•Sa'ed Dababneh1, Joachim Görres2, Michael
Heil1, Franz Käppeler1, Rene Reifarth1
und Michael Wiescher2
2University of Notre Dame, Department of Physics, Notre
Dame, IN 46556, USA
1Forschungszentrum Karlsruhe, Institut für Kernphysik,
76021 Karlsruhe
The 22Ne(a,n) reaction is the dominant neutron source for the weak s process in massive stars and plays also a significant role in s-process nucleosynthesis in thermally pulsing AGB stars. 22Ne is produced by the reaction sequence 14N(a,g)18F(b+)18O(a,g) 22Ne. While the first reaction is well understood, a-capture on 18O is still affected by considerable uncertainties. At the temperatures of interest the reaction rate is dominated by two resonances at a-energies of 470 keV and 566 keV. Since these resonances were not yet observed directly, the rates had to be based on estimated resonance strengths. We have searched for these resonances using an intense a-beam and a Ge-clover detector in combination with BGO detectors. First results of this experiment will be reported, and the implications for stellar neutron production will be discussed.