WorldWideScience

Sample records for collaboration neutron scattering

  1. UA/ORNL Collaboration: Neutron Scattering Studies of Antiferromagnetic Films, Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Mankey, Gary J.

    2006-07-26

    The work reported here was a collaborative project between the research groups of Dr. J.L. Robertson at Oak Ridge National Laboratory and Dr. G.J. Mankey at the University of Alabama. The main thrust is developing neutron optical devices and materials for the study of magnetic thin films and interfaces. The project is particularly timely, since facility upgrades are currently underway at the High Flux Isotope Reactor. A new neutron optical device, a multicrystal analyzer, was designed and built to take maximum advantage of the increased flux that the upgraded beamlines at HFIR will provide. This will make possible detailed studies of the magnetic structure of thin films, multilayers, and interfaces that are not feasible at present. We performed studies of the antiferromagnetic order in thin films and crystals using neutron scattering, determined magnetic structures at interfaces with neutron reflectometry and measured order in magnetic dispersions using small angle neutron scattering. The collaboration has proved fruitful: generating eleven publications, contributing to the training of a postdoc who is now on staff at the High Flux Isotope Reactor and providing the primary support for two recent Ph.D. recipients. The collaboration is still vibrant, with anticipated implementation of the multicrystal analyzer on one of the new cold source beamlines at the High Flux Isotope Reactor.

  2. Neutron scattering. Lectures

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

    2010-07-01

    The following topics are dealt with: Neutron sources, neutron properties and elastic scattering, correlation functions measured by scattering experiments, symmetry of crystals, applications of neutron scattering, polarized-neutron scattering and polarization analysis, structural analysis, magnetic and lattice excitation studied by inelastic neutron scattering, macromolecules and self-assembly, dynamics of macromolecules, correlated electrons in complex transition-metal oxides, surfaces, interfaces, and thin films investigated by neutron reflectometry, nanomagnetism. (HSI)

  3. Neutron scattering. Lectures

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

    2010-07-01

    The following topics are dealt with: Neutron sources, symmetry of crystals, diffraction, nanostructures investigated by small-angle neutron scattering, the structure of macromolecules, spin dependent and magnetic scattering, structural analysis, neutron reflectometry, magnetic nanostructures, inelastic scattering, strongly correlated electrons, dynamics of macromolecules, applications of neutron scattering. (HSI)

  4. Neutron scattering. Experiment manuals

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

    2010-07-01

    The following topics are dealt with: The thermal triple axis spectrometer PUMA, the high-resolution powder diffractometer SPODI, the hot single-crystal diffractometer HEiDi for structure analysis with neutrons, the backscattering spectrometer SPHERES, neutron polarization analysis with tht time-of-flight spectrometer DNS, the neutron spin-echo spectrometer J-NSE, small-angle neutron scattering with the KWS-1 and KWS-2 diffractometers, the very-small-angle neutron scattering diffractrometer with focusing mirror KWS-3, the resonance spin-echo spectrometer RESEDA, the reflectometer TREFF, the time-of-flight spectrometer TOFTOF. (HSI)

  5. Introduction to neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, W.E. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1996-11-01

    We give here an introduction to the theoretical principles of neutron scattering. The relationship between scattering- and correlation-functions is particularly emphasized. Within the framework of linear response theory (justified by the weakness of the basic interaction) the relation between fluctuation and dissipation is discussed. This general framework explains the particular power of neutron scattering as an experimental method. (author) 4 figs., 4 refs.

  6. Virtual neutron scattering experiments

    DEFF Research Database (Denmark)

    Overgaard, Julie Hougaard; Bruun, Jesper; May, Michael

    2016-01-01

    We describe how virtual experiments can be utilized in a learning design that prepares students for hands-on experiments at large-scale facilities. We illustrate the design by showing how virtual experiments are used at the Niels Bohr Institute in a master level course on neutron scattering....... In the last week of the course, students travel to a large-scale neutron scattering facility to perform real neutron scattering experiments. Through student interviews and survey answers, we argue, that the virtual training prepares the students to engage more fruitfully with experiments by letting them focus...

  7. Neutron scattering in dimers

    DEFF Research Database (Denmark)

    Gudel, H. U.; Furrer, A.; Kjems, Jørgen

    1986-01-01

    Insulating compounds containing dimers of transition metal and rare earth ions have been studied by inelastic neutron scattering (INS). Energy splittings can be directly determined, and the corresponding parameters are easily extracted from the experimental data. The intensities of dimer excitati......Insulating compounds containing dimers of transition metal and rare earth ions have been studied by inelastic neutron scattering (INS). Energy splittings can be directly determined, and the corresponding parameters are easily extracted from the experimental data. The intensities of dimer...

  8. Neutron scattering from fractals

    DEFF Research Database (Denmark)

    Kjems, Jørgen; Freltoft, T.; Richter, D.

    1986-01-01

    -angle neutron scattering studies of the variation with aggregation rate are presented. These results allow a very detailed comparison to be made with the theoretical scattering curves. Preliminary incoherent inelastic data on the low-frequency dynamics of hydroxylated silica particle aggregates show a clear...

  9. MAGNETIC NEUTRON SCATTERING

    Energy Technology Data Exchange (ETDEWEB)

    ZALIZNYAK,I.A.; LEE,S.H.

    2004-07-30

    Much of our understanding of the atomic-scale magnetic structure and the dynamical properties of solids and liquids was gained from neutron-scattering studies. Elastic and inelastic neutron spectroscopy provided physicists with an unprecedented, detailed access to spin structures, magnetic-excitation spectra, soft-modes and critical dynamics at magnetic-phase transitions, which is unrivaled by other experimental techniques. Because the neutron has no electric charge, it is an ideal weakly interacting and highly penetrating probe of matter's inner structure and dynamics. Unlike techniques using photon electric fields or charged particles (e.g., electrons, muons) that significantly modify the local electronic environment, neutron spectroscopy allows determination of a material's intrinsic, unperturbed physical properties. The method is not sensitive to extraneous charges, electric fields, and the imperfection of surface layers. Because the neutron is a highly penetrating and non-destructive probe, neutron spectroscopy can probe the microscopic properties of bulk materials (not just their surface layers) and study samples embedded in complex environments, such as cryostats, magnets, and pressure cells, which are essential for understanding the physical origins of magnetic phenomena. Neutron scattering is arguably the most powerful and versatile experimental tool for studying the microscopic properties of the magnetic materials. The magnitude of the cross-section of the neutron magnetic scattering is similar to the cross-section of nuclear scattering by short-range nuclear forces, and is large enough to provide measurable scattering by the ordered magnetic structures and electron spin fluctuations. In the half-a-century or so that has passed since neutron beams with sufficient intensity for scattering applications became available with the advent of the nuclear reactors, they have became indispensable tools for studying a variety of important areas of modern

  10. Virtual neutron scattering experiments

    DEFF Research Database (Denmark)

    Overgaard, Julie Hougaard; Bruun, Jesper; May, Michael

    2017-01-01

    . In the last week of the course, students travel to a large-scale neutron scattering facility to perform real neutron scattering experiments. Through student interviews and survey answers, we argue, that the virtual training prepares the students to engage more fruitfully with experiments by letting them focus......We describe how virtual experiments can be utilized in a learning design that prepares students for hands-on experiments at large-scale facilities. We illustrate the design by showing how virtual experiments are used at the Niels Bohr Institute in a master level course on neutron scattering...... on physics and data rather than the overwhelming instrumentation. We argue that this is because they can transfer their virtual experimental experience to the real-life situation. However, we also find that learning is still situated in the sense that only knowledge of particular experiments is transferred...

  11. Virtual neutron scattering experiments

    DEFF Research Database (Denmark)

    Overgaard, Julie Hougaard; Bruun, Jesper; May, Michael

    2016-01-01

    We describe how virtual experiments can be utilized in a learning design that prepares students for hands-on experiments at large-scale facilities. We illustrate the design by showing how virtual experiments are used at the Niels Bohr Institute in a master level course on neutron scattering....... In the last week of the course, students travel to a large-scale neutron scattering facility to perform real neutron scattering experiments. Through student interviews and survey answers, we argue, that the virtual training prepares the students to engage more fruitfully with experiments by letting them focus...... on physics and data rather than the overwhelming instrumentation. We argue that this is because they can transfer their virtual experimental experience to the real-life situation. However, we also find that learning is still situated in the sense that only knowledge of particular experiments is transferred...

  12. Neutron scattering in Australia

    Energy Technology Data Exchange (ETDEWEB)

    Knott, R.B. [Australian Nuclear Science and Technology Organisation, Menai (Australia)

    1994-12-31

    Neutron scattering techniques have been part of the Australian scientific research community for the past three decades. The High Flux Australian Reactor (HIFAR) is a multi-use facility of modest performance that provides the only neutron source in the country suitable for neutron scattering. The limitations of HIFAR have been recognized and recently a Government initiated inquiry sought to evaluate the future needs of a neutron source. In essence, the inquiry suggested that a delay of several years would enable a number of key issues to be resolved, and therefore a more appropriate decision made. In the meantime, use of the present source is being optimized, and where necessary research is being undertaken at major overseas neutron facilities either on a formal or informal basis. Australia has, at present, a formal agreement with the Rutherford Appleton Laboratory (UK) for access to the spallation source ISIS. Various aspects of neutron scattering have been implemented on HIFAR, including investigations of the structure of biological relevant molecules. One aspect of these investigations will be presented. Preliminary results from a study of the interaction of the immunosuppressant drug, cyclosporin-A, with reconstituted membranes suggest that the hydrophobic drug interdigitated with lipid chains.

  13. Small Angle Neutron Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Urban, Volker S [ORNL

    2012-01-01

    Small Angle Neutron Scattering (SANS) probes structural details at the nanometer scale in a non-destructive way. This article gives an introduction to scientists who have no prior small-angle scattering knowledge, but who seek a technique that allows elucidating structural information in challenging situations that thwart approaches by other methods. SANS is applicable to a wide variety of materials including metals and alloys, ceramics, concrete, glasses, polymers, composites and biological materials. Isotope and magnetic interactions provide unique methods for labeling and contrast variation to highlight specific structural features of interest. In situ studies of a material s responses to temperature, pressure, shear, magnetic and electric fields, etc., are feasible as a result of the high penetrating power of neutrons. SANS provides statistical information on significant structural features averaged over the probed sample volume, and one can use SANS to quantify with high precision the structural details that are observed, for example, in electron microscopy. Neutron scattering is non-destructive; there is no need to cut specimens into thin sections, and neutrons penetrate deeply, providing information on the bulk material, free from surface effects. The basic principles of a SANS experiment are fairly simple, but the measurement, analysis and interpretation of small angle scattering data involves theoretical concepts that are unique to the technique and that are not widely known. This article includes a concise description of the basics, as well as practical know-how that is essential for a successful SANS experiment.

  14. FINAL REPORT: DOE CONTRACT NUMBER FG0205ER64026 Biological Neutron Scattering: A Collaboration with the Oak Ridge Center for Structural Molecular Biology

    Energy Technology Data Exchange (ETDEWEB)

    Trewhella, Jill [Univ. of Utah, Salt Lake City, UT (United States)

    2011-01-12

    The overarching goal of this project was to promote applications of small-angle scattering in structural molecular biology by providing model examples of cutting edge applications that demonstrate the unique capabilities and potential of the DOE national user facilities at Oak Ridge, especially the newly commissioned BioSANS. The approach taken was three-fold: (1) to engage in high impact collaborative research projects that would benefit from small-angle neutron scattering to both demonstrate the power of the technique while expanding the potential user community; (2) to provide access to scattering facilities established at the University of Utah to as broad a set of researchers as possible to increase the expertise in small-angle scattering generally; and (3) to develop new methods and tools for small-angle scattering. To these ends, three major research collaborations were pursued that resulted in a significant body of published work where neutron scattering and contrast variation played a major role. These major collaborations involved studies of protein complexes involved in (1) bacterial transcription regulation and adaptive response (a DOE/BER priority area); (2) regulation of cardiac muscle; and (3) neuronal disorders. In addition, to broaden the impact of the project, smaller collaborative efforts were supported that used either small-angle X-ray or neutron scattering. Finally, the DOE supported facilities at the University of Utah were made available to researchers on a service basis and a number of independent groups took advantage of this opportunity. In all of this work, there was an emphasis on the training of students and post docs in scattering techniques, and a set of publications (a book chapter, a review, and an encyclopedia article) were produced to guide the non-specialist potential user of scattering techniques in successful applications of the techniques. We also developed a suite of user friendly web-based computational tools currently

  15. German neutron scattering conference. Programme and abstracts

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas (ed.)

    2012-07-01

    The German Neutron Scattering Conference 2012 - Deutsche Neutronenstreutagung DN 2012 offers a forum for the presentation and critical discussion of recent results obtained with neutron scattering and complementary techniques. The meeting is organized on behalf of the German Committee for Research with Neutrons - Komitee Forschung mit Neutronen KFN - by the Juelich Centre for Neutron Science JCNS of Forschungszentrum Juelich GmbH. In between the large European and international neutron scattering conferences ECNS (2011 in Prague) and ICNS (2013 in Edinburgh), it offers the vibrant German and international neutron community an opportunity to debate topical issues in a stimulating atmosphere. Originating from ''BMBF Verbundtreffen'' - meetings for projects funded by the German Federal Ministry of Education and Research - this conference series has a strong tradition of providing a forum for the discussion of collaborative research projects and future developments in the field of research with neutrons in general. Neutron scattering, by its very nature, is used as a powerful probe in many different disciplines and areas, from particle and condensed matter physics through to chemistry, biology, materials sciences, engineering sciences, right up to geology and cultural heritage; the German Neutron Scattering Conference thus provides a unique chance for exploring interdisciplinary research opportunities. It also serves as a showcase for recent method and instrument developments and to inform users of new advances at neutron facilities.

  16. Small angle neutron scattering

    Directory of Open Access Journals (Sweden)

    Cousin Fabrice

    2015-01-01

    Full Text Available Small Angle Neutron Scattering (SANS is a technique that enables to probe the 3-D structure of materials on a typical size range lying from ∼ 1 nm up to ∼ a few 100 nm, the obtained information being statistically averaged on a sample whose volume is ∼ 1 cm3. This very rich technique enables to make a full structural characterization of a given object of nanometric dimensions (radius of gyration, shape, volume or mass, fractal dimension, specific area… through the determination of the form factor as well as the determination of the way objects are organized within in a continuous media, and therefore to describe interactions between them, through the determination of the structure factor. The specific properties of neutrons (possibility of tuning the scattering intensity by using the isotopic substitution, sensitivity to magnetism, negligible absorption, low energy of the incident neutrons make it particularly interesting in the fields of soft matter, biophysics, magnetic materials and metallurgy. In particular, the contrast variation methods allow to extract some informations that cannot be obtained by any other experimental techniques. This course is divided in two parts. The first one is devoted to the description of the principle of SANS: basics (formalism, coherent scattering/incoherent scattering, notion of elementary scatterer, form factor analysis (I(q→0, Guinier regime, intermediate regime, Porod regime, polydisperse system, structure factor analysis (2nd Virial coefficient, integral equations, characterization of aggregates, and contrast variation methods (how to create contrast in an homogeneous system, matching in ternary systems, extrapolation to zero concentration, Zero Averaged Contrast. It is illustrated by some representative examples. The second one describes the experimental aspects of SANS to guide user in its future experiments: description of SANS spectrometer, resolution of the spectrometer, optimization of

  17. Progress report on neutron scattering at JAERI

    Energy Technology Data Exchange (ETDEWEB)

    Morii, Yukio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-10-01

    In the first half of fiscal year 1997, JRR-3M was operated for 97 days followed by a long term shut down for its annual maintenance. Three days were lost out of 100 scheduled operation days, due to a trouble in irradiation facility. Neutron scattering research activities at the JRR-3M have been extended from that of fiscal year 1996. In the Research Group for Quantum Condensed Matter System, experimental study under high pressures, low temperatures and high fields as well as coupling of these conditions were planned to find new quantum condensed matter systems. And, obtained experimental results were immediately provided to theorists for their investigations. In cooperation with new group, Research Group for Neutron Scattering of Strongly Correlated Electron Systems and Research Group for Neutron Scattering at Ultralow Temperatures were carrying neutron scattering experiments at JRR-3M. Research Group for Neutron Crystallography in Biology had opened a way for investigating biomatter neutron diffraction research with high experimental accuracy by growing a millimeter-class large single crystal. In fiscal year 1997, 39 research projects were conducted by these four groups and other staffs in JAERI, 27 projects collaborated with university researchers and 3 projects collaborated with private enterprises were also conducted as complementary researches. 2117 days of machine times were requested to use 8 neutron scattering instruments this year, which corresponded to 1.51 times larger than those planned at its beginning. (G.K.)

