Fusion-fission and quasifission of superheavy systems in heavy-ion induced reactions

Mass and energy distributions of fission-like fragments obtained in the reactions with Mg-26, S-36 and Fe-58 ions leading to the formation of the Z=108 composite nucleus are reported. From the analysis of TKE distributions for symmetric fragment it was found that at energies below the Coulomb barrier the bimodal fission of (274)Hs, formed in the reaction Mg-26+Cm-248, is observed, while in the reaction S-36+U-218 at these energies the main part of the symmetric fragments arises from the quasifission process. At energies above the Coulomb barrier the fusion-fission is a main process leading to the formation of symmetric fragment for the both reactions.