New constraints on the F(p,α) O rate in novae from the (d, p) reaction

The degree to which the (p,γ) and (p,α) reactions destroy F at temperatures (1-4) × 10 K is important for understanding the synthesis of nuclei in nova explosions and for using the long-lived radionuclide F, a target of γ-ray astronomy, as a diagnostic of nova mechanisms. The reactions are dominated by low-lying proton resonances near the F+p threshold (E = 6.411 MeV in Ne). To gain further information about these resonances, we used a radioactive F beam from the Holifield Radioactive Ion Beam Facility to selectively populate corresponding mirror states in F via the inverse H( F,p) F neutron transfer reaction. Neutron spectroscopic factors were measured for states in F in the excitation energy range 0-9 MeV. Widths for corresponding proton resonances in Ne were calculated using a Woods-Saxon potential. The results imply significantly lower F(p,γ) Ne and F(p,α) O reaction rates than reported previously, thereby increasing the prospect of observing the 511 keV annihilation radiation associated with the decay of F in the ashes ejected from novae.