Exploring the effect of entrance channel mass asymmetry in the fission of ¹⁹⁷Tl* nucleus

Fission fragment mass ratio distributions have been measured for the reactions ¹⁹F+¹⁷⁸Hf and ¹⁶O + ¹⁸¹Ta, both leading to the same compound nucleus, ¹⁹⁷Tl, at near-Coulomb barrier energies. The measured fission fragment mass width for both these systems does not show any substantial deviation from the statistical model predictions, which indicates the absence of non-compound nuclear reactions like quasi-fission. The measured mass widths of both the reactions at the same excitation energy are comparable within the experimental uncertainty and show a gradual increase with excitation energy. No noticeable influence of effect of entrance channel mass asymmetry on fragment mass distribution in these reactions, which differs from the previously reported entrance channel-dependent variation in average pre-scission neutron multiplicity.