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. So far, available direct measurements do not reach the energy region of astrophysical interest (E-cm similar to 300 keV), because of the hindrance effect of the Coulomb barrier. The Trojan Horse (TH) method was thus used to access this energy region, by extracting the quasi-free contribution to the H-2(F-19,alpha O-16)(n) reaction. The TH measurement of the alpha(0) channel, which is the dominant one at such energies, shows the presence of resonant structures not observed before that cause an increase of the reaction rate at astrophysical temperatures up to a factor of 1.7, with potential important consequences for stellar nucleosynthesis.
The fluorine destruction in stars: first experimental study of the F-19(p, alpha)O-16 reaction at astrophysical energies
CHERUBINI, SILVIO;LAMIA, LIVIO;Pizzone RG;Puglia SMR;Rapisarda GG;ROMANO, Stefano;Sergi ML;
2012-01-01
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. So far, available direct measurements do not reach the energy region of astrophysical interest (E-cm similar to 300 keV), because of the hindrance effect of the Coulomb barrier. The Trojan Horse (TH) method was thus used to access this energy region, by extracting the quasi-free contribution to the H-2(F-19,alpha O-16)(n) reaction. The TH measurement of the alpha(0) channel, which is the dominant one at such energies, shows the presence of resonant structures not observed before that cause an increase of the reaction rate at astrophysical temperatures up to a factor of 1.7, with potential important consequences for stellar nucleosynthesis.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
