Direct Measurement of the Astrophysical <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">F</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>19</mml:mn></mml:mrow></mml:mmultiscripts><mml:mo stretchy="false">(</mml:mo><mml:mi>p</mml:mi><mml:mo>,</mml:mo><mml:mi>α</mml:mi><mml:mi>γ</mml:mi><mml:mo stretchy="false">)</mml:mo><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>16</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow></mml:math> Reaction in the Deepest Operational Underground Laboratory
Lichen Zhang, Jun Su, J. J. He, M. Wiescher, R. J. deBoer, D. Kahl, Yinji Chen, X. Y. Li, J. G. Wang, L. Zhang, F. Cao, Hengliang Zhang, Zhicheng Zhang, T. Y. Jiao, Y. D. Sheng, L. H. Wang, Luyang Song, X. Z. Jiang, Ziming Li, E. T. Li, Shengzhe Wang, Gang Lian, Zhihong Li, Xiaodong Tang, H. W. Zhao, L. T. Sun, Qi Wu, J. Q. Li, Baoqun Cui, L. H. Chen, ROBINSON J.G, Bing Guo, Shutao Xu, Jianyang Li, Ningchun Qi, Wenliang Sun, X. Y. Guo, Peng Zhang, Y. H. Chen, Yong Zhou, Jifang Zhou, Jinjin He, C. S. Shang, M. C. Li, X. H. Zhou, Yuhao Zhang, F. S. Zhang, Ziyao Hu, Honglin Xu, J. P. Chen, W. P. Liu
Abstract
Fluorine is one of the most interesting elements in nuclear astrophysics, where the ^{19}F(p,α)^{16}O reaction is of crucial importance for Galactic ^{19}F abundances and CNO cycle loss in first generation Population III stars. As a day-one campaign at the Jinping Underground Nuclear Astrophysics experimental facility, we report direct measurements of the essential ^{19}F(p,αγ)^{16}O reaction channel. The γ-ray yields were measured over E_{c.m.}=72.4-344 keV, covering the Gamow window; our energy of 72.4 keV is unprecedentedly low, reported here for the first time. The experiment was performed under the extremely low cosmic-ray-induced background environment of the China JinPing Underground Laboratory, one of the deepest underground laboratories in the world. The present low-energy S factors deviate significantly from previous theoretical predictions, and the uncertainties are significantly reduced. The thermonuclear ^{19}F(p,αγ)^{16}O reaction rate has been determined directly at the relevant astrophysical energies.