Abstract
The mass-energy distributions of fission fragments of 254Fm compound nucleus formed in the reaction 16O + 238U have been measured at two lab energies $${{E}_{{{\text{lab}}}}}$$ = 89 and 101 MeV. The experimental data have been described by the multimodal random neck-rupture model. Channel probabilities and the characteristics of different fission modes are obtained and discussed in details. At ∼45 MeV excitation, the enhancement of the mass yield (~10–2%) in the region 60–70 u for the light fragment is observed. This can be explained by the influence of Z = 28 shell closure. This signature of super-asymmetric fission becomes zero at the higher excitation energy (~56 MeV), expectedly. The fission fragment mass distribution widths show a linear dependence with the measured energies.