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Development And Testing Of An Organic Scintillator Detector For Fast Neutron Spectrometry
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Book Synopsis Development and Testing of an Organic Scintillator Detector for Fast Neutron Spectrometry by : George Spencer Mickum
Download or read book Development and Testing of an Organic Scintillator Detector for Fast Neutron Spectrometry written by George Spencer Mickum and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of organic scintillators is an established method for the measurement of neutron spectra above several hundred keV. Fast neutrons are detected largely by proton recoils in the scintillator resulting from neutron elastic scattering with hydrogen. This leads to a smeared rectangular pulse-height distribution for monoenergetic neutrons. The recoil proton distribution ranges in energy from zero to the incident neutron energy. In addition, the pulse-height distribution is further complicated by structure due to energy deposition from alpha particle recoils from interactions with carbon as well as carbon recoils themselves. In order to reconstruct the incident neutron spectrum, the pulse-height spectrum has to be deconvoluted (unfolded) using the computed or measured response of the scintillator to monoenergetic neutrons. In addition gamma rays, which are always present when neutrons are present, lead to Compton electron recoils in the scintillator. Fortunately, for certain organic scintillators, the electron recoil events can be separated from the heavier particle recoil events in turn to distinguish gamma-ray induced events from neutron-induced events. This is accomplished by using the risetime of the pulse from the organic scintillator seen in the photomultiplier tube as a decay of light. In this work, an organic scintillator detection system was assembled which includes neutron-gamma separation capabilities to store the neutron-induced and gamma-induced recoil spectra separately. An unfolding code was implemented to deconvolute the spectra into neutron and gamma energy spectra. In order to verify the performance of the system, a measurement of two reference neutron fields will be performed with the system, unmoderated Cf-252 and heavy-water moderated Cf-252. After the detection system has been verified, measurements will be made with an AmBe neutron source.
Book Synopsis Neutron-Induced Scintillation in Organics by : Nicholai Mauritzson
Download or read book Neutron-Induced Scintillation in Organics written by Nicholai Mauritzson and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Neutrons are widely used as probes of matter to study materials in a broad range of fields from physics, chemistry and medicine to material sciences. Any application utilizing neutrons needs to employ a well-understood and optimized neutron-detector system. This thesis is centered on fundamental aspects of neutron-detector development, including the establishment of the Source Testing Facility at Lund University, experimental methods for the in-depth characterization of scintillator-based neutron detectors and analytical and computational methods for the precise interpretation of results. It focuses on the response of liquid organic scintillators to fast-neutron and gamma-ray irradiations, specifically for NE 213A, EJ 305, EJ 331 and EJ 321P. A simulation-based method for detector calibration was developed which allowed for the use of polyenergetic gamma-ray sources in this low energy-resolution environment. With an actinide/beryllium neutron source and a time-of-flight setup, beams of energy-tagged neutrons were used to study the energy-dependent behaviour of the intrinsic pulse-shape of NE 213A and EJ 305 scintillators. The results demonstrated the advantages of the neutron-tagging method and how the combination of neutron tagging and pulse-shape discrimination can give deeper insight into backgrounds resulting from inelastic neutron scattering. A comprehensive characterization of the neutron scintillation-light yield for NE 213A, EJ 305, EJ 331 and EJ 321P was also performed. It employed the simulation-based calibrations to confirm existing light-yield parametrizations for NE 213A and EJ 305, and resulted in light-yield parametrizations for EJ 331 and EJ 321P extracted for the first time from data. In addition to the development of a simulation-based framework for the study of neutron-induced scintillation in organic scintillators, the methods and results presented in this thesis lay the foundation for future source-based neutron-tagging efforts and scintillator-detector research and development.
Book Synopsis Development of a Multi-purpose Fast Neutron Spectrometric Capability in the Masurca Facility by : Luca Dioni
Download or read book Development of a Multi-purpose Fast Neutron Spectrometric Capability in the Masurca Facility written by Luca Dioni and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This doctoral thesis work is focused on the development of neutron spectroscopy techniques in mixed radiations fields for fast research reactor applications, especially for the MASURCA facility.The first part of the thesis is dedicated to the study of special MASURCA configurations in which a radial channel is built to extract a continuous beam of intermediate-to-fast energy neutrons, tailorable to meet different needs. Operating MASURCA as a neutron beam facility would open up new possibilities of experiments, such as fast neutron attenuation and shielding experiments; measurements in standard (reference) fast neutron fields, development and calibration of fast neutron detection systems etc.The second part of the thesis is dedicated to the development of fast neutron spectrometric capabilities for the on-line characterization of the neutron energy distribution. Different candidate detector systems are compared. A “best compromise” spectrometer is shown to be a system combining proportional counters and organic scintillators. Such a system would be able to cover the neutron energy domain between 10 keV and 10 MeV. The selected organic scintillator is a stilbene single crystal obtained by a recently developed solution-grown process. Overall, it is concluded that a neutron spectrometer based on a solution-grown stilbene detector would be suitable for use in MASURCA and in other mixed radiations fields, and would perform better than traditional detector systems.
