Break-out from the hot-CNO cycle studied with radioactive beams Original Research Article

The 15O(α,γ)19Ne reaction is generally considered as the potential breakout reaction from the hot-CNO cycle. Under nova conditions, the reaction depends dominantly on a single sub-Coulomb resonance at Ec.m.=504 keV which corresponds to a 19Ne excitation energy of ER=4.033 MeV. It is possible to model the 15O(α,γ)19Ne reaction rate, if the branching ratio Γα/Γ and the total resonance width Γ of this state are known. Results from an exploratory 18Ne(d,p) experiment performed in inverse kinematics at Elab=44.1 MeV and 106 pps beam intensity show that the 4.033 MeV state—among other resonances of astrophysical interest—is populated in this reaction (View the MathML source at θlab=138°). The determination of Γα/Γ=0.28±0.13 for another 19Ne resonance at ER=4.600 MeV found to be in good agreement with a stable beam based result shows the feasibility of this radioactive nuclear beam based approach provided that higher 18Ne beam intensities become available.