Decay properties of the new isotopes Hg-172 and Hg-173 - art. no. 031304

The alpha decays of the two neutron-deficient nuclei Hg-172 and Hg-173 were observed for the first time using the Kr-78(Ru-96,2n) and Kr-80(Ru-96,3n) reactions, respectively. The reaction products were dispersed according to their mass-to-charge state ratios in the Argonne Fragment Mass Analyzer and implanted in a double-sided silicon strip detector, where their subsequent decays were studied using spatial and time correlations between implants a nd decays. A half-life of 250((+350)(-90)) mu s and an energy of 7350(12) k eV were deduced for the alpha decay of Hg-172. In Hg-173 the half-life was measured to be 0.93((+0.57)(-0.26)) ms and the corresponding energy is 7211 (11) keV. In addition, the half-life and energy of the alpha decay of Hg-17 4 were measured more precisely. The reduced widths deduced for these Hg iso topes indicate that the observed decays correspond to unhindered Delta l=0 transitions. The alpha-decay Q values are compared with the values calculat ed using mass tables by Moller and Nix, and by Liran and Zeldes. The latter mass tables show better agreement with the data. [S0556-2813(99)50409-3].