Folding analysis for the fusion reactions at extreme sub-barrier energies

The aim of this work is to show the effect of the nucleus–nucleus potential on the fusion process especially at the extreme energy where the cross section exhibits an abrupt decrease in a few systems. The fusion cross section data have been analysed within the optical model, with the real part of the optical potential calculated in the double-folding model using realistic nucleon–nucleon interaction. The dependence of fusion cross section on the nuclear potential at inner, surface and tail regions is studied. It was found that the fusion cross section at extremely low energies is highly sensitive to the shape of the nuclear potential at the inner region below the Coulomb barrier. The inclusion of the folding potential with two WS parametrization to express the potential inside and outside the Coulomb barrier improves the calculations of heavy-ion fusion cross sections at the extreme sub-barrier energies.