First direct measurement of the 23Mg(p,γ)24Al reaction

The lowest-energy resonance in the Mg-23(p,gamma)Al-24 reaction, which is dominant at classical nova temperatures, has been measured directly for the first time using the DRAGON recoil spectrometer. The experiment used a radioactive Mg-23 beam (mixed within a significantly stronger Na-23 beam) of peak intensity 5 x 10(7) s(-1), at the ISAC facility at TRIUMF. We extract values of E-R = 485.7(-1.8)(+1.3) keV and omega gamma = 38(-15)(+21) meV from our data (all values in the center-of-mass frame unless otherwise stated). In addition, the experiment prompted a recalculation of the Q value for this reaction based on a revision of the Al-24 mass. The effect on the uncertainties in the quantities of ejected Na-22 and Al-26 from oxygen-neon classical novae is discussed.