Unexpected properties of the $^{33}$S($\alpha$,p)$^{36}$Cl reaction cross section at low energies

TL;DR

This study presents unexpected experimental findings for the $^{33}$S($ extalpha$,p)$^{36}$Cl reaction at low energies, revealing larger cross sections than predicted and unusual energy dependence, challenging existing models.

Contribution

The paper provides new experimental data showing that statistical models underestimate low-energy cross sections and reveals atypical energy dependence in $ extalpha$-induced reactions.

Findings

Measured cross sections are significantly larger than model predictions at low energies.

The energy dependence of the reaction cross section deviates from established trends.

Additional reaction channels contribute more strength than previously accounted for.

Abstract

New experimental data for the $^{33}$S($\alpha$,p)$^{36}$Cl reaction show a very unusual energy dependence. Contrary to common findings for many other $\alpha$-induced reactions, statistical model calculations underestimate the measured cross sections at very low energies. The relatively huge cross sections at these low energies require a significant amount of single-particle strength in the measured energy range which exceeds by far 100% as soon as the additional strength from the competing $^{33}$S($\alpha$,n)$^{36}$Ar reaction is taken into account. In addition, the new data deviate from a general trend for the energy dependence of $\alpha$-induced reaction cross sections.