BETA-DELAYED ALPHA-SPECTRUM OF N-16 AND THE C-12(ALPHA,GAMMA)O-16 CROSS-SECTION AT LOW ENERGIES

The alpha spectrum following the beta decay of N-16 from the isotope separator TISOL has been measured by detecting 10(6) alpha particles in coincidence with C-12 nuclei. These data, which show a low-energy interference anomaly accompanying the main alpha peak, permit a more precise determination of the p-wave amplitude of the astrophysically important reaction C-12(alpha, gamma)O-16. The alpha spectrum and previous gamma-ray data have been fitted simultaneously by a K-matrix parametrization; a value of S(E = 0.3 MeV)= 57 +/- 13 keV b has been obtained for the E1 part of the C-12(alpha, gamma)O-16 reaction.