A rotating-slit-collimator-based gamma radiation mapper

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A rotating-slit-collimator-based gamma radiation mapper. / Nilsson, Jonas M.C.; Finck, Robert R.; Rääf, Christopher L.

I: Journal of Environmental Radioactivity, Vol. 177, 01.10.2017, s. 225-232.

Forskningsoutput: TidskriftsbidragArtikel i vetenskaplig tidskrift

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TY - JOUR

T1 - A rotating-slit-collimator-based gamma radiation mapper

AU - Nilsson, Jonas M.C.

AU - Finck, Robert R.

AU - Rääf, Christopher L.

PY - 2017/10/1

Y1 - 2017/10/1

N2 - 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.

AB - 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.

KW - Collimator

KW - Deconvolution

KW - Gamma radiation

KW - HPGe

KW - Image reconstruction

KW - Mapping

U2 - 10.1016/j.jenvrad.2017.07.007

DO - 10.1016/j.jenvrad.2017.07.007

M3 - Article

C2 - 28711774

AN - SCOPUS:85023641968

VL - 177

SP - 225

EP - 232

JO - Journal of Environmental Radioactivity

JF - Journal of Environmental Radioactivity

SN - 1879-1700

ER -