One- and two-proton transfer reactions in [sup 32]S+[sup 64]Ni and [sup 28]Si+[sup 68]Zn at near-barrier energies

One- and two-proton transfer reactions were studied at bombarding energies around the barrier in [sup 32]S + [sup 64]Ni and [sup 28]Si + [sup 68]Zn systems. The decrease of one- and two-proton stripping probabilities with the distance of closest approach was observed to be slower than that expected from semiclassical considerations, at above barrier energies, especially for two-proton stripping. The effect of these transfer channels on the sub-barrier fusion enhancement was investigated on the basis of semiclassical theories. It was found that the couplings to the inelastic channels and the one- and two-proton transfer channels cannot explain the observed enhancement, indicating the importance of the one- and two-neutron transfer channels in explaining the fusion data.