| 11. |
- Scherzinger, Julius, et al.
(author)
-
Tagging fast neutrons from a Cf-252 fission-fragment source
- 2017
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In: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 128, s. 270-274
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Journal article (peer-reviewed)abstract
- Coincidence and time-of-flight measurement techniques are employed to tag fission neutrons emitted from a Cf-252 source sealed on one side with a very thin layer of Au. The source is positioned within a gaseous He-4 scintillator detector. Together with a particles, both light and heavy fission fragments pass through the thin layer of Au and are detected. The fragments enable the corresponding fission neutrons, which are detected in a NE-213 liquid-scintillator detector, to be tagged. The resulting continuous polychromatic beam of tagged neutrons has an energy dependence that agrees qualitatively with expectations. We anticipate that this technique will provide a cost-effective means for the characterization of neutron-detector efficiency in the energy range 1-6 MeV.
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| 12. |
- Scherzinger, J., et al.
(author)
-
Tagging fast neutrons from an 241Am/9Be source
- 2015
-
In: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 98, s. 74-79
-
Journal article (peer-reviewed)abstract
- Shielding, coincidence, and time-of-flight measurement techniques are employed to tag fast neutrons emitted from an 241Am/9Be source resulting in a continuous polychromatic energy-tagged beam of neutrons with energies up to 7MeV. The measured energy structure of the beam agrees qualitatively with both previous measurements and theoretical calculations.
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| 13. |
- Vesterlund, Anna, 1980, et al.
(author)
-
Characterization of strong 241Am sources
- 2015
-
In: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 99, s. 162-167
-
Journal article (peer-reviewed)abstract
- Gamma ray spectra of strong 241Am sources may reveal information about the source composition as there may be other radioactive nuclides such as progeny and radioactive impurities present. In this work the possibility to use gamma spectrometry to identify inherent signatures in 241Am sources in order to differentiate sources from each other, is investigated. The studied signatures are age, i.e. time passed since last chemical separation, and presence of impurities. The spectra of some sources show a number of Doppler broadened peaks in the spectrum which indicate the presence of nuclear reactions on light elements within the sources. The results show that the investigated sources can be differentiated between by age and/or presence of impurities. These spectral features would be useful information in a national nuclear forensics library (NNFL) in cases when the visual information on the source, e.g. the source number, is unavailable.
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| 14. |
- Vidmar, T., et al.
(author)
-
Equivalence of computer codes for calculation of coincidence summing correction factors - Part II
- 2016
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In: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 109, s. 482-486
-
Journal article (peer-reviewed)abstract
- The aim of this study was to check for equivalence of computer codes that are capable of performing calculations of true coincidence summing (TCS) correction factors. All calculations were performed for a set of well-defined detector parameters, sample parameters and decay scheme data. The studied geometry was a point source of Ba-133 positioned directly on the detector window of a low-energy (n-type) detector. Good agreement was established between the TCS correction factors computed by the different codes.
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| 15. |
- Bukartas, A., et al.
(author)
-
A Bayesian method to localize lost gamma sources
- 2019
-
In: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043. ; 145, s. 142-147
-
Journal article (peer-reviewed)abstract
- A feasibility study of a Bayesian based algorithm for orphan source localization by means of mobile gamma spectrometry is presented. The method was tested on three types of gamma sources (137Cs, 133Ba and 131I) using a HPGe detector mounted on a vehicle. Estimates on source activity and source locations were within 51% and 29% of actual values, respectively. Further studies are required to validate and develop this method for additional source-detector configurations and gamma radiation background conditions.
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| 16. |
- Herrnsdorf, Lars, et al.
(author)
-
Construction and evaluation of a real-time personal dosemeter based on a Si sensor for eye-dose measurement
- 2019
-
In: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043. ; 147, s. 171-176
-
Journal article (peer-reviewed)abstract
- The objective was to design a thin, flex card based personal dosemeter with low angular and energy dependence. It is based on silicon diodes that can measure the personal dose equivalent. Anisotropic conducting adhesive was used to connect the Si sensor to the flex card. Its intended use is for interventional radiology and after nuclear or radiological accidents, as it provides immediate detailed information about the dose rate to the wearer during shorter periods and integrates the dose rate during hours. It can be freely placed all over the body. By placing the dosemeter close to the eyes, it may be possible to estimate the personal dose equivalent as well as the dose at the lens of the eye.
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| 17. |
- Mandujano-Garcia, C. D., et al.
