Decay properties of No-257, (261)Rf, and (262)Rf - art. no. 064307

In bombardments of Pu-244 targets with 114- and 120-MeV Ne-22 projectiles w e detected 69 alpha-alpha correlations linking cw decays of (261)Rf and No- 257. We observed one alpha peak with E-alpha= 8.30+/-0.06 MeV for (261)Rf a nd peaks with alpha -particle energies 8.07-8.40 MeV for No-257. The half-l ife of No-257 was measured to be 25 +/- 3. No correlations were found betwe en alpha decays and subsequent spontaneous fission events, from which we ca lculated an upper limit of 1.5% for the fission branch of No-257 and estima ted an upper limit of 3% for the alpha -decay branch of (262)Rf. The cross section of the Pu-244(Ne-22,5n)(261)Rf reaction was measured to be about 4 nb at both Ne-22 energies used. We also report on some results from Pu-242Ne-22 and U-238+Mg-26 bombardments.