Impacts of the Cutoff of Coupled-Channels Effects on Heavy-Ion Fusion Reactions at Extreme Sub-Barrier Energies

Abstract

Based on the one dimensional barrier penetration model with semiclassical WKB method, the dynamic polarization potentials in heavy-ion reactions are extracted from the fusion cross sections. By choosing the proper parameters, the real polarization potential can be calculated from the imaginary part according to the dispersion relation in the framework of the linear-schematic model. The imaginary potential comes from the coupled-channels effects and shows a rapid cuttoff at energies far below the Coulomb barrier. Due to the absence of the coupled-channels effects, the fusion excitation function fall off more quickly than the usual expectation. Moreover, the pure potential in fusion reactions is proposed in hopes to reproduce the fusion cross sections at all energies in the full coupled-channels calculation.