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

• Received 5 July 2000

DOI:https://doi.org/10.1103/PhysRevC.62.064307