The ground state half-lives of the gold isotope ${}^{196}\mathrm{Au},$ the mercury isotopes ${}^{195,197,203}\mathrm{Hg},$ the lead isotope ${}^{203}\mathrm{Pb},$ and the half-lives of two isomers in ${}^{199}\mathrm{Hg}$ and ${}^{204}\mathrm{Pb}$ have been measured with high precision using the photoactivation technique. The $\gamma$-ray activity was counted over several half-lives with high-purity germanium detectors. The measured half-lives are: $T_{1/2}{(}^{196}\mathrm{Au})=6.1669\mathrm{}\pm 0.0006$ d; $T_{1/2}{(}^{195}\mathrm{Hg})=10.53\mathrm{}\pm 0.03$ h; $T_{1/2}{(}^{197}\mathrm{Hg})=64.94\mathrm{}\pm 0.07$ h; $T_{1/2}{(}^{203}\mathrm{Hg})=46.6\mathrm{}\pm 0.1$ d; $T_{1/2}{(}^{204}\mathrm{Pb})=51.95\mathrm{}\pm 0.01$ h; $T_{1/2}{(}^{199m}\mathrm{Hg})=42.67\mathrm{}\pm 0.09$ min; $T_{1/2}{(}^{204m}\mathrm{Pb})=1.14\mathrm{}\pm 0.04$ h.

• Received 20 September 2000

DOI:https://doi.org/10.1103/PhysRevC.63.047307