Direct measurement of the ²³Mg(p, γ)²⁴Al reaction using the DRAGON recoil separator and a hybrid array of $γ$-ray detectors

Background: The ²³Mg(p,γ)²⁴Al reaction plays a key role in nova nucleosynthesis, serving as a bridge between the Ne-Na and Mg-Al cycles and impacting synthesis of a wide variety of nuclides. It is crucial that the rate of this reaction be well constrained by experimental data, in particular the properties of the key resonance at Ecm≈480 keV, which dominates the rate at nova temperatures. Purpose: Our study aims to improve experimental constraints on the energy and strength of the key Ecm≈480 keV ²³Mg(p,γ)²⁴Al resonance through a new direct measurement of its strength and energy. Methods: We used a ²³Mg radioactive beam to directly observe capture into the Ecm≈480 keV resonance in inverse kinematics. The ²⁴Al recoils were selected by the DRAGON recoil separator, and coincident $γ$ rays were measured in a hybrid LaBr₃/CeBr₃/BGO scintillator array. The ²⁴Al singles yield was used to determine the resonance strength, while the time difference between the coincident $γ$ rays and the incident beam was used to determine the resonance energy. Results: We obtained a strength of $ωγ=38(7)$ meV and an energy of Ecm=478.8(26) keV for the key astrophysical ²³Mg(p,γ)²⁴Al resonance. Conclusions: Our reported strength is in excellent agreement with the previously reported direct measurement, as well as shell model calculations. Our energy is in good agreement with earlier indirect measurements. Reaction rate calculations incorporating our results indicate that the ²³Mg(p,γ)²⁴Al rate is constrained to a $1σ$ up/down factor of 1.5 or smaller in the nova temperature range of 0.2--0.4 GK.