Measurement of the IAS resonance strength in 23Mg

Beta decay of 23Al to excited states in 23Mg has been studied using low-energy proton and high-energy gamma-ray detection combined with ion-guide-based on-line mass separation. For the first time, a T=3/2 isobaric analogue state, at 7801(2) keV, was observed to decay by both proton and gamma emission, with a proton branching of 0.17(8)%. The deduced resonance strength ωγ=2.2(10) meV is in agreement with upper limits reported from 22Na(p,γ) reaction studies. Shell-model calculations are incorporated.