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Topic: Neutron diffraction

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	Neutron Diffraction Facilities
		The Neutron Residual Stress Facilities complement the x-ray facilities, permitting the RSUC to provide the unique capability to measure stress both very near the surface as well as throughout the volume of a specimen.
		Because of the penetrating nature of neutrons, micro residual strains measured by neutron diffraction are free from surface effects and are particularly useful in characterizing metal matrix composites.
		The neutron diffraction facilities for macro residual stress mapping and micro residual stress characterization are located at the High Flux Isotope Reactor (HFIR) at ORNL and are operated in collaboration with the Neutron Scattering Group, Solid State Division, ORNL.
	www.ms.ornl.gov /htmlhome/rsuc/rsuc-nrsf.html (227 words)

	Neutron - MSN Encarta
		Neutron, electrically neutral elementary particle that is part of the nucleus of the atom.
		The neutron is also affected by the weak nuclear force, an interaction among the building blocks of the neutron that causes the neutron to decay, or break apart.
		The neutrons are responsible for the remaining mass of the atom.
	encarta.msn.com /encyclopedia_761565664/Neutron.html (1501 words)

	Laboratory for Neutron Scattering
		Neutron scattering measurements provide information on an atomic scale about the static and dynamical properties of condensed matter which - in many cases - is obtainable in no other way.
		Besides these research activities the laboratory is responsible for the operation, further development and extension of the instrumentation set up at the spallation source SINQ at the PSI Villigen for neutron scattering experiments.
		In order to run the user program at SINQ efficiently and smoothly, the laboratory is organized in the following three groups: neutron diffraction, neutron spectroscopy, small angle and reflectometry.
	lns.web.psi.ch (0 words)

	Press Release: The 1994 Nobel Prize in Physics
		Neutron scattering techniques are used in such widely differing areas as the study of the new ceramic superconductors, catalytic exhaust cleaning, elastic properties of polymers and virus structure.
		Neutron scattering techniques have since developed considerably and in the past few years neutrons have been used to an increasing extent for studying the structure (arrangement) and dynamics (movement) of solid and fluid matter.
		Neutrons again proved to have unique scattering properties, in this case because their energy is of the same order of magnitude as that of the phonons in solid and fluid matter.
	nobelprize.org /nobel_prizes/physics/laureates/1994/press.html (1994 words)

	Neutron diffraction (Site not responding. Last check: 2007-10-30)
		Diffraction is one of those phenomena; it occurs when waves encounter obstacles whose size is comparable with the wave length.
		Neutron diffraction then reveals structural details of the target material, which are measured by recording the way in which neutrons are deflected.
		Neutrons can also change their speed during the scattering experiment; this is used to study the types of vibrations that can occur in the solid.
	www.serebella.com /encyclopedia/article-Neutron_diffraction.html (410 words)

	[No title]
		The neutron is a powerful tool for the study of condensed matter (solids and liquids) in the world around us, having significant advantages over other forms of radiation in the study of microscopic structure and dynamics.
		Neutrons are stable when bound in an atomic nucleus, whilst having a mean lifetime of approximately 1000 seconds as a free particle.
		The 1994 Nobel Prize in Physics was awarded to Bertram Brockhouse and Clifford Shull for their pioneering contributions to the development of neutron scattering techniques for studies of condensed matter: for the development of the neutron diffraction and neutron spectroscopy techniques.
	www.isis.rl.ac.uk /aboutIsis/whatisaNeutron.htm (746 words)

	STRUBI Gilbert Group: Neutrons Introduction
		Furthermore, the pre-eminence of X-ray diffraction over electrons or neutrons as an approach in structural biology is firmly established due to the colossal endeavour which would be required to realize the theoretical resolving capability of an electron beam (which is comparable to the resolution practically possible with X-rays).
		Neutrons may be scattered coherently or incoherently by nuclei, providing information on the structure of a system or its dynamics respectively.
		In an (elastic, coherent) neutron experiment such as small-angle neutron scattering, neutron reflection, or within the various neutron diffraction geometries, the intensity with which neutrons are scattered from a sample is measured at a variety of angles.
	www.strubi.ox.ac.uk /people/gilbert/neutrons.html (1302 words)

