The decay of the lightest nucleus with Tz=-3, Si-22, was studied by a silicon array. A charged-particle group at 5600 (70) keV in the decay-energy spectrum was identified experimentally as beta-delayed twoproton emission from the isobaric analog state (IAS) of Al-22. Experimental results of the IAS fed by a superallowed Fermi transition were compared with our large-scale shell-model calculations. The groundstate mass of Si-22 was obtained indirectly in the experiment for the first time. Two-proton separation energy for Si-22 is deduced to be -108(125) keV, which indicates that it is a very marginal candidate for two-proton ground-state emission. (C) 2017 The Authors. Published by Elsevier B.V.
