Precise nuclear data of the 14N(p, γ)15O reaction

Abstract:  The 14N(p, )15O reaction is the slowest stage of the carbon-nitrogen-oxygen cycle of hy-drogen burning and thus determines its reaction rate. Precise knowledge of its rate is required to improve the model of hydrogen burning in our sun. The reaction rate is a necessary ingredient for a possible solution of the solar abundance problem that led to discrepancies between predictions of the solar standard model and helioseismology. The solar 13N and 15O neutrino fluxes are used as independent observables that probe the carbon and nitrogen abundances in the solar core. This could settle the disagreement, if the 14N(p, )15O reaction rate is known with high precision. After a review of several measurements its cross section was revised downward due to a much lower contribution by one particular transition, capture to the ground state in 15O. The evaluated total relative uncertainty is still 7 %, in part due to an unsatisfactory knowledge of the excitation function over a wide energy range. The talk reports experimentally determined cross sections as astrophysical S-factor data at twelve energies between 0.357 – 1.292 MeV for the strongest transition, capture to the 6.79 MeV excited state in 15O with lower uncertainties than before and at ten energies between 0.479 – 1.202 MeV for the second strongest transition, capture to the ground state in 15O. In addition, a new R-matrix fit is presented to estimate the impact of the new data on the astrophysical relevant energy range.