  18. Neutron scatter camera

    Science.gov (United States)

    Mascarenhas, Nicholas; Marleau, Peter; Brennan, James S.; Krenz, Kevin D.

    2010-06-22

    An instrument that will directly image the fast fission neutrons from a special nuclear material source has been described. This instrument can improve the signal to background compared to non imaging neutron detection techniques by a factor given by ratio of the angular resolution window to 4.pi.. In addition to being a neutron imager, this instrument will also be an excellent neutron spectrometer, and will be able to differentiate between different types of neutron sources (e.g. fission, alpha-n, cosmic ray, and D-D or D-T fusion). Moreover, the instrument is able to pinpoint the source location.

  19. Neutron scattering and models: Titanium

    Energy Technology Data Exchange (ETDEWEB)

    Smith, A.B.

    1997-07-01

    Differential neutron elastic-scattering cross sections of elemental titanium were measured from 4.5 {r_arrow} 10.0 MeV in incident energy increments of {approx} 0.5 MeV. At each energy the measurements were made at forty or more scattering angles distributed between {approx} 17 and 160{degree}. Concurrently, differential neutron inelastic-scattering cross sections were measured for observed excitations of 0.975 {+-} 0.034, 1.497 {+-} 0.033, 2.322 {+-} 0.058, 3.252 {+-} 0.043, 3.700 {+-} 0.093, 4.317 {+-} 0.075 and 4.795 {+-} 0.100 MeV. All of the observed inelastically-scattered neutron groups were composites of contributions from several isotopes and/or levels. The experimental results were used to develop energy-average optical, statistical and coupled-channels models.

  20. Neutron scattering in liquids

    Energy Technology Data Exchange (ETDEWEB)

    Barocchi, F. [Florence Univ. (Italy). Ist. di Fisica

    1996-12-31

    Together with X-rays, thermal neutrons are the ideal probe to study the microscopic structure of condensed matter, however the precision attainable usually with neutrons for the measurement of atomic position correlation functions in liquids is, at least, one order of magnitude better than for X-rays. In order to measure properly the microscopic dynamics a wide range of momentum transfer with corresponding energy transfer must be available in the range of liquid state excitations. This again is only attainable, with good resolution, with neutrons. (author) 7 figs., 3 refs.

  1. Thermal neutron scattering evaluation framework

    Science.gov (United States)

    Chapman, Chris; Leal, Luiz; Rahnema, Farzad; Danon, Yaron; Arbanas, Goran

    2017-09-01

    A neutron scattering kernel data evaluation framework for computation of model-dependent predictions and their uncertainties is outlined. In this framework, model parameters are fitted to double-differential cross section measurements and their uncertainties. For convenience, the initial implementation of this framework uses the molecular dynamics model implemented in the GROMACS code. It is applied to light water using the TIP4P/2005f interaction model. These trajectories computed by GROMACS are then processed using nMOLDYN to compute the density of states, which is then used to calculate the scattering kernel using the Gaussian approximation. Double differential cross sections computed from the scattering kernel are then fitted to double-differential scattering data measured at the Spallation Neutron Source detector at Oak Ridge National Laboratory. The fitting procedure is designed to yield optimized model-parameters and their uncertainties in the form of a covariance matrix, from which new evaluations of thermal neutron scattering kernel will be generated. The Unified Monte Carlo method will be used to fit the simulation data to the experimental data.

  2. New Techniques in Neutron Scattering

    DEFF Research Database (Denmark)

    Birk, Jonas Okkels

    Neutron scattering is an important experimental technique in amongst others solid state physics, biophysics, and engineering. This year construction of European Spallation Source (ESS) was commenced in Lund, Sweeden. The facility will use a new long pulsed source principle to obtain higher....... The instrument is ideally suited for solid state experiments with extreme sample environments such as large pressures and strong magnetic fields. CAMEA combines the time-of-flight technique to determine the energy of the incoming neutrons with a complex multiplex backend that will analyse and detect...

  3. Fundamentals of neutron scattering by condensed matter

    Energy Technology Data Exchange (ETDEWEB)

    Scherm, R. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1996-12-31

    The purpose of this introductory lecture is to give the basic facts about the scattering of neutrons by condensed matter. This lecture is restricted to nuclear scattering, whereas magnetic scattering will be dealt with in an other course. Most of the formalism, however, can also be easily extended to magnetic scattering. (author) 17 figs., 3 tabs., 10 refs.

  4. American Conference on Neutron Scattering 2014

    Energy Technology Data Exchange (ETDEWEB)

    Dillen, J. Ardie [Materials Research Society, Warrendale, PA (United States)

    2014-12-31

    Scientists from the around the world converged in Knoxville, TN to have share ideas, present technical information and contribute to the advancement of neutron scattering. Featuring over 400 oral/poster presentations, ACNS 2014 offered a strong program of plenary, invited and contributed talks and poster sessions covering topics in soft condensed matter, hard condensed matter, biology, chemistry, energy and engineering applications in neutron physics – confirming the great diversity of science that is enabled by neutron scattering.

  5. Neutron scattering and models : molybdenum.

    Energy Technology Data Exchange (ETDEWEB)

    Smith, A.B.

    1999-05-26

    A comprehensive interpretation of the fast-neutron interaction with elemental and isotopic molybdenum at energies of {le} 30 MeV is given. New experimental elemental-scattering information over the incident energy range 4.5 {r_arrow} 10 MeV is presented. Spherical, vibrational and dispersive models are deduced and discussed, including isospin, energy-dependent and mass effects. The vibrational models are consistent with the ''Lane potential''. The importance of dispersion effects is noted. Dichotomies that exist in the literature are removed. The models are vehicles for fundamental physical investigations and for the provision of data for applied purposes. A ''regional'' molybdenum model is proposed. Finally, recommendations for future work are made.

  6. Neutrons scattering studies in the actinide region

    Science.gov (United States)

    Kegel, G. H. R.; Egan, J. J.

    1992-09-01

    During the last report period, we investigated the following areas: prompt fission neutron energy spectra measurements; neutron elastic and inelastic scattering from Pu-239; neutron scattering in Ta-181 and Au-197; response of a U-235 fission chamber near reaction thresholds; two-parameter data acquisition system; 'black' neutron detector; investigation of neutron-induced defects in silicon dioxide; and multiple scattering corrections. Four Ph.D. dissertations and one M.S. thesis were completed during the report period. Publications consisted of three journal articles, four conference papers in proceedings, and eleven abstracts of presentations at scientific meetings. There are currently four Ph.D. and one M.S. candidates working on dissertations directly associated with the project. In addition, three other Ph.D. candidates are working on dissertations involving other aspects of neutron physics in this laboratory.

  7. Techniques in high pressure neutron scattering

    CERN Document Server

    Klotz, Stefan

    2013-01-01

    Drawing on the author's practical work from the last 20 years, Techniques in High Pressure Neutron Scattering is one of the first books to gather recent methods that allow neutron scattering well beyond 10 GPa. The author shows how neutron scattering has to be adapted to the pressure range and type of measurement.Suitable for both newcomers and experienced high pressure scientists and engineers, the book describes various solutions spanning two to three orders of magnitude in pressure that have emerged in the past three decades. Many engineering concepts are illustrated through examples of rea

  8. Inelastic critical scattering of neutrons from terbium

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage; Dietrich, O.W.; Marshall, W.

    1967-01-01

    We have measured the inelasticity of the critical neutron scattering in Tb above the Néel temperature. The results show that dynamical slowing down of fluctuations does occur at a second order phase transition.......We have measured the inelasticity of the critical neutron scattering in Tb above the Néel temperature. The results show that dynamical slowing down of fluctuations does occur at a second order phase transition....

  9. Grazing incidence polarized neutron scattering in reflection ...

    Indian Academy of Sciences (India)

    This review summarizes recent experimental investigations using neutron scattering on layered nanomagnetic systems (accentuating my contribution), which have applications in spintronics also. Polarized neutron investigations of such artificially structured materials are basically done to understand the interplay between ...

  10. Introduction to neutron scattering. Lecture notes of the introductory course

    Energy Technology Data Exchange (ETDEWEB)

    Furrer, A. [ed.

    1996-12-31

    These proceedings enclose ten papers presented at the 1. European Conference on Neutron scattering (ECNS `96). The aim of the Introductory Course was fourfold: - to learn the basic principles of neutron scattering, - to get introduced into the most important classes of neutron scattering instruments, -to learn concepts and their transformation into neutron scattering experiments in various fields of condensed matter research, - to recognize the limitations of the neutron scattering technique as well as to the complementarity of other methods. figs., tabs., refs.

  11. Neutron Scattering from 36Ar and 4He Films

    DEFF Research Database (Denmark)

    Carneiro, K.

    1977-01-01

    Scale factors for neutron diffraction and neutron inelastic scattering are presented for common adsorbates, and the feasibility of experiments is discussed together with the information gained by each type of experiment. Diffraction, coherent inelastic scattering, and incoherent scattering are tr...

  12. Neutron Scattering in Biology Techniques and Applications

    CERN Document Server

    Fitter, Jörg; Katsaras, John

    2006-01-01

    The advent of new neutron facilities and the improvement of existing sources and instruments world wide supply the biological community with many new opportunities in the areas of structural biology and biological physics. The present volume offers a clear description of the various neutron-scattering techniques currently being used to answer biologically relevant questions. Their utility is illustrated through examples by some of the leading researchers in the field of neutron scattering. This volume will be a reference for researchers and a step-by-step guide for young scientists entering the field and the advanced graduate student.

  13. Inelastic Neutron Scattering from Cerium under Pressure

    DEFF Research Database (Denmark)

    Rainford, B. D.; Buras, B.; Lebech, Bente

    1977-01-01

    Inelastic neutron scattering from Ce metal at 300 K was studied both below and above the first order γ-α phase transition, using a triple axis spectrometer. It was found that (a) there is no indication of any residual magnetic scattering in the collapsed α phase, and (b) the energy width of the p...

  14. Critical Magnetic Scattering of Neutrons in Iron

    DEFF Research Database (Denmark)

    Passell, L.; Blinowski, K.; Brun, T.

    1965-01-01

    Measurements of the angular and energy distributions of 4.28 Å neutrons scattered at small angles from iron at temperatures above the Curie temperature are described. The results are interpreted in terms of Van Hove's theory of critical magnetic scattering and yield information on the range of spin...

  15. Neutron Brillouin scattering in dense fluids

    Energy Technology Data Exchange (ETDEWEB)

    Verkerk, P. [Technische Univ. Delft (Netherlands); FINGO Collaboration

    1997-04-01

    Thermal neutron scattering is a typical microscopic probe for investigating dynamics and structure in condensed matter. In contrast, light (Brillouin) scattering with its three orders of magnitude larger wavelength is a typical macroscopic probe. In a series of experiments using the improved small-angle facility of IN5 a significant step forward is made towards reducing the gap between the two. For the first time the transition from the conventional single line in the neutron spectrum scattered by a fluid to the Rayleigh-Brillouin triplet known from light-scattering experiments is clearly and unambiguously observed in the raw neutron data without applying any corrections. Results of these experiments are presented. (author).

  16. BUILDING A NETWORK FOR NEUTRON SCATTERING EDUCATION

    Energy Technology Data Exchange (ETDEWEB)

    Pynn, Roger [ORNL; Baker, Shenda Mary [ORNL; Louca, Despo A [ORNL; McGreevy, Robert L [ORNL; Ekkebus, Allen E [ORNL; Kszos, Lynn A [ORNL; Anderson, Ian S [ORNL

    2008-10-01

    In a concerted effort supported by the National Science Foundation, the Department of Commerce, and the Department of Energy, the United States is rebuilding its leadership in neutron scattering capability through a significant investment in U.S. neutron scattering user facilities and related instrumentation. These unique facilities provide opportunities in neutron scattering to a broad community of researchers from academic institutions, federal laboratories, and industry. However, neutron scattering is often considered to be a tool for 'experts only' and in order for the U.S. research community to take full advantage of these new and powerful tools, a comprehensive education and outreach program must be developed. The workshop described below is the first step in developing a national program that takes full advantage of modern education methods and leverages the existing educational capacity at universities and national facilities. During March 27-28, 2008, a workshop entitled 'Building a Network for Neutron Scattering Education' was held in Washington, D.C. The goal of the workshop was to define and design a roadmap for a comprehensive neutron scattering education program in the United States. Successful implementation of the roadmap will maximize the national intellectual capital in neutron sciences and will increase the sophistication of research questions addressed by neutron scattering at the nation's forefront facilities. (See Appendix A for the list of attendees, Appendix B for the workshop agenda, Appendix C for a list of references. Appendix D contains the results of a survey given at the workshop; Appendix E contains summaries of the contributed talks.) The workshop brought together U.S. academicians, representatives from neutron sources, scientists who have developed nontraditional educational programs, educational specialists, and managers from government agencies to create a national structure for providing ongoing neutron

  17. Neutron scattering studies of modulated magnetic structures

    Energy Technology Data Exchange (ETDEWEB)

    Aagaard Soerensen, Steen

    1999-08-01

    This report describes investigations of the magnetic systems DyFe{sub 4}Al{sub 8} and MnSi by neutron scattering and in the former case also by X-ray magnetic resonant scattering. The report is divided into three parts: An introduction to the technique of neutron scattering with special emphasis on the relation between the scattering cross section and the correlations between the scattering entities of the sample. The theoretical framework of neutron scattering experiments using polarized beam technique is outlined. The second part describes neutron and X-ray scattering investigation of the magnetic structures of DyFe{sub 4}Al{sub 8}. The Fe sublattice of the compound order at 180 K in a cycloidal structure in the basal plane of the bct crystal structure. At 25 K the ordering of the Dy sublattice shows up. By the element specific technique of X-ray resonant magnetic scattering, the basal plane cycloidal structure was also found for the Dy sublattice. The work also includes neutron scattering studies of DyFe{sub 4}Al{sub 8} in magnetic fields up to 5 T applied along a <110> direction. The modulated structure at the Dy sublattice is quenched by a field lower than 1 T, whereas modulation is present at the Fe sublattice even when the 5 T field is applied. In the third part of the report, results from three small angle neutron experiments on MnSi are presented. At ambient pressure, a MnSi is known to form a helical spin density wave at temperature below 29 K. The application of 4.5 kbar pressure intended as hydrostatic decreased the Neel temperature to 25 K and changed the orientation of the modulation vector. To understand this reorientation within the current theoretical framework, anisotropic deformation of the sample crystal must be present. The development of magnetic critical scattering with an isotropic distribution of intensity has been studied at a level of detail higher than that of work found in the literature. Finally the potential of a novel polarization

  18. Neutron Scattering and High Magnetic Fields

    Energy Technology Data Exchange (ETDEWEB)

    Winn, Barry L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Stone, Matthew B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2014-11-01

    The workshop “Neutron Scattering and High Magnetic Fields” was held September 4-5, 2014 at the Oak Ridge National Laboratory (ORNL). The workshop was held in response to a recent report by the National Research Council of the National Academy of Sciences entitled “High Magnetic Field Science and Its Application in the United States: Current Status and Future Directions.”1 This report highlights the fact that neutron scattering measurements carried out in high magnetic fields provide important opportunities for new science. The workshop explored the range of the scientific discoveries that could be enabled with neutron scattering measurements at high fields (25 Tesla or larger), the various technologies that might be utilized to build specialized instruments and sample environment equipment to enable this research at ORNL, and possible routes to funding and constructing these facilities and portable high field sample environments.

