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On background radiation gradients - the use of airborne surveys when searching for orphan sources using mobile gamma-ray spectrometry

Kock, Peder; Rääf, Christopher LU and Samuelsson, Christer LU (2014) In Journal of Environmental Radioactivity 128. p.84-90
Abstract
Systematic background radiation variations can lead to both false positives and failures to detect an orphan source when searching using car-borne mobile gamma-ray spectrometry. The stochastic variation at each point is well described by Poisson statistics, but when moving in a background radiation gradient the mean count rate will continually change, leading to inaccurate background estimations. Airborne gamma spectrometry (AGS) surveys conducted on the national level, usually in connection to mineral exploration, exist in many countries. These data hold information about the background radiation gradients which could be used at the ground level. This article describes a method that aims to incorporate the systematic as well as stochastic... (More)
Systematic background radiation variations can lead to both false positives and failures to detect an orphan source when searching using car-borne mobile gamma-ray spectrometry. The stochastic variation at each point is well described by Poisson statistics, but when moving in a background radiation gradient the mean count rate will continually change, leading to inaccurate background estimations. Airborne gamma spectrometry (AGS) surveys conducted on the national level, usually in connection to mineral exploration, exist in many countries. These data hold information about the background radiation gradients which could be used at the ground level. This article describes a method that aims to incorporate the systematic as well as stochastic variations of the background radiation. We introduce a weighted moving average where the weights are calculated from existing AGS data, supplied by the Geological Survey of Sweden. To test the method we chose an area with strong background gradients, especially in the thorium component. Within the area we identified two roads which pass through the high-variability locations. The proposed method is compared with an unweighted moving average. The results show that the weighting reduces the excess false positives in the positive background gradients without introducing an excess of failures to detect a source during passage in negative gradients. (C) 2013 Elsevier Ltd. All rights reserved. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Airborne, Background radiation, Orphan source, Mobile gamma spectrometry
in
Journal of Environmental Radioactivity
volume
128
pages
84 - 90
publisher
Elsevier
external identifiers
  • wos:000331481700012
  • scopus:84890232373
ISSN
1879-1700
DOI
10.1016/j.jenvrad.2013.10.022
language
English
LU publication?
yes
id
57c6bfd8-78cd-4703-bd87-1c5245699f08 (old id 4368410)
date added to LUP
2014-05-05 08:36:53
date last changed
2017-08-27 03:44:26
@article{57c6bfd8-78cd-4703-bd87-1c5245699f08,
  abstract     = {Systematic background radiation variations can lead to both false positives and failures to detect an orphan source when searching using car-borne mobile gamma-ray spectrometry. The stochastic variation at each point is well described by Poisson statistics, but when moving in a background radiation gradient the mean count rate will continually change, leading to inaccurate background estimations. Airborne gamma spectrometry (AGS) surveys conducted on the national level, usually in connection to mineral exploration, exist in many countries. These data hold information about the background radiation gradients which could be used at the ground level. This article describes a method that aims to incorporate the systematic as well as stochastic variations of the background radiation. We introduce a weighted moving average where the weights are calculated from existing AGS data, supplied by the Geological Survey of Sweden. To test the method we chose an area with strong background gradients, especially in the thorium component. Within the area we identified two roads which pass through the high-variability locations. The proposed method is compared with an unweighted moving average. The results show that the weighting reduces the excess false positives in the positive background gradients without introducing an excess of failures to detect a source during passage in negative gradients. (C) 2013 Elsevier Ltd. All rights reserved.},
  author       = {Kock, Peder and Rääf, Christopher and Samuelsson, Christer},
  issn         = {1879-1700},
  keyword      = {Airborne,Background radiation,Orphan source,Mobile gamma spectrometry},
  language     = {eng},
  pages        = {84--90},
  publisher    = {Elsevier},
  series       = {Journal of Environmental Radioactivity},
  title        = {On background radiation gradients - the use of airborne surveys when searching for orphan sources using mobile gamma-ray spectrometry},
  url          = {http://dx.doi.org/10.1016/j.jenvrad.2013.10.022},
  volume       = {128},
  year         = {2014},
}