The Experts below are selected from a list of 113184 Experts worldwide ranked by ideXlab platform
Sara A Pozzi - One of the best experts on this subject based on the ideXlab platform.
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imaging special Nuclear Material using a handheld dual particle imager
Scientific Reports, 2020Co-Authors: William M Steinberger, Marc L Ruch, Nathan P Giha, Angela Di Fulvio, Peter Marleau, Shaun D Clarke, Sara A PozziAbstract:A compact radiation imaging system capable of detecting, localizing, and characterizing special Nuclear Material (e.g. highly-enriched uranium, plutonium…) would be useful for national security missions involving inspection, emergency response, or war-fighters. Previously-designed radiation imaging systems have been large and bulky with significant portions of volume occupied by photomultiplier tubes (PMTs). The prototype imaging system presented here uses silicon photomultipliers (SiPMs) in place of PMTs because SiPMs are much more compact and operate at low power and voltage. The SiPMs are coupled to the ends of eight stilbene organic scintillators, which have an overall volume of 5.74 × 5.74 × 7.11 cm3. The prototype dual-particle imager's capabilities were evaluated by performing measurements with a 252Cf source, a sphere of 4.5 kg of alpha-phase weapons-grade plutonium known as the BeRP ball, a 6 kg sphere of neptunium, and a canister of 3.4 kg of plutonium oxide (7% 240Pu and 93% 239Pu). These measurements demonstrate neutron spectroscopic capabilities, a neutron image resolution for a Watt spectrum of 9.65 ± 0.94° in the azimuthal direction and 22.59 ± 5.81° in the altitude direction, imaging of gamma rays using organic scintillators, and imaging of multiple sources in the same field of view.
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localization and spectral isolation of special Nuclear Material using stochastic image reconstruction
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2017Co-Authors: Michael C Hamel, Alexis Poitrassonriviere, Shaun D Clarke, J K Polack, Sara A PozziAbstract:Abstract In this work we present a technique for isolating the gamma-ray and neutron energy spectra from multiple radioactive sources localized in an image. Image reconstruction algorithms for radiation scatter cameras typically focus on improving image quality. However, with scatter cameras being developed for non-proliferation applications, there is a need for not only source localization but also source identification. This work outlines a modified stochastic origin ensembles algorithm that provides localized spectra for all pixels in the image. We demonstrated the technique by performing three experiments with a dual-particle imager that measured various gamma-ray and neutron sources simultaneously. We showed that we could isolate the peaks from 22 Na and 137 Cs and that the energy resolution is maintained in the isolated spectra. To evaluate the spectral isolation of neutrons, a 252 Cf source and a PuBe source were measured simultaneously and the reconstruction showed that the isolated PuBe spectrum had a higher average energy and a greater fraction of neutrons at higher energies than the 252 Cf. Finally, spectrum isolation was used for an experiment with weapons grade plutonium, 252 Cf, and AmBe. The resulting neutron and gamma-ray spectra showed the expected characteristics that could then be used to identify the sources.
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statistical estimation of the performance of a fast neutron multiplicity system for Nuclear Material accountancy
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2015Co-Authors: David L Chichester, James T Johnson, Scott J Thompson, Marek Flaska, Mathew T Kinlaw, J L Dolan, Sara A PozziAbstract:Abstract Statistical analyses have been performed to develop bounding estimates of the expected performance of a conceptual fast-neutron multiplicity system (FNMS) for assaying plutonium. The conceptual FNMS design includes 32 cubic liquid scintillator detectors, measuring 7.62 cm per side, configured into 4 stacked rings of 8 detectors each. Expected response characteristics for the individual FNMS detectors, as well as the response characteristics of the entire FNMS, were determined using Monte Carlo simulations based on prior validation experiments. The results from these simulations were then used to estimate the Pu assay capabilities of the FNMS in terms of counting time, assay mass, and assay mass variance, using assay mass variance as a figure of merit. The analysis results are compared against a commonly used thermal-neutron coincidence counter. The advantages of using a fast-neutron counting system versus a thermal-neutron counting system are significant. Most notably, the time required to perform an assay to an equivalent assay mass variance is greatly reduced with a fast-neutron system, by more than an order of magnitude compared with that of the thermal-neutron system, due to the reduced probability of random summing with the fast system. The improved FNMS performance is especially relevant for assays involving Pu masses of 10 g or more.
