As two conflicting values have been given for the half-lives of both ${}_{}{}^{20}{}_{}{}^{}\mathrm{Na}$ and ${}_{}{}^{36}{}_{}{}^{}\mathrm{K}$, we have carefully measured them with a "pneumatic-shuttle" system. We find $T_{\frac{1}{2}}=446\mathrm{}\pm 8$ msec for ${}_{}{}^{20}{}_{}{}^{}\mathrm{Na}$ and $T_{\frac{1}{2}}=343\mathrm{}\pm 28$ msec for ${}_{}{}^{36}{}_{}{}^{}\mathrm{K}$. In addition, and as a check against systematic errors, the half-lives of ${}_{}{}^{28}{}_{}{}^{}\mathrm{P}$, ${}_{}{}^{32}{}_{}{}^{}\mathrm{Cl}$, ${}_{}{}^{40}{}_{}{}^{}\mathrm{Sc}$, and ${}_{}{}^{64}{}_{}{}^{}\mathrm{Ga}$ were measured.

• Received 4 October 1971

DOI:https://doi.org/10.1103/PhysRevC.5.1122