Determination of the astrophysical S factor for11C(p, )12N from the12N11C+p asymptotic normalization coefficient
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The evolution of very low-metallicity, massive stars depends critically on the amount of CNO nuclei that they produce. Alternative paths from the slow 3 process to produce CNO seed nuclei could change their fate. The11C(p, )12N 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 5 factor for the11C(p, )12N reaction using the asymptotic normalization coefficient for12N11C+p to fix the nonresonant capture rate. In our experiment, a 110 MeV11C radioactive beam was used to study the14N(11C,12N)13C peripheral transfer reaction and the asymptotic normalization coefficient, (Cpeff12N)2= (Cp1/212N)2+ (Cp3/212N)2=1.730.25 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 . We find the S factor for11C(p, )12N 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.
