Alpha-particle optical potential proofs at astrophysically relevant energies

TL;DR

This paper confirms the validity of a regional optical potential for alpha particles at astrophysically relevant energies, highlighting its consistency with recent reaction measurements and discussing limitations of statistical models near nuclear shell closures.

Contribution

It provides evidence supporting the alpha-particle optical potential at low energies and discusses the impact of nuclear shell effects on reaction modeling.

Findings

Optical potential describes recent reaction data well

Features of the potential are confirmed at sub-Coulomb energies

Limitations in statistical models are linked to nuclear shell effects

Abstract

$(\alpha,\gamma)$ and $(\alpha$,n) reaction cross sections recently measured close to the reaction thresholds are rather well described by a previously developed regional optical potential. Thus, particular features of the $\alpha$-particle optical potential at energies below the Coulomb barrier, besides parameters describing $\alpha$-particle elastic scattering at higher energies are confirmed. Additional limitations of similar statistical model calculations for minor reaction channels are shown to be most likely due to an overlooked process or critical values of statistical model parameters around closed nuclear shells.