Effect of dynamical polarization potentials on fusion radial potential barriers and on fusion cross sections for the proton-halo system 8B+58Ni

Abstract

Fusion radial potential (l = 0) barriers of 8B+58Ni are determined from a simultaneous optical model analysis of elastic scattering angular distributions and fusion data at energies around the Coulomb energy. Dynamical energy dependent Woods-Saxon polarization potentials, UF (volume) and UDR (surface) are used in the calculation of the barriers, where UF is a potential that accounts for polarization effects emerging from couplings to the fusion channel and UDR for effects due to direct reaction absorption couplings. Each of these potentials, UF and UDR are in turn, split into real and imaginary potentials VF, WF and VDR, WDR, which are related via the dispersion relation. The parameters of these potentials are determined during the simultaneous fitting process. The effect on fusion cross section from the competitive barrier lowering and rising produced respectively by VF and VDR, is investigated. Also, the net effect of breakup couplings on the fusion cross section is studied by analyzing the particular effect from both direct reaction polarization potentials VDR and WDR. Finally, it is shown that energy dependence of the total polarization potential U(E) = UF(E) + UDR(E) at the strong absorption radius Rsa is consistent with the Breakup Threshold Anomaly as expected for weakly bound nuclei.