  19. Magnetic chirality as probed by neutron scattering

    Science.gov (United States)

    Simonet, V.; Loire, M.; Ballou, R.

    2012-11-01

    We review the concept of chirality, at first briefly in a general context then in the specific framework of the spin networks. We next discuss to what extent neutron scattering appears as an unconvertible tool to probe magnetic chirality in the static and dynamical regimes of the spins. The remarkable chiral ground state and excitations of the Fe-langasite compound finally serves to illustrate the use of neutron polarimetry in the experimental studies of the magnetic chirality.

  20. Neutron scattering of advanced magnetic materials

    Science.gov (United States)

    Yusuf, S. M.; Kumar, Amit

    2017-09-01

    An overview of notable contributions of neutron scattering in the advancement of magnetic materials has been presented. A brief description of static neutron scattering techniques, viz., diffraction, depolarization, small angle scattering, and reflectivity, employed in the studies of advanced magnetic materials, is given. Apart from providing the up-to-date literature, this review highlights the importance of neutron scattering techniques in achieving microscopic as well as mesoscopic understanding of static magnetic properties of the following selective classes of advanced magnetic materials: (i) magnetocaloric materials, (ii) permanent magnets, (iii) multiferroic materials, (iv) spintronic materials, and (v) molecular magnetic materials. In the area of magnetocaloric materials, neutron diffraction studies have greatly improved the understanding of magneto-structural coupling by probing (i) atomic site distribution, (ii) evolution of structural phases and lattice parameters across the TC, and (iii) microscopic details of magnetic ordering in several potential magnetocaloric materials. Such an understanding is vital to enhance the magnetocaloric effect. Structural and magnetic investigations, employing neutron diffraction and allied techniques, have helped to improve the quality of permanent magnets by tailoring (understanding) structural phases, magnetic ordering, crystallinity, microstructure (texture), and anisotropy. The neutron diffraction studies of structural distortions/instabilities and magnetic ordering in multiferroic materials have improved the microscopic understanding of magnetoelectric coupling that allows one to control magnetic order by an electric field and electric order by a magnetic field in multiferroic materials. In the field of molecular magnetic materials, neutron diffraction studies have enhanced the understanding of (i) structural and magnetic ordering, (ii) short-range structural and magnetic correlations, (iii) spin density distribution

  1. Precision Neutron Scattering Length Measurements with Neutron Interferometry

    Science.gov (United States)

    Huber, M. G.; Arif, M.; Jacobson, D. L.; Pushin, D. A.; Abutaleb, M. O.; Shahi, C. B.; Wietfeldt, F. E.; Black, T. C.

    2011-10-01

    Since its inception, single-crystal neutron interferometry has often been utilized for precise neutron scattering length, b, measurements. Scattering length data of light nuclei is particularly important in the study of few nucleon interactions as b can be predicted by two + three nucleon interaction (NI) models. As such they provide a critical test of the accuracy 2+3 NI models. Nuclear effective field theories also make use of light nuclei b in parameterizing mean-field behavior. The NIST neutron interferometer and optics facility has measured b to less than 0.8% relative uncertainty in polarized 3He and to less than 0.1% relative uncertainty in H, D, and unpolarized 3He. A neutron interferometer consists of a perfect silicon crystal machined such that there are three separate blades on a common base. Neutrons are Bragg diffracted in the blades to produce two spatially separate (yet coherent) beam paths much like an optical Mach-Zehnder interferometer. A gas sample placed in one of the beam paths of the interferometer causes a phase difference between the two paths which is proportional to b. This talk will focus on the latest scattering length measurement for n-4He which ran at NIST in Fall/Winter 2010 and is currently being analyzed.

  2. Neutron elastic scattering at very small angles

    CERN Multimedia

    2002-01-01

    This experiment will measure neutron-proton elastic scattering at very small angles and hence very small four-momentum transfer, |t|. The range of |t| depends on the incident neutron momentum of the events but the geometrical acceptance will cover the angular range 0.025 < $\\Theta_{lab}$ < 1.9 mrad. The higher figure could be extended to 8.4 mrad by changing the geometry of the experiment in a later phase. \\\\ \\\\ The neutron beam will be highly collimated and will be derived from a 400 GeV external proton beam of up to $4 \\times 10^{10}$ protons per pulse in the SPS North Area Hall 1. The hydrogen target will be gaseous, operating at 40 atm. pressure and acts as a multiwire proportional chamber to detect the recoil protons. The forward neutron will be detected and located by interaction in a neutron vertex detector and its energy measured by a conventional steel plate calorimeter. \\\\ \\\\ The experiment will cover the angular region of nucleon-nucleon scattering which is dominated by Coulomb scattering ...

  3. Neutron detectors for scattering experiments at HANARO

    Indian Academy of Sciences (India)

    alignment of the monochromator crystal and sample itself. The traditional photo- graphic method is time consuming and does not provide any information on the small variations in intensity. LE PSD is used for beam alignment at all the neutron scattering instruments at HANARO [3]. Figure 3a shows the assembled LE PSD.

  4. Critical scattering of neutrons from terbium

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage; Dietrich, O.W.; Marshall, W.

    1968-01-01

    The inelasticity of the critical scattering of neutrons in terbium has been measured above the Neél temperature at the (0, 0, 2−Q) satellite position. The results show that dynamic slowing down of the fluctuations does occur in a second‐order phase transition in agreement with the general theory...

  5. Magnetic Scattering of Neutrons in Chronium

    DEFF Research Database (Denmark)

    Bjerrum Møller, Hans; Blinowski, K.; Mackintosh, A. R.

    1964-01-01

    The results of a study of the magnetic scattering of neutrons in chromium near the Néel temperature are presented. It is deduced from these results that short range ordering persists in chromium unusually high above the Néel temperature, and that the magnetic structure below the Néel temperature...

  6. NEUTRON-SCATTERING STUDY OF DCN

    DEFF Research Database (Denmark)

    Mackenzie, Gordon A.; Pawley, G. S.

    1979-01-01

    Phonons in deuterium cyanide have been measured by neutron coherent inelastic scattering. The main subject of study was the transverse acoustic mode in the (110) direction polarised along (110) which is associated with the first-order structural phase transition at 160K. Measurements have shown...

  7. 2016 American Conference on Neutron Scattering (ACNS)

    Energy Technology Data Exchange (ETDEWEB)

    Woodward, Patrick [Materials Research Society, Warrendale, PA (United States)

    2017-02-09

    The 8th American Conference on Neutron Scattering (ACNS) was held July 10-14, 2016 in Long Beach California, marking the first time the meeting has been held on the west coast. The meeting was coordinated by the Neutron Scattering Society of America (NSSA), and attracted 285 attendees. The meeting was chaired by NSSA vice president Patrick Woodward (the Ohio State University) assisted by NSSA president Stephan Rosenkranz (Argonne National Laboratory) together with the local organizing chair, Brent Fultz (California Institute of Technology). As in past years the Materials Research Society assisted with planning, logistics and operation of the conference. The science program was divided into the following research areas: (a) Sources, Instrumentation, and Software; (b) Hard Condensed Matter; (c) Soft Matter; (d) Biology; (e) Materials Chemistry and Materials for Energy; (f) Engineering and Industrial Applications; and (g) Neutron Physics.

  8. Neutron Scattering in MoNA detector bars for Comparison with Simulation

    Science.gov (United States)

    Wantz, A.; Boone, J. E.; Rogers, W. F.; Frank, N.; Kuchera, A. N.; Mosby, S.; Thoennessen, M.; MoNA Collaboration

    2017-09-01

    In order to test the effectiveness and accuracy of Monte Carlo simulation (GEANT4 with Menate_R), used by the MoNA collaboration for interpreting neutron-scattering data from the MoNA (Modular Neutron Array) and LISA (Large multi-Institutional Scintillator Arrays at NSCL, MSU, an experiment was conducted at Los Alamos LANSCE center in which 16 MoNA detector bars were exposed to a well characterized neutron beam. Each MoNA bar consists of BC408 organic scintillator measuring 200×10×10 cm3 with PMTs attached to each end. In order to properly characterize important neutron scattering signatures over a wide range of incoming neutron energy, such as scattering angle, mean distance between scatters, multiplicity, and dark-scatter, it is important that background be fully understood and corrected for. Background sources include neutrons scattered from the collimator on entrance to the room, decay of neutron-activation within the bars, neutrons scattering in the room, and cosmic muons. Several methods for accounting for and removing background contributions to data were developed so that data can be compared directly with simulation (which does not contain these background features). Results, including scattering data comparisons with simulation will be presented. Work supported by NSF Grant PHY-1744043.

  9. Neutron scattering from polarised proton domains

    CERN Document Server

    Van den Brandt, B; Kohbrecher, J; Konter, J A; Mango, S; Glattli, H; Leymarie, E; Grillo, I; May, R P; Jouve, H; Stuhrmann, H B; Stuhrmann, H B; Zimmer, O

    2002-01-01

    Time-dependent small-angle polarised neutron scattering from domains of polarised protons has been observed at the onset of dynamic nuclear polarisation in a frozen solution of 98% deuterated glycerol-water at 1 K containing a small concentration of paramagnetic centres (EHBA-Cr sup V). Simultaneous NMR measurements show that the observed scattering arises from protons around the Cr sup V -ions which are polarised to approx 10% in a few seconds, much faster than the protons in the bulk. (authors)

  10. Neutron scattering applications in structural biology: now and the future

    Energy Technology Data Exchange (ETDEWEB)

    Trewhella, J. [Los Alamos National Lab., NM (United States)

    1996-05-01

    Neutrons have an important role to play in structural biology. Neutron crystallography, small-angle neutron scattering and inelastic neutron scattering techniques all contribute unique information on biomolecular structures. In particular, solution scattering techniques give critical information on the conformations and dispositions of the components of complex assemblies under a wide variety of relevant conditions. The power of these methods is demonstrated here by studies of protein/DNA complexes, and Ca{sup 2+}-binding proteins complexed with their regulatory targets. In addition, we demonstrate the utility of a new structural approach using neutron resonance scattering. The impact of biological neutron scattering to date has been constrained principally by the available fluxes at neutron sources and the true potential of these approaches will only be realized with the development of new more powerful neutron sources. (author)

  11. Neutron scattering treatise on materials science and technology

    CERN Document Server

    Kostorz, G

    1979-01-01

    Treatise on Materials Science and Technology, Volume 15: Neutron Scattering shows how neutron scattering methods can be used to obtain important information on materials. The book discusses the general principles of neutron scattering; the techniques used in neutron crystallography; and the applications of nuclear and magnetic scattering. The text also describes the measurement of phonons, their role in phase transformations, and their behavior in the presence of crystal defects; and quasi-elastic scattering, with its special merits in the study of microscopic dynamical phenomena in solids and

  12. Neutron scattering instrumentation for biology at spallation neutron sources

    Energy Technology Data Exchange (ETDEWEB)

    Pynn, R. [Los Alamos National Laboratory, NM (United States)

    1994-12-31

    Conventional wisdom holds that since biological entities are large, they must be studied with cold neutrons, a domain in which reactor sources of neutrons are often supposed to be pre-eminent. In fact, the current generation of pulsed spallation neutron sources, such as LANSCE at Los Alamos and ISIS in the United Kingdom, has demonstrated a capability for small angle scattering (SANS) - a typical cold- neutron application - that was not anticipated five years ago. Although no one has yet built a Laue diffractometer at a pulsed spallation source, calculations show that such an instrument would provide an exceptional capability for protein crystallography at one of the existing high-power spoliation sources. Even more exciting is the prospect of installing such spectrometers either at a next-generation, short-pulse spallation source or at a long-pulse spallation source. A recent Los Alamos study has shown that a one-megawatt, short-pulse source, which is an order of magnitude more powerful than LANSCE, could be built with today`s technology. In Europe, a preconceptual design study for a five-megawatt source is under way. Although such short-pulse sources are likely to be the wave of the future, they may not be necessary for some applications - such as Laue diffraction - which can be performed very well at a long-pulse spoliation source. Recently, it has been argued by Mezei that a facility that combines a short-pulse spallation source similar to LANSCE, with a one-megawatt, long-pulse spallation source would provide a cost-effective solution to the global shortage of neutrons for research. The basis for this assertion as well as the performance of some existing neutron spectrometers at short-pulse sources will be examined in this presentation.

  13. Polarized neutron scattering on HYSPEC: the HYbrid SPECtrometer at SNS

    Energy Technology Data Exchange (ETDEWEB)

    Zaliznyak, Igor [Brookhaven National Laboratory (BNL); Savici, Andrei T [ORNL; Garlea, Vasile O [ORNL; Winn, Barry L [ORNL; Schneelock, John [Brookhaven National Laboratory (BNL); Tranquada, John M. [Brookhaven National Laboratory (BNL); Gu, G. D. [Brookhaven National Laboratory (BNL); Wang, Aifeng [Brookhaven National Laboratory (BNL); Petrovic, C [Brookhaven National Laboratory (BNL)

    2017-01-01

    We describe some of the first polarized neutron scattering measurements performed at HYSPEC spectrometer at the Spallation Neutron Source, Oak Ridge National Laboratory. We discuss details of the instrument setup and the experimental procedures in the mode with the full polarization analysis. Examples of the polarized neutron diffraction and the polarized inelastic neutron data obtained on single crystal samples are presented.

  14. Cryogen free cryostat for neutron scattering experiments

    Science.gov (United States)

    Kirichek, O.; Down, R. B. E.; Manuel, P.; Keeping, J.; Bowden, Z. A.

    2014-12-01

    Most very low temperature (below 1K) experiments at advanced neutron facilities are based on dilution and 3He refrigerator inserts used with Orange cryostats, or similar systems. However recent increases in the cost of liquid helium caused by global helium supply problems, has raised significant concern about the affordability of such cryostats. Here we present the design and test results of a cryogen free top-loading cryostat with a standard KelvinoxVT® dilution refrigerator insert which provides sample environment for neutron scattering experiments in the temperature range 35 mK - 300 K. The dilution refrigerator insert operates in a continuous regime. The cooling time of the insert is similar to one operated in the Orange cryostat. The main performance criteria such as base temperature, cooling power, and circulation rate are compatible with the technical specification of a standard dilution refrigerator. In fact the system offers operating parameters very similar to those of an Orange cryostat, but without the complication of cryogens. The first scientific results obtained in ultra-low temperature neutron scattering experiment with this system are also going to be discussed.

