Neutron absorption

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Topic: Neutron absorption

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	Neutron generator having a target - Patent 4298804
		The target of such a neutron generator is usually formed by a thin layer having a large coefficient of absorption for hydrogen which is vapour-deposited on a carrier layer having small coefficients of absorption and diffusion for hydrogen.
		It is an object of the invention to provide a neutron generator having a target which is hit by a beam of hydrogen ions, in which the target has a longer life upon bombardment with beams of a high ion density.
		In such a neutron generator, neutrons are generated which are formed by reactions between nuclei of the heavy isotopes of hydrogen, deuterium and tritium.
	www.freepatentsonline.com /4298804.html (2418 words)

	f_161812_true_EN.html
		These are (i) the absorption of neutrons, (ii) the scattering of neutrons and (iii) the absorption of photons.
		Directly (prompt) after absorption of the neutrons photons are emitted.
		In this method the large sample is irradiated with neutrons.
	www.library.tudelft.nl /dissertations/2940/f_161812_true_EN.html (2418 words)

	Neutron Life Cycle of a Fast Reactor
		, is the ratio of the number of neutrons produced by fission in one generation to the number of neutrons lost through absorption and leakage in the preceding generation.
		The resonance escape probability is not significant because very few neutrons exist at energies where resonance absorption is significant.
		The infinite multiplication factor, k_, is the ratio of the neutrons produced by fission in one generation to the number of neutrons lost through absorption in the preceding generation.
	www.tpub.com /doenuclearphys/nuclearphysics59.htm (539 words)

	Energy Citations Database (ECD) - Energy and Energy-Related Bibliographic Citations
		400702 -- Radiochemistry & Nuclear Chemistry-- Properties of Radioactive Materials; ANIONS-- ABSORPTION SPECTROSCOPY;ANIONS-- IRRADIATION;HYDROXIDES-- ABSORPTION SPECTROSCOPY;HYDROXIDES-- IRRADIATION;LITHIUM FLUORIDES-- IRRADIATION;TRITIUM COMPOUNDS-- ABSORPTION SPECTROSCOPY;TRITIUM COMPOUNDS-- IRRADIATION; COBALT 60;EXPERIMENTAL DATA;HIGH TEMPERATURE;INFRARED SPECTRA;MONOCRYSTALS;NEUTRON REACTIONS;RADIOLYSIS
		Infrared spectrum of the tritiated hydroxyl ion (OT/sup -/) in a neutron-irradiated LiF crystal
		Energy Citations Database (ECD) Document #5825668 - Infrared spectrum of the tritiated hydroxyl ion (OT/sup -/) in a neutron-irradiated LiF crystal
	www.osti.gov /energycitations/product.biblio.jsp?osti_id=5825668 (156 words)

	Lunar Prospector Spectrometers: Home
		The correlation of measured thermal neutron fluxes with macroscopic absorption cross sections calculated for the Apollo and Luna samples, is fair to good, which is interpreted to indicate that compositions inferred from returned samples are not representative of averages over roughly 450 km diameter areas surrounding each of the landing sites.
		Correlation of the simulated and measured fast/thermal neutron counting rates (both arbitrary units) as a function of the calculated macroscopic neutron absorption cross section.
		This quantity should be directly related to the abundance of thermal neutron absorbers in the regolith.
	lunar.lanl.gov /pages/neutron.html (561 words)

	Neutron bomb - Wikipedia, the free encyclopedia
		The neutron absorption spectrum of air is disputed, and may depend in part on absorption by hydrogen from water vapor.
		Neutron bombs, also called enhanced radiation bombs (ER weapons), are small thermonuclear weapons in which the burst of neutrons generated by the fusion reaction is intentionally not absorbed inside the weapon, but allowed to escape.
		A neutron bomb is a type of nuclear weapon invented by Samuel Cohen specifically designed to release a relatively large portion of its energy as energetic neutron radiation.
	en.wikipedia.org /wiki/Neutron_bomb (1613 words)

