First measurement of the 19F(alpha,p)22Ne reaction at energies of astrophysical relevance

The observational 19F abundance in stellar environments systematically exceeds the predicted one, thus representing one of the unsolved challenges for stellar modeling. It is therefore clear that further investigation is needed in this field. In this work, we focus our attention on the measurement of the 19F(a, p)22Ne reaction in the astrophysical energy range, between 0.2 and 0.8MeV (far below the Coulomb barrier, 3.8 MeV), as it represents the main destruction channel in He-rich environments. The lowest energy at which this reaction has been studied with direct measurements is ∼0.66MeV, covering only the upper tail of the Gamow window, causing the reactionrate evaluation to be based on extrapolation. To investigate lower energies, the 19F(a, p)22Ne reaction has been studied by means of the Trojan horse method, applied to the quasi-free 6Li(19F, p22Ne)2H reaction at Ebeam=6MeV. The indirect cross section of the 19F(a, p)22Ne reaction at energies 1MeV was extracted, fully covering the astrophysical region of interest and overlappingexisting direct data for normalization. Several resonances have been detected for the first time inside the Gamow window. The reaction rate has been calculated, showing an increase up to a factor of 4 with respect to the literature at astrophysical temperatures. This might lead to potential major astrophysical implications.