  15. Significance of collective motions in biopolymers and neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Go, Nobuhiro [Kyoto Univ. (Japan)

    1996-05-01

    Importance of collective variable description of conformational dynamics of biopolymers and the vital role that neutron inelastic scattering phenomena would play in its experimental determination are discussed. (author)

  16. Molecular dynamics using quasielastic neutron scattering

    CERN Document Server

    Mitra, S

    2003-01-01

    Quasielastic neutron scattering (QENS) technique is well suited to study the molecular motions (rotations and translations) in solids or liquids. It offers a unique possibility of analysing spatial dimensions of atomic or molecular processes in their development over time. We describe here some of the systems studied using the QENS spectrometer, designed, developed and commissioned at Dhruva reactor in Trombay. We have studied a variety of systems to investigate the molecular motion, for example, simple molecular solids, molecules adsorbed in confined medium like porous systems or zeolites, monolayer-protected nano-sized metal clusters, water in Portland cement as it cures with time, etc. (author)

  17. Deeply Virtual Compton Scattering off the neutron

    CERN Document Server

    Mazouz, M; Ferdi, C; Gavalian, G; Kuchina, E; Amarian, M; Aniol, K A; Beaumel, M; Benaoum, H; Bertin, P; Brossard, M; Chen, J P; Chudakov, E; Craver, B; Cusanno, F; De Jager, C W; Deur, A; Feuerbach, R; Fieschi, J M; Frullani, S; Garçon, M; Garibaldi, F; Gayou, O; Gilman, R; Gómez, J; Gueye, P; Guichon, P A M; Guillon, B; Hansen, O; Hayes, D; Higinbotham, D; Holmstrom, T; Hyde, C E; Ibrahim, H; Igarashi, R; Jiang, X; Jo, H S; Kaufman, L J; Kelleher, A; Kolarkar, A; Kumbartzki, G; Laveissière, G; Le Rose, J J; Lindgren, R; Liyanage, N; Lu, H J; Margaziotis, D J; Meziani, Z E; McCormick, K; Michaels, R; Michel, B; Moffit, B; Monaghan, P; Nanda, S; Nelyubin, V; Potokar, M; Qiang, Y; Ransome, R D; Real, J S; Reitz, B; Roblin, Y; Roche, J; Sabatie, F; Saha, A; Sirca, S; Slifer, K; Solvignon, P; Subedi, R; Sulkosky, V; Ulmer, P E; Voutier, E; Wang, K; Weinstein, L B; Wojtsekhowski, B; Zheng, X; Zhu, L

    2007-01-01

    The present experiment exploits the interference between the Deeply Virtual Compton Scattering (DVCS) and the Bethe-Heitler processes to extract the imaginary part of DVCS amplitudes on the neutron and on the deuteron from the helicity-dependent D$({\\vec e},e'\\gamma)X$ cross section measured at $Q^2$=1.9 GeV$^2$ and $x_B$=0.36. We extract a linear combination of generalized parton distributions (GPDs) particularly sensitive to $E_q$, the least constrained GPD. A model dependent constraint on the contribution of the up and down quarks to the nucleon spin is deduced.

  18. Complex Magnetic Systems Studied with Neutron Scattering

    DEFF Research Database (Denmark)

    Jacobsen, Henrik

    the spins in the nanoparticle move coherently. One part of the thesis explores the structure and dynamic of magnetic nanoparticles, with emphasis being placed on hematite. Hematite has easy-axis and in-plane anisotropy, as well as being strongly antiferromagnetic. The excitation energies have been derived...... of the lack of conventional long range order in GGG. Several members of the La2􀀀xSrxCuO4+y cuprate family of high-temperature superconductors were investigated using neutron scattering. In La2􀀀xSrxCuO4 with x = 0:12 the correlations along the c-axis were investigated. It was found...

  19. INFLUENCE OF SCATTERED NEUTRON RADIATION ON METROLOGICAL CHARACTERISTICS OF АТ140 NEUTRON CALIBRATION FACILITY

    Directory of Open Access Journals (Sweden)

    D. I. Komar

    2017-01-01

    Full Text Available Today facilities with collimated radiation field are widely used as reference in metrological support of devices for neutron radiation measurement. Neutron fields formed by radionuclide neutron sources. The aim of this research was to study characteristics of experimentally realized neutron fields geometries on АТ140 Neutron Calibration Facility using Monte Carlo method.For calibration, we put a device into neutron field with known flux density or ambient equivalent dose rate. We can form neutron beam from radionuclide fast-neutron source in different geometries. In containercollimator of АТ140 Neutron Calibration Facility we can install special inserts to gather fast-neutron geometry or thermal-neutron geometry. We need to consider neutron scattering from air and room’s walls. We can conduct measurements of neutron field characteristics in several points and get the other using Monte Carlo method.Thermal neutron collimator forms a beam from radionuclide source with a significant amount of neutrons with thermal energies. From found relationship between full neutron flux and distance to neutron source we see that inverse square law is violated. Scattered radiation contribution into total flux increases when we are moving away from neutron source and significantly influences neutron fields characteristics. While source is exposed in shadow-cone geometry neutron specter has pronounced thermal component from wall scattering.In this work, we examined main geometry types used to acquire reference neutron radiation using radionuclide sources. We developed Monte Carlo model for 238Pu-Be neutron source and АТ140 Neutron Calibration Facility’s container-collimator. We have shown the most significant neutron energy distribution factor to be scattered radiation from room’s walls. It leads to significant changes of neutron radiation specter at a distance from the source. When planning location, and installing the facility we should consider

  20. An inelastic neutron scattering study of hematite nanoparticles

    DEFF Research Database (Denmark)

    Hansen, Mikkel Fougt; Klausen, Stine Nyborg; Lefmann, K

    2003-01-01

    We have studied the magnetic dynamics in nanocrystalline hematite by inelastic neutron scattering at the high-resolution time-of-flight spectrometer IRIS at ISIS. Compared to previous inelastic neutron scattering experiments an improvement of the resolution function is achieved and more detailed...

  1. Some applications of polarized inelastic neutron scattering in ...

    Indian Academy of Sciences (India)

    A brief account of applications of polarized inelastic neutron scattering in condensed matter research is given. We show that ... Laboratory for Neutron Scattering, ETH Zürich & Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland; Physik-Department E21, Technische Universität München, D-85747 Garching, Germany ...

  2. Internal motions in proteins: A combined neutron scattering and ...

    Indian Academy of Sciences (India)

    Abstract. It is well-known that water plays a major role in the stability and catalytic function of proteins. Both the effect of hydration water on the dynamics of proteins and that of proteins on the dynamics of water have been studied using inelastic neutron scatter- ing. Inelastic neutron scattering is the most direct probe of ...

  3. Regge Poles in Neutron Scattering by a Cylinder

    Directory of Open Access Journals (Sweden)

    K. V. Protasov

    2014-01-01

    Full Text Available We establish asymptotic expressions for the positions of Regge poles for cold neutron scattering on mesoscopic cylinder mirror as well as for the S-matrix residuals. We outline the correspondence between Regge poles and near-surface quasi-stationary neutron states. Such states are of practical importance for studying subtle effects of neutron-surface interaction.

  4. Optimising polarised neutron scattering measurements--XYZ and polarimetry analysis

    CERN Document Server

    Cussen, L D

    2002-01-01

    The analytic optimisation of neutron scattering measurements made using XYZ polarisation analysis and neutron polarimetry techniques is discussed. Expressions for the 'quality factor' and the optimum division of counting time for the XYZ technique are presented. For neutron polarimetry the optimisation is identified as analogous to that for measuring the flipping ratio and reference is made to the results already in the literature.

  5. Neutron Scattering Investigations of Correlated Electron Systems and Neutron Instrumentation

    DEFF Research Database (Denmark)

    Holm, Sonja Lindahl

    is on correlated electron systems. Here the magnetism of six different compounds have been studied with neutron scattering, including three different hole-doped cuprate high-temperature superconductors (HTSC), an electron-doped iron pnictide HTSC, a mineral with small clusters of geometrically frustrated magnetism...... contains antiferromagnetically coupled Cu2+ S = 1=2 ions forming truncated 24-spin cube clusters of linked triangles. The clusters in boleite afford a situation intermediate between molecular and bulk magnetism, accessible to both experiment and numerical theory, in which a spin liquid can be studied...... phonon modes and a coupling via the single-ion magnetostriction allows to calculate the spectra and the measured cross-section. An external magnetic field along the c-axis reveals a linear splitting of one spin wave branch which allows an exclusion of several proposed magnetic ground states based...

  6. Inelastic neutron scattering to very high pressures

    Science.gov (United States)

    Klotz, S.; Braden, M.; Besson, J. M.

    2000-11-01

    Progress in high-pressure and neutron scattering methods has recently allowed measurements of phonon dispersion curves of simple solids at high pressures to 10 GPa. In this technique single crystals of 10 25 mm3 volume are compressed by the Paris-Edinburgh cell and the phonon frequencies are measured on high-flux triple axis spectrometers. Detailed studies of the lattice dynamics of low-compressible systems are feasible, including measurements of mode Grüneisen parameters, elastic constants, and precursor effects of phase transitions. We describe the experimental set-up and illustrate its potential by results on semiconductors (Ge and GaSb) and metals (Fe and Zn) obtained at the LLB (Saclay) and ILL (Grenoble) reactor sources.

  7. Neutron beam characterization measurements at the Manuel Lujan Jr. neutron scattering center

    Energy Technology Data Exchange (ETDEWEB)

    Mocko, Michal [Los Alamos National Laboratory; Muhrer, Guenter [Los Alamos National Laboratory; Daemen, Luke L [Los Alamos National Laboratory; Kelsey, Charles T [Los Alamos National Laboratory; Duran, Michael A [Los Alamos National Laboratory; Tovesson, Fredrik K [Los Alamos National Laboratory

    2010-01-01

    We have measured the neutron beam characteristics of neutron moderators at the Manuel Lujan Jr. Neutron Scattering Center at LANSCE. The absolute thermal neutron flux, energy spectra and time emission spectra were measured for the high resolution and high intensity decoupled water, partially coupled liquid hydrogen and partially coupled water moderators. The results of our experimental study will provide an insight into aging of different target-moderator-reflector-shield components as well as new experimental data for benchmarking of neutron transport codes.

  8. Neutron scattering for the analysis of biological structures. Brookhaven symposia in biology. Number 27

    Energy Technology Data Exchange (ETDEWEB)

    Schoenborn, B P [ed.

    1976-01-01

    Sessions were included on neutron scattering and biological structure analysis, protein crystallography, neutron scattering from oriented systems, solution scattering, preparation of deuterated specimens, inelastic scattering, data analysis, experimental techniques, and instrumentation. Separate entries were made for the individual papers.

  9. Introduction to the theory of thermal neutron scattering

    CERN Document Server

    Squires, G L

    2012-01-01

    Since the advent of the nuclear reactor, thermal neutron scattering has proved a valuable tool for studying many properties of solids and liquids, and research workers are active in the field at reactor centres and universities throughout the world. This classic text provides the basic quantum theory of thermal neutron scattering and applies the concepts to scattering by crystals, liquids and magnetic systems. Other topics discussed are the relation of the scattering to correlation functions in the scattering system, the dynamical theory of scattering and polarisation analysis. No previous knowledge of the theory of thermal neutron scattering is assumed, but basic knowledge of quantum mechanics and solid state physics is required. The book is intended for experimenters rather than theoreticians, and the discussion is kept as informal as possible. A number of examples, with worked solutions, are included as an aid to the understanding of the text.

  10. Neutron scattering and the search for mechanisms of superconductivity

    DEFF Research Database (Denmark)

    Aeppli, G.; Bishop, D.J.; Broholm, C.

    1999-01-01

    Neutron scattering is a direct probe of mass and magnetization density in solids. We start with a brief review of experimental strategies for determining the mechanisms of superconductivity and how neutron scattering contributed towards our understanding of conventional superconductors. The remai......Neutron scattering is a direct probe of mass and magnetization density in solids. We start with a brief review of experimental strategies for determining the mechanisms of superconductivity and how neutron scattering contributed towards our understanding of conventional superconductors....... The remainder of the article gives examples of neutron results with impact on the search for the mechanism of superconductivity in more recently discovered, 'exotic', materials, namely the heavy fermion compounds and the layered cuprates, (C) 1999 Elsevier Science B.V. All rights reserved....

  11. Multiple small-angle neutron scattering studies of anisotropic materials

    CERN Document Server

    Allen, A J; Long, G G; Ilavsky, J

    2002-01-01

    Building on previous work that considered spherical scatterers and randomly oriented spheroidal scatterers, we describe a multiple small-angle neutron scattering (MSANS) analysis for nonrandomly oriented spheroids. We illustrate this with studies of the multi-component void morphologies found in plasma-spray thermal barrier coatings. (orig.)

  12. International and interlaboratory collaboration on Neutron Science Project

    Energy Technology Data Exchange (ETDEWEB)

    Oyama, Yukio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-11-01

    For effectiveness of facility development for Neutron Science Projects at JAERI, international and interlaboratory collaborations have been extensively planned and promoted, especially in the areas of accelerator and target technology. Here status of two collaborations relevant to a spallation neutron target development is highlighted from those collaborations. The two collaborations are experiments on BNL-AGS spallation target simulation and PSI materials irradiation. Both are planned to start in spring of 1997. (author)

  13. The use of neutron scattering in nuclear weapons research

    Energy Technology Data Exchange (ETDEWEB)

    Juzaitis, R.J. [Los Alamos National Lab., NM (United States)

    1995-10-01

    We had a weapons science breakout session last week. Although it would have been better to hold it closer in time to this workshop, I think that it was very valuable. it may have been less of a {open_quotes}short-sleeve{close_quotes} workshop environment than we would have liked, but as the first time two communities-the weapons community and the neutron scattering community- got together, it was a wonderful opportunity to transfer information during the 24 presentations that were made. This report contains discussions on the fundamental analysis of documentation of the enduring stockpile; LANSCE`s contribution to weapons; spallation is critical to understanding; weapons safety assessments; applied nuclear physics requires cross section information; fission models need refinement; and establishing teams on collaborative projects.

  14. LANSCE '90: The Manuel Lujan Jr. Neutron Scattering Center

    Energy Technology Data Exchange (ETDEWEB)

    Pynn, R.

    1990-01-01

    This paper describes progress that has been made at the Manuel Lujan Jr. Neutron Scattering Center (LANSCE) during the past two years. Presently, LANSCE provides a higher peak neutron flux than any other pulsed spallation neutron source. There are seven spectrometers for neutron scattering experiments that are operated for a national user program sponsored by the US Department of Energy. Two more spectrometers are under construction. Plans have been made to raise the number of beam holes available for instrumentation and to improve the efficiency of the target/moderator system. 9 refs., 4 figs.

  15. Small-angle neutron scattering studies of sodium butyl benzene ...

    Indian Academy of Sciences (India)

    Na-NBBS), in aqueous solutions is investigated by small-angle neutron scattering (SANS). Nearly ellipsoidal aggregates of Na-NBBS at concentrations well above its minimum hydrotrope concentration were detected by SANS. The hydrotrope ...

  16. Dynamics of Magnetic Nanoparticles Studied by Neutron Scattering

    DEFF Research Database (Denmark)

    Hansen, Mikkel Fougt; Bødker, Franz; Mørup, Steen

    1997-01-01

    We present the first triple-axis neutron scattering measurements of magnetic fluctuations in nanoparticles using an antiferromagnetic reflection. Both the superparamagnetic relaxation and precession modes in similar to 15 nm hematite particles are: observed. The results have been consistently...

  17. Orbital effects in cobaltites by neutron scattering

    Science.gov (United States)

    Louca, Despina

    2005-03-01

    The orbital degree of freedom can play a central role in the physics of transition metal perovskite oxides because of its intricate coupling with other degrees of freedom such as spin, charge and lattice. In this talk the case of La1-xSrxCoO3 will be presented. Using elastic and inelastic neutron scattering, we investigated the thermal evolution of the local atomic structure and lattice dynamics in the pure sample and with the addition of charge carriers as the system crosses over from a paramagnetic insulator to a ferromagnetic metal. In LaCoO3, the thermal activation of the Co ions from a nonmagnetic ground state to an intermediate spin state gives rise to orbital degeneracy. This leads to Jahn-Teller distortions that are dynamical in nature. Doping stabilizes the intermediate spin configuration of the Co ions in the paramagnetic insulating phase. Evidence for local static Jahn-Teller distortions is observed but without long-range ordering. The size of the JT lattice is proportional to the amount of charge. However, with cooling to the metallic phase, static JT distortions disappear for x Louca and J. L. Sarrao, Phys. Rev. Lett. 91, 155501 (2003).

  18. Measurement of the small angle scattering of polarized neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Giordano, V.; Manduchi, C.; Russo-Manduchi, M.T.; Segato, G.F. (Padua Univ. (Italy). Ist. di Fisica; Istituto Nazionale di Fisica Nucleare, Padua (Italy))

    1980-06-01

    Described herein is an apparatus designed merely for the purpose of extending previous measurements of the differential cross section and polarization of fast neutrons to scattering angles lower than 1/sup 0/. The principles and properties of the device are developed and discussed in detail. The quality of the performance is illustrated by measuring absolute cross sections of 2.50 MeV neutrons scattered by Bi.