	United States Patent Application: 0040022341
		In particular, neutron absorption spectroscopy is a technique in which materials are identified by absorption of neutrons from a neutron source and emission of gamma rays which are detected with gamma ray detectors.
		The compact neutron generator of claim 1, further comprising: a plasma electrode having a plurality of spaced extraction apertures on the surface of-the toroidal shaped plasma chamber facing the center of the neutron generator for extracting the ions in a plurality of ion beamlets.
		Neutron generator 15 and collimator 29 are surrounded by wall 21 with a plurality of apertures 23 which are aligned with channels 17 so that neutrons produced by generator 15 are output through apertures 23.
	appft1.uspto.gov /netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=/netahtml/PTO/search-bool.html&r=6&f=G&l=50&co1=AND&d=PG01&s1=100962&OS=100962&RS=100962 (5173 words)

	Lunar Prospector Spectrometers: Home
		The correlation of measured thermal neutron fluxes with macroscopic absorption cross sections calculated for the Apollo and Luna samples, is fair to good, which is interpreted to indicate that compositions inferred from returned samples are not representative of averages over roughly 450 km diameter areas surrounding each of the landing sites.
		Correlation of the simulated and measured fast/thermal neutron counting rates (both arbitrary units) as a function of the calculated macroscopic neutron absorption cross section.
		This quantity should be directly related to the abundance of thermal neutron absorbers in the regolith.
	lunar.lanl.gov /pages/neutron.html (561 words)

	Neutron
		Three time intervals are involved: (a) the time it takes a fast neutron to slow down to thermal energy, (b) the time the now thermal neutron exists prior to absorption in fuel, and (c) the time required for a fissionable nucleus to emit a fast neutron after neutron absorption.
		A prompt neutron generation time is the sum of the amount of time it takes a fast neutron to thermalize, the amount of time the neutron exists as a thermal neutron before it is absorbed, and the amount of time between a fissionable nuclide absorbing a neutron and fission neutrons being released.
		The delayed neutron generation time is the total time from the birth of the fast neutron to the emission of the delayed neutron in the next generation.
	www.tpub.com /doenuclearphys/nuclearphysics48.htm (561 words)

	Cross
		For many elements the absorption cross sections are small, ranging from a fraction of a barn to a few barns for slow (or thermal) neutrons.
		That is, when the binding energy of a neutron plus the kinetic energy of the neutron are exactly equal to the amount required to raise a compound nucleus from its ground state to a quantum level, resonance absorption occurs.
		Whether a neutron will interact with a certain volume of material depends not only on the microscopic cross section of the individual nuclei but also on the number of nuclei within that volume.
	www.infodotinc.com /doenuclearphys/nuclearphysics39.htm (561 words)

	The magnetic field of an isolated neutron star from X-ray cyclotron absorption lines
		The magnetic field of an isolated neutron star from X-ray cyclotron absorption lines
	www.nature.com /doifinder/10.1038/nature01703 (561 words)

	Neutron transport with MCNP
		Neutron histories in arbitrary geometries are tracked from the instant of creation by the use of evaluated cross sections data libraries for elastic scattering, inelastic scattering and absorption on nuclei present in specified (fixed) materials.
		The spallation neutron source is to be approximated with a point source in the centre of the target, emitting neutrons with an evaporation spectrum.
		The resulting collection of neutron tracks represents the neutron flux and can be folded track by track with reaction cross sections and heating functions in order to obtain estimates of transmutation rates and power densities, including statistical error estimations.
	www.neutron.kth.se /courses/transmutation/NeutronTransport/NeutronTransport.html (1752 words)

	ASQ Home Page Template
		Since it is essential to minimise neutron absorption in the region of the coolant/moderator in order to obtain a high neutron flux, the part of the target unit extending into the moderator tank is filled with heavy water, except for the rod bundle.
		The vertical and horizontal inserts of the cold neutron source are enclosed in vacuum for thermal insulation and in a protective gas enclosure for prevention of potentially explosive hydrogen-oxygen mixtures in case of a leak in the system.
		This "cold neutron source" is situated in a horizontal insert inside the moderator tank and near the target, where the thermal neutron flux has its maximum.
	asq.web.psi.ch /ASQ/facilities/SINQSYSTEMS.html (1289 words)

	SDV Nuclear Glossary
		Absorption of a neutron by an atomic nucleus.
		N, the neutron is the projectile, and the proton is the ejectile.
		Neutrons in one generation that are successfully moderated and that induce further fission reactions produce a new generation of neutrons.
	glossary.dataenabled.com /sdvglossary_N.html (1500 words)

