Nearside-farside analyses of heavy-ion direct reactions to the continuum

Decompositions into nearside and farside (NF) components are made of heavy-ions continuum cross sections calculated within the multi-step direct reaction (MSDR) method including one- and two-step processes. The approach is applied to the 16O+48Ti system at Esub(lab) around 100 MeV and to the 16O+208Pb system at Esub(lab)=192 MeV, and both cross sections and polarizations of the residual nucleus are considered. It is seen that at higher energy losses the two-step contributions become dominant, and that for scattering angles beyond the grazing angle these two-step contributions are mainly farsided. The relative importance of the NF components depends sensitively on the balance between Coulomb repulsion and nuclear attraction. The magnitude of the farside contribution also depends critically on the use of a polarization potential in the excited states. This potential is treated empirically. The decompositions are usefully interpreted in terms of a simple model for multi-step deflection functions. The results of the present quantum-mechanical approach to continuum heavy-ion reactions exhibit many of the features of classical calculations of deep-inelastic processes. (orig.)