Münster 2002 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 25: Nuclear and Particle Astrophysics III

HK 25.2: Talk

Wednesday, March 13, 2002, 11:15–11:30, C

The ¹⁸O(α,γ) rate during stellar He burning — •Sa’ed Dababneh¹, Joachim Görres², Michael Heil¹, Franz Käppeler¹, Rene Reifarth¹, and Michael Wiescher² — ¹Forschungszentrum Karlsruhe, Institut für Kernphysik, 76021 Karlsruhe — ²University of Notre Dame, Department of Physics, Notre Dame, IN 46556, USA

The ²²Ne(α,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(α,γ)¹⁸F(β⁺)¹⁸O(α,γ)²² Ne. While the first reaction is well understood, α-capture on ¹⁸O is still affected by considerable uncertainties. At the temperatures of interest the reaction rate is dominated by two resonances at α-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 α-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.