Studies of heavy ion reactions around Coulomb barrier

The angular distributions of fission fragments for the S-32+W-184 reaction near Coulomb barrier energies were measured. The experimental fission excitation function is obtained. The measured fission cross sections are decomposed into fusion-fission, quasifission and fast fission contributions by the dinuclear system model. The hindrance to complete fusion both at small and large collision energies is explained. The fusion excitation functions of S-32+Zr-90,Zr-96 in an energy range from above to below Coulomb barrier were measured and analyzed. The obvious effect of positive Q-value neutron transfers has been observed in the S-32+Zr-96 system. In addition, the excitation functions of quasielastic scattering at a backward angle have been measured for the systems of O-16 + (208)pb, (196)pt, W-184, and Sm-154,Sm-152 at energies well below the Coulomb barrier. Considering the coupling effects, the extracted diffuseness parameters are close to the values extracted from the systematic analysis of elastic and inelastic scattering data.