Elastic scattering of 3He particles on Ca at five incident energies between 18.8 and 39.3 MeV

Abstract

Differential cross sections for the elastic scattering of 3He particles by natural Ca at incident energies of 18.8, 24.9, 31.0, 34.4 and 39.3 MeV were measured and analysed in terms of the optical model. Angular distributions have been measured in steps of 2.5° or 5° between 10° and 170°. The present analysis shows that the optical model gives a good description for the elastic scattering of 3He particles on Ca in the measured energy range. However, there exist some ambiguities in optical-model parameters as in the case of other particles, that is, the parameter groups with the real potential depth of 90, 130, 180, 240 or 320 MeV and those with the imaginary potential of a volume or surface absorption type, reproduce experimental angular distributions of differential cross sections. The form factor of surface absorption does not need an anomalously large radius for the imaginary potential of the 3He scatterings. Furthermore, comparisons of reproducibility of angular distributions with and without the real part of the spin-orbit potential are made for each parameter group. A spin-orbit potential of about 4 MeV explains the backward behaviour of angular distributions. The analysis was carried out with an automatic parameter search program.