Mg24(α,γ)Si28 resonance parameters at low α-particle energies

The reaction Mg24(α,γ)Si28 is involved in the nucleosynthesis of Mg24 and Si28 in massive stars. The reaction has not been examined with sufficient sensitivity at α-particle energies below 1.5 MeV. Several Si28 states appear favorable for formation by this reaction in the α-particle energy range of 1.0 1.5 MeV, motivating a new study of this reaction at the University of Notre Dame. To maximize experimental sensitivity, a high efficiency coincidence detection system was developed. Several previously unknown resonances were observed between 1.1 and 1.5 MeV, and an upper limit for any lower energy resonances was obtained. Resonance parameters were determined and reaction rates were calculated. The astrophysical implications of these results are discussed.