Nuclear spins, magnetic moments and quadrupole moments of Cu isotopes from N = 28 to N = 46: probes for core polarization effects

TL;DR

This study measures nuclear spins, magnetic, and quadrupole moments of copper isotopes to investigate core polarization effects and shell evolution, comparing experimental data with shell-model calculations.

Contribution

It provides new experimental data on copper isotopes and analyzes core polarization effects across neutron shell closures with theoretical comparisons.

Findings

Magnetic moments trend aligns with shell-model predictions.

Quadrupole moments indicate core polarization varies with neutron number.

No enhanced core polarization observed beyond N=40.

Abstract

Measurements of the ground-state nuclear spins, magnetic and quadrupole moments of the copper isotopes from 61Cu up to 75Cu are reported. The experiments were performed at the ISOLDE facility, using the technique of collinear laser spectroscopy. The trend in the magnetic moments between the N=28 and N=50 shell closures is reasonably reproduced by large-scale shell-model calculations starting from a 56Ni core. The quadrupole moments reveal a strong polarization of the underlying Ni core when the neutron shell is opened, which is however strongly reduced at N=40 due to the parity change between the $pf$ and $g$ orbits. No enhanced core polarization is seen beyond N=40. Deviations between measured and calculated moments are attributed to the softness of the 56Ni core and weakening of the Z=28 and N=28 shell gaps.