München 2009 – wissenschaftliches Programm
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T: Fachverband Teilchenphysik
T 103: Niederenergie-Neutrinophysik & Suche nach dunkler Materie 4
T 103.6: Vortrag
Donnerstag, 12. März 2009, 18:05–18:20, A140
Low background gamma spectroscopy and neutron activation analysis for Double Chooz — •Martin Hofmann, Franz von Feilitzsch, Marianne Göger-Neff, Hermann Hagn, Lothar Oberauer, and Water Potzel — Technische Universität München
To check the radiopurity of detector components of the reactor neutrino oscillation experiment Double Chooz, low background gamma spectroscopy measurements have been performed at the Garching underground lab using a 150% germanium counter surrounded by active and passive shielding systems. The active shielding consists of an anti-Compton veto and a muon veto. Upper limits on the activities of radioisotopes originating from the uranium and thorium decay chains, as well as potassium-40, can be given in the order of 10−10 g/g. An even higher sensitivity can be obtained by neutron activation analysis performed on the wavelength shifter PPO and the acrylics used for the detector tank. The samples were irradiated for ten minutes at the FRM2 with a thermal neutron flux of (1.63 ± 0.05) · 1013 cm−2s−1. Thereafter, the spectra of the irradiated samples were recorded using the germanium counting system mentioned above, mainly focussing on the isotope potassium-42. The content of potassium-40 could be determined to be of the order of 10−11 g/g.
This work has been supported by funds of the DFG (Transregio 27: Neutrinos and beyond), the Excellence Cluster Universe and the Maier-Leibnitz-Laboratorium Garching.