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A rotating-slit-collimator-based gamma radiation mapper

Nilsson, Jonas M.C. LU ; Finck, Robert R. LU and Rääf, Christopher L. LU (2017) In Journal of Environmental Radioactivity 177. p.225-232
Abstract

For situations with radioactive material out of control where it may be physically difficult or prohibited to access areas close to the source, measurements from distance may be the only way to assess the radiation environment. Using collimated detectors will provide means to locate the direction of the radiation from the source. To investigate the possibilities of mapping gamma emitting radioactive material in a closed non-enterable area, a tentative system for mapping radioactive materials from a distance was built. The system used a computer controlled cylindrical rotating slit collimator with a high purity germanium detector placed in the cylinder. The system could be placed on a car-towed trailer, with the centre of the detector... (More)

For situations with radioactive material out of control where it may be physically difficult or prohibited to access areas close to the source, measurements from distance may be the only way to assess the radiation environment. Using collimated detectors will provide means to locate the direction of the radiation from the source. To investigate the possibilities of mapping gamma emitting radioactive material in a closed non-enterable area, a tentative system for mapping radioactive materials from a distance was built. The system used a computer controlled cylindrical rotating slit collimator with a high purity germanium detector placed in the cylinder. The system could be placed on a car-towed trailer, with the centre of the detector about 1.4 m above ground. Mapping was accomplished by the use of a specially developed image reconstruction algorithm that requires measurements from two or more locations around the area to be investigated. The imaging capability of the system was tested by mapping an area, 25 by 25 m2, containing three 330 MBq 137Cs point sources. Using four locations outside the area with about 20 min measuring time in each location and applying the image reconstruction algorithm on the deconvoluted data, the system indicated the three source locations with an uncertainty of 1–3 m. The results demonstrated the potential of using collimated mobile gamma radiometry combined with image reconstruction to localize gamma sources inside non-accessible areas.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Collimator, Deconvolution, Gamma radiation, HPGe, Image reconstruction, Mapping
in
Journal of Environmental Radioactivity
volume
177
pages
8 pages
publisher
Elsevier
external identifiers
  • scopus:85023641968
  • wos:000411301700025
ISSN
0265-931X
DOI
10.1016/j.jenvrad.2017.07.007
language
English
LU publication?
yes
id
a6839fb5-fdc7-41bf-8fe8-ebb4a7595191
date added to LUP
2017-07-27 08:51:03
date last changed
2018-01-16 13:21:53
@article{a6839fb5-fdc7-41bf-8fe8-ebb4a7595191,
  abstract     = {<p>For situations with radioactive material out of control where it may be physically difficult or prohibited to access areas close to the source, measurements from distance may be the only way to assess the radiation environment. Using collimated detectors will provide means to locate the direction of the radiation from the source. To investigate the possibilities of mapping gamma emitting radioactive material in a closed non-enterable area, a tentative system for mapping radioactive materials from a distance was built. The system used a computer controlled cylindrical rotating slit collimator with a high purity germanium detector placed in the cylinder. The system could be placed on a car-towed trailer, with the centre of the detector about 1.4 m above ground. Mapping was accomplished by the use of a specially developed image reconstruction algorithm that requires measurements from two or more locations around the area to be investigated. The imaging capability of the system was tested by mapping an area, 25 by 25 m<sup>2</sup>, containing three 330 MBq <sup>137</sup>Cs point sources. Using four locations outside the area with about 20 min measuring time in each location and applying the image reconstruction algorithm on the deconvoluted data, the system indicated the three source locations with an uncertainty of 1–3 m. The results demonstrated the potential of using collimated mobile gamma radiometry combined with image reconstruction to localize gamma sources inside non-accessible areas.</p>},
  author       = {Nilsson, Jonas M.C. and Finck, Robert R. and Rääf, Christopher L.},
  issn         = {0265-931X},
  keyword      = {Collimator,Deconvolution,Gamma radiation,HPGe,Image reconstruction,Mapping},
  language     = {eng},
  month        = {10},
  pages        = {225--232},
  publisher    = {Elsevier},
  series       = {Journal of Environmental Radioactivity},
  title        = {A rotating-slit-collimator-based gamma radiation mapper},
  url          = {http://dx.doi.org/10.1016/j.jenvrad.2017.07.007},
  volume       = {177},
  year         = {2017},
}