Download or read book Modern essays written by and published by . This book was released on 1936 with total page 97 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Response of Some Organic Scintillators to Fast Neutrons by :
Download or read book The Response of Some Organic Scintillators to Fast Neutrons written by and published by . This book was released on 1964 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Recent Developments In Fast Neutron Detection And Multiplicity Counting With Verification With Liquid Scintillator by :
Download or read book Recent Developments In Fast Neutron Detection And Multiplicity Counting With Verification With Liquid Scintillator written by and published by . This book was released on 2011 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: For many years at LLNL, we have been developing time-correlated neutron detection techniques and algorithms for applications such as Arms Control, Threat Detection and Nuclear Material Assay. Many of our techniques have been developed specifically for the relatively low efficiency (a few percent) attainable by detector systems limited to man-portability. Historically, we used thermal neutron detectors (mainly 3He), taking advantage of the high thermal neutron interaction cross-sections. More recently, we have been investigating the use of fast neutron detection with liquid scintillators, inorganic crystals, and in the near future, pulse-shape discriminating plastics which respond over 1000 times faster (nanoseconds versus tens of microseconds) than thermal neutron detectors. Fast neutron detection offers considerable advantages, since the inherent nanosecond production time-scales of spontaneous fission and neutron-induced fission are preserved and measured instead of being lost by thermalization required for thermal neutron detectors. We are now applying fast neutron technology to the safeguards regime in the form of fast portable digital electronics as well as faster and less hazardous scintillator formulations. Faster detector response times and sensitivity to neutron momentum show promise for measuring, differentiating, and assaying samples that have modest to very high count rates, as well as mixed fission sources like Cm and Pu. We report on measured results with our existing liquid scintillator array, and progress on the design of a nuclear material assay system that incorporates fast neutron detection, including the surprising result that fast liquid scintillator detectors become competitive and even surpass the precision of 3He-based counters measuring correlated pairs in modest (kg) samples of plutonium.
Book Synopsis Investigation of an Organic Scintillator as a Fast-neutron Spectrometer by : Dan J. Ropson
Download or read book Investigation of an Organic Scintillator as a Fast-neutron Spectrometer written by Dan J. Ropson and published by . This book was released on 1973 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Fast Neutron Spectroscopy with Organic Scintillation Detectors in a High-radiation Environment by : B. Baramsai
Download or read book Fast Neutron Spectroscopy with Organic Scintillation Detectors in a High-radiation Environment written by B. Baramsai and published by . This book was released on 2020 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Development of a Solid State Neutron Detector for SNAP 10A by : A. Chesavage
Download or read book Development of a Solid State Neutron Detector for SNAP 10A written by A. Chesavage and published by . This book was released on 1966 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Construction and Testing of a Neutron and Gamma Spectrometry System Using Pulse Shape Discrimination with an Organic Scintillator by : Robert S. Pope
Download or read book Construction and Testing of a Neutron and Gamma Spectrometry System Using Pulse Shape Discrimination with an Organic Scintillator written by Robert S. Pope and published by . This book was released on 1993 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this thesis was to construct and test a neutron detector to measure the energy spectrum of 1 to 14-MeV neutrons in the presence of gammas. A spectrometer based on the process of pulse shape discrimination (PSD) was constructed, in which the scintillator NE-213 was used. The primary neutron/ gamma sources used were 78-mCi and 4.7-Ci 239PuBe sources, while 4.7-micro-Ci and 97.6-micro-Ci 22Na gamma sources were used for energy calibration and additional testing of the detector. Proton recoil spectra and Compton electron spectra were unfolded with the neutron and gamma unfolding code FORIST to generate the incident neutron and gamma spectra, respectively. FORIST, which was written for a CDC computer, was modified to run on a VAX 6420. The experimental spectra were compared to those in the literature. The locations of the peaks in the 239PuBe spectrum agreed with the literature to within 8.3%, the 239PuBe gamma spectrum agreed to within 0.7%, while the 22Na gamma spectrum agreed exactly. Uncertainties in the detection system and unfolding procedure are on the order of 5-10%. This thesis is intended to be a summary of the relevant literature and a user's guide to the PSD spectrometer ... Neutron unfolding code, Gamma spectrometry, Neutron spectrometry, Pulse shape discrimination.
