Hot CNO breakout: Status of the d(Ne-18,p)Ne-19*(alpha) O-15 reaction

Post-accelerated radioactive ion beams produced at Louvain-la-Neuve, Belgium have been used to investigate the O-15(alpha,gamma)Ne-19 reaction, which is generally considered as the potential breakout reaction from the hot CNO cycle. This reaction may not only lead to the synthesis of proton-rich nuclei via the rp-process, but is also thought to initiate the massive release of energy which can trigger stellar explosions such as novae and Xray bursters. The properties of this reaction have been investigated via a study of the relevant decays of excited states in Ne-19, which were populated using an inverse Ne-18(d,p) reaction. The measurements were aimed at the determination of branching ratios which, combined with knowledge of the total width of the states under investigation, allow for the modelling of the O-15(alpha,gamma)Ne-19 reaction rate. The result for the branching ratio of the E-R=4.600MeV state is found to be in good agreement with an alternative approach. The experiments have been carried out using an especially designed high granularity large solid angle silicon strip detector array consisting of 320 elements to compensate for the high decay background and limited intensity of this radioactive beam environment. The method and experimental set-up will be presented. The decay properties of selected populated resonances will be discussed. An upper limit of 10(-2) for the branching ratio of the astrophysically important state at 4.033MeV was obtained.