	Nuclear fission - Wikipedia, the free encyclopedia
		Though fission is most often and most easily initiated by the absorption of a free neutron, it can also be induced by striking a fissionable nucleus with other particles.
		Thermal neutrons (that is, slow neutrons) have the highest probability of producing fission of U-235 but the neutrons emitted in the process of fission have high speeds (they are not thermal).
		If there are enough neutrons captured so that the ones causing immediate fission are sufficient to lead to exponential growth, then the mass is called prompt critical and it becomes very difficult to control.
	en.wikipedia.org /wiki/Nuclear_fission (1500 words)

	Archimedes Plutonium
		Sm has a high absorption cross-section for thermal neutrons and is used in nuclear reactor control rods and for neutron shielding.
		Neutrons are indispensable in the building-upof the elements for it is impossible for 2 or more protons to exist stably in a nucleus (distance range of about 10-13 cm) without neutrons.
		Neutrons are small magnets allowing for the production of beams of neutrons.
	www.iw.net /~a_plutonium/File041.html (1500 words)

	Neutron transport with MCNP
		Neutron histories in arbitrary geometries are tracked from the instant of creation by the use of evaluated cross sections data libraries for elastic scattering, inelastic scattering and absorption on nuclei present in specified (fixed) materials.
		The resulting collection of neutron tracks represents the neutron flux and can be folded track by track with reaction cross sections and heating functions in order to obtain estimates of transmutation rates and power densities, including statistical error estimations.
		Multiplication eigenvalue calculations can be made in order to find critical configurations, while in sub-critical systems, source neutron multiplication is explicitly modelled.
	www.neutron.kth.se /courses/transmutation/NeutronTransport/NeutronTransport.html (1500 words)

	Patent 4626400: Variable control of neutron albedo in toroidal fusion devices
		Neutron albedo materials may be arranged in layers adjacent to the inboard plasma device wall to provide the selected energy spectrum, multiplication, reflection, and other desired properties such as absorption, and moderation, depending on the particular toroidal device application device involved.
		Neutron albedo material may be comprised of neutron reflector material, neutron absorber material, neutron multiplying material, as well as material which also suppresses gamma radiation.
		Neutron albedo material is disposed immediately adjacent the inboard wall, and is movable, preferably in vertical directions, so as to be brought into and out of neutron modifying communication with the fusion neutrons.
	www.freepatentsonline.com /4626400.html (1500 words)

	intas 93-0298
		Morosov’s group (Kurchtov Inst.)has worked on two kinds of UCN experiments and spent several months at the ILL. The absorption of neutrons by hydrogen and fluorine on beryllium surfaces was studied, whether it lead to an upscattering of UCN or to neutron capture.
		This project aims at an improved experimental determination of the free neutron lifetime which is of fundamental importance for particle physics and cosmology.
		The most precise values for neutron lifetime were obtained recently by storage of ultracold neutrons (UCN) in material bottles and the project participants were involved in these experiments.
	www.intas.be /catalog/93-0298.htm (556 words)

	Thermal emission from neutron star atmospheres
		Detection of absorption lines corresponding to elements on the neutron star atmosphere and measurement of their gravitational redshift would provide rather accurate data (e.g., Özel and Psaltis 2003).
		Observations of isolated neutron stars (or neutron stars in quiescent X-ray binaries) are extremely important in fundamental physics, as thermal emission from the surface of a neutron star carries signatures of its gravitational field, which may be used to infer its mass and radius.
		From the gravitational redshift at the surface of the neutron star, the ratio between its mass and radius may be measured, providing a very strong constraint on neutron star models.
	sea.am.ub.es /Boletin/b18/HTML/node52.html (336 words)

	Reservoir Monitoring - Reservoir Performance Monitor (RPM)
		Pulsed Neutron Capture mode – principle measurement is sigma, the thermal neutron absorption cross section In the PNC logging mode, the neutron generator pulses at 1 kHz while the detectors record complete time spectra, and an energy spectrum, used to monitor instrument stability.
		Carbon/Oxygen spectroscopy mode – principal measurement is the C/O ratio The neutron generator pulses at 10 kHz in the C/O acquisition mode with the full inelastic and capture gamma ray energy spectra recorded by each detector.
		Carbon/Oxygen (C/O) and pulsed neutron capture (PNC) measurements acquired with the RPM tool provide water saturation and three-phase holdup determination nation, while oxygen activation measurements allow water flow and channel detection.
	www.bakerhughes.com /bakeratlas/reservoir_production/RPM_index.htm (409 words)