(author)
-
Radiological impact of natural radionuclides from soils of Salamanca, Mexico
- 2016
-
In: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043. ; 117, s. 91-95
-
Journal article (peer-reviewed)abstract
- Salamanca is the centre of a large industrial complex associated with the production and refining of oil-derived products in the state of Guanajuato, Mexico. The city also hosts a large chemical industry, and in past years a major fertilizer industry. All of them followed NORM (naturally occurring radioactive materials) industrial activities, where either raw materials or residues enriched in natural radionuclides are handled or generated, which can have an environmental radiological impact on their environmental compartments (e.g. soils and aquatic systems). In this study, activity concentrations of radionuclides from the U-238 and Th-232 natural series present in superficial urban soils surrounding an industrial complex in Salamanca, Mexico, have been determined to analyse the possible environmental radiological impact of some of the industrial activities. The alpha-particle and gamma-ray spectrometry is used for the radiometric characterization. The results revealed the presence of 10-42, 11-51 and 178-811 Bq/kg of (238)u, Th-232 and K-40, respectively, without any clear anthropogenic increment in relation to the values normally found in unaffected soils. Thus, the radioactive impact of the industrial activities on the surrounding soils can be evaluated as very low, representing no radiological risk for the health of the population. (C) 2016 Elsevier Ltd. All rights reserved.
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| 18. |
- Nilsson, Jenny, et al.
(author)
-
Identifying key surface parameters for optical photon transport in GEANT4/GATE simulations
- 2015
-
In: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043. ; 103, s. 15-24
-
Journal article (peer-reviewed)abstract
- For a scintillator used for spectrometry, the generation, transport and detection of optical photons have a great impact on the energy spectrum resolution. A complete Monte Carlo model of a scintillator includes a coupled ionizing particle and optical photon transport, which can be simulated with the GEANT4 code. The GEANT4 surface parameters control the physics processes an optical photon undergoes when reaching the surface of a volume. In this work the impact of each surface parameter on the optical transport was studied by looking at the optical spectrum: the number of detected optical photons per ionizing source particle from a large plastic scintillator, i.e. the output signal. All simulations were performed using GATE v6.2 (GEANT4 Application for Tomographic Emission). The surface parameter finish (polished, ground, front-painted or back-painted) showed the greatest impact on the optical spectrum whereas the surface parameter sigma alpha, controls the surface roughness, had a relatively small impact. It was also shown how the surface parameters reflectivity and reflectivity types (specular spike, specular lobe, Lambertian and backscatter) changed the optical spectrum depending on the probability for reflection and the combination of reflectivity types. A change in the optical spectrum will ultimately have an impact on a simulated energy spectrum. By studying the optical spectra presented in this work, a GEANT4 user can predict the shift in an optical spectrum caused be the alteration of a specific surface parameter. (C) 2015 Elsevier Ltd. All rights reserved.
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| 19. |
- Scherzinger, Julius, et al.
(author)
-
Tagging fast neutrons from an (241)Am/(9)Be source.
- 2015
-
In: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043. ; 98, s. 74-79
-
Journal article (peer-reviewed)abstract
- Shielding, coincidence, and time-of-flight measurement techniques are employed to tag fast neutrons emitted from an (241)Am/(9)Be source resulting in a continuous polychromatic energy-tagged beam of neutrons with energies up to 7MeV. The measured energy structure of the beam agrees qualitatively with both previous measurements and theoretical calculations.
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| 20. |
- Östlund, Karl, et al.
(author)
-
Experimentally determined vs. Monte Carlo simulated peak-to-valley ratios for a well-characterised n-type HPGe detector.
- 2015
-
In: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043. ; 95, s. 94-100
-
Journal article (peer-reviewed)abstract
- Measurements and simulations to investigate the contributing factors to the peak-to-valley (PTV) ratio have been both experimentally determined as well as Monte Carlo simulated for a well-characterised HPGe n-type detector together with a Cs-137 gamma source encapsulated in thin polystyrene. Measurements were carried out in a low-background gamma counting facility at Lund University. The results of the PTV ratio have been compared to distinguish what components or variables in the setup that significantly influence the ratio. In addition to manufacture specifications, the detector components have been examined using planar X-ray, source scanning and computer tomography in order to determine and verify component dimensions when necessary. In spite of these efforts a discrepancy of approximately 25% for thin absorbers in the PTV ratio between measurements and calculations is observed. However, this discrepancy becomes less significant for larger absorbing layers of copper (>1mm). This indicates that it would be difficult to achieve a field calibration for in-situ gamma spectrometry using the PTV ratio that could position a Cs-137 source in soil depth shallower than corresponding 1mm layer of copper. The results also showed that when building a detector in simulations part by part, the inner dead layer, and the contact pin are of great importance for the accuracy of the PTV ratio simulations.
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