Derivation of an optical potential for statically deformed rare-earth nuclei from a global spherical potential

TL;DR

This paper extends a global spherical optical potential to account for nuclear deformation effects in rare-earth nuclei, improving the accuracy of scattering predictions by coupling collective excitations in a coupled-channel framework.

Contribution

The authors generalize the Koning-Delaroche spherical optical potential to include deformation effects for coupled-channel calculations on rare-earth nuclei, demonstrating improved predictive capability.

Findings

Predictions agree reasonably with experimental data for cross sections and angular distributions.

Deformation effects significantly influence scattering observables.

The deformed potential is effective for nearly perfect rotor nuclei.

Abstract

The coupled-channel theory is a natural way of treating nonelastic channels, in particular those arising from collective excitations characterized by nuclear deformations. A proper treatment of such excitations is often essential to the accurate description of experimental nuclear-reaction data and to the prediction of a wide variety of scattering observables. Stimulated by recent work substantiating the near validity of the adiabatic approximation in coupled-channel calculations for scattering on statically deformed nuclei, we explore the possibility of generalizing a global spherical optical model potential (OMP) to make it usable in coupled-channel calculations on this class of nuclei. To do this, we have deformed the Koning-Delaroche global spherical potential for neutrons, coupling a sufficient number of states of the ground state band to ensure convergence. We present an extensive study of the effects of collective couplings and nuclear deformations on integrated cross sections as well as on angular distributions for neutron-induced reactions on statically deformed nuclei in the rare-earth region. We choose isotopes of three rare-earth elements (Gd, Ho, W), which are known to be nearly perfect rotors, to exemplify the results of the proposed method. Predictions from our model for total, elastic and inelastic cross sections, as well as for elastic and inelastic angular distributions, are in reasonable agreement with measured experimental data. These results suggest that the deformed Koning-Delaroche potential provides a useful regional neutron optical potential for the statically deformed rare earth nuclei.