Complementary optical-potential analysis of alpha-particle elastic scattering and induced reactions at low energies

TL;DR

This paper extends a semi-microscopic optical model for alpha-particle scattering to medium-mass nuclei and low energies, providing a unified potential description that fits elastic scattering and reaction data.

Contribution

It introduces a regional optical potential based on elastic scattering data that accurately describes low-energy alpha-induced reactions across a range of nuclei.

Findings

Modified surface imaginary potential improves data fit

Diffuseness of real part affects scattering and reactions

Unified potential describes elastic and reaction data well

Abstract

A previously derived semi-microscopic analysis based on the Double Folding Model, for alpha-particle elastic scattering on A~100 nuclei at energies below 32 MeV, is extended to medium mass A ~ 50-120 nuclei and energies from ~13 to 50 MeV. The energy-dependent phenomenological imaginary part for this semi-microscopic optical model potential was obtained including the dispersive correction to the microscopic real potential, and used within a concurrent phenomenological analysis of the same data basis. A regional parameter set for low-energy alpha-particles entirely based on elastic-scattering data analysis was also obtained for nuclei within the above-mentioned mass and energy ranges. Then, an ultimate assessment of (alpha,gamma), (alpha,n) and (alpha,p) reaction cross sections concerned target nuclei from 45Sc to 118Sn and incident energies below ~12 MeV. The former diffuseness of the real part of optical potential as well as the surface imaginary-potential depth have been found responsible for the actual difficulties in the description of these data, and modified in order to obtain an optical potential which describe equally well both the low energy elastic-scattering and induced-reaction data of alpha-particles.