Book Synopsis Improvements in Apparatus and Procedures for Using an Organic Liquid Scintillator as a Fast-neutron Spectrometer for Radiation Protection Applications by :
Download or read book Improvements in Apparatus and Procedures for Using an Organic Liquid Scintillator as a Fast-neutron Spectrometer for Radiation Protection Applications written by and published by . This book was released on 1987 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: For use in radiation protection measurements, a neutron spectrometer must have a wide energy range, good sensitivity, medium resolution, and ease of taking and reducing data. No single spectrometer meets all of these requirements. Several experiments aimed at improving and characterizing the detector response to gamma rays and neutrons were conducted. A light pipe (25 mm) was needed between the scintillator cell and the photomultiplier tube to achieve the best resolution. The light output of the scintillator as a function of gamma-ray energy was measured. Three experiments were conducted to determine the light output as a function of neutron energy. Monte Carlo calculations were made to evaluate the effects of multiple neutron scattering and edge effects in the detector. The electronic systems associated with the detector were improved with a transistorized circuit providing the bias voltage for the photomultiplier tube dynodes. This circuit was needed to obtain pulse-height linearity over the wide range of signal sizes. A special live-time clock was built to compensate for the large amount of dead time generated by the pulse-shape discrimination circuit we chose to use. 64 refs., 58 figs., 9 tabs.
Book Synopsis V ysehorovicko, Cernokostelecko a okoli Uhlirskych Janovic by :
Download or read book V ysehorovicko, Cernokostelecko a okoli Uhlirskych Janovic written by and published by . This book was released on 1962 with total page 103 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Construction and Testing of a Neutron and Gamma Spectrometry System Using Pulse Shape Discrimination with an Organic Scintillator by : Robert S. Pope
Download or read book Construction and Testing of a Neutron and Gamma Spectrometry System Using Pulse Shape Discrimination with an Organic Scintillator written by Robert S. Pope and published by . This book was released on 1993 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this thesis was to construct and test a neutron detector to measure the energy spectrum of 1 to 14-MeV neutrons in the presence of gammas. A spectrometer based on the process of pulse shape discrimination (PSD) was constructed, in which the scintillator NE-213 was used. The primary neutron/ gamma sources used were 78-mCi and 4.7-Ci 239PuBe sources, while 4.7-micro-Ci and 97.6-micro-Ci 22Na gamma sources were used for energy calibration and additional testing of the detector. Proton recoil spectra and Compton electron spectra were unfolded with the neutron and gamma unfolding code FORIST to generate the incident neutron and gamma spectra, respectively. FORIST, which was written for a CDC computer, was modified to run on a VAX 6420. The experimental spectra were compared to those in the literature. The locations of the peaks in the 239PuBe spectrum agreed with the literature to within 8.3%, the 239PuBe gamma spectrum agreed to within 0.7%, while the 22Na gamma spectrum agreed exactly. Uncertainties in the detection system and unfolding procedure are on the order of 5-10%. This thesis is intended to be a summary of the relevant literature and a user's guide to the PSD spectrometer ... Neutron unfolding code, Gamma spectrometry, Neutron spectrometry, Pulse shape discrimination.
