Nuclear structure study around Z=28

TL;DR

This paper investigates the nuclear structure of Ni, Cu, and Zn isotopes around Z=28 using shell model calculations, revealing limitations in current models and suggesting the need for expanded orbital considerations.

Contribution

It highlights the inadequacy of existing shell model interactions for neutron-rich nuclei and emphasizes the importance of including additional orbitals for accurate predictions.

Findings

Large E(2^+) for neutron-rich nuclei

Small B(E2) compared to experimental data

Indicates need for expanded model space

Abstract

Yrast levels of Ni, Cu and Zn isotopes for $40 \leq N \leq50$ have been described by state-of-the-art shell model calculations with three recently available interactions using $^{56}$Ni as a core in the $f_{5/2}pg_{9/2}$ model space. The results are unsatisfactory viz. large $E(2^+)$ for very neutron rich nuclei, small B(E2) values in comparison to experimental values. These results indicate an importance of inclusion of $\pi f_{7/2}$ and $\nu d_{5/2}$ orbitals in the model space to reproduce collectivity in this region.