The $\alpha$-decay chains originating from the $\pi s_{1/2}$ and $\pi h_{11/2}$ states in ${}^{173}$Au have been investigated following fusion-evaporation reactions. Four generations of $\alpha$ radioactivities have been correlated with ${}^{173}$Au${}^m$ leading to a measurement of the $\alpha$ decay of ${}^{161}$Ta${}^m$. It has been found that the known $\alpha$ decay of ${}^{161}$Ta, which was previously associated with the decay of the ground state, is in fact the decay of an isomeric state. This work also reports on the first observation of prompt $\gamma$ rays feeding the ground state of ${}^{173}$Au. This prompt $\gamma$ radiation was used to aid the study of the $\alpha$-decay chain originating from the $\pi s_{1/2}$ state in ${}^{173}$Au. Three generations of $\alpha$ decays have been correlated with this state, leading to the observation of a previously unreported activity which is assigned as the decay of ${}^{165}$Re${}^g$. This work also reports the excitation energy of an $\alpha$-decaying isomer in ${}^{161}$Ta and the $Q_{\alpha }$ value of the decay of ${}^{161}$Ta${}^g$.

• Received 11 October 2012

DOI:https://doi.org/10.1103/PhysRevC.86.064315