Multidimensional Langevin approach to describing the 18O + 208Pb fusion-fission reaction

The fusion-fission reaction is treated as a multistep process. Langevin equations are used to describe the evolution of the system at each reaction stage. The parameters of the fusion process are calculated at the first stage. The results obtained in the input channel are employed as initial conditions in calculating the features of the fission process. The cross sections for fusion and fission are successfully described, and the cross sections for the formation of evaporation residues are estimated. In addition, the procedure used makes it possible to describe the mass distribution of fission fragments and the fragment-mass dependence of the multiplicity of prefission neutrons and to determine the mass-energy distribution of fission fragments. From the calculations, it follows that all the fission features of the reaction in question can be reproduced without considering the formation of a classical compound nucleus. The reaction times are so long that it is impossible to separate experimentally such events from the case of true fission through a compound nucleus.