The F-19(p,alpha)O-16 reaction is an important fluorine destruction channel in the proton-rich outer layers of asymptotic giant branch (AGB) stars and it might also play a role in hydrogen-deficient post-AGB star nucleosynthesis. At present, theoretical models overproduce F abundances in AGB stars with respect to the observed values, thus calling for further investigation of the nuclear reaction rates involved in the production and destruction of fluorine. In the last years, new direct and indirect measurements improved significantly the knowledge of F-19(p,alpha)O-16 cross section at deeply sub-Coulomb energies (below 0.8 MeV). However, those data are larger by a factor of 1.4 with respect the previous data reported in the NACRE compilation in the energy region 0.6-0.8 MeV. Using the Large High resolution Array of Silicons for Astrophysics (LHASA), we performed a new direct measurement of the F-19(p,alpha)O-16. The goal of this experiment is to reduce the uncertainties in the nuclear reaction rate of the F-19(p,alpha)O-16 reaction. Here, experimental details, the calibration procedure and angular distributions are presented.
Preliminary results for the F-19(p,alpha)O-16 reaction cross section measured at INFN-LNS
Palmerini, S;
2020
Abstract
The F-19(p,alpha)O-16 reaction is an important fluorine destruction channel in the proton-rich outer layers of asymptotic giant branch (AGB) stars and it might also play a role in hydrogen-deficient post-AGB star nucleosynthesis. At present, theoretical models overproduce F abundances in AGB stars with respect to the observed values, thus calling for further investigation of the nuclear reaction rates involved in the production and destruction of fluorine. In the last years, new direct and indirect measurements improved significantly the knowledge of F-19(p,alpha)O-16 cross section at deeply sub-Coulomb energies (below 0.8 MeV). However, those data are larger by a factor of 1.4 with respect the previous data reported in the NACRE compilation in the energy region 0.6-0.8 MeV. Using the Large High resolution Array of Silicons for Astrophysics (LHASA), we performed a new direct measurement of the F-19(p,alpha)O-16. The goal of this experiment is to reduce the uncertainties in the nuclear reaction rate of the F-19(p,alpha)O-16 reaction. Here, experimental details, the calibration procedure and angular distributions are presented.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
