Optical-Model Analysis with Spin-Orbit Potential for 30- and 35-MeVHe3Elastic Scattering

Abstract

Measured differential cross sections are reported for 30-MeV ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ ions elastically scattered from ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$, ${}_{}{}^{51}{}_{}{}^{}\mathrm{V}$, ${}_{}{}^{59}{}_{}{}^{}\mathrm{Co}$, ${}_{}{}^{60}{}_{}{}^{}\mathrm{Ni}$, ${}_{}{}^{89}{}_{}{}^{}\mathrm{Y}$, ${}_{}{}^{114}{}_{}{}^{}\mathrm{Cd}$, ${}_{}{}^{115}{}_{}{}^{}\mathrm{In}$, and ${}_{}{}^{116}{}_{}{}^{}\mathrm{Sn}$ for angles between 6° and 165° and for 35-MeV ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ ions elastically scattered from ${}_{}{}^{59}{}_{}{}^{}\mathrm{Co}$, ${}_{}{}^{60}{}_{}{}^{}\mathrm{Ni}$, ${}_{}{}^{115}{}_{}{}^{}\mathrm{In}$, and ${}_{}{}^{116}{}_{}{}^{}\mathrm{Sn}$ for angles between 6° and 140°. The data are compared with predictions of the nuclear optical model, and potential parameters that produce optimum fits with a least-squares computer routine are reported. Good fits at back angles for ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$, ${}_{}{}^{51}{}_{}{}^{}\mathrm{V}$, ${}_{}{}^{59}{}_{}{}^{}\mathrm{Co}$, and ${}_{}{}^{60}{}_{}{}^{}\mathrm{Ni}$ are obtained only with the inclusion of a spin-orbit interaction with a magnitude between 2 and 5 MeV for most cases. The back-angle data for these nuclei also tend to suppress discrete ambiguities in the potential well depths. A continuous ambiguity between the radius and the diffuseness parameters is found to be related to a constancy of the root-mean-square radius. Effects of experimental uncertainties on the potential parameters are also presented.