Improved S factor of the 13C(p,γ)14N reaction at 𝐸𝑝=330−740keV and parameters of resonances at 448 keV and 551 keV

The 13C(p, gamma ) 14N reaction is the second reaction of the CNO cycle. This cycle takes place in our Sun and fuels massive, red, and asymptotic giant branch stars. The 13C(p, gamma ) 14N rate affects the final abundances of 12,13C and 19F nuclides, with impact on our understanding of the i and s process, giant star nucleosynthesis and mixing processes, and ultimately the chemical evolution of the galaxy. Here, we report on a new measurement of the 13C(p, gamma ) 14N cross section, which has been performed at the Felsenkeller shallow underground laboratory in Dresden (Germany). The present S-factor results agree at low energy with LUNA data but are about 20% lower than previous literature data over the whole energy range explored, E = 310 - 680 keV. The narrow resonance corresponding to the 7966.9(5) keV excited state has been investigated and we report a new resonance strength, omega gamma = 18(2) meV. In addition, a new R-matrix fit is presented, from which new parameters for the broad resonance corresponding to the 8062.0(10) keV excited state are derived and a new extrapolation for the total S factor down to zero energy is obtained, Stot(0) = 6.4(4) keV b. Finally a new reaction rate is calculated and reported here.