A new low-level γ-ray spectrometry system for environmental radioactivity at the underground laboratory Felsenkeller
M. Köhler a , *, D.Degering a, M.Laubenstein b, P.Quirin c, M.-O.Lampert c, M.Hult d, D.Arnold e, S. Neumaier e, J.-L.Reyss f
a Verein für Kernverfahrenstechnik und Analytik Rossendorf e.V.(VKTA), P.O. Box 510119, D-01314 Dresden,Germanyb Laboratori Nazionali del Gran Sasso, INFN, S.S.17/bis km 18+910,I-67010 Assergi(AQ), Italy
c CANBERRA France, 1,chemin de la Roseraie, B.P.311, F-67834 Tanneries Cedex, France
d European Commission, Joint Research Centre, Institute for Reference Materials and Measurements (EC-JRC-IRMM) , Retieseweg111, B-2440Geel, Belgium
e Physikalisch-Technische Bundesanstalt, Bundesallee100, D-38116 Braunschweig, Germany
f LSCE/Valle´e, Centre des Faibles Radioactivite´s, Domaine du CNRS, Avenuede la Terrasse, F-91198 Gif-sur-Yvette Cedex, France
ABSTRACT
A low-level γ-ray spectrometry system, based on an HPGe-detector with 92% relative efficiency recently installed in the underground laboratory Felsenkeller at 110m water equivalent (w.e.) depth, is described. The integral background count rate normalised to the Ge-crystal mass in the energy range from 40 keV until 2.7 MeV of 0.034s¹ kg¹ has beena chieved by careful material selection of the detector construction material, a graded shielding construction and effective radon suppression. The detector is highly suitable for the effective surveillance of water for human consumption with decision thresholds for 226Ra and 228Ra in the order of some mBqL¹.
Keywords:
- Underground laboratory
- Low-level γ-ray spectrometry
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