Speaker
Description
The ${}^{19}\mathrm{F}(p,\alpha){}^{16}\mathrm{O}$ reaction is important for understanding the fluorine abundance in the outer layers of AGB stars and it might also play a role in hydrogen-deficient post-AGB star nucleosynthesis. Up to now, theoretical models overproduce F abundances in AGB stars with respect to the observed values. Besides, for the $(p,\alpha_0)$ channel there are discrepancies between the experimental data from the literature. In order to solve these discrepancies we present here a direct experiment performed at INFN-LNS using a silicon strip detector array (LHASA).
The ${}^{19}\mathrm{F}(p,\alpha){}^{16}\mathrm{O}$ reaction rate is the sum over the $(p,\alpha_0)$, $(p,\alpha_\pi)$ and the $(p,\alpha\gamma)$ channels. While the $(p,\alpha_0)$ rate is well constrained by the present existing data, down to the lowest energies, almost nothing is known from experiments on the $(p,\alpha_\pi)$ and $(p,\alpha\gamma)$ rates. Despite its importance, the $S$-factors and the branching ratio between the $\alpha_0$, $\alpha_\pi$ and $\alpha_\gamma$ outgoing channels in the ${}^{19}\mathrm{F}(p,\alpha){}^{16}\mathrm{O}$ reaction are still largely uncertain at astrophysical energies. Thus, a direct measurement using the new detector, ELISSA, coupled with LHASA was performed at IFIN-HH. This setup is allowing us to discriminate the $(p,\alpha_\pi)$ and $(p,\alpha\gamma)$ reaction rates at very low energies and extract the $(p,\alpha_\pi)$ and $(p,\alpha\gamma)$ reaction cross section.
