Direct measurement of the $^{19}$F(p,$\alpha _0$)$^{16}$O reaction at E$_{cm}$ = 0.4–0.9 MeV using the LHASA detector array

Abstract

The $^{19}$F(p,$\alpha$)$^{16}$O reaction is of paramount importance for understanding the fluorine abundance in the outer layers of asymptotic giant branch (AGB) stars and it might also play a role in hydrogen-deficient post-AGB star nucleosynthesis. Theoretical models overestimate F abundances in AGB stars with respect to the observed values, thus calling for further investigation of the reactions involved in the fluorine nucleosynthesis. In the last years, new direct and indirect measurements improved significantly the knowledge of the $^{19}$F(p,$\alpha _0$)$^{16}$O cross section at deeply sub-Coulomb energies (below 0.8 MeV). Those data are larger by a factor of about 1.4 with respect to the previous data reported in the NACRE compilation in the energy region 0.6–0.8 MeV. In order to solve these discrepancies, here we present a new direct experiment performed using a silicon strip detector array (LHASA – Large High-resolution Array of Silicon for Astrophysics). Our results clearly confirm the trend of the latest experimental data in the energy region of interest, pointing towards a larger S-factor value than the one reported in the NACRE compilation.