title: New Short-Lived Isotope ^{221}U and the Mass Surface Near N=126.
abstract: Two short-lived isotopes ^{221}U and ^{222}U were produced as evaporation residues in the fusion reaction ^{50}Ti+^{176}Yb at the gas-filled recoil separator TASCA. An α decay with an energy of E_{α}=9.31(5)  MeV and half-life T_{1/2}=4.7(7)  μs was attributed to ^{222}U. The new isotope ^{221}U was identified in α-decay chains starting with E_{α}=9.71(5)  MeV and T_{1/2}=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 α-decay reduced width.
authors.affiliation: Helmholtz Institute Mainz, 55099 Mainz, Germany.|GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
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authors.affiliation: Helmholtz Institute Mainz, 55099 Mainz, Germany.|GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
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authors.affiliation: Helmholtz Institute Mainz, 55099 Mainz, Germany.|GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.|Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany.
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authors.affiliation: Helmholtz Institute Mainz, 55099 Mainz, Germany.|GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.|Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany.
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