First in-beam γ-ray spectroscopy study of Al24 and its implications for the astrophysical Mg23(p,γ)Al24 reaction rate in ONe novae

The first in-beam {gamma}-ray spectroscopy study of {sup 24}Al is presented. A complete level structure of {sup 24}Al incorporating all states below the proton-emission threshold, has been constructed. The first excited state above the proton threshold has also been identified as a 3{sup +} state at 2345.1 {+-} 1.4 keV. This state, corresponding to a resonance energy of 473 {+-} 3 keV, has been suggested to be the dominant resonance contributing to the {sup 23}Mg(p,{gamma}){sup 24}Al stellar reaction rate. The improved precision of the level energy and unambiguous assignment of the state has reduced the uncertainty of the {sup 23}Mg(p,{gamma}){sup 24}Al stellar reaction rate, which constrains the production of A > 20 nuclei in ONe novae.

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