The $\alpha$ decays of the two neutron-deficient nuclei ${}^{172}\mathrm{Hg}$ and ${}^{173}\mathrm{Hg}$ were observed for the first time using the ${}^{78}\mathrm{Kr}{(}^{96}\mathrm{Ru},2n)$ and ${}^{80}\mathrm{Kr}{(}^{96}\mathrm{Ru},3n)$ 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 and decays. A half-life of ${250(}_{-90}^{+350\mathrm{}})\hspace{0.5em}\mu \mathrm{s}$ and an energy of 7350(12) keV were deduced for the $\alpha$ decay of ${}^{172}\mathrm{Hg}$. In ${}^{173}\mathrm{Hg}$ the half-life was measured to be ${0.93(}_{-0.26}^{+0.57\mathrm{}})\hspace{0.5em}\mathrm{ms}$ and the corresponding energy is 7211(11) keV. In addition, the half-life and energy of the $\alpha$ decay of ${}^{174}\mathrm{Hg}$ were measured more precisely. The reduced widths deduced for these Hg isotopes indicate that the observed decays correspond to unhindered $\Delta l=0\mathrm{}$ transitions. The $\alpha$-decay Q values are compared with the values calculated using mass tables by Möller and Nix, and by Liran and Zeldes. The latter mass tables show better agreement with the data.

• Received 2 June 1999

DOI:https://doi.org/10.1103/PhysRevC.60.031304