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HK: Physik der Hadronen und Kerne
HK 34: Nuclear and Particle Astrophysics II
HK 34.7: Talk
Wednesday, March 10, 2004, 15:45–16:00, F
A measurement of the 14C(n,γ)15C reaction with the fast cyclic activation technique — •F. Käppeler1, J. Görres2, R.C. Haight3, M. Heil1, R. Plag1, R. Reifarth3, R.S. Rundberg3, M. Wiescher2, and J.B. Wilhelmy3 — 1Forschungszentrum Karlsruhe, Institut für Kernphysik, Postfach 3640, D-76021 Karlsruhe, Germany — 2Department of Physics, University of Notre Dame, Notre Dame, IN 46556, USA — 3Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
Inhomogeneous big bang models offer a possibility to bridge the mass gaps at A=5 and 8 via the reaction sequence 7Li(n,γ)8Li(α,n)11B(n,γ) 12B(β−)12C. Subsequent neutron captures 12C(n,γ)13C(n,γ)14C will then lead to the production of 14C which has a half-life of 5730 years. On the time scale of big bang nucleosynthesis 14C can be considered as stable and further proton, alpha, deuteron, and neutron capture reactions on 14C will result in the production of heavier nuclei (A≥20). Due to the high neutron abundance it is expected that the 14C(n,γ) reaction competes strongly with the other reactions. The 14C(n,γ) reaction is also important to validate (n,γ) cross sections obtained via the inverse reaction by the Coulomb breakup method. 14C is one of the few nuclei where the (n,γ) reaction can be measured directly and compared with results of Coulomb breakup experiments, in this case on the neutron-rich isotope 15C. In this contribution we report on new measurements of the 14C(n,γ) reaction at neutron energies of 30, 150, and 500 keV using the fast cyclic activation technique.