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Title: An unattended device for high-voltage sampling and passive measurement of thoron decay products

An integrating measurement device for the concentration of airborne thoron decay products was designed and calibrated. It is suitable for unattended use over up to several months also in inhabited dwellings. The device consists of a hemispheric capacitor with a wire mesh as the outer electrode on ground potential and the sampling substrates as the inner electrode on +7.0 kV. Negatively charged and neutral thoron decay products are accelerated to and deposited on the sampling substrates. As sampling substrates, CR39 solid-state nuclear track detectors are used in order to record the alpha decay of the sampled decay products. Nuclide discrimination is achieved by covering the detectors with aluminum foil of different thickness, which are penetrated only by alpha particles with sufficient energy. Devices of this type were calibrated against working level monitors in a thoron experimental house. The sensitivity was measured as 9.2 tracks per Bq/m{sup 3} × d of thoron decay products. The devices were used over 8 weeks in several houses built of earthen material in southern Germany, where equilibrium equivalent concentrations of 1.4–9.9 Bq/m{sup 3} of thoron decay products were measured.
Authors:
; ; ;  [1] ;  [2]
  1. Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Radiation Protection, Ingolstädter Landstr. 1, 85764 Neuherberg (Germany)
  2. Helmholtz Zentrum München, German Research Center for Environmental Health, Auswertungsstelle für Strahlendosimeter, Otto-Hahn-Ring 6, 81739 München (Germany)
Publication Date:
OSTI Identifier:
22255047
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 85; Journal Issue: 2; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; ABUNDANCE; ALPHA DECAY; ALPHA PARTICLES; ALUMINIUM; CONCENTRATION RATIO; DAUGHTER PRODUCTS; HOUSES; PARTICLE TRACKS; RADIOECOLOGICAL CONCENTRATION; RADON 220; SAMPLING; SUBSTRATES