New Short-Lived Isotope 221U and the Mass Surface Near N = 126.

Authors :: Khuyagbaatar, J.
Yakushev, A.
Dullmann, Ch. E.
Ackermann, D.
Andersson, L.-L.
Block, M.
Brand, H.
Cox, D. M.
Even, J.
Forsberg, U.
Golubev, P.
Hartmann, W.
Herzberg, R.-D.
Heßberger, F. P.
Hoffmann, J.
Hübner, A.
Jäger, E.
Jeppsson, J.
Kindler, B.
Kratz, J. V.
Source :: Physical Review Letters. 12/11/2015, Vol. 115 Issue 24, p242502-1-242502-5. 5p.
Publication Year :: 2015
Abstract: Two short-lived isotopes 221U and 222U were produced as evaporation residues in the fusion reaction 50Ti + 176Yb at the gas-filled recoil separator TASCA. An a decay with an energy of Eα = 9.31(5) MeV and half-life T1/2 = 4.7(7) μs was attributed to 222U. The new isotope 221U was identified in α-decay chains starting with Eα = 9.71(5) MeV and T1/2 = 0.66(14) μs leading to known daughters. Synthesis and detection of these unstable heavy nuclei and their descendants were achieved thanks to a fast data readout system. The evolution of the N = 126 shell closure and its influence on the stability of uranium isotopes are discussed within the framework of a-decay reduced width. [ABSTRACT FROM AUTHOR]