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Title: Low-level measuring techniques for neutrons: High accuracy neutron source strength determination and fluence rate measurement at an underground laboratory

We report on measuring techniques for neutrons that have been developed at the Physikalisch-Technische Bundesanstalt (PTB), the German National Metrology Institute. PTB has characterized radioactive sources used in the BOREXINO and XENON100 experiments. For the BOREXINO experiment, a {sup 228}Th gamma radiation source was required which would not emit more than 10 neutrons per second. The determination of the neutron emission rate of this specially designed {sup 228}Th source was challenging due to the low neutron emission rate and because the ratio of neutron to gamma radiation was expected to be extremely low, of the order of 10{sup −6}. For the XENON100 detector, PTB carried out a high accuracy measurement of the neutron emission rate of an AmBe source. PTB has also done measurements in underground laboratories. A two month measurement campaign with a set of {sup 3}He-filled proportional counters was carried out in PTB's former UDO underground laboratory at the Asse salt mine. The aim of the campaign was to determine the intrinsic background of detectors, which is needed for the analysis of data taken in lowintensity neutron fields. At a later time, PTB did a preliminary measurement of the neutron fluence rate at the underground laboratory Felsenkeller operatedmore » by VKTA. By taking into account data from UDO, Felsenkeller, and detector calibrations made at the PTB facility, it was possible to estimate the neutron fluence rate at the Felsenkeller underground laboratory.« less
Authors:
; ; ;  [1] ;  [2] ;  [3]
  1. Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig (Germany)
  2. Verein für Kernverfahrenstechnik und Analytik Rossendorf e. V. (VKTA), D-01314 Dresden (Germany)
  3. Technische Universität Dresden, D-01069 Dresden (Germany)
Publication Date:
OSTI Identifier:
22218201
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1549; Journal Issue: 1; Conference: LRT 2013: 4. international workshop on low radioactivity techniques, Assergi (Italy), 10-12 Apr 2013; Other Information: (c) 2013 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; ACCURACY; ASSE SALT MINE; CALIBRATION; DATA ANALYSIS; DESIGN; GAMMA DETECTION; GAMMA RADIATION; HELIUM 3; NEUTRON DETECTION; NEUTRON EMISSION; NEUTRON FLUENCE; NEUTRON SOURCES; NEUTRONS; PROPORTIONAL COUNTERS; SOLID SCINTILLATION DETECTORS; THORIUM 228; UNDERGROUND