K isomerism in (255)Rf and total kinetic energy measurements for spontaneous fission of (255,256,258)Rf

Spontaneous fission properties of the isotopes (255)Rf, (256)Rf, and (258)Rf produced in the reactions Ti-50 Pb-20, Ti-50 + Pb-208, and Ti-50 + Bi-209 were studied. The method of time and position correlations was used to identify spontaneous fission events. The correction to the energy deficit in measured total kinetic energy (TKE) determined on the basis of a study of No-252 was applied to evaluate the (TKE) over bar of investigated rutherfordium isotopes. A signature which we assigned tentatively to bimodal fission was observed in TKE distributions of (255)Rf and (256)Rf. Two new high-K isomeric states in (255)Rf were identified by ER-CE-(CE)-alpha/SF correlation search, with half-lives of 38(-7)(+12 )and 15(-4)(+6)( )its at excitation energies 1150-1450 and 900-1200 keV, respectively. Including those metastable states a tentative partial level scheme was proposed.