Precision half-life measurements and branching ratio determinations have been carried out for some $T=\frac{1}{2}$ mirror nuclei. The following results have been obtained for the half-life and for the branching ratios: ${}_{}{}^{13}{}_{}{}^{}\mathrm{N}$ (597.9 ± 0.6 s), ${}_{}{}^{15}{}_{}{}^{}\mathrm{O}$ (122.23 ± 0.23 s), ${}_{}{}^{17}{}_{}{}^{}\mathrm{F}$ (64.31 ± 0.09 s), ${}_{}{}^{21}{}_{}{}^{}\mathrm{Na}$ [(95.8 ± 0.2)%], ${}_{}{}^{23}{}_{}{}^{}\mathrm{Mg}$ [11.317 ± 0.011 s, (92.2 ± 0.2)%], ${}_{}{}^{25}{}_{}{}^{}\mathrm{Al}$ [(99.16 ± 0.04)%], ${}_{}{}^{27}{}_{}{}^{}\mathrm{Si}$ [(99.812 ± 0.010)%], ${}_{}{}^{29}{}_{}{}^{}\mathrm{P}$ [(98.11 ± 0.30)%], ${}_{}{}^{31}{}_{}{}^{}\mathrm{S}$ [2.543 ± 0.008 s, (98.89 ± 0.20)%], ${}_{}{}^{33}{}_{}{}^{}\mathrm{Cl}$ (2.507 ± 0.008 s), ${}_{}{}^{35}{}_{}{}^{}\mathrm{Ar}$ [1.774 ± 0.003 s, (98.0 ± 0.2)%], ${}_{}{}^{37}{}_{}{}^{}\mathrm{K}$ [1.223 ± 0.008 s, (97.8 ± 0.2)%], ${}_{}{}^{39}{}_{}{}^{}\mathrm{Ca}$ (0.8594 ± 0.0016 s, >99.72%).

RADIOACTIVITY ${}_{}{}^{13}{}_{}{}^{}\mathrm{N}$, ${}_{}{}^{15}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{17}{}_{}{}^{}\mathrm{F}$, ${}_{}{}^{21}{}_{}{}^{}\mathrm{Na}$, ${}_{}{}^{23}{}_{}{}^{}\mathrm{Mg}$, ${}_{}{}^{25}{}_{}{}^{}\mathrm{Al}$, ${}_{}{}^{27}{}_{}{}^{}\mathrm{Si}$, ${}_{}{}^{31}{}_{}{}^{}\mathrm{S}$, ${}_{}{}^{33}{}_{}{}^{}\mathrm{Cl}$, ${}_{}{}^{35}{}_{}{}^{}\mathrm{Ar}$, ${}_{}{}^{37}{}_{}{}^{}\mathrm{K}$, ${}_{}{}^{39}{}_{}{}^{}\mathrm{Ca}$; measured $T=\frac{1}{2}$, branching ratios.

• Received 10 December 1976

DOI:https://doi.org/10.1103/PhysRevC.15.1847