Detailed low-spin spectroscopy of 65Ni via neutron capture reaction

TL;DR

This study expanded the low-spin level scheme of 65Ni using neutron capture, identifying new levels and transitions, and compared findings with shell model predictions to understand nuclear shapes.

Contribution

The paper provides the first extensive low-spin level scheme of 65Ni with new levels and transitions, and assigns spins and parities through angular correlation analysis.

Findings

Level scheme expanded with 2 new levels and 87 transitions.

Spin and parity assignments for multiple states achieved.

Shell model predicts spherical shapes except for specific states.

Abstract

An extended investigation of the low-spin structure of the $^{65}$Ni nucleus was performed at the Institut Laue-Langevin, Grenoble, via the neutron capture reaction $^{64}$Ni(n,$\gamma$)$^{65}$Ni, using the FIPPS HPGe array. The level scheme of $^{65}$Ni was significantly expanded, with 2 new levels and 87 newly found transitions. Angular correlation analyses were also performed, allowing us to assign spins and parities for a number of states, and to determine multipolarity mixing ratios for selected $\gamma$ transitions. The low-energy part of the experimental level scheme (up to about 1.4 MeV) was compared with Monte Carlo Shell Model calculations, which predict spherical shapes for all states, apart from the 9/2$^+$ and the second excited 1/2$^-$ states of oblate deformation.