  19. Study Magnetic Excitations in Doped Transition Metal Oxides Using Inelastic Neutron Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Pengcheng [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics and Astronomy

    2014-02-18

    Understanding the interplay between magnetism and superconductivity continues to be a “hot” topic in modern condensed matter physics. The discovery of high-temperature superconductivity in iron-based materials in 2008 provided an unique opportunity to compare and contrast these materials with traditional high-Tc copper oxide superconductors. Neutron scattering plays an important role in determining the dynamical spin properties in these materials. This proposal is a continuation of previous DOE supported proposal. This report summarizes the final progress we have made over from May 2005 till Aug. 2013. Overall, we continue to carry out extensive neutron scattering experiments on Fe-based materials, focusing on understanding their magnetic properties. In addition, we have established a materials laboratory at UT that has allowed us to grow these superconductors. Because neutron scattering typically demands a large amount of samples, by growing these materials in our own laboratory, we can now pursuit neutron scattering experiments over the entire electronic phase diagram, focusing on regions of interests. The material synthesis laboratory at UT was established entirely with the support of DOE funding. This not only allowed us to carry out neutron scattering experiments, but also permit us to provide samples to other US/International collaborators for studying these materials.

  20. Small Angle Neutron Scattering instrument at Malaysian TRIGA reactor

    Energy Technology Data Exchange (ETDEWEB)

    Shukri Mohd; Razali Kassim; Zal Uyun Mahmood [Malaysian Inst. for Nuclear Technology Research (MINT), Bangi, Kajang (Malaysia); Shahidan Radiman

    1998-10-01

    The TRIGA MARK II Research reactor at the Malaysian Institute for Nuclear Research (MINT) was commissioned in July 1982. Since then various works have been performed to utilise the neutrons produced from this steady state reactor. One of the project involved the Small Angle Neutron Scattering (SANS). (author)

  1. Elastic and Inelastic Scattering of Neutrons using a CLYC array

    Science.gov (United States)

    Brown, Tristan; Doucet, E.; Chowdhury, P.; Lister, C. J.; Wilson, G. L.; Devlin, M.; Mosby, S.

    2015-10-01

    CLYC scintillators, which have dual neutron and gamma response, have recently ushered in the possibility of fast neutron spectroscopy without time-of-flight (TOF). A 16-element array of 1'' x 1'' 6Li-depleted CLYC crystals, where pulse-shape-discrimination is achieved via digital pulse processing, has been commissioned at UMass Lowell. In an experiment at LANSCE, high energy neutrons were used to bombard 56Fe and 238U targets, in order to measure elastic and inelastic neutron scattering cross sections as a function of energy and angle with the array. The array is placed very close to the targets for enhanced geometrical solid angles for scattered neutrons compared to standard neutron-TOF measurements. A pulse-height spectrum of scattered neutrons in the detectors is compared to the energy of the incident neutrons, which is measured via the TOF of the pulsed neutrons from the source to the detectors. Recoil corrections are necessary to combine the energy spectra from all the detectors to obtain angle-integrated elastic and inelastic cross-sections. The detection techniques, analysis procedures and results will be presented. Supported by NNSA-SSAA program through DOE Grant DE-NA00013008.

  2. Inelastic neutron scattering for materials science and engineering

    Energy Technology Data Exchange (ETDEWEB)

    Shapiro, S.M.

    1995-12-31

    The neutron is the ideal probe for studying the positions and motions of atoms in condensed matter. The main advantage of the neutron in inelastic scattering results from its heavy mass when compared to other particles which are used to probe materials such as the photon (light, x-rays, or {gamma}-rays) or the electron. The author discusses the application of neutron scattering to study a number of different materials related problems, including, hard magnets, shape memory effects, and hydrogen distribution in metals.

  3. Recent Deuteron Compton Scattering Results and Extracted Neutron Polarizabilities

    Directory of Open Access Journals (Sweden)

    Myers L.S.

    2016-01-01

    Full Text Available The COMPTON@MAX-lab collaboration has recently published a new measurement of elastic photon scattering from deuterium using tagged photons at the MAX IV Laboratory [1]. The experiment utilized the Tagged Photon Facility at MAX IV and three of the largest NaI(Tl detectors in the world. Correction terms to the cross section were determined via Monte Carlo simulations [2, 3] and were confirmed by comparisons to the well-known 12C(γ,γ12C reaction [4]. These results represent the most extensive data on deuteron Compton scattering ever measured and effectively double the world data set. In addition, the energy range overlaps previous experiments and extends nearly 20 MeV higher where the sensitivity to the polarizabilities is enhanced. As a result, we have obtained the neutron polarizabilities as αn=[11.55 ± 1.25(stat ± 0.2(BSR ± 0.8(th] × 10−4 fm3 and βn=[3.65 ∓ 1.25(stat ± 0.2(BSR ± 0.8(th] × 10−4 fm3, which represents a 30% reduction in the statistical uncertainty.

  4. The hydrogen anomaly problem in neutron Compton scattering

    Science.gov (United States)

    Karlsson, Erik B.

    2018-03-01

    Neutron Compton scattering (also called ‘deep inelastic scattering of neutrons’, DINS) is a method used to study momentum distributions of light atoms in solids and liquids. It has been employed extensively since the start-up of intense pulsed neutron sources about 25 years ago. The information lies primarily in the width and shape of the Compton profile and not in the absolute intensity of the Compton peaks. It was therefore not immediately recognized that the relative intensities of Compton peaks arising from scattering on different isotopes did not always agree with values expected from standard neutron cross-section tables. The discrepancies were particularly large for scattering on protons, a phenomenon that became known as ‘the hydrogen anomaly problem’. The present paper is a review of the discovery, experimental tests to prove or disprove the existence of the hydrogen anomaly and discussions concerning its origin. It covers a twenty-year-long history of experimentation, theoretical treatments and discussions. The problem is of fundamental interest, since it involves quantum phenomena on the subfemtosecond time scale, which are not visible in conventional thermal neutron scattering but are important in Compton scattering where neutrons have two orders of magnitude times higher energy. Different H-containing systems show different cross-section deficiencies and when the scattering processes are followed on the femtosecond time scale the cross-section losses disappear on different characteristic time scales for each H-environment. The last section of this review reproduces results from published papers based on quantum interference in scattering on identical particles (proton or deuteron pairs or clusters), which have given a quantitative theoretical explanation both regarding the H-cross-section reduction and its time dependence. Some new explanations are added and the concluding chapter summarizes the conditions for observing the specific quantum

  5. Small-angle neutron scattering on polymer gels

    Energy Technology Data Exchange (ETDEWEB)

    Shibayama, Mitsuhiro [Department of Polymer Science and Engineering, Kyoto Institute of Technology, Kyoto (Japan)

    1999-10-01

    Recent development on the small-angle neutron scattering studies on polymer gels has been reviewed with an emphasis of the importance of the static inhomogeneities. The well-known phenomenon of the cross-linking inhomogeneities, i.e., a strong upturn of the scattered intensity at low scattering angles, is interpreted with the static inhomogeneities. It is demonstrated that the gel structures are now well characterized with the novel theories, which take account of the static inhomogeneities. (author)

  6. 2010 American Conference on Neutron Scattering (ACNS 2010)

    Energy Technology Data Exchange (ETDEWEB)

    Billinge, Simon

    2011-06-17

    The ACNS provides a focal point for the national neutron user community to strengthen ties within this diverse group, while at the same time promoting neutron research among colleagues in related disciplines identified as “would-be” neutron users. The American Conference on Neutron Scattering thus serves a dual role as a national user meeting and a scientific meeting. As a venue for scientific exchange, the ACNS showcases recent results and provides forums for scientific discussion of neutron research in diverse fields such as hard and soft condensed matter, liquids, biology, magnetism, engineering materials, chemical spectroscopy, crystal structure, and elementary excitations, fundamental physics and development of neutron instrumentation through a combination of invited talks, contributed talks and poster sessions. As a “super-user” meeting, the ACNS fulfills the main objectives of users' meetings previously held periodically at individual national neutron facilities, with the advantage of a larger and more diverse audience. To this end, each of the major national neutron facilities (NIST, LANSCE, HFIR and SNS) have an opportunity to exchange information and update users, and potential users, of their facility. This is also an appropriate forum for users to raise issues that relate to the facilities. For many of the national facilities, this super-user meeting should obviate the need for separate user meetings that tax the time, energy and budgets of facility staff and the users alike, at least in years when the ACNS is held. We rely upon strong participation from the national facilities. The NSSA intends that the American Conference on Neutron Scattering (ACNS) will occur approximately every two years, but not in years that coincide with the International or European Conferences on Neutron Scattering. The ACNS is to be held in association with one of the national neutron centers in a rotating sequence, with the host facility providing local

  7. Survey of background scattering from materials found in small-angle neutron scattering

    OpenAIRE

    Barker, J. G.; Mildner, D. F. R.

    2015-01-01

    Measurements and calculations of beam attenuation and background scattering for common materials placed in a neutron beam are presented over the temperature range of 300?700?K. Time-of-flight (TOF) measurements have also been made, to determine the fraction of the background that is either inelastic or quasi-elastic scattering as measured with a 3He detector. Other background sources considered include double Bragg diffraction from windows or samples, scattering from gases, and phonon scatter...

  8. Quasielastic Neutron Scattering by Superionic Strontium Chloride

    DEFF Research Database (Denmark)

    Dickens, M. H.; Hutchings, M. T.; Kjems, Jørgen

    1978-01-01

    The scattering, from powder and single crystal samples, appears only above the superionic transition temperature, 1000K. The integrated intensity is found to be strongly dependent on the direction and magnitude of the scattering vector, Q, (which suggests the scattering is coherent) but does not ...

  9. NEUTRON SCATTERING INSTRUMENTATION FOR MEASUREMENT OF MELT STRUCTURE

    Energy Technology Data Exchange (ETDEWEB)

    Richard Weber, Christopher Benmore

    2004-10-21

    acquisition software was developed and implemented. As part of a larger initiative at IPNS, PC-based programs are being developed for acquisition and processing of neutron data. The PC-based beamline data handling system will enable compatibility with the levitator software. The instrument was bench tested at CRI and operated in three campaigns at the GLAD beamline at IPNS. Samples approximately 3.5 mm in diameter were levitated for periods up to 6 hours and at temperatures up to 3300 K. Structure factors were obtained for liquid oxide materials and hot solids. Details are given in this report and in published or submitted papers. During the course of the Phase I and Phase II projects, technical presentations were made at the Materials Research Society meeting in Boston, November, 2001, the American Conference on Neutron Scattering in Knoxville, TN, June, 2002, the Gordon Research Conference on High Temperature Chemistry (poster) in Waterville, ME, August 2002, the ACNS meeting in Baltimore, MD, June, 2004 and the Non-crystalline Materials-9 meeting in Corning NY, July, 2004. Two manuscripts were prepared, one is published, one is in review. The presentations have resulted in contact with the user community and we have received several requests to use the instrument. As a result, we are seeking support for collaborative research and plan to offer beamline instruments for commercial sale.

  10. A Neutron Scattering Kernel of Solid Methane in phase II

    Science.gov (United States)

    Shin, Yunchang; Snow, William Michael; Liu, Cnen-Yu; Lavelle, Christopher M.; Baxter, David V.

    2008-04-01

    A neutron scattering cross section model of solid methane was studied for the cold neutron moderator of Low Energy Neutron Source (LENS) at IUCF/Indiana University especially in temperature range of 20.4 4K. The analytical scattering kernel was adapted from Ozaki.et al .[1][2] to describe molecular rotation in this temperature range. This model includes a molecular translation and intra-molecular vibration as well as the rotational degree of freedom in effective ways. For more broad applications into monte carlo simulations, neutron scattering libraries for MCNP were produced from the frequency spectrums using NJOY code. We have tested this newly- developed scattering kernels for phase II solid methane by calculating the neutron spectral intensity expected from the methane moderator at the LENS neutron source using MCNP. The predictions are compared to the measured energy spectra. The simulations agree with the measurement data at both temperatures. The simulation results show good agreement with measurement data in different temperatures. [1] Y. Ozaki, Y. Kataoka, and T. Yamamoto, The Journal of Chemical Physics 73, 3442 (1980). [2] Y. Ozaki, Y. Kataoka, K. Otaka, and T. Yamamoto, Can. J. Physics. 59, 275 (1981).

  11. The thermal neutron scattering cross section of {sup 86}Kr

    Energy Technology Data Exchange (ETDEWEB)

    Terburg, B.P.

    1992-05-01

    The availability of 27 1 STP krypton-86 gas, an isotope with unknown thermal neutron scattering cross section, was an excellent occasion to determine the (bound atom) scattering cross section and its coherent part by application of the neutron transmission method and neutron interferometry. The transmission method was applied in a diffractometer, a Larmor spectrometer and a TOF-spectrometer. In addition to {sup 86}Kr also natural krypton ({sup n}Kr) was used for sample in the diffractometer. The diffractometer measurements result in bound atom scattering cross sections {sigma}{sub s}=8.92(46) b for {sup 86}Kr and {sigma}{sub s}=7.08(95) b for {sup n}Kr. The Larmor transmission measurements lead to a final result {sigma}{sub s}=8.44(9) b for {sup 86}Kr. In the TOF-spectrometer the wavelength-dependent total cross section of water was determined. Coherent neutron scattering lengths were determined using the neutron interferometry method with a skew symmetric neutron interferometer. Scans with {sup 86}Kr and {sup n}Kr led to b{sub c}=8.07(26) fm for {sup 86}Kr and 7.72(33) fm for {sup n}Kr, corresponding to coherent scattering cross sections {sigma}{sub c}=8.18(53) b and 7.49(64) b respectively. Due to the large errors in the bound atom scattering cross section and coherent scattering cross section of {sup 86}Kr and {sup n}Kr, the incoherent cross section of both gases, {sigma}{sub i} = 0 within its inaccuracy, {sigma}{sub i}=0.26(54) b for {sup 86}Kr and {sigma}{sub i}=0.41(1.15) b for {sup n}Kr. (orig.).

  12. Software for simulation and design of neutron scattering instrumentation

    DEFF Research Database (Denmark)

    Bertelsen, Mads

    designed using the software. The Union components uses a new approach to simulation of samples in McStas. The properties of a sample are split into geometrical and material, simplifying user input, and allowing the construction of complicated geometries such as sample environments. Multiple scattering...... from conventional choices. Simulation of neutron scattering instrumentation is used when designing instrumentation, but also to understand instrumental effects on the measured scattering data. The Monte Carlo ray-tracing package McStas is among the most popular, capable of simulating the path of each...... neutron through the instrument using an easy to learn language. The subject of the defended thesis is contributions to the McStas language in the form of the software package guide_bot and the Union components.The guide_bot package simplifies the process of optimizing neutron guides by writing the Mc...

  13. Inelastic scattering of neutrons by spin waves in terbium

    DEFF Research Database (Denmark)

    Bjerrum Møller, Hans; Houmann, Jens Christian Gylden

    1966-01-01

    Measurements of spin-wave dispersion relations for magnons propagating in symmetry directions in ferromagnetic Tb; it is first experiment to give detailed information on magnetic excitations in heavy rare earths; Tb was chosen for these measurements because it is one of few rare-earth metals whic...... does not have very high thermal-neutron capture cross section, so that inelastic neutron scattering experiments can give satisfactory information on magnon dispersion relations....

  14. Critical Magnetic Scattering of Neutrons in Iron

    DEFF Research Database (Denmark)

    Passell, L.; Blinowski, K.; Brun, T.

    1964-01-01

    scattered at small angles in iron and determined the spin correlation range 1∕κ1 and a parameter Λ associated with the lifetime of the fluctuations. Our results confirm the recent observation of Jacrot, Konstantinovic, Parette, and Cribier that the scattering is not elastic even at the Curie temperature. We...

  15. Scattered Neutron Tomography Based on A Neutron Transport Inverse Problem

    Energy Technology Data Exchange (ETDEWEB)

    William Charlton

    2007-07-01

    Neutron radiography and computed tomography are commonly used techniques to non-destructively examine materials. Tomography refers to the cross-sectional imaging of an object from either transmission or reflection data collected by illuminating the object from many different directions.

