The $Q$ values for ($p,t$) reactions leading to ${}_{}{}^{22}{}_{}{}^{}\mathrm{Mg}$, ${}_{}{}^{26}{}_{}{}^{}\mathrm{Si}$, ${}_{}{}^{30}{}_{}{}^{}\mathrm{S}$, and ${}_{}{}^{34}{}_{}{}^{}\mathrm{Ar}$ have been measured, yielding mass excesses for these nuclei of -399 ± 3 keV, -713 ± 3 keV, -14 062 ± 3 keV, and -18 379 ± 3 keV, respectively. The results for ${}_{}{}^{22}{}_{}{}^{}\mathrm{Mg}$ and ${}_{}{}^{34}{}_{}{}^{}\mathrm{Ar}$ are significantly different from average values quoted in the 1971 Mass Tables. For all four nuclei, these results allow the $\mathrm{ft}$ values for their Fermi $\beta$-decay branches to be calculated with improved precision, and in the cases of $A=26\mathrm{}$ and $A=34\mathrm{}$ more exacting comparisons of mirror Fermi decays become possible. The measured asymmetries now are $\Delta \mathrm{}\left(26\right)=-1.2\mathrm{}\pm 1.6\%$ and $\Delta \mathrm{}\left(34\right)=0.2\mathrm{}\pm 0.6\%$, thus removing any obvious disagreement with calculations of charge-dependent mixing.

[NUCLEAR REACTIONS ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$, ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$, ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$, ${}_{}{}^{36}{}_{}{}^{}\mathrm{Ar}\mathrm{}(p,t)\mathrm{}$, $E=40.2\mathrm{}$ MeV; measured $Q$ values. ${}_{}{}^{22}{}_{}{}^{}\mathrm{Mg}$, ${}_{}{}^{26}{}_{}{}^{}\mathrm{Si}$, ${}_{}{}^{30}{}_{}{}^{}\mathrm{S}$, ${}_{}{}^{34}{}_{}{}^{}\mathrm{Ar}$ deduced masses, $\mathrm{ft}$ values, mirror asymmetries for $A=26,34\mathrm{}$.]

• Received 3 October 1973

DOI:https://doi.org/10.1103/PhysRevC.9.252