s-wave resonances for the 18 F(p, α ) 15 O reaction in novae

. The 18 F( p , α ) reaction determines the rate of destruction of 18 F in novae. It represents the key nuclear physics uncertainty in modelling the calculated flux of annihilation radiation emitted following the radioactive decay of 18 F. The major uncertainties relate to states representing s-wave resonances in the compound system, 19 Ne. We report a first study of the 19 F( 3 He, t ) 19 Ne reaction at intermediate energies and forward angles. This reaction has a simple, model-independent, mechanism that we use here to identify states near the proton threshold energy in 19 Ne corresponding to Δ L=0 transitions. In particular, we observe a Δ L=0 state at 6.13 MeV which could significantly affect the 18 F( p , α ) astrophysical S -factor at nova burning temperatures.