A Comparison of Neutron Detection Systems PDF Download

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Publisher:
ISBN:
Category :
Languages : en
Pages : 10

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Author: Anna M. Johnson Teachout
Publisher:
ISBN:
Category : Neutrons
Languages : en
Pages : 186

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Author: J. B. Birks
Publisher: Elsevier
ISBN: 1483156060
Category : Technology & Engineering
Languages : en
Pages : 685

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The Theory and Practice of Scintillation Counting is a comprehensive account of the theory and practice of scintillation counting. This text covers the study of the scintillation process, which is concerned with the interactions of radiation and matter; the design of the scintillation counter; and the wide range of applications of scintillation counters in pure and applied science. The book is easy to read despite the complex nature of the subject it attempts to discuss. It is organized such that the first five chapters illustrate the fundamental concepts of scintillation counting. Chapters 6 to 10 detail the properties and applications of organic scintillators, while the next four chapters discuss inorganic scintillators. The last two chapters provide a review of some outstanding problems and a postscript. Nuclear physicists, radiation technologists, and postgraduate students of nuclear physics will find the book a good reference material.

Author: Mark S. Rowland
Publisher:
ISBN:
Category : Neutron counters
Languages : en
Pages :

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A neutron detector system and method for discriminating fissile material from non-fissile material wherein a digital data acquisition unit collects data at high rate, and in real-time processes large volumes of data directly into information that a first responder can use to discriminate materials. The system comprises counting neutrons from the unknown source and detecting excess grouped neutrons to identify fission in the unknown source. Comparison of the observed neutron count distribution with a Poisson distribution is performed to distinguish fissile material from non-fissile material.

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Languages : en
Pages :

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This report documents the work performed for the Department of Homeland Security Domestic Nuclear Detection O ce as the project Fast Neutron Detection Evaluation under contract HSHQDC-14-X-00022. This study was performed as a follow-on to the project Study of Fast Neutron Signatures and Measurement Techniques for SNM Detection - DNDO CFP11-100 STA-01. That work compared various detector technologies in a portal monitor con guration, focusing on a comparison between a number of fast neutron detection techniques and two standard thermal neutron detection technologies. The conclusions of the earlier work are contained in the report Comparison of Fast Neutron Detector Technologies. This work is designed to address questions raised about assumptions underlying the models built for the earlier project. To that end, liquid scintillators of two di erent sizes{ one a commercial, o -the-shelf (COTS) model of standard dimensions and the other a large, planer module{were characterized at Los Alamos National Laboratory. The results of those measurements were combined with the results of the earlier models to gain a more complete picture of the performance of liquid scintillator as a portal monitor technology.

Author: Kayla Jane Sax
Publisher:
ISBN:
Category : Dosimeters
Languages : en
Pages : 0

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The purpose of this project was to convert a low-power static random access memory (SRAM) chip into a neutron detector and then compare it to other standard neutron detectors. This project serves as a proof of principle for the use of memory chips as radiation detectors and provides insights about design parameters to chip designers, facilitating the development of the next generation of low-powered neutron detectors capable of providing real-time data.

Author: Scottie Walker
Publisher:
ISBN:
Category : Helium
Languages : en
Pages :