Book Synopsis Investigating the Anisotropic Scintillation Response in Organic Crystal Scintillator Detectors by : Patricia Frances Schuster
Download or read book Investigating the Anisotropic Scintillation Response in Organic Crystal Scintillator Detectors written by Patricia Frances Schuster and published by . This book was released on 2016 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic scintillator materials have long been used as radiation detectors. They offer simultaneous detection of fast neutrons and gamma rays for applications in nuclear nonproliferation, international safeguards, and national security. The recent development of high quality stilbene crystals with excellent neutron-gamma pulse shape discrimination (PSD) has generated renewed interest in using crystalline materials. However, crystal organic scintillators are subject to a directional dependence in their response to heavy charged particle interactions, degrading their energy resolution for neutron measurements and worsening their PSD performance. This dissertation presents several studies that experimentally characterize the scintillation anisotropy in organic crystal scintillators. These include measurements of neutron, gamma-ray and cosmic muon interactions in anthracene, a historical benchmark among organic scintillator materials, to confirm and extend measurements previously available in the literature. The gamma-ray and muon measurements provide new experimental confirmation that no scintillation anisotropy is present in their interactions. Observations from these measurements have updated the hypothesis for the physical mechanism that is responsible for the scintillation anisotropy concluding that a relatively high dE/dx is required in order to produce a scintillation anisotropy. The directional dependence of the scintillation output in liquid and plastic materials was measured to experimentally confirm that no scintillation anisotropy correlated to detector orientation exists in amorphous materials. These observations confirm that the scintillation anisotropy is not due to an external effect on the measurement system, and that a fixed, repeating structure is required for a scintillation anisotropy. The directional dependence of the scintillation output in response to neutron interactions was measured in four stilbene crystals of various sizes and growth-methods. The scintillation anisotropy in these materials was approximately uniform, indicating that the crystal size, geometry, and growth method do not significantly impact the effect. Measurements of three additional pure crystals and two mixed crystals were made. These measurements showed that 1) the magnitude of the effect varies with energy and material, 2) the relationship between the light output and pulse shape anisotropy varies across materials, and 3) the effect in mixed materials is very complex. These measurements have informed the hypothesis of the mechanism that produces the directional dependence. By comparing the various relationships between the light output and pulse shape anisotropy across materials, these measurements indicate that the preferred directions of singlet and triplet excitation transport may be the same in some materials and different in other materials. The measurements performed in this work serve as a resource to groups who aim to correct for the scintillation anisotropy or employ it as a directional detection modality. Additionally, this work has advanced the understanding of what physical processes and properties dictate the magnitude and behavior of the scintillation anisotropy in a given material. It has added new information to the body of knowledge surrounding the scintillation mechanism in organic crystal scintillator materials. This information may be used to construct models to predict the scintillation anisotropy effect in materials that have not been experimentally characterized. Such work can contribute to work in producing a new generation of organic scintillator materials, advancing many applications in nuclear science and security.
Book Synopsis A Double Time of Flight Method For Measuring Proton Light Yield by : Josh Arthur Brown
Download or read book A Double Time of Flight Method For Measuring Proton Light Yield written by Josh Arthur Brown and published by . This book was released on 2017 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic scintillators have been used in conjunction with photomultiplier tubes to detect fast neutrons since the early 1950s. The utility of these detectors is dependent on an understanding of the characteristics of their response to incident neutrons. Since the detected light in organic scintillators in a fast neutron radiation field comes primarily from neutron-proton elastic scattering, the relationship between the light generated in an organic scintillator and the energy of a recoiling proton is of paramount importance for spectroscopy and kinematic imaging. This relationship between proton energy deposited and light production is known as proton light yield. Several categories of measurement methods for proton light yield exist. These include direct methods, indirect methods, and edge characterization techniques. In general, measurements for similar or identical materials in the literature show a large degree of variance among the results. This thesis outlines the development of a new type of indirect method that exploits a double neutron time of flight technique. This new method is demonstrated using a pulsed broad spectrum neutron source at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory. The double time of flight method for proton light yield measurements was established using two commercially available materials from Eljen Technology. The first is EJ-301, a liquid scintillator with a long history of use. Equivalent materials offered by other manufacturers include NE-213 from Nuclear Enterprise and BC-501A from Saint-Gobain Crystals. The second material tested in this work is EJ-309, a liquid scintillator with a proprietary formulation recently introduced by Eljen Technology with no commercial equivalents. The proton light yield measurements were conducted in concert with several system characterization measurements to provide a result to the community that is representative of the material itself. Additionally, the errors on the measurement were characterized with respect to systematic uncertainties, including an evaluation of the covariance of data points produced and the covariance of fit parameters associated with a semi-empirical model. This work demonstrates the viability of the double time of flight technique for continuous measurement of proton light yield over a broad range of energies without changes to the system configuration. The results of the light yield measurements on EJ-301 and EJ-309 suggest answers to two open questions in the literature. The first is that the size of the scintillation detector used to measure the proton light yield should not effect the result if the spatial distributions of Compton electrons and proton recoils are equivalent. Second, the shape of the scintillation detector should not effect the light yield with the same constraint on the spatial distributions. A characterized hardware and software framework has been developed, capable of producing proton light yield measurements on additional materials of interest. The acquisition, post processing, error analysis, and simulation software were developed to permit characterization of double time of flight measurements for a generic system, allowing it to be utilized to acquire and analyze data for an array of scintillation detectors regardless of detector size or geometric configuration. This framework establishes an extensible capability for performing proton light yield measurements to support basic and applied scientific inquiry and advanced neutron detection using organic scintillators.
