THE COMPETITION BETWEEN FUSION-FISSION AND DEEPLY INELASTIC REACTIONSIN THE MEDIUM MASS SYSTEMS

The competition between fusion-fission and deeply inelastic reactions in the Cl + Ni system has been studied by investigating the exit chann el Q-value dependence of the Z-distributions of fission-like fragments . The Z-, kinetic energy- and angular distributions of the fissionlike fragments produced in the Cl-37 + Ni-64 system at E(lab) = 170, 186 M eV and in the Si-28 + Ge-74 system at E(lab) = 176 MeV have been measu red by counter telescopes. The Z-distribution of the Cl-37 + Ni-64 sys tem was found to be essentially the same as that of the Cl-35 + Ni-62 system at the same bombarding energy. It is shown that this result can not be explained by the statistical fusion fission model but is consi stent with a deeply inelastic model. A systematic study of the fission -like phenomenon in this mass region indicates that the maximum angula r momenta for fusion reactions as well as the minimum angular momenta for DIC can be reproduced by the Bass model in the sliding limit (f = 1.0) while the maximum angular momenta for fully energy-damped deeply inelastic reactions are governed by the strong interaction radius as p redicted by the successive critical distance fusion model. The signifi cance of these results are discussed.