Statistical model calculations of pre-scission neutron multiplicity for the heavy ion induced fusion-fission reactions with actinide target ²³²Th

¹ Department of Physics, Panjab University, Chandigarh 160014, India
² CS - 6/1, Golf Green, Kolkata 700095, India (Formerly with VECC, Kolkata )
³ Inter University Accelerator Centre Aruna Asaf Ali Marg, New Delhi, 110067, India

^a e-mail: meenu.thakuroct@gmail.com

Published online: 29 January 2015

Abstract

The reaction mechanism of ¹⁹F + ²³²Th and ²⁸Si + ²³²Th systems populating the near-super-heavy compound nuclei ²⁵¹Es and ²⁶⁰Rf respectively are investigated using neutron multiplicity as a probe. The prescission neutron multiplicities of these compound nuclei are calculated at different excitation energies using a statistical model code. These calculations are performed using the Bohr-Wheeler transition state fission width as well as the dissipative dynamical fission width based on the Kramers’ prescription. For ¹⁹F + ²³²Th system, the measured yield of pre-scission is compared with the statistical model calculations for the decay of a compound nucleus in the excitation energy range of 54-90 MeV. The comparison between the measured and the calculated values indicates that the Bohr-Wheeler fission width underestimates the pre-scission neutron yield and a large amount of dissipation strength is required to reproduce the experimental pre-scission neutron multiplicities. The excitation energy dependence of the fitted values of the dissipation coefficient is also discussed. In addition, exploratory statistical model calculations of pre-scission neutron multiplicity for the ²⁸Si + ²³²Th system are presented in the above range of excitation energy.