We have studied β -decay of23Al with a novel detector setup at the focal plane of the MARS separator at the Texas A&M University. Absolute proton-decay branching ratios from excited states of23Mg are determined by combining our results to the latest γ-decay data. Contrary to previous β -decay studies, no strong proton intensity from the isobaric analogue state (IAS) in23Mg (Ex= 7803 keV) was observed. Instead, we assign the lowest observed proton group at Ecm= 206 keV to the state 16 keV below the IAS. In this contribution, a description of the used technique along with results of the experiment are given and their relevance for astrophysics discussed. © Copyright owned by the author(s).