Decay of aTz=−2Nucleus: Argon-32

$\beta$-delayed protons have been observed from ${}_{}{}^{32}{}_{}{}^{}\mathrm{Ar}$ ($t_{\frac{1}{2}}\sim 75$ msec), the most neutron-deficient nucleus whose radioactive decay has ever been recorded. From the proton spectrum, the $T=2\mathrm{}$ state in ${}_{}{}^{32}{}_{}{}^{}\mathrm{Cl}$ has been identified to have a mass excess of -8295.6±5.2 keV. As the fourth accurately known member of an isobaric quintet, it provides an accurate test for a cubic term in the isobaric-multiplet mass equation as applied to narrow $T=2\mathrm{}$ states: The coefficient of such a possible term is determined to be 0.5±2.5 keV.