Exploring the Onset of Collectivity Approaching N=40 through Manganese Masses

TL;DR

This study presents precise mass measurements of manganese isotopes near N=40, providing evidence for the onset of nuclear collectivity and the potential emergence of a new island of inversion in this region.

Contribution

First precision mass measurements of $^{67}$Mn and $^{68}$Mn, offering new data to understand nuclear structure near N=40.

Findings

Masses of $^{67}$Mn and $^{68}$Mn measured for the first time.

Results indicate increasing collectivity approaching N=40.

Data supports the onset of a new island of inversion.

Abstract

Isotopes in the region of the nuclear chart below $^{68}\mathrm{Ni}$ have been the subject of intense experimental and theoretical effort due to the potential onset of a new ``island of inversion'' when crossing the harmonic oscillator subshell closure at $N = 40$. We have measured the masses of $^{64-68}\textrm{Mn}$ using TITAN's multiple-reflection time-of-flight mass spectrometer, resulting in the first precision mass measurements of $^{67}\mathrm{Mn}$ and $^{68}\mathrm{Mn}$. These results are compared to \textit{ab initio} calculations and modern shell model calculations and show an increase in collectivity approaching $N=40$.