Fusion and Quasi-elastic Transfer In the Systems Ni-58+(zr-90,zr-91,zr-94) Near the Coulomb Barrier

Cross sections for evaporation residues formation have been measured in the range E(lab) = 199-280 MeV in the system Ni-58+ Zr-90, 91, 94. Cross sections for transfer of charged particles and neutrons have been measured at E(lab) = 235, 250 MeV; at these energies both quasi-elastic and deep-inelastic reactions have been observed. The sub-barrier fusion shows enhancement with repect to one-dimensional tunneling and also isotopic effects are evident. An approximate coupled channel description of fusion seems adequate when the contribution of quasi-elastic neutron transfer is considered. The influence of the deep-inelastic processes on fusion remains an open question.