Description of dipole strength in heavy nuclei in conformity with their quadrupole degrees of freedom

TL;DR

This paper proposes a triaxiality-based Lorentzian sum model for describing dipole strength in heavy nuclei, aligning with experimental data and theoretical resonance width relations.

Contribution

It introduces a three-Lorentzian (TLO) parameterization for giant dipole resonance that accounts for triaxiality and resonance width energy dependence.

Findings

Good agreement with nuclear photo-effect data

Resonance widths follow a power law relation

Photon strength beyond E1 has minimal impact

Abstract

In conformity to new findings about the widespread occurrence of triaxiality arguments are given in favor of a description of the giant dipole resonance in heavy nuclei by the sum of three Lorentzians. This TLO parameterization allows a strict use of resonance widths {\Gamma} in accordance to the theoretically founded power law relation to the resonance energy. No additional variation of {\Gamma} with the photon energy and no violation of the sum rule are necessary to obtain a good agreement to nuclear photo-effect, photon scattering and radiative capture data. Photon strength other than E1 has a small effect, but the influence of the level density on photon emission probabilities needs further investigation.