Abstract
The first in-beam γ-ray spectroscopy study of Al24 is presented. A complete level structure of Al24 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+ 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 Mg23(p,γ)Al24 stellar reaction rate. The improved precision of the level energy and unambiguous assignment of the state has reduced the uncertainty of the Mg23(p,γ)Al24 stellar reaction rate, which constrains the production of A>20 nuclei in ONe novae. © 2008 The American Physical Society.