Spins and magnetic moments of 58;60;62;64Mn ground states and isomers

TL;DR

This study measures the spins and magnetic moments of manganese isotopes using laser spectroscopy, confirming ground state assignments and comparing results with shell-model calculations to understand nuclear structure changes.

Contribution

It provides definitive spin assignments for Mn isotopes and demonstrates the importance of proton and neutron excitations in nuclear models beyond N=37.

Findings

Ground state spins confirmed as I=1 for most isotopes.

Magnetic moments decrease with increasing neutron number.

Shell-model calculations with LNPS agree well with experimental data.

Abstract

The odd-odd 54;56;58;60;62;64Mn isotopes (Z = 25) were studied using bunched-beam collinear laser spectroscopy at ISOLDE, CERN. From the measured hyperfine spectra the spins and magnetic moments of Mn isotopes up to N = 39 were extracted. The previous tentative ground state spin assignments of 58;60;62;64Mn are now firmly determined to be I = 1 along with an I = 4 assignment for the isomeric states in 58;60;62Mn. The I = 1 magnetic moments show a decreasing trend with increasing neutron number while the I = 4 moments remain quite constant between N = 33 and N = 37. The results are compared to large-scale shell-model calculations using the GXPF1A and LNPS effective interactions. The excellent agreement of the ground state moments with the predictions from the LNPS calculations illustrates the need for an increasing amount of proton excitations across Z = 28 and neutron excitations across N = 40 in the ground state wave functions from N = 37 onwards.