New astrophysical S factor for the N-15(p,gamma)O-16 reaction via the asymptotic normalization coefficient (ANC) method
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The 15N(p,)16O reaction provides a path from the CN cycle to the CNO bi-cycle and CNO tri-cycle. The measured astrophysical factor for this reaction is dominated by resonant capture through two strong J=1- resonances at ER=312 and 962 keV and direct capture to the ground state. Asymptotic normalization coefficients (ANCs) for the ground and seven excited states in O16 were extracted from the comparison of experimental differential cross sections for the N15(He3,d)O16 reaction with distorted-wave Born approximation calculations. Using these ANCs and proton and resonance widths determined from an R-matrix fit to the data from the 15N(p,)12C reaction, we carried out an R-matrix calculation to obtain the astrophysical factor for the 15N(p,)16O reaction. The results indicate that the direct capture contribution was previously overestimated. We find the astrophysical factor to be S(0)=36.06.0 keV b, which is about a factor of 2 lower than the presently accepted value. We conclude that for every 2200300 cycles of the main CN cycle one CN catalyst is lost due to this reaction. 2008 The American Physical Society.
author list (cited authors)
Mukhamedzhanov, A. M., Bem, P., Burjan, V., Gagliardi, C. A., Goldberg, V. Z., Hons, Z., ... Vincour, J.