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

Abstract

γ-multiplicityMγ 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 experimentalMγ 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.