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

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.

Comments: 5 pages, 4 figures, Phys. Rev. C, accepted as Brief Report; misprint (overestimate -> underestimate) "in "Note added in proof" replaced