Role of nuclear dissipation and entrance channel mass asymmetry in pre-scission neutron multiplicity enhancement in fusion-fission reactions

Pre-scission neutron multiplicities are measured for (12)C + (204)Pb and (19)F + (197)Au reactions at laboratory energies of 75-95 MeV for the (12)C beam and 98-118 MeV for the (19)F beam. The chosen projectile-target combinations in the present study lie on either side of the Businaro-Gallone mass asymmetry (alpha(BG)) and populate the (216)Ra compound nucleus. The dissipation strength is deduced after comparing the experimentally measured neutron yield with the statistical model predictions which contains the nuclear viscosity as a free parameter. Present results demonstrate the combined effects of entrance channel mass asymmetry and the dissipative property of nuclear matter on the pre-scission neutron multiplicity in fusion-fission reactions.