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

The lowest-energy resonance in the ²³Mg(p,γ)²⁴Al 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 ²³Mg beam (mixed within a significantly stronger ²³Na beam) of peak intensity 5×10⁷ s^-1, at the ISAC facility at TRIUMF. We extract values of E_R=485.7_-1.8^+1.3keV and ωγ=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 ²⁴Al mass. The effect on the uncertainties in the quantities of ejected ²²Na and ²⁶Al from oxygen-neon classical novae is discussed.