Nuclear level densities and gamma-ray strength functions in 44,45Sc

TL;DR

This study investigates the nuclear level densities and gamma-ray strength functions of scandium isotopes 44 and 45 using experimental methods and compares the results with theoretical models, revealing unexplained low-energy enhancements.

Contribution

It provides new experimental data on 44,45Sc and compares these with microscopic models, highlighting discrepancies at low gamma energies.

Findings

Experimental level densities align with microscopic models at certain energies.

Observed gamma-ray strength functions show low-energy enhancement.

Standard models do not fully explain the low-energy strength increase.

Abstract

The scandium isotopes 44,45Sc have been studied with the 45Sc(3He,alpha gamma)44Sc and 45Sc(3He,3He' gamma)45Sc reactions, respectively. The nuclear level densities and gamma-ray strength functions have been extracted using the Oslo method. The experimental level densities are compared to calculated level densities obtained from a microscopic model based on BCS quasiparticles within the Nilsson level scheme. This model also gives information about the parity distribution and the number of broken Cooper pairs as a function of excitation energy. The experimental gamma-ray strength functions are compared to theoretical models of the E1, M1, and E2 strength, and to data from (gamma,n) and (gamma,p) experiments. The strength functions show an enhancement at low gamma energies that cannot be explained by the present, standard models.