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gamma neutron time correlation for special Nuclear Material detection active stimulation of highly enriched uranium
Annals of Nuclear Energy, 2014Co-Authors: Marc G Paff, Peter Marleau, Shaun D Clarke, Mateusz Monterial, Scott D Kiff, Aaron B Nowack, Sara A PozziAbstract:Abstract The time-correlated pulse-height technique can distinguish multiplying (special Nuclear Material) from non-multiplying sources. The technique relies upon the measurement of correlated photon–neutron pairs using organic liquid scintillation detectors. For such interactions, the distribution of measured neutron recoil energy versus the time-of-flight difference between correlated photons and neutrons are imprinted with the fission chain dynamics of the source. The theoretical time-of-arrival assuming the photons and neutrons are created in the same fission is calculated. Correlated pairs with longer time-of-arrival indicate delays caused by self-induced fission chains in a multiplying source. For the specific circumstances of simulated measurements of 25.4 kg of highly enriched uranium at 50 cm source to detector distance, correlated pairs from fission chains can arrive upwards of 40 ns later than correlated pairs with the same neutron energies from non-multiplying sources like 252 Cf at the same source detector distance. The use of detectors with ns scale time resolution and the use of pulse digitization allows for the distinction of these events. This method has been used successfully in the past to measure a variety of plutonium-bearing samples. The particle transport code MCNPX-PoliMi has been used to simulate and validate these measurements as well. Due to the much lower signature emission rate of 235 U, this technique has not yet been used to measure the presence of highly enriched uranium. In this work we therefore explore the use of the time-correlated pulse-height technique with the introduction of an interrogating neutron source to stimulate fission. The applicability of 252 Cf, AmLi and a DD generator neutron sources is explored in a series of simulations. All three sources are viable options with their own pros and cons with the choice of appropriate source depending upon the intended application. The TCPH technique is envisioned as a viable measurement solution of special Nuclear Material in situations in which the presence of shielding Material disqualifies the use of passive gamma spectroscopy or gamma spectroscopy reveals classified information on the special Nuclear Material’s isotopic composition.
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dual particle imager for standoff detection of special Nuclear Material
IEEE Nuclear Science Symposium, 2011Co-Authors: Kyle J Polack, Shaun D Clarke, Alexis Poitrassonriviere, Michael C Hamel, Kiyotaka Ide, Kyle Mcmillan, Marek Flaska, Sara A PozziAbstract:An advanced dual-particle imaging system is being developed for standoff, passive detection of special Nuclear Material. This system consists of three detector planes and will be capable of imaging both photons and fast neutrons. The ability of the system to detect fast neutrons makes it more difficult to effectively shield a threat source. This feature has an advantage over the commonly used Compton-camera systems, which are only sensitive to photons. Additionally, the detection of fast neutrons will allow for increased performance in regions with high levels of photon background radiation. The first two planes of the system consist of EJ-309 liquid scintillators and the third plane consists of NaI scintillators. This detector/plane combination allows image reconstruction using both neutrons and photons. In the liquid scintillators, neutron interactions are distinguished from photon interactions using an optimized pulse shape discrimination technique. The Monte Carlo transport code MCNPX-PoliMi has been used for the initial studies of this system due to its ability to track detailed information on interactions of interest and time-correlated particle production. This information has been used to optimize system parameters and has also allowed for investigation of image reconstruction techniques including simple backprojection and maximum likelihood expectation maximization (MLEM). A small-scale prototype is being developed for testing and validation of the simulations. This paper will analyze preliminary measurements and will also discuss simulations of several shielded source scenarios.
Michael J Kristo - One of the best experts on this subject based on the ideXlab platform.
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Nuclear forensic science analysis of Nuclear Material out of regulatory control
Annual Review of Earth and Planetary Sciences, 2016Co-Authors: Michael J Kristo, Amy M Gaffney, N E Marks, K B Knight, William S Cassata, I D HutcheonAbstract:Nuclear forensic science seeks to identify the origin of Nuclear Materials found outside regulatory control. It is increasingly recognized as an integral part of a robust Nuclear security program. This review highlights areas of active, evolving research in Nuclear forensics, with a focus on analytical techniques commonly employed in Earth and planetary sciences. Applications of Nuclear forensics to uranium ore concentrates (UOCs) are discussed first. UOCs have become an attractive target for Nuclear forensic researchers because of the richness in impurities compared to Materials produced later in the fuel cycle. The development of chronometric methods for age dating Nuclear Materials is then discussed, with an emphasis on improvements in accuracy that have been gained from measurements of multiple radioisotopic systems. Finally, papers that report on casework are reviewed, to provide a window into current scientific practice.
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Nuclear forensics scientific analysis supporting law enforcement and Nuclear security investigations
Analytical Chemistry, 2016Co-Authors: Elizabeth Keegan, Michael J Kristo, Kaitlyn Toole, Ruth Kips, Emma YoungAbstract:Nuclear forensic science, or "Nuclear forensic", aims to answer questions about Nuclear Material found outside of regulatory control. In this Feature, we provide a general overview of Nuclear forensics, selecting examples of key "Nuclear forensic signatures" which have allowed investigators to determine the identity of unknown Nuclear Material in real investigations.
