Suppression of the stellar enhancement factor and the reaction 85Rb(p,n)85Sr

TL;DR

This paper demonstrates that Coulomb suppression reduces the stellar enhancement factor in many endothermic reactions, suggesting that astrophysical reaction measurements should focus on these reactions rather than their reverses, and provides experimental data for the 85Rb(p,n)85Sr reaction.

Contribution

The study shows the occurrence of Coulomb suppression in stellar enhancement factors and provides experimental cross sections for the 85Rb(p,n)85Sr reaction, challenging common assumptions in astrophysics.

Findings

Coulomb suppression occurs in many endothermic reactions.

Experimental cross sections for 85Rb(p,n)85Sr were measured.

Results support a modified global optical proton potential.

Abstract

It is shown that a Coulomb suppression of the stellar enhancement factor occurs in many endothermic reactions at and far from stability. Contrary to common assumptions, reaction measurements for astrophysics with minimal impact of stellar enhancement should be preferably performed for those reactions instead of their reverses, despite of their negative reaction Q-value. As a demonstration, the cross section of the astrophysically relevant 85Rb(p,n)85Sr reaction has been measured by activation between 2.16<=E_{c.m.}<= 3.96 MeV and the astrophysical reaction rates at p-process temperatures for (p,n) as well as (n,p) are directly inferred from the data. Additionally, our results confirm a previously derived modification of a global optical proton potential. The presented arguments are also relevant for other alpha- and proton-induced reactions in the p-, rp-, and nu-p-processes.