The very neutron deficient odd-odd nucleus ${}^{172}\mathrm{Au}$ was studied in reactions of 342 and 348 MeV ${}^{78}\mathrm{Kr}$ beams with an isotopically enriched ${}^{96}\mathrm{Ru}$ target. The $\alpha$ decays previously reported for ${}^{172}\mathrm{Au}$ were confirmed and the decay chain extended down to ${}^{152}\mathrm{Tm}$ through the discovery of a new $\alpha$-decaying state in ${}^{164}\mathrm{Re}$ [$E_{\alpha }=5623(10)$ keV; $t_{1/2}={864}_{-110}^{+150}$ ms; $b_{\alpha }=3(1)\%$]. Fine structure in these $\alpha$ decays of ${}^{172}\mathrm{Au}$ and ${}^{168}\mathrm{Ir}$ were identified. A new $\alpha$-decaying state was also observed and assigned as the ground state in ${}^{172}\mathrm{Au}$ [$E_{\alpha }=6762(10)$ keV; $t_{1/2}={22}_{-5}^{+6}$ ms]. This decay chain was also correlated down to ${}^{152}\mathrm{Tm}$ through previously reported $\alpha$ decays. Prompt $\gamma$ rays from excited states in ${}^{172}\mathrm{Au}$ have been identified using the recoil-decay tagging technique. The partial level scheme constructed for ${}^{172}\mathrm{Au}$ indicates that it has an irregular structure. Possible configurations of the $\alpha$-decaying states in ${}^{172}\mathrm{Au}$ are discussed in terms of the systematics of nuclei in this region and total Routhian surface calculations.

• Received 30 September 2009

DOI:https://doi.org/10.1103/PhysRevC.80.064310