Mass and charge distribution in²³²Th(α, f) reaction in the projectile energy range 28 to 72 MeV

Abstract

The cumulative yields for 13 short-lived neutron rich nuclei in the mass rangeA=99 toA=118, produced via the²³²Th (α, f) reaction were determined at four incident beam energies covering the range from 28 to 72 MeV usingγ-spectroscopy of fission products. The charge distribution parameter Z _p was determined for theA=99 mass chain at all the four incident beam energies of 28.5, 39.7, 50.8 and 71.4 MeV and was found to fit into a description of fission process with unchanged charge division (UCD). The measured cumulative yields were converted into chain yields assuming UCD and the yieldmass distribution was obtained at all the above energies. The mass distribution remains asymmetric even at 71.4 MeV, the highest energy studied in this work. The excitation energy dependence of the mass and the charge distribution and of the cumulative yields indirectly suggests that the fission has predominantly proceeded from a relatively low level of excitation allowing most of the excitation energy to be carried away by light particles prior to scission.