Evidence of quasifission in the 180Hg composite system formed in the 68Zn + 112Sn reaction

Abstract For the 68Zn + 112Sn reaction the Coulomb parameter Z 1 Z 2 is equal to 1500 that is close to the threshold value for the appearance of quasifission process. It was found that mass-energy distributions of the reaction fragments differ significantly from those obtained in the 36Ar + 144Sm reaction leading to the formation of the same composite system of 180Hg at similar excitation energies of about 50 MeV. In the case of the reaction with 68Zn ions, the mass distribution of fissionlike fragments has a wide two-humped shape with maximum yields at 70 and 110 u for the light and heavy fragments, respectively, instead of 80 and 100 u observed in the fission of 180Hg formed in the 36Ar + 144Sm reaction. The difference is explained by an unexpectedly large contribution (more than 70%) of quasifission in the case of the 68Zn + 112Sn reaction.