  16. Neutron scattering from α-Ce at epithermal neutron energies

    Indian Academy of Sciences (India)

    to the neutron spectra which yield parameters that are in good accord with Fermi liquid relations obtained for the ... erties of Ce-based systems is best illustrated with reference to the data on pseudo- binary compounds ..... [11] A P Murani, Z A Bowden, A D Taylor, R Osborn and W G Marshall, Phys. Rev. B48, 13981 (1993).

  17. Small angle neutron scattering and small angle X-ray scattering ...

    Indian Academy of Sciences (India)

    Abstract. The morphology of carbon nanofoam samples comprising platinum nanopar- ticles dispersed in the matrix was characterized by small angle neutron scattering (SANS) and small angle X-ray scattering (SAXS) techniques. Results show that the structure of pores of carbon matrix exhibits a mass (pore) fractal nature ...

  18. Methods of Information Processing for Neutron Scattering Data

    Science.gov (United States)

    Nave, Patrick; Jiao, Lin; Mourigal, Martin; Stone, Matthew

    Inferring complex dispersion relations from resolution-limited neutron scattering measurements is a task which has been approached from a variety of perspectives from Monte Carlo (MC) scattering simulations to resolution function methods which convolve an approximate resolution function with a theoretical model dispersion. However, detailed MC simulations require a highly-accurate framework such as MCViNE, which is not available for all neutron scattering facilities and is also time consuming, while resolution function methods are faster yet more dependent on accurate analytical models of the instrument to construct a valid approximation. Our research investigates two methods for analyzing neutron scattering data in a more general context. The first is a numerical covariance method designed to be fast while retaining high enough accuracy to be useful and enough generality to be applicable to any time-of-flight direct geometry neutron spectrometer. The second is a theoretical method based in topological data analysis concepts. In particular, we explore the computation of invariant topological features which may be useful in algorithmically learning from large databases of scattering data and identifying resolution correlations across sets of instrument parameters.

  19. Ultrathin aluminum sample cans for single crystal inelastic neutron scattering.

    Science.gov (United States)

    Stone, M B; Loguillo, M J; Abernathy, D L

    2011-05-01

    Single crystal inelastic neutron scattering measurements are often performed using a sample environment for controlling sample temperature. One difficulty associated with this is establishing appropriate thermal coupling from the sample to the temperature controlled portion of the sample environment. This is usually accomplished via a sample can which thermally couples the sample environment to the sample can and the sample can to the sample via an exchange gas. Unfortunately, this can will contribute additional background signal to one's measurement. We present here the design of an ultrathin aluminum sample can based upon established technology for producing aluminum beverage cans. This design minimizes parasitic sample can scattering. Neutron scattering measurements comparing a machined sample can to our beverage can design clearly indicate a large reduction in scattering intensity and texture when using the ultrathin sample can design. We also examine the possibility of using standard commercial beverage cans as sample cans.

  20. Some Notes on Neutron Up-Scattering and the Doppler-Broadening of High-Z Scattering Resonances

    Energy Technology Data Exchange (ETDEWEB)

    Parsons, Donald Kent [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-09-28

    When neutrons are scattered by target nuclei at elevated temperatures, it is entirely possible that the neutron will actually gain energy (i.e., up-scatter) from the interaction. This phenomenon is in addition to the more usual case of the neutron losing energy (i.e., down-scatter). Furthermore, the motion of the target nuclei can also cause extended neutron down-scattering, i.e., the neutrons can and do scatter to energies lower than predicted by the simple asymptotic models. In recent years, more attention has been given to temperature-dependent scattering cross sections for materials in neutron multiplying systems. This has led to the inclusion of neutron up-scatter in deterministic codes like Partisn and to free gas scattering models for material temperature effects in Monte Carlo codes like MCNP and cross section processing codes like NJOY. The free gas scattering models have the effect of Doppler Broadening the scattering cross section output spectra in energy and angle. The current state of Doppler-Broadening numerical techniques used at Los Alamos for scattering resonances will be reviewed, and suggestions will be made for further developments. The focus will be on the free gas scattering models currently in use and the development of new models to include high-Z resonance scattering effects. These models change the neutron up-scattering behavior.

  1. Neutron Scattering from fcc Pr and Pr3Tl

    DEFF Research Database (Denmark)

    Birgeneau, R. J.; Als-Nielsen, Jens Aage; Bucher, E.

    1972-01-01

    Elastic-neutron-scattering measurements on the singlet-ground-state ferromagnets fcc Pr and Pr3 Tl are reported. Both exhibit magnetic phase transitions, possibly to a simple ferromagnetic state at 20 and 11.6 °K, respectively. The transitions appear to be of second order although that in fcc Pr ...... is clearly anomalous. Additional information on the inelastic scattering studies of the Γ1-Γ4 excitons in these systems is presented. dhcp Pr is also briefly discussed....

  2. Optics for Advanced Neutron Imaging and Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Moncton, David E. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Khaykovich, Boris [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2016-03-30

    During the report period, we continued the work as outlined in the original proposal. We have analyzed potential optical designs of Wolter mirrors for the neutron-imaging instrument VENUS, which is under construction at SNS. In parallel, we have conducted the initial polarized imaging experiment at Helmholtz Zentrum, Berlin, one of very few of currently available polarized-imaging facilities worldwide.

  3. Neutron scattering effects on fusion ion temperature measurements.

    Energy Technology Data Exchange (ETDEWEB)

    Ziegler, Lee (Bechtel/Nevada, Las Vegas, NV); Starner, Jason R.; Cooper, Gary Wayne; Ruiz, Carlos L.; Franklin, James Kenneth (Ktech Corporation, Albuquerque, NM); Casey, Daniel T.

    2006-06-01

    To support the nuclear fusion program at Sandia National Laboratories (SNL), a consistent and verifiable method to determine fusion ion temperatures needs to be developed. Since the fusion temperature directly affects the width in the spread of neutron energies produced, a measurement of the neutron energy width can yield the fusion temperature. Traditionally, the spread in neutron energies is measured by using time-of-flight to convert a spread in neutron energies at the source to a spread in time at detector. One potential obstacle to using this technique at the Z facility at SNL is the need to shield the neutron detectors from the intense bremsstrahlung produced. The shielding consists of eight inches of lead and the concern is that neutrons will scatter in the lead, artificially broaden the neutron pulse width and lead to an erroneous measurement. To address this issue, experiments were performed at the University of Rochester's Laboratory for Laser Energetics, which demonstrated that a reliable ion temperature measurement can be achieved behind eight inches of lead shielding. To further expand upon this finding, Monte Carlo N-Particle eXtended (MCNPX) was used to simulate the experimental geometric conditions and perform the neutron transport. MCNPX was able to confidently estimate results observed at the University of Rochester.

  4. Immersive Visual Analytics for Transformative Neutron Scattering Science

    Energy Technology Data Exchange (ETDEWEB)

    Steed, Chad A [ORNL; Daniel, Jamison R [ORNL; Drouhard, Margaret [University of Washington, Seattle; Hahn, Steven E [ORNL; Proffen, Thomas E [ORNL

    2016-01-01

    The ORNL Spallation Neutron Source (SNS) provides the most intense pulsed neutron beams in the world for scientific research and development across a broad range of disciplines. SNS experiments produce large volumes of complex data that are analyzed by scientists with varying degrees of experience using 3D visualization and analysis systems. However, it is notoriously difficult to achieve proficiency with 3D visualizations. Because 3D representations are key to understanding the neutron scattering data, scientists are unable to analyze their data in a timely fashion resulting in inefficient use of the limited and expensive SNS beam time. We believe a more intuitive interface for exploring neutron scattering data can be created by combining immersive virtual reality technology with high performance data analytics and human interaction. In this paper, we present our initial investigations of immersive visualization concepts as well as our vision for an immersive visual analytics framework that could lower the barriers to 3D exploratory data analysis of neutron scattering data at the SNS.

  5. A workshop on enhanced national capability for neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Hurd, Alan J [Los Alamos National Laboratory; Rhyne, James J [Los Alamos National Laboratory; Lewis, Paul S [Los Alamos National Laboratory

    2009-01-01

    This two-day workshop will engage the international neutron scattering community to vet and improve the Lujan Center Strategic Plan 2007-2013 (SP07). Sponsored by the LANL SC Program Office and the University of California, the workshop will be hosted by LANSCE Professor Sunny Sinha (UCSD). Endorsement by the Spallation Neutron Source will be requested. The discussion will focus on the role that the Lujan Center will play in the national neutron scattering landscape assuming full utilization of beamlines, a refurbished LANSCE, and a 1.4-MW SNS. Because the Lujan Strategic Plan is intended to set the stage for the Signature Facility era at LANSCE, there will be some discussion of the long-pulse spallation source at Los Alamos. Breakout groups will cover several new instrument concepts, upgrades to present instruments, expanded sample environment capabilities, and a look to the future. The workshop is in keeping with a request by BES to update the Lujan strategic plan in coordination with the SNS and the broader neutron community. Workshop invitees will be drawn from the LANSCE User Group and a broad cross section of the US, European, and Pacific Rim neutron scattering research communities.

  6. Fast-neutron scattering from vibrational palladium nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Smith, A.B. [Argonne National Lab., IL (United States)]|[Univ. of Arizona, Tucson, AZ (United States); Guenther, P.T. [Argonne National Lab., IL (United States)

    1993-10-01

    Neutron total cross sections of elemental palladium are measured from {approx}0.6--4.5 MeV. These results, combined with others previously reported from this laboratory, provide a detailed knowledge of the neutron total cross sections of palladium from {approx}0.1--20 MeV. Differential neutron elastic-scattering cross sections are measured from {approx}1.5--10 MeV in sufficient energy and angle detail to well define the energy-average behavior. Concurrently, neutron inelastic-scattering cross sections are measured from {approx}1.5--8 MeV. Inelastically-scattered neutron groups are observed corresponding to excitations of: 306 {+-} 14, 411 {+-} 47, {approx}494, 791 {+-} 20, 924 {+-} 20, 1,156 {+-} 24, 1,358 {+-} 35, 1,554 {+-} 47 and 1,706 {+-} 59 keV, with additional tentative groups at 1,938 and 2,059 keV. Particular attention is given to the inelastic excitation of the 2{sup +} yrast states of the even isotopes. This broad data base is examined in the context of optical-statistical and coupled-channels models. The resulting model parameters are consistent with systematic trends in this vibrational mass region previously noted at this laboratory, and provide a suitable vehicle for many applications.

  7. Development of new methods for studying nanostructures using neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Pynn, Roger [Indiana Univ., Bloomington, IN (United States)

    2016-03-18

    The goal of this project was to develop improved instrumentation for studying the microscopic structures of materials using neutron scattering. Neutron scattering has a number of advantages for studying material structure but suffers from the well-known disadvantage that neutrons’ ability to resolve structural details is usually limited by the strength of available neutron sources. We aimed to overcome this disadvantage using a new experimental technique, called Spin Echo Scattering Angle Encoding (SESAME) that makes use of the neutron’s magnetism. Our goal was to show that this innovation will allow the country to make better use of the significant investment it has recently made in a new neutron source at Oak Ridge National Laboratory (ORNL) and will lead to increases in scientific knowledge that contribute to the Nation’s technological infrastructure and ability to develop advanced materials and technologies. We were successful in demonstrating the technical effectiveness of the new method and established a baseline of knowledge that has allowed ORNL to start a project to implement the method on one of its neutron beam lines.

  8. Inelastic neutron scattering and lattice dynamics of minerals

    Indian Academy of Sciences (India)

    transitions, high pressure–temperature melting, etc. Keywords. Inelastic neutron scattering ... structural phase transitions, thermodynamic properties, elasticity and melting. These, in combination with .... 18–35 GPa [4]. Although pressure- induced amorphization occurs in a variety of solids like α-quartz, coesite, ice, etc.

  9. Small angle neutron scattering study on the aggregation behaviour ...

    Indian Academy of Sciences (India)

    Small angle neutron scattering (SANS) measurements on aqueous solutions of four polyethylene oxide–polypropylene oxide–polyethylene oxide block copolymers (commercially known as Pluronic®)F88, P85, F127 and P123 in the presence of hydrophobic C14Diol (also known as Surfynol® 104) reveal information on ...

  10. Small angle neutron scattering studies of mixed micelles of sodium ...

    Indian Academy of Sciences (India)

    2015-11-27

    Nov 27, 2015 ... The aqueous solutions of sodium cumene sulphonate (NaCS) and its mixtures with each of cetyl trimethylammonium bromide (CTAB) and sodium dodecyl sulphate (SDS) are characterized by small angle neutron scattering (SANS). NaCS when added to CTAB solution leads to the formation of long ...

  11. Small angle neutron scattering study of mixed micelles of oppositely ...

    Indian Academy of Sciences (India)

    Structures of mixed micelles of oppositely charged surfactants dodecyltrimethylammonium bromide (DTAB) and sodium dodecyl sulphate (SDS) have been studied using small angle neutron scattering. The concentration of one of the components was kept fixed (0.3 M) and that of another varied in the range 0 to 0.1 M. The ...

  12. Inelastic Neutron Scattering and Separation Coefficient of Absorbed Hydrogen

    DEFF Research Database (Denmark)

    Silvera, I. F.; Nielsen, Mourits

    1976-01-01

    Inelastic neutron scattering and measurement of the ortho-para separation coefficient have been used to study the low lying rotational states of molecular hydrogen adsorbed on activated alumina. The observations are consistent with a picture in which the orientational motion of the molecules is s...

  13. Small angle neutron scattering studies on the interaction of cationic ...

    Indian Academy of Sciences (India)

    The structure of the protein–surfactant complex of bovine serum albumin (BSA) and cationic surfactants has been studied by small angle neutron scattering. At low concentrations, the CTAB monomers are observed to bind to the protein leading to an increase in its size. On the other hand at high concentrations, surfactant ...

  14. Small-angle neutron scattering from micellar solutions

    Indian Academy of Sciences (India)

    The structure (shape and size) and the interaction of these aggregates, referred to as micelles, depend on the molecular architecture of the surfactant molecule, presence of additives and the solution conditions such as temperature, concentration etc. This paper gives the usefulness of small-angle neutron scattering to the ...

  15. Temperature dependent small-angle neutron scattering of CTABr ...

    Indian Academy of Sciences (India)

    Small-angle neutron scattering studies have been carried out to check the structural integrity of citryltrimethylammonium bromide (CTABr) micelles in a magnetic fluid for different magnetic fluid concentrations at two different temperatures 303 and 333 K. It is found that the CTABr micelles grow with increasing magnetic fluid ...

  16. The vibrational spectrum of solid ferrocene by inelastic neutron scattering

    NARCIS (Netherlands)

    Kemner, E.; De Schepper, I.M.; Kearley, G.J.; Jayasooriya, U.A.

    2000-01-01

    We calculate the spectrum of internal vibrations of a single ferrocene Fe(C5H5)2 molecule using ab initio density functional theory (without free parameters) and compare this with inelastic neutron scattering data on ferrocene in the solid state at 28 K. Due to the good agreement, we can assign each

  17. Spin-Echo Small-Angle Neutron Scattering Development

    NARCIS (Netherlands)

    Uca, O.

    2003-01-01

    Spin-Echo Small-Angle Neutron Scattering (SESANS) instrument is a novel SANS technique which enables one to characterize distances from a few nanometers up to the micron range. The most striking difference between normal SANS and SESANS is that in SESANS one gets information in real space, whereas

  18. Small-angle neutron scattering in materials science - an introduction

    Energy Technology Data Exchange (ETDEWEB)

    Fratzl, P. [Vienna Univ., Inst. fuer Materialphysik, Vienna (Austria)

    1996-12-31

    The basic principles of the application of small-angle neutron scattering to materials research are summarized. The text focusses on the classical methods of data evaluation for isotropic and for anisotropic materials. Some examples of applications to the study of alloys, porous materials, composites and other complex materials are given. (author) 9 figs., 38 refs.

