First Measurement of the 19 F(α, p) 22 Ne Reaction at Energies of Astrophysical Relevance

• Published in: The Astrophysical journal 2017-02, Vol.836 (1), p.57
• Main Authors: Pizzone, R. G., D’Agata, G., Cognata, M. La, Indelicato, I., Spitaleri, C., Blagus, S., Cherubini, S., Figuera, P., Grassi, L., Guardo, G. L., Gulino, M., Hayakawa, S., Kshetri, R., Lamia, L., Lattuada, M., Mijatović, T., Milin, M., Miljanić D., Đ., Prepolec, L., Rapisarda, G. G., Romano, S., Sergi, M. L., Skukan, N., Soić, N., Tokić, V., Tumino, A., Uroić, M.
• Format: Article
• Language: English
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/836/1/57

The observational 19 F 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 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 reaction-rate evaluation to be based on extrapolation. To investigate lower energies, the reaction has been studied by means of the Trojan horse method, applied to the quasi-free reaction at E beam  = 6 MeV. The indirect cross section of the 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.