A fully-automated, liquid-moderated neutron spectrometer system Saull, Patrick R.B.; Archambault, John Paul
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2022, Letnik:
1041
Journal Article
Recenzirano
A novel, water-based, neutron spectroscopy system has been designed, simulated, and tested at the National Research Council of Canada. The active part of the detection system is a small proportional ...counter sensitive to thermal neutrons. The proportional counter is suspended along the symmetry axis of a large, rectangular water bath, and can be positioned remotely anywhere along this axis down to the bottom face. Measured count rates as a function of depth of the counter for both an americium-beryllium and a californium-252 neutron source demonstrate the ability of the system to discriminate between sources with different energy spectra. An MCNP6 simulation of an AmBe source agrees with the data within uncertainties at the 2%-level and is used to construct the response functions of the spectrometer system. Unfolded energy spectra are determined using an analysis of the singular value decomposition of the response matrix. Finally, a Monte Carlo study of the system indicates an ability to measure the fluence rate of the radionuclide sources.
A nuclear forensics investigation involving a uranium ore concentrate relies on accurate and precise analysis of impurities. Analytical data defensibility requires the use of reference materials as ...part of quality control. This study presents a compilation of trace element concentration results of the CUP-2 Uranium Ore Concentrate Standard measured by 11 different laboratories. The laboratories employed various dissolution methods, analytical preparation methods, and instrumental platforms. The data presented here contain concentrations of 66 impurities with up to 138 individual data points for each impurity. Consensus values have been assigned to each impurity following a statistical analysis of the data set.
The Silicon photomultiplier-based Compton Telescope for Safety and Security (SCoTSS) has been developed incorporating end-user requirements into the design process. The end-user group includes those ...responsible for mobile survey in the event of a radiological or nuclear accident, those responsible for radiation survey support to security operations at major events and at Canadian borders, as well as some of those responsible for Canadian defense applications. The SCoTSS development program has reached a technology readiness level of eight, and we are proceeding with field trials of the instrument in high-fidelity operational environments. Prospective end users have been involved in trial set up and execution, assuring applicability in their mission spaces. SCoTSS has been subject to trials involving hidden sources, heavily shielded sources, imager moving with respect to source, and complicated man-made surroundings. Our operators value high sensitivity for anomaly geolocation and mapping. End users also require an instrument which is capable of direction reconstruction in motion, as well as rapid imaging of a field of view. We have developed a “time to image” measure which allows for quantitative comparison of imagers of fundamentally different technology, where one design may have an advantage in terms of energy resolution and compactness and another design may have an advantage in terms of efficiency and cost effectiveness. We present here the performance of the SCoTSS imager in rapid direction finding. As well, we compare the time to image quantity for the SCoTSS imager and the H3D Polaris-H Quad imager where the data were taken under equivalent conditions. This quantitative measure of imaging performance can allow operators to make an informed choice of the design that meets their needs taking into consideration also weight and size as well as budgetary constraints.
The SiPM-based Compton Telescope for Safety and Security (SCoTSS) has been developed with inorganic crystalline scintillator material for gamma detection. The instrument is sensitive enough to be ...used in a mobile survey mode, accumulating energy deposited in any crystal second-by-second and tagging these spectra with GPS position. The SCoTSS imager of course has the additional advantage of being able to produce an image of the radioactive objects in its field of view using events that satisfy a coincidence trigger between the scatter and absorber layers. The Advanced Radiation Detector for UAV Operations (ARDUO) on the other hand, is a non-imaging directional detector intended for use aboard a small unmanned aerial vehicle (UAV). The ARDUO detector features exactly the same volume of CsI(Tl) as is used in the absorber layer of a single SCoTSS module, giving it similar detection and alarming sensitivity, and mapmaking capability. However, in the ARDUO detector, the crystals are arranged closely together to optimize direction determination from self-shielding effects. Flown in a grid pattern with a UAV over an area of extended contamination, the ARDUO detector is also capable of making a map or image of that area. With its close-packed crystal arrangement, the ARDUO detector makes a poor Compton imager but does have some ability to produce a peripheral image in a fly-by. In this presentation we investigate the relative merits of Compton imaging versus mobile directional detection.
