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

The 15O(alpha, gamma)(19)Ne 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 E(c.m). = 504 keV which corresponds to a (19)Ne excitation energy of E(R) = 4.033 MeV. It is possible to model the (15)O(alpha,gamma)(19)Ne reaction rate, if the branching ratio Gamma(alpha)/Gamma and the total resonance width F of this state are known. Results from an exploratory (18)Ne(d, P) experiment performed in inverse kinematics at E(lab) = 44.1 MeV and 10(6) pps beam intensity show that the 4.033 MeV state-among other resonances of astrophysical interest-is populated in this reaction (dsigma/dOmega = 0.5 +/- 0.2 mb/sr at theta(lab) = 138degrees). The determination of Gamma(alpha)/Gamma = 0.28 +/- 0.13 for another (19)Ne resonance at E(R) = 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. (C) 2002 Elsevier Science B.V. All rights reserved.