New astrophysical S factor for the N15(p,γ)O16 reaction via the asymptotic normalization coefficient (ANC) method

A. M. Mukhamedzhanov, P. Bém, V. Burjan, C. A. Gagliardi, V. Z. Goldberg, Z. Hons, M. La Cognata, V. Kroha, J. Mrázek, J. Novák, Š. Piskoř, R. G. Pizzone, A. Plunkett, S. Romano, E. Šimečková, C. Spitaleri, L. Trache, R. E. Tribble, F. Veselý, and J. Vincour
Phys. Rev. C 78, 015804 – Published 22 July 2008

Abstract

The 15N(p,γ)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 Jπ=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 α resonance widths determined from an R-matrix fit to the data from the 15N(p,α)12C reaction, we carried out an R-matrix calculation to obtain the astrophysical factor for the 15N(p,γ)16O reaction. The results indicate that the direct capture contribution was previously overestimated. We find the astrophysical factor to be S(0)=36.0±6.0 keV b, which is about a factor of 2 lower than the presently accepted value. We conclude that for every 2200±300 cycles of the main CN cycle one CN catalyst is lost due to this reaction.

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  • Received 8 November 2007

DOI:https://doi.org/10.1103/PhysRevC.78.015804

©2008 American Physical Society

Authors & Affiliations

A. M. Mukhamedzhanov1, P. Bém2, V. Burjan2, C. A. Gagliardi1, V. Z. Goldberg1, Z. Hons2, M. La Cognata3, V. Kroha2, J. Mrázek2, J. Novák2, Š. Piskoř2, R. G. Pizzone3, A. Plunkett1, S. Romano3, E. Šimečková2, C. Spitaleri3, L. Trache1, R. E. Tribble1, F. Veselý2, and J. Vincour2

  • 1Cyclotron Institute, Texas A&M University, College Station, Texas 77843, USA
  • 2Nuclear Physics Institute, Czech Academy of Sciences, 250 68 Řež near Prague, Czech Republic
  • 3Università di Catania and INFN Laboratori Nazionali del Sud, Catania, Italy

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Vol. 78, Iss. 1 — July 2008

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