Hannover 2010 – wissenschaftliches Programm

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MS: Fachverband Massenspektrometrie

MS 4: Beschleunigermassenspektrometrie und Anwendungen I

MS 4.5: Vortrag

Mittwoch, 10. März 2010, 11:45–12:00, F 428

Production of a ⁵⁵Fe-AMS standard and Neutron Capture on ⁵⁴Fe — •Kathrin Buczak¹, Tamás Belgya², Max Bichler³, Oliver Forstner¹, Robin Golser¹, Walter Kutschera¹, Claudia Lederer¹, Alfred Priller¹, Peter Steier¹, and Anton Wallner¹ — ¹VERA Laboratory, Faculty of Physics - Isotope Research, Univ. of Vienna, Austria — ²Institute of Isotopes HAS, Dept. of Nuclear Research, Hungary — ³Atominstitut, TU Wien, Austria

The interest in neutron capture on ⁵⁴Fe is linked to: studies of nucleo-synthesis in stellar environments, radioactive waste generation in fusion reactors and the half-life value of the long-lived ⁵⁹Ni. For the measurement of the thermal neutron capture cross section σ(⁵⁴Fe(n,γ)⁵⁵Fe), irradiations have been performed at the TRIGA reactor in Vienna, and with cold neutrons at the Budapest Research Reactor. The radionuclide ⁵⁵Fe (t_1/2 = 2.7 yr) produced in these activations, was measured at VERA (Vienna Environmental Research Accelerator) via accelerator mass spectrometry (AMS). Such isotope-ratio measurements, however, require an accurate ⁵⁵Fe-AMS standard as reference material: (1) At VERA, iron samples, highly enriched in ⁵⁴Fe, were bombarded with 5.5 MeV protons to produce ⁵⁵Co (t_1/2 = 17.53 h), which decays to ⁵⁵Fe. The total number of daughter-nuclides ⁵⁵Fe was determined from the measured ⁵⁵Co-activity. (2) Another, independent standard was produced by a dilution series of a certified ⁵⁵Fe-standard-solution. The cross section value is expected to be accurate at a level of ± 3% and is directly coupled to a previous ⁵⁹Ni half-life value. The measurement procedure and the latest results will be presented.