Particle decay branching ratios for states of astrophysical importance in ¹⁹Ne

We have measured proton and α-particle branching ratios of states formed using the ¹⁹F(³He,t)¹⁹Ne^* reaction at a beam energy of 25 MeV. These ratios have a large impact on the astrophysical reaction rates of ¹⁵O(α,γ)¹⁹Ne, ¹⁸F(p,γ)¹⁹Ne, and ¹⁸F(p,α)¹⁵O, which are of interest in understanding energy generation in x-ray bursts and in interpreting anticipated γ-ray observations of novae. We detected decay protons and α particles using a silicon detector array in coincidence with tritons measured in the focal plane detector of our Enge split-pole spectrograph. The silicon array consists of five strip detectors of the type used in the Louvain-Edinburgh Detector Array, subtending angles from 130° to 165° with ≈14% lab efficiency. The correlation angular distributions give additional confidence in some prior spin-parity assignments that were based on γ branchings. We measure Γ_p∕Γ=0.387±0.016 for the 665 keV proton resonance, which agrees well with the direct measurement of Bardayan et al.