Evidence for Increased neutron and proton excitations between 51 − 63Mn

C Babcock,H Heylen,J Billowes,M.L Bissell,K Blaum,P Campbell,B Cheal,R.F Garcia Ruiz,C Geppert,W Gins,M Kowalska,K Kreim,S.M Lenzi,I.D Moore,R Neugart,G Neyens,W Nörtershäuser,J Papuga,D.T Yordanov

doi:10.1016/j.physletb.2015.09.012

Abstract

The hyperfine structures of the odd-even 51−63Mn atoms (N=26−38) were measured using bunched beam collinear laser spectroscopy at ISOLDE, CERN. The extracted spins and magnetic dipole moments have been compared to large-scale shell-model calculations using different model spaces and effective interactions. In the case of 61,63Mn, the results show the increasing importance of neutron excitations across the N=40 subshell closure, and of proton excitations across the Z=28 shell gap. These measurements provide the first direct proof that proton and neutron excitations across shell gaps are playing an important role in the ground state wave functions of the neutron-rich Mn isotopes.

Highlights

The complexity of nuclear interactions has made it difficult to define a single model that describes the variety of nuclear properties observed
Collinear laser spectroscopy is a technique that is used to measure the atomic hyperfine structure, resulting from the interplay between the nucleus and the magnetic and electric fields generated by the electrons
Neutron-rich manganese isotopes ( Z = 25) provide an opportunity for studying shell structure evolution towards the suspected subshell closure at N = 40 [3,4]. This appears as a possible subshell closure for 68Ni, observed through a low quadrupole transition probability and a high lying 2+1 state [5], mass measurements of neutron-rich Ni indicate that the closure is a weak one

Summary

Introduction

The complexity of nuclear interactions has made it difficult to define a single model that describes the variety of nuclear properties observed. Comparisons of shell-model calculations with experimental results, such as electric and magnetic properties, provide a powerful tool to understand nuclear structure evolution and improve its description within the shell model. Neutron-rich manganese isotopes ( Z = 25) provide an opportunity for studying shell structure evolution towards the suspected subshell closure at N = 40 [3,4]. This appears as a possible subshell closure for 68Ni, observed through a low quadrupole transition probability and a high lying 2+1 state [5], mass measurements of neutron-rich Ni indicate that the closure is a weak one [6].

Methods

Results

Discussion

Conclusion