Level Structure Of Mg-21: Nuclear And Astrophysical Implications

Resonant elastic scattering of a radioactive Na-20 beam incident upon protons in a polyethylene target has been used to probe the level structure of Mg-21 above the proton decay threshold. Three states have been observed, and their properties deduced through analysis based on the R-matrix formalism. The results improve and extend previous studies of this nucleus. An estimate of the Na-20(p,gamma)Mg-21 reaction rate, including these new data, suggests this reaction will not play a significant role in explosive hydrogen burning in astrophysical sites such as novae and x-ray bursts.