  19. Small-angle neutron scattering studies of nonionic surfactant: Effect ...

    Indian Academy of Sciences (India)

    concentration of sugar. The structure of micelles is almost independent of the different types of sugars used. Keywords. Small-angle neutron scattering; nonionic surfactant; micellar aggregation number. PACS Nos 61.12.Ex; 82.70.Uv. 1. Introduction. Surfactant molecules self assemble into aggregates in aqueous solution to ...

  20. Diffuse neutron scattering from anion-excess strontium chloride

    DEFF Research Database (Denmark)

    Goff, J.P.; Clausen, K.N.; Fåk, B.

    1992-01-01

    The defect structure and diffusional processes have been studied in the anion-excess fluorite (Sr, Y)Cl2.03 by diffuse neutron scattering techniques. Static cuboctahedral clusters found at ambient temperature break up at temperatures below 1050 K, where the anion disorder is highly dynamic. The a...

  1. Temperature dependent small-angle neutron scattering of CTABr ...

    Indian Academy of Sciences (India)

    K. It is found that the CTABr micelles grow with increasing magnetic fluid concentration and there is a decrease in the micellar size with increase in temperature. Keywords. Magnetic fluids; micellar solutions; small-angle neutron scattering. .... studies [16] where viscosity increases when the magnetic fluid concentration in the.

  2. Small angle neutron scattering studies on the interaction of cationic ...

    Indian Academy of Sciences (India)

    Abstract. The structure of the protein–surfactant complex of bovine serum albumin. (BSA) and cationic surfactants has been studied by small angle neutron scattering. At low concentrations, the CTAB monomers are observed to bind to the protein leading to an increase in its size. On the other hand at high concentrations, ...

  3. Spin-wave and critical neutron scattering from chromium

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage; Axe, J.D.; Shirane, G.

    1971-01-01

    Chromium and its dilute alloys are unique examples of magnetism caused by itinerant electrons. The magnetic excitations have been studied by inelastic neutron scattering using a high-resolution triple-axis spectrometer. Spin-wave peaks in q scans at constant energy transfer ℏω could, in general...

  4. On measuring the neutron coherent scattering length with ultrahigh ...

    Indian Academy of Sciences (India)

    We propose an order of magnitude improvement in the present five parts in 105 precision of a nondispersive interferometric measurement of the neutron coherent scattering length c. For this purpose we make a judicious selection of the Bragg angle for the interferometer and the sample thickness. The precision is further ...

  5. Small-angle neutron scattering studies on water soluble complexes ...

    Indian Academy of Sciences (India)

    neutron scattering. SANS data showed a positive indication of the formation of RCP–. SDS complexes. Even though the complete structure of the polyion complexes could not be ascertained, the results obtained give us the information on the local structure in these polymer–surfactant systems. The data were analysed using ...

  6. Inelastic neutron scattering and lattice dynamics studies in complex ...

    Indian Academy of Sciences (India)

    At Trombay, lattice dynamics studies employing coherent inelastic neutron scattering (INS) experiments have been carried out at the two research reactors, CIRUS and Dhruva. While the early work at CIRUS involved many elemental solids and ionic molecular solids, recent experiments at Dhruva have focussed on certain ...

  7. Small angle neutron scattering study of mixed micelles of oppositely ...

    Indian Academy of Sciences (India)

    is significantly different from that of the addition of DTAB on SDS. The contrast variation. SANS experiments using deuterated surfactant suggests the homogeneous mixing of two components in mixed micellar system. Keywords. Surfactants; mixed micelles; small angle neutron scattering. PACS Nos 61.12.Ex; 82.70.Uv. 1.

  8. Inelastic Neutron Scattering Investigations of the Magnetic Excitations

    DEFF Research Database (Denmark)

    Feile, R; Kjems, Jørgen; Hauser, A.

    1984-01-01

    The magnetic excitations perpendicular to the antiferromagnetic chains in CsVX3 (X = Cl, Br, I) have been measured in the ordered state by inelastic neutron scattering. The dispersion relations and intensity distributions are those expected for ordinary spin waves in a triangular xy-model....

  9. Ultrasound effects and neutron scattering in UPt3

    DEFF Research Database (Denmark)

    Bruls, G.; Weber, D.; Kouroudis, I.

    1993-01-01

    We present results of sound propagation measurements and neutron scattering experiments on one and the same sample of the heavy fermion substance UPt3. From these experiments we deduce a B-T phase diagram of the small-moment spin density wave region in this compound for magnetic field B parallel-...

  10. Lattice dynamics of solid deuterium by inelastic neutron scattering

    DEFF Research Database (Denmark)

    Nielsen, Mourits; Bjerrum Møller, Hans

    1971-01-01

    The dispersion relations for phonons in solid ortho-deuterium have been measured at 5 °K by inelastic neutron scattering. The results are in good agreement with recent calculations in which quantum effects are taken into account. The data have been fitted to a third-neighbor general force model...

  11. Benchmarking the inelastic neutron scattering soil carbon method

    Science.gov (United States)

    The herein described inelastic neutron scattering (INS) method of measuring soil carbon was based on a new procedure for extracting the net carbon signal (NCS) from the measured gamma spectra and determination of the average carbon weight percent (AvgCw%) in the upper soil layer (~8 cm). The NCS ext...

  12. Collective Excitations in Liquid Hydrogen Observed by Coherent Neutron Scattering

    DEFF Research Database (Denmark)

    da Costa Carneiro, Kim; Nielsen, M.; McTague, J. P.

    1973-01-01

    Coherent scattering of neutrons by liquid parahydrogen shows the existence of well-defined collective excitations in this liquid. Qualitative similarity with the scattering from liquid helium is found. Furthermore, in the range of observed wave vectors, 0.7 Å-1 ≤κ≤3.1 Å-1, extending from the firs...... through the third Brillouin zones in the solid, S(κ,ω) is remarkably similar to the scattering law expected from a polycrystal. For κ≤2.3 Å-1 the observed spectra satisfy the one-phonon sum rule with mean square displacement 〈u2〉=1.0 Å2....

  13. A Neutron Scattering Study of Collective Excitations in Superfluid Helium

    DEFF Research Database (Denmark)

    Graf, E. H.; Minkiewicz, V. J.; Bjerrum Møller, Hans

    1974-01-01

    Extensive inelastic-neutron-scattering experiments have been performed on superfluid helium over a wide range of energy and momentum transfers. A high-resolution study has been made of the pressure dependence of the single-excitation scattering at the first maximum of the dispersion curve over...... of the multiexcitation scattering was also studied. It is shown that the multiphonon spectrum of a simple Debye solid with the phonon dispersion and single-excitation cross section of superfluid helium qualitatively reproduces these data....

  14. Neutron scattering and models: Iron. Nuclear data and measurements series

    Energy Technology Data Exchange (ETDEWEB)

    Smith, A.B. [Argonne National Lab., IL (United States)

    1995-08-01

    Differential elastic and inelastic neutron-scattering cross sections of elemental iron are measured from 4.5 to 10 MeV in increments of {approx} 0.5 MeV. At each incident energy the measurements are made at forty or more scattering angles distributed between {approx} 17{degrees} and 160{degrees}, with emphasis on elastic scattering and inelastic scattering due to the excitation of the yrast 2{sup +} state. The measured data is combined with earlier lower-energy results from this laboratory, with recent high-precision {approx} 9.5 {yields} 15 MeV results from the Physilalisch Technische Bundesanstalt and with selected values from the literature to provide a detailed neutron-scattering data base extending from {approx} 1.5 to 26 MeV. This data is interpreted in the context of phenomenological spherical-optical and coupled-channels (vibrational and rotational) models, and physical implications discussed. Deformation, coupling, asymmetry and dispersive effects are explored. It is shown that, particularly in a collective context, a good description of the interaction of neutrons with iron is achieved over the energy range {approx} 0 {yields} 26 MeV, avoiding the dichotomy between high and low-energy interpretations found in previous work.

  15. Neutron Angular Scatter Effects in 3DHZETRN: Quasi-Elastic

    Science.gov (United States)

    Wilson, John W.; Werneth, Charles M.; Slaba, Tony C.; Badavi, Francis F.; Reddell, Brandon D.; Bahadori, Amir A.

    2017-01-01

    The current 3DHZETRN code has a detailed three dimensional (3D) treatment of neutron transport based on a forward/isotropic assumption and has been compared to Monte Carlo (MC) simulation codes in various geometries. In most cases, it has been found that 3DHZETRN agrees with the MC codes to the extent they agree with each other. However, a recent study of neutron leakage from finite geometries revealed that further improvements to the 3DHZETRN formalism are needed. In the present report, angular scattering corrections to the neutron fluence are provided in an attempt to improve fluence estimates from a uniform sphere. It is found that further developments in the nuclear production models are required to fully evaluate the impact of transport model updates. A model for the quasi-elastic neutron production spectra is therefore developed and implemented into 3DHZETRN.

  16. Proceedings of the fifteenth meeting of the international collaboration on advanced neutron sources (ICANS-XV). Advanced neutron sources towards the next century

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Jun-ichi [Center for Neutron Science, Tokai Research Establishment, Japan Atomic Energy Research Institute, Tokai, Ibaraki (Japan); Itoh, Shinichi [Neutron Science Laboratory, High Energy Accelerator Research Organization, Tsukuba, Ibaraki (JP)] (eds.)

    2001-03-01

    The fifteenth meeting of the International Collaboration on Advanced Neutron Sources (ICANS-XV) was held at Epocal Tsukuba, International Congress Center on 6-9 November 2000. It was hosted by Japan Atomic Energy Research Institute (JAERI) and High Energy Accelerator Research Organization (KEK). This meeting focused on 'Neutron Sources toward the 21st Century' and research activities related to targets and moderators, neutron scattering instruments and accelerators were presented. The 151 of the presented papers are indexed individually. (J.P.N.)

  17. Fostering applications of neutron scattering techniques in developing countries: IAEA's role

    Energy Technology Data Exchange (ETDEWEB)

    Paranjpe, Shriniwas K. [Division of Physical and Chemical Sciences, International Atomic Energy Agency, Wagramer Strasse 5, A-1400 Vienna (Austria)]. E-mail: S.K.Paranjpe@iaea.org; Mank, G. [Division of Physical and Chemical Sciences, International Atomic Energy Agency, Wagramer Strasse 5, A-1400 Vienna (Austria); Ramamoorthy, N. [Division of Physical and Chemical Sciences, International Atomic Energy Agency, Wagramer Strasse 5, A-1400 Vienna (Austria)

    2006-11-15

    Over the last 60 years research reactors have played an important role in technological and socio-economical development of mankind. Neutron scattering has been the workhorse for research and development in materials science. Developing countries with moderate flux research reactors have also been involved in using this technique. The reactors and the facilities around them have a large potential for applications, while their under-utilization has been a concern for many member states. The International Atomic Energy Agency (IAEA) has been supporting its member states in the enhancement of utilization of their research reactors. Technical meetings focussing on the area of current interests with potential applications are organized under the project on 'effective utilization of research reactors,' e.g. on residual stress measurement, neutron reflectometry. Coordinated research projects (CRPs) bring together scientists from developed and developing countries, build collaborations, and exchange expertise and technology. The CRPs on research reactor utilization include topics like development of small-angle neutron scattering applications and development of sources and imaging systems for neutron radiography. New CRPs on the measurement of residual stress and accelerator-driven neutron sources will be initiated soon. The results from these meetings of CRPs are published as technical documents of the IAEA that would act as guidelines for capacity building for research reactor managers. This paper will present some of the salient features of IAEA activities in promoting research reactor utilization.

  18. 2009 International Conference on Neutron Scattering (ICNS 2009)

    Energy Technology Data Exchange (ETDEWEB)

    Gopal Rao, PhD; Gillespie, Donna

    2010-08-05

    The ICNS provides a focal point for the worldwide neutron user community to strengthen ties within this diverse group, while at the same time promoting neutron research among colleagues in related disciplines identified as would-be neutron users. The International Conference on Neutron Scattering thus serves a dual role as an international user meeting and a scientific meeting. As a venue for scientific exchange, the ICNS showcases recent results and provides forums for scientific discussion of neutron research in diverse fields such as hard and soft condensed matter, liquids, biology, magnetism, engineering materials, chemical spectroscopy, crystal structure, and elementary excitations, fundamental physics and development of neutron instrumentation through a combination of invited talks, contributed talks and poster sessions. Each of the major national neutron facilities (NIST, LANSCE, ANL, HFIR and SNS), along with their international counterparts, has an opportunity to exchange information with each other and to update users, and potential users, of their facility. This is also an appropriate forum for users to raise issues that relate to the facilities.

  19. SANS-polymer and functional materials with neutron in Indonesia. Progress report on the collaboration activities?

    Energy Technology Data Exchange (ETDEWEB)

    Ikram, A.; Gunawan; Sukirman, E.; Ridwan; Jahja, A.K. [R and D Center for Materials Science and Technology, National Nuclear Energy Agency, Serpong (Indonesia)

    2000-10-01

    Activities on SANS-polymer collaboration program are reported. This paper presents SANS-data from Sodium Dodecyl Sulphate that have been obtained using BATAN's SANS machine in Serpong. Reports are also presented about activities in the groups for functional materials structural determination which includes magnetic, HTc superconducting and superionic conducting materials. Discussions are also given towards the way the collaboration activities were carried out in the last three years as well as impact of neutron scattering facility conditions in Indonesia. (author)

  20. A neutron scattering study of hydrogel surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Struth, B.; Vorobiev, A.; Seydel, T.; Wiegart, L.; Major, J

    2004-07-15

    Hydrogels are jelly-like materials consisting mainly of water (up to 99 wt%) and a small amount of clay mineral gelator. Hydrogel surfaces in many respects resemble to free water surfaces. In particular, they can be as smooth as water surfaces and may serve as a substrate for hydrophilic monolayers such as lipids with polar head groups. Remarkably, gel surfaces may be tilted by a few degrees out of the horizontal plane. Here, we report on a neutron reflectivity study of hydrogel surfaces with a lipid coverage.

  1. Neutrons for Catalysis: A Workshop on Neutron Scattering Techniques for Studies in Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Overbury, Steven {Steve} H [ORNL; Coates, Leighton [ORNL; Herwig, Kenneth W [ORNL; Kidder, Michelle [ORNL

    2011-10-01

    This report summarizes the Workshop on Neutron Scattering Techniques for Studies in Catalysis, held at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) on September 16 and 17, 2010. The goal of the Workshop was to bring experts in heterogeneous catalysis and biocatalysis together with neutron scattering experimenters to identify ways to attack new problems, especially Grand Challenge problems in catalysis, using neutron scattering. The Workshop locale was motivated by the neutron capabilities at ORNL, including the High Flux Isotope Reactor (HFIR) and the new and developing instrumentation at the SNS. Approximately 90 researchers met for 1 1/2 days with oral presentations and breakout sessions. Oral presentations were divided into five topical sessions aimed at a discussion of Grand Challenge problems in catalysis, dynamics studies, structure characterization, biocatalysis, and computational methods. Eleven internationally known invited experts spoke in these sessions. The Workshop was intended both to educate catalyst experts about the methods and possibilities of neutron methods and to educate the neutron community about the methods and scientific challenges in catalysis. Above all, it was intended to inspire new research ideas among the attendees. All attendees were asked to participate in one or more of three breakout sessions to share ideas and propose new experiments that could be performed using the ORNL neutron facilities. The Workshop was expected to lead to proposals for beam time at either the HFIR or the SNS; therefore, it was expected that each breakout session would identify a few experiments or proof-of-principle experiments and a leader who would pursue a proposal after the Workshop. Also, a refereed review article will be submitted to a prominent journal to present research and ideas illustrating the benefits and possibilities of neutron methods for catalysis research.

  2. Reactors and neutron-scattering instruments in Western Europe -an update on continuous neutron sources

    Science.gov (United States)

    Bauer, G. S.; Thamm, G.

