The half-lives of ${}_{}{}^6{}_{}{}^{}\mathrm{He}$, ${}_{}{}^{19}{}_{}{}^{}\mathrm{Ne}$, and ${}_{}{}^{42}{}_{}{}^{}\mathrm{Sc}_{}^m{}_{}{}^{}$ have been measured as 808.1 ± 2.0 msec, 17.36 ± 0.06 sec, and 62.0 ± 0.3 sec, respectively. The activities were formed in the ${}_{}{}^9{}_{}{}^{}\mathrm{Be}(n,\alpha ){}_{}{}^6{}_{}{}^{}\mathrm{He}$, ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}\mathrm{}(p,n)\mathrm{}{}_{}{}^{19}{}_{}{}^{}\mathrm{Ne}$, and ${}_{}{}^{42}{}_{}{}^{}\mathrm{Ca}\mathrm{}(p,n)\mathrm{}{}_{}{}^{42}{}_{}{}^{}\mathrm{Sc}$ reactions. Half-lives of ${}_{}{}^6{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^{19}{}_{}{}^{}\mathrm{Ne}$ were determined by multiscaling $\beta$ rays detected in a plastic scintillator, whereas the ${}_{}{}^{42}{}_{}{}^{}\mathrm{Sc}_{}^m{}_{}{}^{}$ half-life was obtained from the decay of the $\gamma$-ray spectrum in a Ge(Li) detector. The $\mathrm{ft}$ values deduced for ${}_{}{}^6{}_{}{}^{}\mathrm{He}$, ${}_{}{}^{19}{}_{}{}^{}\mathrm{Ne}$, and ${}_{}{}^{42}{}_{}{}^{}\mathrm{Sc}_{}^m{}_{}{}^{}$ are, respectively, 815.7 ± 4.2 sec, 1728.4 ± 6.7 sec, and 14 758 ± 91 sec. The values $\left|〈\sigma 〉\right|$ of the Gamow-Teller matrix elements are given by, respectively, $R_e\left|〈\sigma 〉\right|=2.7472\mathrm{}\pm 0.0077, 1.6006\pm 0.0042, \mathrm{and} 0.6448\pm 0.0021$, where $R_e$ is the magnitude of the ratio of the axial to vector coupling constants appropriate for the respective complex nuclei.

RADIOACTIVITY ${}_{}{}^6{}_{}{}^{}\mathrm{He}$, ${}_{}{}^{19}{}_{}{}^{}\mathrm{Ne}$, ${}_{}{}^{42}{}_{}{}^{}\mathrm{Sc}_{}^m{}_{}{}^{}$: measured $T_{\frac{1}{2}}$; deduced $\mathrm{ft}$ values and GT matrix elements.

• Received 13 August 1974

DOI:https://doi.org/10.1103/PhysRevC.10.1993