A novel, water-based, neutron spectroscopy system has been designed, simulated, and tested at the National Research Council of Canada. The active part of the detection system is a small proportional ...counter sensitive to thermal neutrons. This is suspended along the symmetry axis of a large, rectangular water bath, and can be positioned remotely anywhere along this axis down to the bottom face. The energy spectrum of any constant neutron field impinging on this face from below the detector may be reconstructed with this system by mapping the thermal neutron response as a function of distance from the face, and using singular value decomposition to deduce the energy distribution. Agreement between experimental data from americium-beryllium neutron sources and the Monte Carlo software MCNP5 is excellent. Monte Carlo techniques are used to test the energy spectrum reconstruction using singular value decomposition for americium-boron and americium-beryllium neutron spectra.
Herein, a nuclear forensics investigation involving a uranium ore concentrate relies on accurate and precise analysis of impurities. Analytical data defensibility requires the use of reference ...materials as part of quality control. This study presents a compilation of trace element concentration results of the CUP-2 Uranium Ore Concentrate Standard measured by 11 different laboratories. The laboratories employed various dissolution methods, analytical preparation methods, and instrumental platforms. The data presented here contain concentrations of 66 impurities with up to 138 individual data points for each impurity. Consensus values have been assigned to each impurity following a statistical analysis of the data set.
The Silicon photomultiplier-based Compton Telescope for Safety and Security (SCoTSS) has been developed incorporating end-user requirements into the design process. The end-user group includes those ...responsible for mobile survey in the event of a radiological or nuclear accident, those responsible for radiation survey support to security operations at major events and at Canadian borders, as well as some of those responsible for Canadian defense applications. The SCoTSS development program has reached a technology readiness level of eight, and we are proceeding with field trials of the instrument in high-fidelity operational environments. Prospective end users have been involved in trial set up and execution, assuring applicability in their mission spaces. SCoTSS has been subject to trials involving hidden sources, heavily shielded sources, imager moving with respect to source, and complicated man-made surroundings. Our operators value high sensitivity for anomaly geolocation and mapping. End users also require an instrument which is capable of direction reconstruction in motion, as well as rapid imaging of a field of view. We have developed a "time to image" measure which allows for quantitative comparison of imagers of fundamentally different technology, where one design may have an advantage in terms of energy resolution and compactness and another design may have an advantage in terms of efficiency and cost effectiveness. We present here the performance of the SCoTSS imager in rapid direction finding. As well, we compare the time to image quantity for the SCoTSS imager and the H3D Polaris-H Quad imager where the data were taken under equivalent conditions. This quantitative measure of imaging performance can allow operators to make an informed choice of the design that meets their needs taking into consideration also weight and size as well as budgetary constraints.
The SiPM-based Compton Telescope for Safety and Security (SCoTSS) has been developed with inorganic crystalline scintillator material for gamma detection. The instrument is sensitive enough to be ...used in a mobile survey mode, accumulating energy deposited in any crystal second-by-second and tagging these spectra with GPS position. The SCoTSS imager of course has the additional advantage of being able to produce an image of the radioactive objects in its field of view using events that satisfy a coincidence trigger between the scatter and absorber layers. The Advanced Radiation Detector for UAV Operations (ARDUO) on the other hand, is a non-imaging directional detector intended for use aboard a small unmanned aerial vehicle (UAV). The ARDUO detector features exactly the same volume of CsI(Tl) as is used in the absorber layer of a single SCoTSS module, giving it similar detection and alarming sensitivity, and map-making capability. However, in the ARDUO detector, the crystals are arranged closely together to optimize direction determination from self-shielding effects. Flown in a grid pattern with a UAV over an area of extended contamination, the ARDUO detector is also capable of making a map or image of that area. With its close-packed crystal arrangement, the ARDUO detector makes a poor Compton imager but does have some ability to produce a peripheral image in a fly-by. In this presentation we investigate the relative merits of Compton imaging versus mobile directional detection.
A Compton gamma imager has been developed for use in consequence management operations and in security investigations. The imager uses solid inorganic scintillator, known for robust performance in ...field survey conditions. The design was constrained in overall size by the requirement that it be person transportable and operable from a variety of platforms. In order to introduce minimal dead material in the path of the incoming and scattered gamma rays, custom silicon photomultipliers (SiPMs), with a thin glass substrate, were used to collect the scintillation light from the scatter layers. To move them out of the path of the gamma rays, preamplification electronics for the silicon photomultipliers were located a distance from the imager. This imager, the Silicon photomultiplier Compton Telescope for Safety and Security (SCoTSS) is able to provide a one-degree image resolution in a plus-minus 45 degree field of view for a 10 mCi point source 40 m distant, within about one minute, for gamma-ray energies ranging from 344 keV to 1274 keV. Here, we present a comprehensive performance study of the SCoTSS imager.
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