Half-Lives ofN17andF17

The radioactivities ${}_{}{}^{17}{}_{}{}^{}\mathrm{N}$ and ${}_{}{}^{17}{}_{}{}^{}\mathrm{F}$ have been produced in the reactions ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}\mathrm{}(t,p)\mathrm{}{}_{}{}^{17}{}_{}{}^{}\mathrm{N}$ and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}\mathrm{}(d,n)\mathrm{}{}_{}{}^{17}{}_{}{}^{}\mathrm{F}$, respectively, and their half-lives have been measured by observing the decay of neutrons from ${}_{}{}^{17}{}_{}{}^{}\mathrm{N}$ and 0.51-MeV $\gamma$ rays from ${}_{}{}^{17}{}_{}{}^{}\mathrm{F}$. The half-life obtained for ${}_{}{}^{17}{}_{}{}^{}\mathrm{N}$ is 4.169±0.008 sec in agreement with earlier measurements. Our value for ${}_{}{}^{17}{}_{}{}^{}\mathrm{F}$, $T_{\frac{1}{2}}=64.50\mathrm{}\pm 0.25$ sec, is considerably lower than previous measurements. The relevance of the ${}_{}{}^{17}{}_{}{}^{}\mathrm{N}$ result to the question of mirror symmetry in the $\beta$ decay of the $A=17\mathrm{}$ system is discussed.