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Updated: Aug 15, 2026

Quantification of Hydrogen Concentrations in Surface and Interface Layers and Bulk Materials through Depth Profiling with Nuclear Reaction Analysis
Published on: March 29, 2016
Direct measurement of the 14N(p,gamma)15O S factor
R C Runkle1, A E Champagne, C Angulo
1The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3255, USA.
Abstract:
The 14N(p,gamma)15O reaction regulates the rate of energy generation in the stellar CN cycle. Because discrepancies have been found in the analysis and interpretation of previous capture data, we have measured the 14N(p,gamma)15O excitation function for energies in the range E(lab)(p)=155-524 keV. Fits of these data using R-matrix theory yield a value for the S factor at zero energy of 1.68+/-0.09(stat)+/-0.16(syst) keV b, which is significantly smaller than the previous result. The corresponding reduction in the stellar reaction rate for 14N(p,gamma)15O has a number of interesting consequences, including an impact on estimates for the age of the Galaxy derived from globular clusters.
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