New low-energy measurement of the 18F(p,α)15O reaction

The 18F, produced during nova explosions, is the main responsible for the 511 keV γ-ray emitted during the outburst that could be detected with satellite missions or future γ-ray telescopes. In spite of many experimental efforts, the amount of 18F synthesized still suffers from large uncertainties concerning mainly the 18F(p,α)15O reaction. We report here on a new direct measurement of the 18F(p,α)15O cross section recently carried out at the RIB facility at Louvain-la-Neuve. Cross section data down to a center-of-mass energy of 400 keV have been obtained using an isobarically pure 18F beam (averaged intensity of the order of 106 pps) and a thin polyethylene target. The reaction products were detected using the multi-strip detector array LEDA. The cross section data are analysed in the framework of the R-matrix model. Our main aim is to determine the interference sign between three 3/2+ resonances above threshold that can significantly affect the extrapolation of the 18F(p,α)15O cross section to the energies relevant for novae, and thus, the modeling of nova explosions.