The amounts of excess ${}_{}{}^{128}{}_{}{}^{}\mathrm{Xe}$ and ${}_{}{}^{130}{}_{}{}^{}\mathrm{Xe}$ in xenon which had been extracted by stepwise heating of an old telluride ore from the Mattagami Lake area, Quebec, indicate that the $\beta \beta$-decay half-life of ${}_{}{}^{128}{}_{}{}^{}\mathrm{Xe}$ exceeds that of ${}_{}{}^{130}{}_{}{}^{}\mathrm{Te}$ by a factor of (1.57 ± 0.10) × ${10}^3$. These results agree with the relative half-lives reported earlier for ${}_{}{}^{128}{}_{}{}^{}\mathrm{Te}$ and ${}_{}{}^{130}{}_{}{}^{}\mathrm{Te}$ in tellurides from Kalgoorlie, Western Australia.

RADIOACTIVITY $\beta \beta$ decay ${}_{}{}^{128}{}_{}{}^{}\mathrm{Te}$ and ${}_{}{}^{130}{}_{}{}^{}\mathrm{Te}$; measured excess ${}_{}{}^{128}{}_{}{}^{}\mathrm{Xe}$ and ${}_{}{}^{130}{}_{}{}^{}\mathrm{Xe}$; deduced relative $T_{\frac{1}{2}}$ values.

• Received 18 July 1977

DOI:https://doi.org/10.1103/PhysRevC.17.1168