QUASI-ELASTIC TRANSFER IN THE XE-136-64 REACTION(NI)

Single and multinucleon transfer yields for the Xe-136+Ni-64 reaction at a scattering energy approximate to 5% above the Coulomb barrier ene rgy are studied using particle-gamma-ray coincidence data. Q-value and scattering-angle distributions are extracted for the stronger channel s. A fast transfer mechanism dominates the yields to these channels ov er an extended Q-value range, leading to a concentration of the cross section near the grazing angle. Analysis of the angular distributions based on a semiclassical barrier penetration model suggests that the s ingle-nucleon and two-neutron exchange channels are dominated, respect ively, by direct and two-step sequential transfer from the ground or l ow-lying excited states of the participating nuclei. The multiproton t ransfer channels have angular distributions that indicate a more compl ex mechanism, although direct cluster transfer From an excited configu ration cannot be fully discounted. Ln a separate analysis, the relativ e population of different mass channels is found to be in general agre ement with the expectations of a ''random walk'' model of particle exc hange.