6533b86dfe1ef96bd12c9485

RESEARCH PRODUCT

α decay studies of the nuclidesU218andU219

subject

description

Very neutron deficient uranium isotopes were produced in fusion evaporation reactions using $^{40}\mathrm{Ar}$ ions on $^{182}\mathrm{W}$ targets. The gas-filled recoil separator RITU was employed to collect the fusion products and to separate them from the scattered beam and other reaction products. The activities were implanted into a position sensitive silicon detector after passing through a gas-counter system. The isotopes were identified using spatial and time correlations between the implants and the decays. Two $\ensuremath{\alpha}$-decaying states, with ${E}_{\ensuremath{\alpha}}=(8612\ifmmode\pm\else\textpm\fi{}9)$ keV and ${T}_{1/2}=(0.{51}_{\ensuremath{-}0.10}^{+0.17})$ ms for the ground state and ${E}_{\ensuremath{\alpha}}=(10678\ifmmode\pm\else\textpm\fi{}17)$ keV and ${T}_{1/2}=(0.{56}_{\ensuremath{-}0.14}^{+0.26})$ ms for an isomeric state, were identified in $^{218}\mathrm{U}$. In addition, the half-life and $\ensuremath{\alpha}$-decay energy of $^{219}\mathrm{U}$ were measured with improved precision. The measured decay properties deduced for $^{218}\mathrm{U}$ suggest that there is no subshell closure at $Z=92$.