Impact of Triaxiality on the Emission and Absorption of Neutrons and Gamma Rays in Heavy Nuclei

TL;DR

This paper investigates how triaxiality affects neutron and gamma-ray emission in heavy nuclei, proposing a combined parameterization for level densities and photon strength that aligns well with experimental data.

Contribution

It introduces a unified parameterization for level densities and photon strength functions incorporating triaxiality, improving predictions for radiative processes in heavy nuclei.

Findings

Good description of low-spin capture data for 124 nuclei

Few global parameters needed when considering ground state shapes

Enhanced understanding of deformation effects on nuclear emission

Abstract

For many spin-0 target nuclei neutron capture measurements yield information on level densities at the neutron separation energy. Also the average photon width has been determined from capture data as well as Maxwellian average cross sections for the energy range of unresolved resonances. Thus it is challenging to use this data set for a test of phenomenological prescriptions for the prediction of radiative processes. An important ingredient for respective calculations is the photon strength function for which a parameterization was proposed using a fit to giant dipole resonance shapes on the basis of theoretically determined ground state deformations including triaxiality. Deviations from spherical and axial symmetry also influence level densities and it is suggested to use a combined parameterization for both, level density and photon strength. The formulae presented give a good description of the data for low spin capture into 124 nuclei with 72<A<244 and only very few global parameters have to be adjusted when the predetermined information on ground state shapes of the nuclei involved is accounted for.