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The 18F(p,\alpha)15O reaction rate is crucial for constraining modelpredictions of the \gamma-ray observable radioisotope 18F produced in novae.The determination of this rate is challenging due to particular features of thelevel scheme of the compound nucleus, 19Ne, which result in interferenceeffects potentially playing a significant role. The dominant uncertainty inthis rate arises from interference between J\pi=3/2+ states near the protonthreshold (Sp = 6.411 MeV) and a broad J\pi=3/2+ state at 665 keV abovethreshold. This unknown interference term results in up to a factor of 40uncertainty in the astrophysical S-factor at nova temperatures. Here we reporta new measurement of states in this energy region using the 19F(3He,t)19Nereaction. In stark contrast with previous assumptions we find at least 3resonances between the proton threshold and Ecm=50 keV, all with differentangular distributions. None of these are consistent with J\pi= 3/2+ angulardistributions. We find that the main uncertainty now arises from the unknownproton-width of the 48 keV resonance, not from possible interference effects.Hydrodynamic nova model calculations performed indicate that this unknown widthaffects 18F production by at least a factor of two in the model considered.

Is \gamma-ray emission from novae affected by interference effects in the 18F(p,\alpha)15O reaction?