Open Shell Effects in a Microscopic Optical Potential for Elastic Scattering of $^{6(8)}$He

TL;DR

This paper develops a microscopic optical potential for elastic scattering of helium isotopes that accounts for open-shell effects, and investigates how these effects influence scattering observables at various energies.

Contribution

It introduces a novel folding optical potential incorporating open-shell effects for helium isotopes, extending traditional models for closed-shell nuclei.

Findings

Open-shell effects significantly alter scattering observables.

The exponential tail of p-shell wave functions impacts the results.

Elastic scattering for $^8$He is successfully modeled at selected energies.

Abstract

Elastic scattering observables (differential cross section and analyzing power) are calculated for the reaction $^6$He(p,p)$^6$He at projectile energies starting at 71 MeV/nucleon. The optical potential needed to describe the reaction is based on a microscopic Watson first-order folding potential, which explicitly takes into account that the two neutrons outside the $^4$He-core occupy an open p-shell. The folding of the single-particle harmonic oscillator density matrix with the nucleon-nucleon t-matrix leads for this case to new terms not present in traditional folding optical potentials for closed shell nuclei. The effect of those new terms on the elastic scattering observables is investigated. Furthermore, the influence of an exponential tail of the p-shell wave functions on the scattering observables is studied, as well as the sensitivity of the observables to variations of matter and charge radius. Finally elastic scattering observables for the reaction $^8$He(p,p)$^8$He are presented at selected projectile energies.