Absolute cross section of the 12C(p, ?)13N reaction

Solar neutrino measurements have recently reached a level of sensitivity such that CNO fluxes can now be experimentally determined. While these first measurements are still only sensitive to the higher energy neutrinos resulting from the & beta;+ decays of 15O produced by the 14N(p, & gamma; ) 15O reaction, future measurements will work towards detection of neutrinos from the & beta;+ decay of 13N from the 12C(p, & gamma; )13N reaction. This paper reports on a recent measurement of the 12C(p, & gamma; ) 13N reaction covering a broad laboratory energy range between 1.0 and 2.5 MeV. The measurement was made to better determine the overall normalization of the absolute cross section and to explore the interference effects between the two broad, overlapping resonances at proton energies of 0.460 and 1.689 MeV and the direct capture to the ground state of 13N in the framework of a multichannel R-matrix analysis. This work takes into account previous radiative capture as well as elastic 12C(p, p) 12C scattering data, making uncertainty estimations using a Bayesian framework, to determine a reliable extrapolation of the low energy S factor towards the stellar energy range of CNO hydrogen burning. These new experimental results, and a detailed investigation of the past literature data, suggest that the resonant component of the cross section should be 30% lower than previously accepted.

Automated summary

Recent solar neutrino measurements have reached a level of sensitivity that allows for the determination of CNO fluxes. This paper reports on a new measurement of the 12C(p,γ)13N reaction to better understand cross section normalization and interference effects. The results suggest that the resonant component of the cross section should be lower than previously accepted.