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Title: A Novel Low Background Cryogenic Detector for Radon in Gas

Abstract

A prototype of a new detector for measurements of radon in gases and radon emanation investigations is presented. It is based on the low-temperature collection of 222Rn on a stainless steel plate and the following counting of emitted alpha particles using a standard ORTEC semiconductor detector for alpha spectroscopy. A low background of the constructed system was achieved, in the order of 25 counts per day for the 222Rn energy window. Relatively high detection efficiency of 32% in 2{pi} geometry, and large volume of the detector allow radon concentration measurements at the level of 12 mBq/m3 with a 30% accuracy. The detector can be also used to measure short-lived 220Rn. In the next step we plan to improve the system so that we could reach the sensitivity of 1 mBq/m3. This can be achieved by reducing the background, improving the detection efficiency and/or increasing the active volume of the detector (with respect to the prototype)

Authors:
 [1];  [2]
  1. Marian Smoluchowski Institute of Physics, Reymonta 4, 30-059 Cracow (Poland)
  2. Max Planck Institute for Nuclear Physics, Saupfercheckweg 1, 69117 Heidelberg (Germany)
Publication Date:
OSTI Identifier:
21055025
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 897; Journal Issue: 1; Conference: LRT 2006: Topical workshop on low radioactivity techniques, Aussois (France), 1-4 Oct 2006; Other Information: DOI: 10.1063/1.2722066; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; ALPHA DETECTION; ALPHA PARTICLES; ALPHA SPECTROSCOPY; CRYOGENICS; EFFICIENCY; ION EMISSION; RADON; RADON 220; RADON 222; SEMICONDUCTOR DETECTORS; SEMICONDUCTOR DEVICES; SENSITIVITY; STAINLESS STEELS

Citation Formats

Wojcik, Marcin, and Zuzel, Grzegorz. A Novel Low Background Cryogenic Detector for Radon in Gas. United States: N. p., 2007. Web. doi:10.1063/1.2722066.
Wojcik, Marcin, & Zuzel, Grzegorz. A Novel Low Background Cryogenic Detector for Radon in Gas. United States. doi:10.1063/1.2722066.
Wojcik, Marcin, and Zuzel, Grzegorz. Wed . "A Novel Low Background Cryogenic Detector for Radon in Gas". United States. doi:10.1063/1.2722066.
@article{osti_21055025,
title = {A Novel Low Background Cryogenic Detector for Radon in Gas},
author = {Wojcik, Marcin and Zuzel, Grzegorz},
abstractNote = {A prototype of a new detector for measurements of radon in gases and radon emanation investigations is presented. It is based on the low-temperature collection of 222Rn on a stainless steel plate and the following counting of emitted alpha particles using a standard ORTEC semiconductor detector for alpha spectroscopy. A low background of the constructed system was achieved, in the order of 25 counts per day for the 222Rn energy window. Relatively high detection efficiency of 32% in 2{pi} geometry, and large volume of the detector allow radon concentration measurements at the level of 12 mBq/m3 with a 30% accuracy. The detector can be also used to measure short-lived 220Rn. In the next step we plan to improve the system so that we could reach the sensitivity of 1 mBq/m3. This can be achieved by reducing the background, improving the detection efficiency and/or increasing the active volume of the detector (with respect to the prototype)},
doi = {10.1063/1.2722066},
journal = {AIP Conference Proceedings},
number = 1,
volume = 897,
place = {United States},
year = {Wed Mar 28 00:00:00 EDT 2007},
month = {Wed Mar 28 00:00:00 EDT 2007}
}
  • Environmental radon ({sup 222}Rn) monitors that incorporate electret detectors are confounded by background gamma radiation, which may cause the electret to discharge by as much as 7.5 volts per mR. Although background gamma corrections were formerly made by multiplying the known background gamma exposure rate with a constant conversion factor, this research demonstrates that doing so introduces an error ranging up to about 20%, especially in high gamma background areas. A new, more accurate method of background gamma correction has been developed that uses an average, voltage-dependent discharge factor, D{sub {gamma}} (V Kg C{sup {minus}1}). This factor and its coefficientsmore » were experimentally determined by separately exposing groups of electret radon detectors to photons from {sup 60}Co and {sup 137}Cs. Statistical analysis shows that D{sub {gamma}} is independent of the orientation of the electret during irradiation but that some dependency on dose rate or energy of the irradiating photons may be expected. The discharge of the electret due only to gamma irradiation, V{sub {gamma}}, is determined by multiplying the total integrated gamma exposure by D{sub {gamma}}. The discharge of the electret during a radon measurement can then be corrected for background gamma radiation by subtracting V{sub {gamma}} from the total discharge of the electret resulting in a net discharge due solely to radon. A new equation has also been developed in this study for the radon discharge factor, D{sub Rn} (V m{sup 3}Bq{sup {minus}1} s{sup {minus}1}), that is entirely consistent with the gamma discharge radon detectors to known concentrations of radon.« less
  • The possibility of distortion in determinations of low radon concentration levels, typical for sea and ocean waters, due to radium-contamination of materials and matters of the apparatus for direct bubbling of water samples has been examined. The emanation effect for various adsorbents, drying agents, filtering and constructional materials has been measured. The apparatus back-ground could be reduced 3.5 times by using the results obtained. At least two washing cycles are needed to remove the background radon accumulated in the apparatus during the breaks in the work.