Low-energy 23Al β-delayed proton decay and 22Na destruction in novae

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