Nuclear Level Density and $\gamma$-ray Strength Function of $^{63}\mathrm{Ni}$

TL;DR

This study investigates the nuclear level density and gamma-ray strength function of $^{63}$Ni using the Oslo method, revealing a low energy enhancement likely due to M1 strength and systematic isotopic variations.

Contribution

It provides new measurements of NLD and $ ext{γ}$SF for $^{63}$Ni, including the first comparison with shell model calculations and systematic trends across Ni isotopes.

Findings

Observed a strong low energy $ ext{γ}$SF enhancement in $^{63}$Ni.

Compared NLD with previous measurements and neutron resonance data.

Identified systematic changes in $ ext{γ}$SF$<$5 MeV across Ni isotopes.

Abstract

The nuclear level density (NLD) and $\gamma$-ray strength function ($\gamma$SF) of $^{63}\mathrm{Ni}$ have been investigated using the Oslo method. The extracted NLD is compared with previous measurements using particle evaporation and those found from neutron resonance spacing. The $\gamma$SF was found to feature a strong low energy enhancement that could be explained as M1 strength based on large scale shell model calculations. Comparison of $\gamma$SFs measured with the Oslo method for various $\mathrm{Ni}$ isotopes reveals systematic changes to the strength below $5$ MeV with increasing mass.