Determination of the astrophysical S factor for C-11(p,gamma)N-12 from the N-12 -> C-11+p asymptotic normalization coefficient
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Date
2003
Journal Title
Journal ISSN
Volume Title
Publisher
American Physical Society
Abstract
The evolution of very low-metallicity, massive stars depends critically on the amount of CNO nuclei that they produce. Alternative paths from the slow 3alpha process to produce CNO seed nuclei could change their fate. The C-11(p,gamma)N-12 reaction is an important branch point in one such alternative path. At energies appropriate to stellar evolution of very low-metallicity, massive stars, nonresonant capture dominates the reaction rate. We have determined the astrophysical S factor for the C-11(p,gamma)N-12 reaction using the asymptotic normalization coefficient for N-12-->C-11+p to fix the nonresonant capture rate. In our experiment, a 110 MeV C-11 radioactive beam was used to study the(14)N(C-11,N-12)C-13 peripheral transfer reaction and the asymptotic normalization coefficient, (C-peff(12N))(2)=(C-p1/2(12N))(2)+(C-p3/2(12N))(2)=1.73+/-0.25 fm(-1), was extracted from the measured cross section. The contributions from the second resonance and interference effects were estimated using an R-matrix approach with the measured asymptotic normalization coefficient and the latest value for Gamma(gamma). We find the S factor for C-11(p,gamma)N-12 is significantly larger than previous estimates. As a result, the required density for it to contribute is reduced, and more CNO material may be produced.
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Keywords
COUPLED-CHANNELS CALCULATIONS, NUCLEI, MODEL, Physics
Citation
XD Tang, A. Azhari, Carl A. Gagliardi, A. M. Mukhamedzhanov, F. Pirlepesov, L. Trache, Robert E. Tribble, V. Burjan, V. Kroha and F. Carstoiu. Phys.Rev.C 67 015804 2003. "Copyright (2003) by the American Physical Society."