	Reference.com/Encyclopedia/Neutron diffraction
		Neutron diffraction is a crystallographic method for the determination of the atomic structure of a material.
		When neutrons from a reactor are slowed down and selected properly, their wavelength lies near one angstrom (0.1 nanometer), the typical separation between atoms in a solid material.
		Neutron diffraction can be used to establish the structure of low atomic number materials like proteins and surfactants much more easily with lower flux than at a synchrotron radiation source.
	www.reference.com /browse/wiki/Neutron_diffraction (682 words)

	In protein crystallography neutron diffraction is used much less than X-ray diffraction due to low availability of ... (Site not responding. Last check: 2007-10-30)
		Neutron diffraction is therefore used to determine the positions of important hydrogen atoms, such as atoms involved in enzymatic reactions or in important hydrogen bonds and to study hydratation of biomolecules.
		Neutron diffraction can tell us whether a particular acidic group is dissociated or has a hydrogen atom bound to it, it can discriminate between water and hydroxyl anion in the active site of an enzyme, it can determine the orientation of a water molecule.
		The main problem in data treatment is normalisation of the data for spectral distribution of the neutron beam, that is, reflections have to be scaled according to the intensity of the part of the source beam with wavelength that fulfilled diffraction conditions.
	www.xray.cz /xray/csca/kol2002/doc/eva_buchtelova.htm (1604 words)

	X-ray, Neutron, and Electron Simulation in MOE
		The diffraction pattern generated from a single crystal is an array of sharp spots.
		Neutron diffraction is similar to that of X-rays, and has a wavelength on the order of 1 Ångstrom.
		Although, in theory, a diffraction pattern is a projection of the weighted crystal reciprocal lattice, in practice, the observed pattern is more complex, being affected by many factors including experimental setup, thermal vibration of the atoms in the crystal, internal reflections which cause interference, and so forth.
	www.chemcomp.com /journal/diffr.htm (1615 words)

	Introduction (Site not responding. Last check: 2007-10-30)
		Diffraction may be defined as the deviation of a wave from its natural direction of propagation when it encounters an object or a medium with spatially varying transmittance.A barrier or an opening (aperture) will cause a wave to bend or diffract.
		As the diffraction intensity from orientated crystals is concentrated onto a smaller detector area, better resolution is obtained than with powder diffraction, where the intensity is effectively attenuated over 2 pi radians.
		The neutron diffraction experiment is very similar to simple light microscopy in that the wave trains of the main beam are scattered by the sample.
	leaflet.vet.ed.ac.uk /webpage/research/techniques/neutron.html (3441 words)

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		The X-ray diffraction pattern of a crystal is the sampling at the reciprocal lattice points of the X-ray diffraction pattern of the contents of a single unit cell.
		The spatial arrangement of the diffracted beams is determined by the geometry of the crystal lattice while the intensities are determined by the arrangement of atoms within one unit cell.
		The diffraction cones are photographed as arcs of circles as illustrated in Fig 18.
	perso.fundp.ac.be /~jwouters/DRX/diffraction.html (6586 words)

	Neutron Vision
		Passing neutrons through a pinhole creates a tightly collimated beam, while refraction from a suitable crystal--separating wavelengths a bit like a prism--can yield neutrons of a single energy or wavelength.
		Neutrons from a 2-centimeter-wide beam first hit a coarse grating, which creates a series of bright neutron "lines." Each neutron line acts independently as a single "coherent" source of waves, like light from a pinhole used in classic optics experiments, because the slits are widely spaced (several millimeters apart).
		Neutron refraction can cleanly distinguish between, say, titanium and molybdenum, even though their absorption of neutrons is similar.
	focus.aps.org /story/v17/st20 (687 words)

	Neutron Diffraction Online Encyclopedia Article About Neutron Diffraction (Site not responding. Last check: 2007-10-30)
		Because neutrons have no electric charge they are very penetrating, and their magnetic moment makes them useful for determining the magnetic aspects of materials, such as high-temperature superconducting compounds.
		Neutron scattering was pioneered by Bertram Brockhouse and Cliff Shull who were awarded the 1994 Nobel Prize for Physics for this work.
		Neutron scattering is used to study many systems including plastics, ceramics, liquid crystal, proteins, and biological materials.
	encyclopedia.jrank.org /Cambridge/entries/021/neutron-diffraction.html (211 words)