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Neutron radiation detectors are an integral part of the Department of Homeland Security (DHS) efforts to detect the illicit trafficking of radioactive or special nuclear materials into the U.S. In the past decade, the DHS has deployed a vast network of radiation detection systems at various key positions to prevent or to minimize the risk associated with the malevolent use of these materials. The greatest portion of this detection burden has been borne by systems equipped with 3He because of its highly desirable physical and nuclear properties. However, a dramatic increase in demand and dwindling supply, combined with a lack of oversight for the existing 3He stockpile has produced a critical shortage of this gas which has virtually eliminated its viability for detector applications. A number of research efforts have been undertaken to develop suitable 3He replacements; however, these studies have been solely targeted toward simple detection cases where the overall detection efficiency is the only concern. For these cases, an insertion of additional detectors or materials can produce reaction rates that are sufficient, because the neutron spectral response is essentially irrelevant. However, in applications such as safeguards, non-proliferation efforts, and material control and accountability programs (MC & A), a failure to use detectors that are spectrally matched to 3He can potentially produce dire consequences. This is because these more difficult detection scenarios are associated with fissile material assessments for 239Pu and other actinides and these analyses have almost universally been calibrated to an equivalent 3He response. In these instances, a "simple" detector or material addition approach is neither appropriate nor possible, due to influences resulting from the complex nature of neutron scattering in moderators, cross sections, gas pressure variations, geometries, and surrounding structural interference. These more challenging detection cases require a detailed computational transport analysis be performed for each specific application. A leveraged approach using adjoint transport computations that are validated by forward transport and Monte Carlo computations and laboratory measurements can address these more complex detection cases and this methodology was utilized in the execution of the research. The initial task was to establish the fidelity of a computational approach by executing radiation transport models for existing BF3 and 3He tubes and then comparing the modeling results to laboratory measurements made using these identical devices. Both tubes were 19.6 cm in height, 1-inch in diameter, and operated at 1 and 4 atm pressure respectively. The models were processed using a combination of forward Monte Carlo and forward and adjoint 3-D discrete ordinates (SN) transport methods. The computer codes MCNP5 and PENTRAN were used for all calculations of a nickel-shielded plutonium-beryllium (PuBe) source term that provided a neutron output spectra equivalent to that of weapons-grade plutonium (WGPu). Once the computational design approach was validated, the adjoint SN method was used to iteratively identify six distinct plug-in models that matched the neutron spectral response and reaction rate of a 1-inch diameter 3He tube with a length of 10 cm and operating at 4 atm pressure. The equivalent designs consist of large singular tubes and dual tubes containing BF3 gas, 10B linings, and/or 10B-loaded polyvinyl toluene (PVT). The reaction rate for each plug-in design was also verified using forward PENTRAN and MCNP5 calculations. In addition to the equivalent designs, the adjoint method also yielded various insights into neutron detector design that can lead to additional designs using a combination of different detector materials such as BF3/10B-loaded PVT, 10B-lined tubes/10B-loaded PVT, etc.

Author: J. M. Carpenter
Publisher: Cambridge University Press
ISBN: 0521857813
Category : Science
Languages : en
Pages : 539

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This book provides a comprehensive and up-to-date introduction to the fundamental theory and applications of slow-neutron scattering.

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ISBN:
Category :
Languages : en
Pages : 16

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Neutron detection efficiency is an important figure of merit for waste assay applications that must measure small quantities of material. It is also important for neutron coincidence counting and multiplicity counting because the detection of double- and triple-correlated events scales as the detection efficiency squared and cubed, respectively. Conventional thermal neutron detection systems typically employ 3He detector tubes embedded in polyethylene. The polyethylene moderates the neutrons so they can be detected by the 3He tubes. However, the hydrogen in the moderator also absorbs neutrons and reduces the diffusion length. We have extensively explored alternate designs that use both polyethylene and other industrial plastics with lower concentrations of hydrogen. In MCNP studies, we have achieved higher detection efficiency by using both polyethylene and other plastics in a hybrid design. In this paper we will present the design of a nominal 30%-efficient, 200-liter neutron counter that uses a hybrid design. We will show comparison results of this design compared to a standard polyethylene design. Finally, this counter has been constructed and tested, and was used in the Los Alamos waste assay course. We will show comparisons of the experimental results from this counter to the MCNP predictions.

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Category :
Languages : en
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Reported here are the results of measurements performed to determine the efficiency of 3He filled proportional counters as a function of gas pressure in the SAIC system. Motivation for these measurements was largely to validate the current model of the SAIC system. Those predictions indicated that the neutron detection efficiency plotted as a function of pressure has a simple, logarithmic shape. As for absolute performance, the model results indicated the 3He pressure in the current SAIC system could not be reduced appreciably while meeting the current required level of detection sensitivity. Thus, saving 3He by reducing its pressure was predicted not to be a viable option in the current SAIC system.