Improved <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>S</mml:mi></mml:math> factor of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi mathvariant="normal">C</mml:mi><mml:mprescripts/><mml:none/><mml:mn>12</mml:mn></mml:mmultiscripts><mml:mo>(</mml:mo><mml:mrow><mml:mi>p</mml:mi><mml:mo>,</mml:mo><mml:mi>γ</mml:mi><mml:mo>)</mml:mo><mml:mmultiscripts><mml:mi mathvariant="normal">N</mml:mi><mml:mprescripts/><mml:none/><mml:mn>13</mml:mn></mml:mmultiscripts></mml:mrow></mml:math> reaction at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>E</mml:mi><mml:mo>=</mml:mo><mml:mn>320</mml:mn><mml:mo>–</mml:mo><mml:mn>620</mml:mn><mml:mo> </mml:mo><mml:mi>keV</mml:mi></mml:mrow></mml:math> and the 422 keV resonance
J. Skowronski, E. Masha, D. Piatti, M. Aliotta, H. Aswath Babu, D. Bemmerer, A. Boeltzig, R. Depalo, A. Caciolli, F. Cavanna, L. Csedreki, Zsolt Fülöp, G. Imbriani, D. Rapagnani, Simon Rümmler, Konrad Schmidt, R. S. Sidhu, T. Szücs, S. Turkat, Anup Yadav
Abstract
The $^{12}\mathrm{C}(p,\ensuremath{\gamma})^{13}\mathrm{N}$ 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 $^{12}\mathrm{C}(p,\ensuremath{\gamma})^{13}\mathrm{N}$ 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 $^{12}\mathrm{C}(p,\ensuremath{\gamma})^{13}\mathrm{N}$ 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.