Scission point model for the mass distribution of ternary fission

Abstract

A modified scission point model is adopted to study the mass distribution of thermal neutron induced binary and ternary fission of 235U. The scission configuration and the most favourable fragment deformation is identified through an energy balance criterion where the macroscopic part due to liquid drop and the microscopic part due to shell correction together with the deformation dependent interaction potential are used. The available energy for each channel together with fragment deformation is used to evaluate nuclear level densities in the Fermi gas model. Since the model is found to give the expected double humped mass distribution for binary fission of 236U, this is then applied for the ternary fission of the same nuclei with fixed third fragment. Two different third fragments with two cases of collinear arrangement were studied with the model. The obtained ternary mass distribution was then compared with the calculated binary mass distribution. In all the cases, the influence of shell effects is found to be prominent with one of the fragments associated with the Sn nucleus. The closed shell nuclei possess maximum yield in both binary and ternary mass distribution.