Destruction of 18F via 18F(p,α)15O burning through the Ec.m.=665 keV resonance -: art. no. 065802

Knowledge of the astrophysical rate of the F-18(p, alpha)O-15 reaction is important for understanding the gamma -ray emission expected from novae and heavy-element production in x-ray bursts. The rate of this reaction is dominated at temperatures above similar to0.4 GK by a resonance near 7.08 MeV excitation energy in Ne-19. The F-18(p, alpha) O-15 rate has been uncertain in part because of disagreements among previous measurements concerning the resonance strength and excitation energy of this state. To resolve these uncertainties, we have made simultaneous measurements of the H-1(F-18, p)F-18 and H-1(F-18, alpha)O-15 excitation functions using a radioactive F-18 beam at the ORNL Holifield Radioactive Ion Beam Facility. A simultaneous fit of the data sets has been performed, and the best fit was obtained with a center-of-mass resonance energy of 664.7 +/- 1.6 keV (E-chi = 7076 +/- 2 keV), a total width of 39.0 +/- 1.6 keV, a proton branching ratio of Gamma (p)/Gamma= 0.39 +/- 0.02, and a resonance strength of omega gamma = 6.2 +/- 0.3 keV.