On sub-Coulomb heavy-ion scattering and the problem of nuclear absorption

Abstract The sub-Coulomb elastic scattering of nuclei near closed shells is sensitive to absorptive processes governed by the valence nucleons and thus is suited for testing microscopic theories of nuclear absorption in heavy-ion collisions. Semi-classical perturbation theory is used to obtain a direct relation between an optical potential and the corresponding angular distribution. An analytic expression is derived for the asymptotic form of a valence neutron contribution to the optical potential within the single-folding model. Numerical calculations using semi-microscopic optical potentials and taking direct reaction channels into account are compared with the available sub-Coulomb data for 13 C and 17,18 O scattering on 208 Pb.