Bimodal Fission Of Hs

Mass and energy distributions of fission fragments obtained in the reactions Ne-22 + Cf-249, Mg-26 + Cm-248, and Ne-22 + U-238 have been measured. A special attention will be paid on the properties of mass-energy distribution of fission fragments obtained in the reaction Mg-26 + Cm-248 at an excitation energy of 35 MeV. At this energy shell effects should become more effective in fission, the TKE distribution of symmetric fragments obtained in the reaction Mg-26 + Cm-248 differs strongly from a Gaussian shape. Besides a low-energy component, a high-energy component, not foreseen in the LDM, arises. This is attributed to the fact that both fission fragments are close to the spherical neutron shell N = 82. It means that for the compound nucleus (274)Hs*, formed in the reaction Mg-26 + Cm-248, the phenomenon of bimodal fission was observed for the first time. For the compound nucleus No-260* formed in the reaction Ne-22 + U-238 at the initial excitation energy of 41 MeV the bimodal fission as well as superasymmetric fission were observed.