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Title: Obelix, a new low-background HPGe at Modane Underground Laboratory

An ultra-low background coaxial HPGe detector for gamma-ray spectrometry with a relative efficiency of 160%, corresponding to a 600 cm{sup 3} Ge crystal, was installed at the Laboratoire Souterrain de Modane, France (4800 m.w.e). To reduce the instrinsic detector background, all parts involved in the detector cryostat were selected for their low radioactivity contamination. A shielding, composed of an inner layer of roman lead and an external layer of regular lead was installed, together with a system to reduce the Rn level inside the sample chamber. The shielding was designed to allow the measurement of Marinelli-shaped samples. We present the constructional details which lead to a remarkable low detector background of 73 cts/kg·d in [40, 3000] keV. Measured samples showed that sensitivities about 100 μBq/kg in {sup 226}Ra and {sup 228}Th are reached for samples of some kg and 30 days of lifetime.
Authors:
 [1] ;  [2] ; ;  [3] ;  [1] ;  [2] ; ;  [4] ; ;  [1]
  1. Laboratoire Souterrain de Modane, CNRS-CEA, 1125 route de Bardonnèche, 73500 Modane (France)
  2. (France)
  3. JINR, Joint Institute for Nuclear Research, 141980, Dubna (Russian Federation)
  4. IEAP, Czech Techincal University in Prague, 12800 Prague (Czech Republic)
Publication Date:
OSTI Identifier:
22488727
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1672; Journal Issue: 1; Conference: LRT 2015: 5. international workshop in low radioactivity techniques, Seattle, WA (United States), 18-20 Mar 2015; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; COMPUTERIZED TOMOGRAPHY; CRYOSTATS; CRYSTALS; DESIGN; EFFICIENCY; FRANCE; GAMMA DETECTION; GAMMA SPECTROSCOPY; HIGH-PURITY GE DETECTORS; KEV RANGE; LAYERS; LIFETIME; RADIOACTIVITY; RADIUM 226; SENSITIVITY; SHIELDING; THORIUM 228; UNDERGROUND