	JOM 0603: Structure Determination of Phase Analysis by the Use of Neutron Diffraction
		Neutron diffuse scattering from single-crystal benzil measured at the SXD single-crystal diffractometer at ISIS.
		The neutron is scattered by the atomic nucleus, which is a point on the length-scale of the neutron wavelength (10—15 m compared to 10—10 m).
		Neutron diffraction is set to have a large impact here, too, for the same reasons as in crystalline materials: the complementarity of neutron and x-ray data.
	www.tms.org /pubs/journals/jom/0603/billinge-0603.html (3457 words)

	Structure of Polyunsaturated Lipid Bilayers Important for Rhodopsin Function: A Neutron Diffraction Study, The ... (Site not responding. Last check: 2007-10-30)
		The structure of oriented 1-stearoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine bilayers with perdeuterated stearoyl- or docosahexaenoyl hydrocarbon chains was investigated by neutron diffraction.
		Diffraction experiments were performed on the advanced neutron diffractometer/reflectometer (3) at the NIST Center for Neutron Research, Gaithersburg, MD. The diffraction data were collected in a θ-2θ (specular) mode.
		Neutron extinction effects appeared as a nonlinearity of structure factors versus ^sup 2^H2O content of the low-Q, high-intensity diffraction peaks (mainly for n = 1), (5).
	findarticles.com /p/articles/mi_qa3938/is_200601/ai_n15972191 (846 words)

	Los Alamos National Laboratory (LANL): Lab survey reveals high demand for neutron diffraction experiments
		"This neutron diffraction station will be the only resource of its kind in the nation serving the structural biology community for determining macromolecular structures, once it's completed," said Paul Langan of Los Alamos' Life Sciences Division.
		With neutron diffraction, a beam of neutrons passes through a material under study and scatters into a pattern that reveals the relative positions of the atoms in the target material.
		Neutron diffraction's big advantage over X-ray diffraction is that neutrons can pinpoint the positions of hydrogen atoms.
	www.lanl.gov /news/index.php/fuseaction/home.story/story_id/2000 (650 words)

	The Structure of Polyunsaturated Lipid Bilayers Important for Rhodopsin Function: A Neutron Diffraction Study - Science ...
		The structure of oriented 1-stearoyl-2-docosahexaenoyl-sn- glycero-3-phosphocholine bilayers with perdeuterated stearoyl- or docosahexaenoyl hydrocarbon chains was investigated by neutron diffraction.
		Diffraction experiments were performed on the advanced neutron diffractometer/reflectometer (3) at the NIST Center for Neutron Research, Gaithersburg, MD. The diffraction data were collected in a &952; (specular) mode.
		The AND/R, constructed by the Cold Neutrons for Biology and Technology (CNBT) partnership, is supported by the National Institute of Standards and Technology, the Regents of the University of California, and by a grant from the National Institute for Research Resources awarded to the Un\iversity of California at Irvine.
	www.redorbit.com /news/science/345969/the_structure_of_polyunsaturated_lipid_bilayers_important_for_rhodopsin_function/index.html?source=r_science (1647 words)

	Division of ENGINEERING & APPLIED SCIENCE at Caltech
		Diffraction techniques use a material's crystalline lattice as an "internal gauge," and are therefore sensitive to changes occurring on the atomic scale.
		On exiting the guide, neutrons pass to the center of the cave where some are scattered by the sample to the detectors.
		However, we were able to use diffraction data to develop new mechanics models (finite-element or self-consistent) that allowed deduction of the behavior of the BMG matrix.
	www.eas.caltech.edu /engenious/win03/ustundag.html (2099 words)

	SCIMEDIA: Neutron Diffraction (Site not responding. Last check: 2007-10-30)
		Neutron beams interact more strongly with nuclei than do x-rays and neutron diffraction is more useful than x-ray diffraction for determining proton positions.
		Neutrons interact with a solid to a much lesser degree than x-rays and therefore have advantages in studying materials that are damaged by x-rays and in cases where a large penetration depth is desired.
		Neutrons are produced by nuclear reactions in either a nuclear reactor or in an accelerator.
	www.uam.es /docencia/quimcursos/Scimedia/chem-ed/diffract/neutron.htm (170 words)

