Mass distribution of fission fragments from ¹⁹⁷Tl

When two nuclei collide near Coulomb barrier, they fuse together to form a compound nucleus (CN). This compound nucleus either emits few neutrons and light charged particles to form a stable nucleus called evaporation residue (ER) or fissions into two equal fragments. Another interesting phenomenon which takes place, in the mentioned energy regime is quasi-fission where in after collision, instead of forming an equilibrated CN, the dinuclear system reseparates resembling fission. Quasi fission has been theoretically predicted for heavy target projectile combinations, where the product of charges of the target and projectile is greater than 1600. However, it has been experimentally noticed that, quasi-fission is present even for much lighter systems. Keeping these factors in mind we have made an investigation near mass 200 region, where the presence of quasi-fission has been interpreted based on spin distribution while the fission fragment mass distribution has not shown any signature of the presence of quasi-fission. It has been observed that the entrance channel mass asymmetry with respect to the Businnaro-Gallone critical mass asymmetry plays an important role in determining the fate of the dinuclear system. We have carried out the study of the fission fragment mass distribution of these systems considering the fact that presence of quasi-fission in general widens the width of the mass distribution