Peculiarities of cluster formation in true ternary fission of 252Cf and 236U

The existence of a new type of cluster decay called ‘collinear cluster tri-partition’ (CCT) is discussed by an analysis of the landscape of the potential energy surface (PES). The total energy of the ternary system is found as a sum of the binding energies of fragments and nucleus–nucleus interaction between them. The pre-scission state of the ternary system is assumed to be arranged as a chain of the three fragments along a straight line. Minima and valleys of the PES are determined by variation of the proton and neutron distributions between them. Pre-scission prompt emission of neutrons is assumed and PES is calculated for the cases of emission of two neutrons. The presence of the valley corresponding to the formation of the isotopes of Sn with masses A = 130–136 is inherent for all PES calculated for CCT for spontaneous fission of Cf 252