Sean M Mcdeavitt - One of the best experts on this subject based on the ideXlab platform.
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tension metastable fluid detection systems for special Nuclear Material detection and monitoring
Nuclear Engineering and Design, 2010Co-Authors: J Lapinskas, Rusi P Taleyarkhan, Stephen M Zielinski, Jeffrey A Webster, Sean M McdeavittAbstract:Abstract Tension metastable fluid states offer unique potential for radical transformation in radiation detection capabilities. States of tension metastability may be obtained in tailored resonant acoustic systems such as the acoustic tension metastable fluid detector (ATMFD) system or via centrifugal force based systems such as the centrifugal tension metastable fluid detector (CTMFD) system; both under development at Purdue University. In this paper we describe research results with CTMFD systems for use in the detection of key actinide isotopes constituting special Nuclear Materials (SNMs) in spent fuel. Tests in a CTMFD system demonstrate the ability to detect alpha activity (at ∼100% efficiency) of U-isotopes at concentrations of ∼100 ppb (which is unprecedented and about ×100–1000 more sensitive than from conventional liquid scintillation spectroscopy). An inherent capability of TMFD systems concerns on demand tailoring of fluid tension levels allowing for energy discrimination and spectroscopy. This appears especially useful to detect the key isotopes of U and other transuranic isotopes of Pu, Np, Am, and Cm that are at different stages of Nuclear fuel reprocessing (i.e., UREX+).
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tension metastable fluid detection systems for special Nuclear Material detection and monitoring
Volume 4: Codes Standards Licensing and Regulatory Issues; Student Paper Competition, 2009Co-Authors: J Lapinskas, Rusi P Taleyarkhan, Stephen M Zielinski, Jeffrey A Webster, Sean M McdeavittAbstract:Tension metastable fluid states offer unique potential for radical transformation in radiation detection capabilities. States of tension metastability may be obtained in tailored resonant acoustic systems such as the acoustic tension metastable fluid detector (ATMFD) system or via centrifugal force based systems such as the centrifugal tension metastable fluid detector (CTMFD) system; both under development at Purdue University. Tension metastable fluid detector (TMFD) systems take advantage of the weakened intermolecular bonds of liquids in sub-vacuum states. Nuclear particles incident onto sufficiently tensioned fluids can nucleate critical size vapor bubbles which grow from nanoscales and are then possible to see, hear and record with unprecedented efficiency and capability [1]. Previous work by our group has shown the ability of TMFD systems to detect neutrons with energies spanning eight orders of magnitude with 95%+ intrinsic efficiency [2] while remaining insensitive to gamma photons and also giving directional information [3] on the source of the radiation. In this paper we describe research results with CTMFD systems for use in the detection of key actinide isotopes constituting special Nuclear Materials (SNMs) in spent fuel. Tests in a CTMFD system demonstrate the ability to detect alpha activity (at ∼100% efficiency) of U-isotopes at concentrations of ∼100 ppb (which is unprecedented and about x100–1000 more sensitive than from conventional liquid scintillation spectroscopy). An inherent capability of TMFD systems concerns on demand tailoring of fluid tension levels allowing for energy discrimination and spectroscopy. This appears especially useful to detect the key isotopes of U and other transuranic isotopes of Pu, Np, Am, and Cm that are at different stages of Nuclear fuel reprocessing (i.e. UREX+).Copyright © 2009 by ASME
Rusi P Taleyarkhan - One of the best experts on this subject based on the ideXlab platform.
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large array special Nuclear Material sensing with tensioned metastable fluid detectors
IEEE Sensors Journal, 2018Co-Authors: Brian C Archambault, A Hagen, T F Grimes, Rusi P TaleyarkhanAbstract:Combatting Nuclear terrorism is a 21st century grand challenge (US-NAE report-2008). This paper discusses how tensioned metastable fluid detector (TMFD) radiation sensors in large-array format attain and exceed the global challenge efficiency metric announced by the U.S. Department of Defense for detection of neutron emissions from special Nuclear Materials such as Plutonium. The challenge calls for detector array area $(A-cm^{2})$ times Nuclear fission spectrum neutron detection fractional efficiency ( ${\epsilon }$ ) to exceed 1000; furthermore, using detectors in array form with linear dimension to not exceed 1 m based on use of He-3 based sensors—considered the industry “gold” standard. Based on experimentally validated efficiency of TMFD sensors, this paper presents evidence that an array of TMFDs (using either isopentane or trimethyl borate as sensing fluids) when optimally placed in array form can enable $\text{A}\times {\epsilon }$ ~ 2000—therefore, exceeding the challenge goal by over 100%. Additional advancements are reported on TMFD sensor characterizations for instrinsic efficiency of neutron detection (~80%) and spectroscopic alpha radiation emitter Pu/U isotopic detection (~99%) at $\times 100$ lower levels versus state-of-the-art spectrometers; comparisons versus conventional sensors are also presented—evidence is provided for $\times 75$ higher detection efficiency compared with the moderated BF3 industry standard and toward $\times 25$ to $\times 800$ versus NE-213 fast neutron detector standard.
