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

Abstract

The 18F(p,α) reaction determines the rate of destruction of 18F in novae. It represents the key nuclear physics uncertainty in modelling the calculated flux of annihilation radiation emitted following the radioactive decay of 18F. The major uncertainties relate to states representing s-wave resonances in the compound system, 19Ne. We report a first study of the 19F(3He, t)19Ne 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 19Ne corresponding to ΔL= 0 transitions. In particular, we observe a ΔL= 0 state at 6.13 MeV which could significantly affect the 18F(p,α) astrophysical S-factor at nova burning temperatures.