A helium jet system and the ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}({}_{}{}^3{}_{}{}^{}\mathrm{He}, p4n){}_{}{}^{22}{}_{}{}^{}\mathrm{Al}$ reaction at 110 MeV have been used to discover the first odd-odd $T_z=-2\mathrm{}$ nuclide ${}_{}{}^{22}{}_{}{}^{}\mathrm{Al}$ ($t_{\frac{1}{2}}\sim 70$ ms), which has been predicted to lie on the edge of stability. Beta-delayed protons from its decay establish the mass excess of the lowest $T=2\mathrm{}$ state in ${}_{}{}^{22}{}_{}{}^{}\mathrm{Mg}$ as 13.650 ± 0.015 MeV corresponding to an excitation energy of 14.044 MeV.

RADIOACTIVITY ${}_{}{}^{22}{}_{}{}^{}\mathrm{Al}$ from ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}({}_{}{}^3{}_{}{}^{}\mathrm{He}, p4n)$; measured $\beta$-delayed protons, $T_{\frac{1}{2}}$; deduced branching and $\sigma$; derived mass excess of lowest $T=2\mathrm{}$ state in ${}_{}{}^{22}{}_{}{}^{}\mathrm{Mg}$.

• Received 17 May 1982

DOI:https://doi.org/10.1103/PhysRevC.26.1778