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tension metastable fluid detection systems for special Nuclear Material detection and monitoring
Nuclear Engineering and Design, 2010Co-Authors: J Lapinskas, Rusi P Taleyarkhan, Stephen M Zielinski, Jeffrey A Webster, Sean M McdeavittAbstract:Abstract Tension metastable fluid states offer unique potential for radical transformation in radiation detection capabilities. States of tension metastability may be obtained in tailored resonant acoustic systems such as the acoustic tension metastable fluid detector (ATMFD) system or via centrifugal force based systems such as the centrifugal tension metastable fluid detector (CTMFD) system; both under development at Purdue University. In this paper we describe research results with CTMFD systems for use in the detection of key actinide isotopes constituting special Nuclear Materials (SNMs) in spent fuel. Tests in a CTMFD system demonstrate the ability to detect alpha activity (at ∼100% efficiency) of U-isotopes at concentrations of ∼100 ppb (which is unprecedented and about ×100–1000 more sensitive than from conventional liquid scintillation spectroscopy). An inherent capability of TMFD systems concerns on demand tailoring of fluid tension levels allowing for energy discrimination and spectroscopy. This appears especially useful to detect the key isotopes of U and other transuranic isotopes of Pu, Np, Am, and Cm that are at different stages of Nuclear fuel reprocessing (i.e., UREX+).
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tension metastable fluid detection systems for special Nuclear Material detection and monitoring
Volume 4: Codes Standards Licensing and Regulatory Issues; Student Paper Competition, 2009Co-Authors: J Lapinskas, Rusi P Taleyarkhan, Stephen M Zielinski, Jeffrey A Webster, Sean M McdeavittAbstract:Tension metastable fluid states offer unique potential for radical transformation in radiation detection capabilities. States of tension metastability may be obtained in tailored resonant acoustic systems such as the acoustic tension metastable fluid detector (ATMFD) system or via centrifugal force based systems such as the centrifugal tension metastable fluid detector (CTMFD) system; both under development at Purdue University. Tension metastable fluid detector (TMFD) systems take advantage of the weakened intermolecular bonds of liquids in sub-vacuum states. Nuclear particles incident onto sufficiently tensioned fluids can nucleate critical size vapor bubbles which grow from nanoscales and are then possible to see, hear and record with unprecedented efficiency and capability [1]. Previous work by our group has shown the ability of TMFD systems to detect neutrons with energies spanning eight orders of magnitude with 95%+ intrinsic efficiency [2] while remaining insensitive to gamma photons and also giving directional information [3] on the source of the radiation. In this paper we describe research results with CTMFD systems for use in the detection of key actinide isotopes constituting special Nuclear Materials (SNMs) in spent fuel. Tests in a CTMFD system demonstrate the ability to detect alpha activity (at ∼100% efficiency) of U-isotopes at concentrations of ∼100 ppb (which is unprecedented and about x100–1000 more sensitive than from conventional liquid scintillation spectroscopy). An inherent capability of TMFD systems concerns on demand tailoring of fluid tension levels allowing for energy discrimination and spectroscopy. This appears especially useful to detect the key isotopes of U and other transuranic isotopes of Pu, Np, Am, and Cm that are at different stages of Nuclear fuel reprocessing (i.e. UREX+).Copyright © 2009 by ASME
Emma Young - One of the best experts on this subject based on the ideXlab platform.
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Nuclear forensics scientific analysis supporting law enforcement and Nuclear security investigations
Analytical Chemistry, 2016Co-Authors: Elizabeth Keegan, Michael J Kristo, Kaitlyn Toole, Ruth Kips, Emma YoungAbstract:Nuclear forensic science, or "Nuclear forensic", aims to answer questions about Nuclear Material found outside of regulatory control. In this Feature, we provide a general overview of Nuclear forensics, selecting examples of key "Nuclear forensic signatures" which have allowed investigators to determine the identity of unknown Nuclear Material in real investigations.