Book Synopsis Computational Development of the Planar Miniaturized Fast Neutron Detector by : Luke Stegeman
Download or read book Computational Development of the Planar Miniaturized Fast Neutron Detector written by Luke Stegeman and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A novel fast neutron spectrometer concept called the Miniaturized Fast Neutron Detector has been computationally developed and characterized via a series of radiation transport simulations. The planar version of the Miniaturized Fast Neutron Detector consists of a plastic converter layer situated in front of an arbitrary number of stacked, electrically isolated thin-silicon diode detectors. Ideally, incoming neutrons impinge upon the plastic, produce recoil ions, and those recoil ions deposit energy in one or more of the diode detectors placed behind the plastic. The spectrometer is capable of reconstructing incident neutron energy spectra without a priori information via at least two distinct unfolding algorithms. The ultimate purpose of the device is to act as an advanced personal dosimeter or area monitor with high position resolution to improve the accuracy of local radiation risk estimates due to secondary neutron radiation. In this work, the device's ability to unfold three distinct incident neutron energy spectra, the spectroscopic effectiveness of the device as a function of incident integral neutron fluence, and a set of strategies for optimizing and mathematically generalizing the device geometry are all presented. Radiation transport simulations were conducted to generate absorbed dose response functions for each diode detector and to compute the absorbed dose in each diode detector due to incident 252Cf, AmB, and AmBe neutron energy spectra as a function of integral neutron fluence. These data are used to test the unfolding capability of the device and characterize its spectroscopic effectiveness. Two unfolding algorithms are considered: the matrix inversion unfolding method, which employs a non-negative least-squares algorithm, and the SPUNIT method. Further radiation transport simulations and analyses were conducted to develop a strategy to optimize the dimensions of the plastic conversion layer and the diode detectors for any arbitrary neutron energy range so that individual device iterations can be tailored to various environments. The results of this work demonstrate that the planar Miniaturized Fast Neutron Detector is capable of unfolding a diverse range of incident neutron energy spectra without a priori information. The effectiveness of the device is quantified as a function of integral neutron fluence and this quantity can be used to determine the minimum integral neutron fluence necessary to generate acceptable unfolded neutron energy spectra (and, by extension, dosimetric quantities and risk-related metrics). The results also demonstrate that the efficiency and energy discrimination capabilities of the current iteration of the device (one with 20 stacked diode detectors) can be improved by decreasing the thickness of the plastic conversion block and increasing the number of uniformly sized diode detectors (or gradually increasing the thickness of diode detectors as a function of device depth).
Book Synopsis Recent Developments in Neutron Detection and Multiplicity Counting with Liquid Scintillator by :
Download or read book Recent Developments in Neutron Detection and Multiplicity Counting with Liquid Scintillator written by and published by . This book was released on 2010 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: For many years at LLNL we have been developing time-correlated neutron detection techniques and algorithms for many applications including Arms Control, Threat Detection and Nuclear Material Assaying. Many of our techniques have been developed specifically for relatively low efficiency (a few %) inherent in the man-portable systems. Historically we used thermal neutron detectors (mainly 3He) taking advantage of the high thermal neutron interaction cross-sections but more recently we have been investigating fast neutron detection with liquid scintillators and inorganic crystals. We have discovered considerable detection advantages with fast neutron detection as the inherent nano-second production time-scales of fission and neutron induced fission are preserved instead of being lost in neutron thermalization required for thermal neutron detectors. We are now applying fast neutron technology (new fast and portable digital electronics as well as new faster and less hazardous scintillator formulations) to the safeguards regime and faster detector response times and neutron momentum sensitivity show promise in measuring, differentiating and assaying samples that have very high count rates as well as mixed fission sources (e.g. Cm and Pu). We report on measured results with our existing liquid scintillator array and progress on design of nuclear material assaying system that incorporates fast neutron detection.
