Near-Barrier Quasi-Elastic Cross Sections And Barrier Distribution Of S-32+Zr-90,Zr-96

Quasi-elastic cross sections have been measured for S-32+Zr-90,Zr-96 with high accuracy near the Coulomb barrier at backward angles and the barrier distributions are extracted from them. We find that barrier distribution of S-32+Zr-96 is flat and extends to low energies. The sub-barrier fusion cross sections are strongly enhanced because of such barrier distribution. Compared with the reaction of S-32+Zr-90, S-32+Zr-96 has stronger neutron transfers up to the six-neutron pickup, which is due to the positive Q values of neutron transfers in the latter. This indicates that the neutron transfer may play a role in the enhancement of sub-barrier fusion for S-32+Zr-96.