Fission and quasifission modes in heavy-ion-induced reactions leading to the formation of Hs

Mass and energy distributions of binary reaction products obtained in the reactions Ne-22+Cf-249,Mg-26+Cm-248, S-36+U-238, and Fe-58+Pb-208 have been measured. All reactions lead to Hs isotopes. At energies below the Coulomb barrier the bimodal fission of Hs*, formed in the reaction Mg-26+Cm-248, is observed. In the reaction S-36+U-238, leading to the formation of a similar compound nucleus, the main part of the symmetric fragments arises from the quasifission process. At energies above the Coulomb barrier fusion-fission is the main process leading to the formation of symmetric fragments for both reactions with Mg and S ions. In the case of the Fe-58+Pb-208 reaction the quasifission process dominates at all measured energies.