	Protein Labeling Kits
		Unlike other methods, such as atomic absorption spectrophotometry, neutron activation is not chemically or physically destructive.
		Neutron activation analysis is well known for its excellent sensitivity and elemental specificity for the simultaneous measurement of trace elements (1-3).
		Neutrons are highly penetrating, therefore this method can be used to assay samples having a wide range of material compositions and densities.
	www.biopal.com /neutron_activation.htm (409 words)

	An intense fast neutron beam in
		The contamination of a high intensity neutron beam after the production target is rather difficult to measure accurately although the presence of charged particles is easily shown with photographic emulsions and differential absorption with lead sheets [9].
		The drawback of the filter is that the inelastic neutron scattering on carbon nuclei (from the polyethylene slab) induces 4.43 MeV gamma-rays which are essentially not stopped and contribute to the gamma contamination of the final beam.
		The absolute neutron flux is estimated from the activation [4] of several metallic foils through reactions (Table 1) of known cross-sections (Fig.
	www.fynu.ucl.ac.be /themes/he/cms/neutron_beam/neutrons-beam.html (1048 words)

	Summary -- Assessment of the Practicality of Pulsed Fast Neutron Analysis for Aviation Security -- Executive Summary
		PFNA identifies explosives and drugs by the specific material- and energy-dependent absorption and scattering cross sections of neutrons as they interact with the nuclei of different elements.
		PFNA uses a collimated, nanosecond-pulse-width beam of monoenergetic fast neutrons to excite the nuclei of common elements in bulk materials to produce gamma-ray emissions (Brown, 1994; Gozani, 1995).
		PFNA uses a collimated, nanosecond-pulse-width beam of monoenergetic fast neutrons to excite the nuclei of common elements in bulk materials.
	www.nap.edu /execsumm/NI000414.html (7079 words)

	Core
		This shaping, or flattening, of the neutron flux is normally achieved through the use of reflectors that affect the flux profile across the core, or by the installation of poisons to suppress the neutron flux where desired.
		Reflector materials are normally not fissionable, have a high scattering cross section, and have a low absorption cross section.
		In fast reactor systems, reflectors are not composed of moderating materials because it is desired to keep neutron energy high.
	www.infodotinc.com /doenuclearphys/nuclearphysics86.htm (7079 words)

	Neutron Radiation
		In the absorption reaction, the neutron is actually absorbed into the nucleus of an atom.
		neutron is captured, but the atom is left in an excited state.
		Neutrons are attenuated (reduced in energy and numbers) by three major interactions, elastic
	www.tpub.com /content/doe/h1019v1/css/h1019v1_89.htm (345 words)

	Nuclear Weapon Radiation Effects
		The intensity of initial nuclear radiation decreases rapidly with distance from the point of burst due to the spread of radiation over a larger area as it travels away from the explosion, and to absorption, scattering, and capture by the atmosphere.
		The neutrons result almost exclusively from the energy producing fission and fusion reactions, while the initial gamma radiation includes that arising from these reactions as well as that resulting from the decay of short-lived fission products.
		Neutrons emitted as part of the initial nuclear radiation will cause activation of the weapon residues.
	www.fas.org /nuke/intro/nuke/radiation.htm (1995 words)

	SDV Nuclear Glossary
		Absorption of a neutron by an atomic nucleus.
		Neutrons in one generation that are successfully moderated and that induce further fission reactions produce a new generation of neutrons.
		Delayed neutrons account for approximately 0.75% of the neutron output from fission and this is an important aspect of controlling the increase in energy output of reactors.
	glossary.dataenabled.com /sdvglossary_neutrons.html (1995 words)

	Abstract: Numerical Simulations of Neutron Transport.
		The goal of this research is to develop data that will aid in analyses involving neutron absorption-produced
		These parameters are determined by fitting curves to the data produced by Monte Carlo computational simulations of the appropriate neutron transport phenomena.
		This is not understood as thoroughly as spallation, and due to its complexity is difficult to model with simple analytical expressions.
	www.laserhen.net /mc_abstract.htm (210 words)

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