Nuclear level densities and $\gamma$-ray strength functions of $^{87}\mathrm{Kr}$ -- First application of the Oslo Method in inverse kinematics

TL;DR

This paper demonstrates the first application of the Oslo Method in inverse kinematics to extract gamma-ray strength functions and nuclear level densities for $^{87}$Kr, enabling studies of previously inaccessible nuclei.

Contribution

It introduces a novel inverse kinematic technique for applying the Oslo Method to measure gamma-ray strength functions and nuclear level densities.

Findings

The gamma-ray strength function in $^{87}$Kr shows M1 dominance at low energies.

The extracted NLD and $ ext{γ}$SF constrain neutron capture cross sections.

Comparison with direct measurements validates the new method.

Abstract

The $\gamma$-ray strength function ($\gamma$SF) and nuclear level density (NLD) have been extracted for the first time from inverse kinematic reactions with the Oslo Method. This novel technique allows measurements of these properties across a wide range of previously inaccessible nuclei. Proton-$\gamma$ coincidence events from the $\mathrm{d}(^{86}\mathrm{Kr}, \mathrm{p}\gamma)^{87}\mathrm{Kr}$ reaction were measured at iThemba LABS and the $\gamma$SF and NLD in $^{87}\mathrm{Kr}$ obtained. The low-energy region of the $\gamma$SF is compared to Shell Model calculations which suggest this region to be dominated by M1 strength. The $\gamma$SF and NLD are used as input parameters to Hauser-Feshbach calculations to constrain $(\mathrm{n},\gamma)$ cross sections of nuclei using the TALYS reaction code. These results are compared to $^{86}\mathrm{Kr}(n,\gamma)$ data from direct measurements.