	TAML: Structural Materials - Neutron Scattering
		Neutron powder diffraction data collected as a function of temperature allows the determination of the expansivity of clathrate hydrates with various guest molecules.
		Neutron diffraction is a powerful tool for characterizing structural materials with complex microstructures because (1) neutrons penetrate most engineering materials three to four orders of magnitude deeper than conventional x-rays (cm vs. µm), and (2) neutrons distinguish phases and crystal planes.
		The underlying goal of the proposal is to “accomplish the national agenda of advancing neutron science and engineering in the USA to the leadership position in the world” by providing the most-advanced research and education opportunities to the user community.
	www.phys.utk.edu /taml/fields/neutron.html (1557 words)

	Protein crystallography resource at neutron research center for imaging proteins
		The neutron diffraction station may provide critical data for pharmaceutical companies to develop new designer drugs to combat debilitating diseases.
		This diffraction pattern is manipulated and then analyzed by a computer to reveal the 3-D structure of the sample.
		Moreover, because neutron diffraction can see hydrogen, researchers will be able to better understand the role that water (two hydrogen atoms bound to an oxygen atom) plays in proteins and polymers.
	www.eurekalert.org /features/doe/2001-06/danl-pcr061702.php (395 words)

	Neutron Physics Division
		The general purpose of this project is the study, by means of neutron diffraction techniques, of the structure of the Omega phase in quenched Zr-Nb alloys, and the Omega - Beta mixtures in metastable equilibrium which are present in thermally treated alloys.
		Neutron moderation in media heterogeneously poisoned with a suitable neutron absorber is studied through extensive experimental research, and by means of numerical simulation.
		To obtain structural information from Neutron Scattering data of liquid and amorphous systems, it is imperative the evaluation of corrections due to multiple scattering and inelasticity, in order to extract the elastic coherent component in the observed spectra.
	www.cab.cnea.gov.ar /cab/ingNuclear/neutrones.html (1145 words)

	Neutron Diffraction Studies of C4KHg
		Because neutrons are sensitive to hydrogen, unlike x-rays or electrons, this experiment could even allow the determination of the hydrogen positions, should they be ordered.
		The neutron diffraction data consists of (00l) scans on a pink sample, a gold sample, a gold sample with hydrogen, and a gold sample with deuterium.
		Thermal neutrons, on the other hand, have a penetration depth of about one centimeter, which is more than enough to see the whole thickness of a GIC.[184] The idea that all gold stage I KHg-GIC's contain the beta phase may be important for understanding the hydrogenation experiments, as discussed in Chapter 5.
	www.wsrcc.com /alison/thesis2/qthesis/node18.html (3015 words)

	Line profiles of neutron powder-diffraction peaks for structure refinement.<SUP></SUP> (Site not responding. Last check: 2007-10-30)*
		A structure refinement procedure is described, which obtains a least-squares fit between the calculated and observed intensities measured at equal angular intervals on a neutron powder-diffractometer.
		While the structure determination from a well resolved powder diffraction diagram often proves to be quite feasible, the inherent presence of overlapping reflections generally prevents the full use of the available information to refine the structural parameters.
		In the case of neutron diffraction, a more direct method to solve this problem was found when it appeared that the peak shapes of the single diffraction peaks obtained from the powder-diffractometer at Petten were Gaussian.
	crystal.tau.ac.il /xtal/paper1/paper1.html (516 words)

	Neutron diffraction analysis of myoglobin: structure of the carbon monoxide derivative -- Norvell et al. 190 (4214): ...
		Neutron diffraction analysis of myoglobin: structure of the carbon monoxide derivative -- Norvell et al.
		Neutron diffraction analysis of myoglobin: structure of the carbon monoxide derivative
		The locations of hydrogen and deuterium atoms and water molecules have been investigated in carbon monoxide myoglobin using neutron diffraction, and the results are compared with earlier work on metmyoglobin.
	www.sciencemag.org /cgi/content/abstract/190/4214/568 (278 words)

	Conference on New Frontiers in Neutron Macromolecular Crystallography
		X-ray diffraction beyond this limit can only be achieved with highly ordered crystals which accounts for less than 1% of all protein systems being studied by x-ray diffraction.
		Poster winners were Brad Bennett for presenting results that utilized neutron diffraction and Zoe Fisher for the proposed concept of neutron use to further her research.
		A Neutron Biological Diffractometer in J-PARC, I. Tanaka
	www.sns.gov /workshops/mandi2005 (976 words)

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