The ${}^{12}\mathrm{C}(p,\gamma ){}^{13}\mathrm{N}$ reaction is the onset process of both the CNO and hot CNO cycles that drive massive star, red and asymptotic giant branch star, and novae nucleosynthesis. The ${}^{12}\mathrm{C}(p,\gamma ){}^{13}\mathrm{N}$ rate affects the final abundances of the stable ${}^{12,13}\mathrm{C}$ nuclides with ramifications for meteoritic carbon isotopic abundances and the $s$-process neutron source strength. Here, an underground measurement of the ${}^{12}\mathrm{C}(p,\gamma ){}^{13}\mathrm{N}$ cross section is reported. The present data, obtained at the Felsenkeller shallow-underground laboratory in Dresden (Germany), encompass the 320–620 keV center of mass energy range to include the wide and poorly constrained $E=422$ keV resonance that dominates the rate at high temperatures. This work's $S$-factor results, lower than literature by 25%, are included in a comprehensive $R$-matrix fit, and the energy of the ${\frac{1}{2}}^{+}$ first excited state of ${}^{13}\mathrm{N}$ is found to be 2369.6(4) keV with a radiative and proton width of 0.49(3) eV and 34.9(2) keV, respectively. A reaction rate, based on the present $R$-matrix fit and extrapolation, is suggested.

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• Explosive burning
• H & He burning
• Nuclear reaction rates
• Nuclear reactions
• Radiative capture
• S-factor
• 6 ≤ A ≤ 19
• Nuclear data analysis & compilation
• Spectrometers & spectroscopic techniques