The Multi-dimensional Langevin Approach to the Description of Fusion-fission Reactions

Abstract

The two stage approach to the description of fusion-fission reactions is suggested. On each stage (fusion or fission) the tree-dimensional Langevin equation for the variables describing the shape of nuclear system is solved. The results obtained on the first stage are used as the input data for description of fission dynamics. In this way it turned out possible to describe for the reaction ¹⁸O + ²⁰⁸Pb simultaneously both fusion and fission cross sections, the energy and mass distribution of fission fragments, the probability of the evaporation residue formation, the dependence of pre-fission neutron multiplicities on the fragment mass number. From the results of the computations it follows that the observed quantities of the fission process can be reproduced without formation of compound nucleus. At the same time the duration of the process is so large that events of quasi-fission and "true" fission of compound nucleus can not be distinguished.