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A method to determine the distance, shielding and activity of orphan 137Cs sources in mobile gamma spectrometric search

Rääf, Christopher LU orcid ; Jönsson, Mattias LU ; Dinca, Marius Catalin LU orcid and Finck, Robert LU (2025) In Radiation Protection Dosimetry 201(13-14). p.934-940
Abstract

A mobile gamma spectrometer's series of pulse height distributions (gamma spectra) acquired when passing a point source contains enough information to derive the distance to the source, its shielding and activity. Two Excel routines, SODAC and SSC, have been developed to determine these source parameters. SODAC determines the source-road distance by finding the best fit of the measured series of the primary photon peak count rates to a count rate function characteristic of the distance to the source. A possible source shield reduces the primary count rate and raises the count rate from Compton scattered photons in the shield. SSC calculates the shield mass thickness for common building material using ratio functions of scattered to... (More)

A mobile gamma spectrometer's series of pulse height distributions (gamma spectra) acquired when passing a point source contains enough information to derive the distance to the source, its shielding and activity. Two Excel routines, SODAC and SSC, have been developed to determine these source parameters. SODAC determines the source-road distance by finding the best fit of the measured series of the primary photon peak count rates to a count rate function characteristic of the distance to the source. A possible source shield reduces the primary count rate and raises the count rate from Compton scattered photons in the shield. SSC calculates the shield mass thickness for common building material using ratio functions of scattered to primary count rates obtained from measurements on known shielding geometries. SODAC then calculates the source activity. The technique was practically tested for 137Cs point sources but can also be applied to other gamma-emitting radionuclides.

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author
; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Radiation Protection Dosimetry
volume
201
issue
13-14
pages
7 pages
publisher
Oxford University Press
external identifiers
  • scopus:105014632238
  • pmid:40875268
ISSN
0144-8420
DOI
10.1093/rpd/ncaf016
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2025 The Author(s). Published by Oxford University Press.
id
678974ff-5983-404a-82c1-8d594abfb671
date added to LUP
2025-10-16 12:32:16
date last changed
2025-11-13 14:34:01
@article{678974ff-5983-404a-82c1-8d594abfb671,
  abstract     = {{<p>A mobile gamma spectrometer's series of pulse height distributions (gamma spectra) acquired when passing a point source contains enough information to derive the distance to the source, its shielding and activity. Two Excel routines, SODAC and SSC, have been developed to determine these source parameters. SODAC determines the source-road distance by finding the best fit of the measured series of the primary photon peak count rates to a count rate function characteristic of the distance to the source. A possible source shield reduces the primary count rate and raises the count rate from Compton scattered photons in the shield. SSC calculates the shield mass thickness for common building material using ratio functions of scattered to primary count rates obtained from measurements on known shielding geometries. SODAC then calculates the source activity. The technique was practically tested for <sup>137</sup>Cs point sources but can also be applied to other gamma-emitting radionuclides.</p>}},
  author       = {{Rääf, Christopher and Jönsson, Mattias and Dinca, Marius Catalin and Finck, Robert}},
  issn         = {{0144-8420}},
  language     = {{eng}},
  number       = {{13-14}},
  pages        = {{934--940}},
  publisher    = {{Oxford University Press}},
  series       = {{Radiation Protection Dosimetry}},
  title        = {{A method to determine the distance, shielding and activity of orphan <sup>137</sup>Cs sources in mobile gamma spectrometric search}},
  url          = {{http://dx.doi.org/10.1093/rpd/ncaf016}},
  doi          = {{10.1093/rpd/ncaf016}},
  volume       = {{201}},
  year         = {{2025}},
}