Potential description of anomalous large angle scattering of α particles

Abstract

Angular distributions of the differential cross section of \ensuremath{\alpha} elastic scattering by ${}^{24}\mathrm{Mg},$ ${}^{28}\mathrm{Si},$ and ${}^{30}\mathrm{Si}$ nuclei have been studied for various incident energies. The observed enhancement of differential cross sections at back angles, usually known as anomalous large angle scattering (ALAS), cannot be explained in terms of the normal optical model potential. A molecular type or squared Woods-Saxon optical potential can account for the ALAS and produce satisfactory fits to the angular distributions. A mass dependence of the potential parameters in the range $A=24--30$ and energy variation in the region ${E}_{\ensuremath{\alpha}}=15--45\mathrm{MeV}$ for the ${}^{28}\mathrm{Si}$ target and 22--120 MeV for the ${}^{24}\mathrm{Mg}$ target have been investigated.