Spontaneous fission properties of 104262Rf.

Abstract

We have measured the mass and kinetic-energy distributions of fragments from the spontaneous fission (SF) of $_{104}^{262}\mathrm{Rf}$. The $_{104}^{262}\mathrm{Rf}$ was produced via the $^{244}\mathrm{Pu}$${(}^{22}$Ne,4n) reaction with a production cross section of \ensuremath{\sim}0.7 nb using 114.4-MeV projectiles. The kinetic energies and times of the coincident fission fragments were measured using our rotating wheel system. From these data the half-life, mass, and kinetic-energy distributions were derived. The total kinetic-energy (TKE) distribution appears to consist of a single component with a most probable pre-neutron-emission TKE of 215\ifmmode\pm\else\textpm\fi{}2 MeV. The mass distribution is symmetric with a full width at half maximum of about 22 mass numbers. These results are consistent with trends observed for other trans-berkelium spontaneously fissioning isotopes. We determined the half-life to be 2.1\ifmmode\pm\else\textpm\fi{}0.2 s by measuring its spontaneous fission decay. We also attempted to observe the alpha decay of $_{104}^{262}\mathrm{Rf}$ by searching for alpha decay correlated in time with SF from the alpha daughter, 1.2-ms $^{258}\mathrm{No}$. We observed no such decays and have set an upper limit of 0.8% (68% confidence level) on the alpha decay branch of $_{104}^{262}\mathrm{Rf}$. \textcopyright{} 1996 The American Physical Society.