Precise Mass Measurement of the Longest Odd-Odd Chain of \boldmath $1^+$ Ground States

TL;DR

This study precisely measured the masses of specific Rh isotopes, identified a new isomeric state, and used theoretical models to explain the unique properties of the longest odd-odd chain of 1+ ground states.

Contribution

It provides the first phenomenological explanation for the odd-odd Rh chain's unique properties using mean-field calculations and identifies a new isomeric state in $^{114}$Rh.

Findings

Good agreement with previous measurements

Identification of a new isomeric state in $^{114}$Rh

Theoretical explanation of the chain's properties

Abstract

Precise mass measurements of the ground and isomeric states of the odd-odd $^{108, 110, 112, 114, 116}$Rh were performed using the Canadian Penning Trap at Argonne National Laboratory, showing good agreement with recent JYFLTRAP measurements. A new possible isomeric state of $^{114}$Rh was also observed. These isotopes are part of the longest odd-odd chain of identical ground-state spin-parity assignment of 1$^+$, spanning $^{104-118}$Rh, despite being in a region of deformation. Realistic phenomenological mean-field calculations using ``universal'' Wood-Saxon Hamiltonian were performed, which explained this phenomenon for the first time. In addition, multi-quasiparticle blocking calculations were performed to study the configuration of low-lying states in the odd-odd Rh nuclei, elucidating anomalous isomeric yield ratio observed for $^{114}$Rh.