Clusters in Nuclear Fission
The study of nuclear fission gives us an unique possibility to investigate the clusterization effects in heavy nuclei. The special role in the formation of clusters in fission plays the late stage of fission process near the scission point. On the early stage the fission mechanism is governed by the hydrodynamical and shell properties of collective motion along the fission path because the cluster substructures are washed out due to internucleon interaction. In the clusterization region near the scission point the initial mass distribution is defined by double magic nuclei 132Sn, mass ditribution is rather narrow and is centered around A ~ 132. To obtain the final (observed) mass distribution it is necessary to take into account the nucleon exchange between fragments. The process of nucleon exchange which corresponds in cluster approach to the antysymmetrization of the total wave function taken in a two-cluster representation leads to the increasing of initial mass asymmetry and width of distribution. This results are due to the high stability of double magic cluster 132Sn. The difference between chemical potentials of fragments violates the chemical equilibrium in the system of separated nuclei and cause the mass flow from the light fragment to a complimentary double magic one in order to equilibrate the chemical potentials over the whole system .