Measurement of the half-life of ${}^{198}\mathrm{Au}$ in a nonmetal: High-precision measurement shows no host-material dependence

We have measured the half-life of the ${\beta }^{-}$ decay of ${}^{198}\mathrm{Au}$ to be $2.6948(9)$ d, with the nuclide sited in an insulating environment. Comparing this result with the half-life we measured previously with a metallic environment, we find the half-lives in both environments to be the same within $0.04\%$, thus contradicting a prediction that screening from a “plasma” of quasifree electrons in a metal increases the half-life by as much as $7\%$.

Figure 1

The decay of ${}^{198}\mathrm{Au}$ in gold (III) oxide, at room temperature. Experimental data appear as dots in the upper portion of the figure; the straight line is the fit to these data. Normalized residuals are shown at the bottom.