Decay properties of 257No, 261Rf, and 262Rf

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