Na-21(P,Gamma)Mg-22 Reaction And Oxygen-Neon Novae

The Na-21(p,gamma)Mg-22 reaction is expected to play an important role in the nucleosynthesis of Na-22 in oxygen-neon novae. The decay of Na-22 leads to the emission of a characteristic 1.275 MeV gamma-ray line. This report provides the first direct measurement of the rate of this reaction using a radioactive Na-21 beam, and discusses its astrophysical implications. The energy of the important state was measured to be E-c.m.=205.7+/-0.5 keV with a resonance strength omegagamma=1.03+/-0.16(stat)+/-0.14(sys) meV.