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Author: Publisher: ISBN: Category : Languages : en Pages : 6
Book Description
Neutron interrogation techniques have specific advantages for detection of hidden, shielded, or buried threats over other detection modalities in that neutrons readily penetrate most materials providing backscattered gammas indicative of the elemental composition of the potential threat. Such techniques have broad application to military and homeland security needs. Present neutron sources and interrogation systems are expensive and relatively bulky, thereby making widespread use of this technique impractical. Development of a compact, high intensity crystal driven neutron source is described. The crystal driven neutron source approach has been previously demonstrated using pyroelectric crystals that generate extremely high voltages when thermal cycled [1-4]. Placement of a sharpened needle on the positively polarized surface of the pyroelectric crystal results in sufficient field intensification to field ionize background deuterium molecules in a test chamber, and subsequently accelerate the ions to energies in excess of (almost equal to)100 keV, sufficient for either D-D or D-T fusion reactions with appropriate target materials. Further increase in ion beam current can be achieved through optimization of crystal thermal ramping, ion source and crystal accelerator configuration. The advantage of such a system is the compact size along with elimination of large, high voltage power supplies. A novel implementation discussed incorporates an independently controlled ion source in order to provide pulsed neutron operation having microsecond pulse width.
Author: Publisher: ISBN: Category : Languages : en Pages : 6
Book Description
Neutron interrogation techniques have specific advantages for detection of hidden, shielded, or buried threats over other detection modalities in that neutrons readily penetrate most materials providing backscattered gammas indicative of the elemental composition of the potential threat. Such techniques have broad application to military and homeland security needs. Present neutron sources and interrogation systems are expensive and relatively bulky, thereby making widespread use of this technique impractical. Development of a compact, high intensity crystal driven neutron source is described. The crystal driven neutron source approach has been previously demonstrated using pyroelectric crystals that generate extremely high voltages when thermal cycled [1-4]. Placement of a sharpened needle on the positively polarized surface of the pyroelectric crystal results in sufficient field intensification to field ionize background deuterium molecules in a test chamber, and subsequently accelerate the ions to energies in excess of (almost equal to)100 keV, sufficient for either D-D or D-T fusion reactions with appropriate target materials. Further increase in ion beam current can be achieved through optimization of crystal thermal ramping, ion source and crystal accelerator configuration. The advantage of such a system is the compact size along with elimination of large, high voltage power supplies. A novel implementation discussed incorporates an independently controlled ion source in order to provide pulsed neutron operation having microsecond pulse width.
Author: Publisher: ISBN: Category : Languages : en Pages : 15
Book Description
The LLNL Crystal Driven Neutron Source is operational and has produced record ion currents of (almost equal to)10 nA and neutron output of 1.9 (±0.3) x 105 per thermal cycle using a crystal heating rate of 0.2 C/s from 10 C to 110 C.A 3 cm diameter by 1 cm thick LiTaO3 crystal with a socket secured field emitter tip is thermally cycled with feedback control for ionization and acceleration of deuterons onto a deuterated target to produce D-D fusion neutrons. The entire crystal and temperature system is mounted on a bellows which allows movement of the crystal along the beam axis and is completely contained on a single small vacuum flange. The modular crystal assembly permitted experimental flexibility. Operationally, flashover breakdowns along the side of the crystal and poor emitter tip characteristics can limit the neutron source. The experimental neutron results extend earlier published work by increasing the ion current and pulse length significantly to achieve a factor-of-two higher neutron output per thermal cycle. These findings are reviewed along with details of the instrument.
Author: Publisher: Academic Press ISBN: 0128192143 Category : Science Languages : en Pages : 408
Book Description
Neutron Crystallography in Structural Biology, Volume 634, the latest volume in the Methods in Enzymology series, continues the legacy of this premier serial with quality chapters authored by leaders in the field. Chapters in this updated release include Fundamentals of neutron crystallography in structural biology, Large crystal growth for neutron protein crystallography, Prospects for membrane protein crystals in NMX, IMAGINE: The neutron protein crystallography beamline at the high flux isotope reactor, The macromolecular neutron diffractometer at the spallation neutron source, Current status and near future plan of neutron protein crystallography at J-PARC, Neutron macromolecular crystallography at the European spallation source, and much more. Provides the authority and expertise of leading contributors from an international board of authors Presents the latest release in the Methods in Enzymology series Includes the latest information on neutron crystallography in structural biology
Author: Chick C Wilson Publisher: World Scientific Publishing Company ISBN: 9813105402 Category : Technology & Engineering Languages : en Pages : 386
Book Description
This important book presents a comprehensive account of the techniques and applications of single crystal neutron diffraction in the area of chemical crystallography and molecular structure. Beginning with a brief description of the general principles and the reasons for choosing the technique — the “why” — the book covers the methods for both the production of neutrons and the measurement of their scattering by molecular crystals — the “how” — followed by a detailed survey of past, present and future applications — the “what”. The coverage of both steady state and pulsed neutron sources and instrumentation is extensive, while the survey of applications is the most comprehensive yet undertaken. The book endeavours to show why the technique is an essential method for studying areas as diverse as hydrogen bonding and weak interactions, organometallics, supramolecular chemistry and crystal engineering, metal hydrides, charge density and pharmaceuticals. It is an ideal reference source for the research worker interested in using neutron diffraction to study the structure of molecules.
Author: Ashim Kumar Bain Publisher: John Wiley & Sons ISBN: 3527351019 Category : Technology & Engineering Languages : en Pages : 260
Book Description
Pyroelectric Materials An authoritative and practical discussion of pyroelectric materials and their applications In Pyroelectric Materials: Physics and Applications, the authors deliver a comprehensive exploration of the physics of pyroelectric materials and their applications. With authoritative coverage of a wide variety of critical topics in the field, the authors provide the readers with chapters on dielectric fundamentals, pyroelectricity, pyroelectric materials and their applications such as pyroelectric infrared detectors, pyroelectric energy harvesting, and pyroelectric fusion. Readers will also find: A thorough introduction to the fundamentals of dielectrics, including discussions of polarization, dispersion, relaxation, and the molecular theory of induced charges in a dielectric Comprehensive explorations of pyroelectricity, including its history, theory, and a simple model of pyroelectric effect Perfect for researchers and professionals with an interest in pyroelectric materials, the book is also useful for graduate students taking courses involving pyroelectric materials and their applications.
Author: International Atomic Energy Agency Publisher: IAEA Radiation Technology Repo ISBN: 9789201251107 Category : Science Languages : en Pages : 145
Book Description
This publication addresses recent developments in neutron generator (NG) technology. It presents information on compact instruments with high neutron yield to be used for neutron activation analysis (NAA) and prompt gamma neutron activation analysis in combination with high count rate spectrometers. Traditional NGs have been shown to be effective for applications including borehole logging, homeland security, nuclear medicine and the on-line analysis of aluminium, coal and cement. Pulsed fast thermal neutron analysis, as well as tagged and timed neutron analysis, are additional techniques which can be applied using NG. Furthermore, NG can effectively be used for elemental analysis and is also effective for analysis of hidden materials by neutron radiography. Useful guidelines for developing NG based research laboratories are also provided in this publication.
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Author: J. M. Carpenter
Author: Chick C Wilson
Author: Ashim Kumar Bain
Author: W. J. Sturm
Author: R. G. Sachs
Author: E. Frank Martina
Author: International Atomic Energy Agency