Isotopic effects in elastic and inelastic 12C + 16, 18O scattering

Abstract

Complete angular distributions of the 12C + 18O elastic and inelastic scattering were measured at the energy E lab(18O) = 105 MeV (E c.m. = 42 MeV) . Comparison of these elastic-scattering data with those from previously measured 12C + 16O data show their large-angle cross-sections to differ by as much as a factor of 100 with the 16O data being the largest. These and the 12C + 18O scattering data taken from the literature at the energies E c.m. = 12.9-56 MeV were analysed within the optical model and coupled-reaction-channels methods. Sets of Woods-Saxon 12C + 18O optical potential parameters were obtained and their energy dependence was deduced. A similar analysis was carried out for 12C + 16O where it was shown that over a wide energy range, the primary difference in the 16O and 18O scattering potentials is in their imaginary parts. The large-angle enhancement for the 12C + 18O elastic-scattering was shown to arise from the transfer of nucleons. The inelastic-scattering data were well described over the entire angular range as arising from collective excitations of the states in the target and projectile nuclei.