THE O + PB INTERACTION NEAR THE COULOMB BARRIER

We present the local and l-rmindependent potentials which are equivalent, in the sense that they yield the same Sl, to the implicit polarization potentials generated by channel coupling, and which have been found by Thompson et al. to explain the threshold anomaly for the case of 16O on 208Pb. Potentials which fit Sl for all partial waves are irreducibly wavy in r, an effect which appears to be a consequence of the l-dependence of the dynamic polarization potential. To establish these potentials, the "IP" inversion procedure was further developed. Some of our results are unexpected, including a very low degree of energy dependence in the real potential in the energy range between 80 and 102 MeV. The most general aspects of what we find here appear to be consistent with behaviour common to all nucleus-nucleus potentials, including those involving nucleons as projectiles. © 1990.