Speaker
Description
Fluorine is one of the most interesting elements in nuclear astrophysics, where the ${}^{19}\mathrm{F}(p,\alpha){}^{16}\mathrm{O}$ 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 ${}^{19}\mathrm{F}(p,\alpha\gamma){}^{16}\mathrm{O}$ reaction channel. The $\gamma$-ray yields were measured over $E_\mathrm{c.m.}$ = 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-rayinduced 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 ${}^{19}\mathrm{F}(p,\alpha\gamma){}^{16}\mathrm{O}$ reaction rate has been determined directly at the relevant astrophysical energies.