.