Fusion-fission Dynamics of Pt188,190 Through Fission Fragment Mass Distribution Measurements

Fission fragment mass distributions have been measured for relatively neutron-deficient compound nuclei, Pt-188 and Pt-190, formed in the fusion reactions, Si-28 + Gd-160 and C-12 + Hf-178, respectively. The data were obtained for a similar initial excitation energy range of 49-68 MeV for both the systems. The fragment mass distributions for both the Pt isotopes were found to be single peaked and no appreciable change in the mass symmetry was observed throughout the measured excitation energy range, for both the reactions. However, relatively broader mass distributions observed in the fission of Pt-188 in the studied energy domain indicates the presence of fission events originating from a nonequilibrated source as well. This signifies that the mass equilibrium has not been fully achieved in the Si-28 + Gd-160 system as compared to the C-12 + Hf-178 system, indicating the presence of quasifission events in the former reaction.