The origin of symmetric splitting events in the32S+58,64Ni reactions at 160 and 180 MeV

Summary  γ-multiplicityM γ and missing charge ΔZ from fragment-fragment coincidences have been measured for fissionlike events in the reactions32S+58,64Ni at 160 and 180 MeV bombarding energies. The experimental data have been compared with a Monte Carlo simulation of the sequential decay of primary fragments assumed to be in thermal equilibrium. Statistical-model calculations have been performed with different assumptions on the spin distribution of the composite system decaying in two symmetric fragments. The experimentalM γ data are well described by model calculations with spin values inside the fusion region. Those spin values are close to the first moments of the angular-momentum distributions for fusion-fission of the compound nucleus as computed by statistical model using finite-range corrected fission barriers. Model calculations describe also well the experimental ΔZ values for the32S+58Ni reaction but overestimate the data relative to the64Ni target, evidencing difficulties in the complete reconstruction of the sequential decay of the reaction products.