Low-energy( 23)Al beta-delayed proton decay and Na-22 destruction in novae

The radionuclide22Na is a target of¿-ray astronomy searches, predicted to be produced during thermonuclearrunaways driving classical novae. The22Na(p,¿)23Mg reaction is the main destruction channel of22Na during anova, hence, its rate is needed to accurately predict the22Na yield. However, experimental determinations of theresonance strengths have led to inconsistent results. In this Rapid Communication, we report a measurementof the branching ratios of the23Alß-delayed protons as a probe of the key 204-keV (center-of-mass)22Na(p,¿)23Mg resonance strength. We report a factor of 5 lower branching ratio compared to the most recentliterature value. The variation in22Na yield due to nuclear data inconsistencies was assessed using a series ofhydrodynamic nova outburst simulations and has increased to a factor of 3.8, corresponding to a factor of˜2uncertainty in the maximum detectability distance. This is the first reported scientific measurement using theGaseous Detector with Germanium Tagging system.