Light fragment emission during mass asymmetry relaxation in heavy-ion induced fission

The entrance channel dynamics in a heavy-ion fusion reaction is followed by solving the Langevin equations of motion for the elongation and mass asymmetry degrees of freedom. Thermal diffusion over the conditional barrier in early stages of the dynamics is shown to result in a small number of fission-like reaction events having a memory of the entrance channel mass asymmetry. Evidence for such a component arising from the precompound nucleus phase of the reaction is shown to exist in the measured data on the yield of binary fragments in the reaction ²³²Th{+}¹²$C reported earlier. {} 1996 The American Physical Society.