    1991-10-01

    Research reactors as sources of continuous neutron beams have been operational in Western Europe since the late fifties and have triggered a series of successful developments in reactor technology and in particular in neutron-scattering instrumentation. The culmination point so far was the construction and operation of the high-flux reactor at the ILL in Grenoble. Although only one new reactor has been built since then, there were-and still are-efforts going on especially in Germany to provide a modern substitute for the older multi-purpose reactors still in operation or shut down already. Substantial effort also went into the modernization of the scattering instruments and experiment infrastructure (cold neutron sources, neutron guides, etc.) at several locations, showing that the scientific merits of neutron scattering are well recognized also on the political level. The ongoing construction of a cw-spallation neutron source in Switzerland might constitute an important step on the way to a new generation of high-flux sources.

  3. Theory of neutron scattering by electrons in magnetic materials

    Science.gov (United States)

    Lovesey, S. W.

    2015-10-01

    A theory of neutron scattering by magnetic materials is reviewed with emphasis on the use of electronic multipoles that have universal appeal, because they are amenable to calculation and appear in theories of many other experimental techniques. The conventional theory of magnetic neutron scattering, which dates back to Schwinger (1937 Phys. Rev. 51 544) and Trammell (1953 Phys. Rev. 92 1387), yields an approximation for the scattering amplitude in terms of magnetic dipoles formed with the spin (S) and orbital angular momentum (L) of valence electrons. The so-called dipole-approximation has been widely adopted by researchers during the past few decades that has seen neutron scattering develop to its present status as the method of choice for investigations of magnetic structure and excitations. Looking beyond the dipole-approximation, however, reveals a wealth of additional information about electronic degrees of freedom conveniently encapsulated in magnetic multipoles. In this language, the dipole-approximation retains electronic axial dipoles, S and L. At the same level of approximation are polar dipoles—called anapoles or toroidal dipoles—allowed in the absence of a centre of inversion symmetry. Anapoles are examples of magneto-electric multipoles, time-odd and parity-odd irreducible tensors, that have come to the fore as signatures of electronic complexity in materials.

  4. System Construction of the Stilbene Compact Neutron Scatter Camera

    Energy Technology Data Exchange (ETDEWEB)

    Goldsmith, John E. M. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Gerling, Mark D. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Brennan, James S. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Throckmorton, Daniel J. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Helm, Jonathan Ivers [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2016-10-01

    This report documents the construction of a stilbene-crystal-based compact neutron scatter camera. This system is essentially identical to the MINER (Mobile Imager of Neutrons for Emergency Responders) system previously built and deployed under DNN R&D funding,1 but with the liquid scintillator in the detection cells replaced by stilbene crystals. The availability of these two systems for side-by-side performance comparisons will enable us to unambiguously identify the performance enhancements provided by the stilbene crystals, which have only recently become commercially available in the large size required (3” diameter, 3” deep).

  5. Quantifying the information measured by neutron scattering instruments

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, M.W. [Rutherford Appleton Lab., Oxon (United Kingdom)

    1997-09-01

    The concept of the information content of a scientific measurement is introduced, and a theory is presented which enables the information that may be obtained by a neutron scattering instrument to be calculated. When combined with the time taken to perform the measurement the bandwidth of the instrument is obtained. This bandwidth is effectively a figure of merit which is of use in three respects: in the design of neutron instrumentation, the optimisation of measurements, and in the comparison of one instrument with another.

  6. Participant Support for Speakers and Early-Career Scientists at the 2012 American Conference on Neutron Scattering (ACNS)

    Energy Technology Data Exchange (ETDEWEB)

    Leighton, Chris [Materials Research Society, Warrendale, PA (United States); Dillen, J. Ardie [Materials Research Society, Warrendale, PA (United States)

    2012-11-07

    The ACNS provides a focal point for the North American neutron user community, strengthening ties within this diverse group, and promoting neutron research in related disciplines. The conference thus serves a dual role as both a national user meeting and a scientific meeting. As a venue for scientific exchange, the ACNS showcases recent results and provides a forum for scientific discussion of neutron-enabled research in fields as diverse as hard and soft condensed matter, liquids, biology, magnetism, engineering materials, chemical spectroscopy, crystal structure, elementary excitations, fundamental physics, and development of neutron instrumentation. This is achieved through a combination of invited oral presentations, contributed oral presentations, and poster sessions. Adequate opportunity for spontaneous discussion and collaboration is also built into the ACNS program in order to foster free exchange of new scientific ideas and the potential for use of powerful neutron scattering methods beyond the current realms of application. The sixth American Conference on Neutron Scattering (ACNS 2012) provided essential information on the breadth and depth of current neutron-related research worldwide. A strong program of plenary, invited and contributed talks showcased recent scientific results in neutron science in a wide range of fields, including soft and hard condensed matter, biology, chemistry, energy and engineering applications, and neutron physics.

  7. Identification and rejection of scattered neutrons in AGATA

    CERN Document Server

    Şenyiğit, M; Akkoyun, S; Kaşkaş, A; Bazzacco, D; Nyberg, J; Recchia, F; Brambilla, S; Camera, F; Crespi, F C L; Farnea, E; Giaz, A; Gottardo, A; Kempley, R; Ljungvall, J; Mengoni, D; Michelagnoli, C; Million, B; Palacz, M; Pellegri, L; Riboldi, S; Şahin, E; Söderström, P A; Dobon, J J Valiente

    2013-01-01

    Gamma rays and neutrons, emitted following spontaneous fission of 252Cf, were measured in an AGATA experiment performed at INFN Laboratori Nazionali di Legnaro in Italy. The setup consisted of four AGATA triple cluster detectors (12 36-fold segmented high-purity germanium crystals), placed at a distance of 50 cm from the source, and 16 HELENA BaF2 detectors. The aim of the experiment was to study the interaction of neutrons in the segmented high-purity germanium detectors of AGATA and to investigate the possibility to discriminate neutrons and gamma rays with the gamma-ray tracking technique. The BaF2 detectors were used for a time-of-flight measurement, which gave an independent discrimination of neutrons and gamma rays and which was used to optimise the gamma-ray tracking-based neutron rejection methods. It was found that standard gamma-ray tracking, without any additional neutron rejection features, eliminates effectively most of the interaction points due to recoiling Ge nuclei after elastic scattering of...

  8. Active helium target: Neutron scalar polarizability extraction via Compton scattering

    Energy Technology Data Exchange (ETDEWEB)

    Morris, Meg, E-mail: mmorris@mta.ca; Hornidge, David [Mount Allison University, Sackville, New Brunswick (Canada); Annand, John; Strandberg, Bruno [University of Glasgow, Scotland (United Kingdom)

    2015-12-31

    Precise measurement of the neutron scalar polarizabilities has been a lasting challenge because of the lack of a free-neutron target. Led by the University of Glasgow and the Mount Allison University groups of the A2 collaboration in Mainz, Germany, preparations have begun to test a recent theoretical model with an active helium target with the hope of determining these elusive quantities with small statistical, systematic, and model-dependent errors. Apparatus testing and background-event simulations have been carried out, with the full experiment projected to run in 2015. Once determined, these values can be applied to help understand quantum chromodynamics in the nonperturbative region.

  9. Scientific opportunities with advanced facilities for neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Lander, G.H.; Emery, V.J. (eds.)

    1984-01-01

    The present report documents deliberations of a large group of experts in neutron scattering and fundamental physics on the need for new neutron sources of greater intensity and more sophisticated instrumentation than those currently available. An additional aspect of the Workshop was a comparison between steady-state (reactor) and pulsed (spallation) sources. The main conclusions were: (1) the case for a new higher flux neutron source is extremely strong and such a facility will lead to qualitatively new advances in condensed matter science and fundamental physics; (2) to a large extent the future needs of the scientific community could be met with either a 5 x 10/sup 15/ n cm/sup -2/s/sup -1/ steady state source or a 10/sup 17/ n cm/sup -2/s/sup -1/ peak flux spallation source; and (3) the findings of this Workshop are consistent with the recommendations of the Major Materials Facilities Committee.

  10. The MCLIB library: Monte Carlo simulation of neutron scattering instruments

    Energy Technology Data Exchange (ETDEWEB)

    Seeger, P.A.

    1995-09-01

    Monte Carlo is a method to integrate over a large number of variables. Random numbers are used to select a value for each variable, and the integrand is evaluated. The process is repeated a large number of times and the resulting values are averaged. For a neutron transport problem, first select a neutron from the source distribution, and project it through the instrument using either deterministic or probabilistic algorithms to describe its interaction whenever it hits something, and then (if it hits the detector) tally it in a histogram representing where and when it was detected. This is intended to simulate the process of running an actual experiment (but it is much slower). This report describes the philosophy and structure of MCLIB, a Fortran library of Monte Carlo subroutines which has been developed for design of neutron scattering instruments. A pair of programs (LQDGEOM and MC{_}RUN) which use the library are shown as an example.

  11. Quasielastic neutron scattering study of POSS ligand dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Jalarvo, Niina H [ORNL; Tyagi, Madhusudan [NIST Center for Neutron Research (NCRN), Gaithersburg, MD; Crawford, Michael [DuPont Experimental Station

    2015-01-01

    Polyoligosilsesquioxanes are molecules having cage-like structures composed of silicon and oxygen. These molecules can have a wide variety of functional ligands attached to them. Depending on the nature of the ligand, interesting properties and applications are found. In this work we present results from quasielastic neutron scattering measurements of four different POSS molecules that illustrate the presence of strong coupling between the ligand dynamics and the POSS crystal structures.

  12. Bragg optics computer codes for neutron scattering instrument design

    Energy Technology Data Exchange (ETDEWEB)

    Popovici, M.; Yelon, W.B.; Berliner, R.R. [Missouri Univ. Research Reactor, Columbia, MO (United States); Stoica, A.D. [Institute of Physics and Technology of Materials, Bucharest (Romania)

    1997-09-01

    Computer codes for neutron crystal spectrometer design, optimization and experiment planning are described. Phase space distributions, linewidths and absolute intensities are calculated by matrix methods in an extension of the Cooper-Nathans resolution function formalism. For modeling the Bragg reflection on bent crystals the lamellar approximation is used. Optimization is done by satisfying conditions of focusing in scattering and in real space, and by numerically maximizing figures of merit. Examples for three-axis and two-axis spectrometers are given.

  13. Simulation of a complete inelastic neutron scattering experiment

    DEFF Research Database (Denmark)

    Edwards, H.; Lefmann, K.; Lake, B.

    2002-01-01

    A simulation of an inelastic neutron scattering experiment on the high-temperature superconductor La2-xSrxCuO4 is presented. The complete experiment, including sample, is simulated using an interface between the experiment control program and the simulation software package (McStas) and is compared...... with the experimental data. Simulating the entire experiment is an attractive alternative to the usual method of convoluting the model cross section with the resolution function, especially if the resolution function is nontrivial....

  14. Elastic and inelastic scattering of neutrons on 238U nucleus

    Directory of Open Access Journals (Sweden)

    Capote R.

    2014-04-01

    Full Text Available Advanced modelling of neutron induced reactions on the 238U nucleus is aimed at improving our knowledge of neutron scattering. Capture and fission channels are well constrained by available experimental data and neutron standard evaluation. A focus of this contribution is on elastic and inelastic scattering cross sections. The employed nuclear reaction model includes – a new rotational-vibrational dispersive optical model potential coupling the low-lying collective bands of vibrational character observed in even-even actinides; – the Engelbrecht-Weidenmüller transformation allowing for inclusion of compound-direct interference effects; – and a multi-humped fission barrier with absorption in the secondary well described within the optical model for fission. Impact of the advanced modelling on elastic and inelastic scattering cross sections including angular distributions and emission spectra is assessed both by comparison with selected microscopic experimental data and integral criticality benchmarks including measured reaction rates (e.g. JEMIMA, FLAPTOP and BIG TEN. Benchmark calculations provided feedback to improve the reaction modelling. Improvement of existing libraries will be discussed.

  15. Chamber for mechanical testing in H2 with observation by neutron scattering

    Science.gov (United States)

    Connolly, Matthew; Bradley, Peter; Slifka, Andrew; Drexler, Elizabeth

    2017-06-01

    A gas-pressure chamber has been designed, constructed, and tested at a moderate pressure (3.4 MPa, 500 psi) and has the capability of mechanical loading of steel specimens for neutron scattering measurements. The chamber will allow a variety of in situ neutron scattering measurements: in particular, diffraction, quasielastic scattering, inelastic scattering, and imaging. The chamber is compatible with load frames available at the user facilities at the NIST Center for Neutron Research and Oak Ridge National Laboratory Spallation Neutron Source. A demonstration of neutron Bragg edge imaging using the chamber is presented.

  16. TOF-SEMSANS—Time-of-flight spin-echo modulated small-angle neutron scattering

    NARCIS (Netherlands)

    Strobl, M.; Tremsin, A.S.; Hilger, A.; Wieder, F.; Kardjilov, N.; Manke, I.; Bouwman, W.G.; Plomp, J.

    2012-01-01

    We report on measurements of spatial beam modulation of a polarized neutron beam induced by triangular precession regions in time-of-flight mode and the application of this novel technique spin-echo modulated small-angle neutron scattering (SEMSANS) to small-angle neutron scattering in the very

  17. Electron Scattering From a High-Momentum Neutron in Deuterium

    Energy Technology Data Exchange (ETDEWEB)

    Klimenko, Alexei [Old Dominion Univ., Norfolk, VA (United States)

    2004-05-01

    The deuterium nucleus is a system of two nucleons (proton and neutron) bound together. The configuration of the system is described by a quantum-mechanical wave function and the state of the nucleons at a given time is not know a priori. However, by detecting a backward going proton of moderate momentum in coincidence with a reaction taking place on the neutron in deuterium, the initial state of that neutron can be inferred if we assume that the proton was a spectator to the reaction. This method, known as spectator tagging, was used to study the electron scattering from high-momentum neutrons in deuterium. The data were taken with a 5.765 GeV polarized electron beam on a deuterium target in Jefferson Laboratory's Hall B, using the CLAS detector. The accumulated data cover a wide kinematic range, reaching values of the invariant mass of the unobserved final state W* up to 3 GeV. A data sample of approximately 5 - 105 events, with protons detected at large scattering angles (as high as 136 degrees) in coincidence with the forward electrons, was selected. The product of the neutron structure function with the initial nucleon momentum distribution F2n. S was extracted for different values of W*, backward proton momenta ps and momentum transfer Q2. The data were compared to a calculation based on the spectator approximation and using the free nucleon form factors and structure functions. A strong enhancement in the data, not reproduced by the model, was observed at cos(thetapq) > -0.3 (where theta{sub pq} is the proton scattering angle relative to the direction of the momentum transfer) and can be associated with the contribution of final state interactions (FSI) that were not incorporated into the model. The bound nucleon structure function F2n was studied in the region cos(thetapq) < -0.3 as a function of W* and scaling variable x*. At high spectator proton momenta the struck neutron is

  18. Small-angle neutron scattering study on irradiated kappa carrageenan

    Energy Technology Data Exchange (ETDEWEB)

    Abad, Lucille [Neutron Science Laboratory, Institute for Solid State Physics, University of Tokyo, 106-1 Shirakata, Tokai, Ibaraki 319-1106 (Japan) and Philippine Nuclear Research Institute, Commonwealth Ave., Diliman, Quezon City (Philippines) and Advanced Science Research Center, Japan Atomic Energy Research Institute, 2-4 Shirane Shirakata, Tokai, Ibaraki 319-1195 (Japan)]. E-mail: lvabad@pnri.dost.gov.ph; Okabe, Satoshi [Neutron Science Laboratory, Institute for Solid State Physics, University of Tokyo, 106-1 Shirakata, Tokai, Ibaraki 319-1106 (Japan); Koizumi, Satoshi [Advanced Science Research Center, Japan Atomic Energy Research Institute, 2-4 Shirane Shirakata, Tokai, Ibaraki 319-1195 (Japan); Shibayama, Mitsuhiro [Neutron Science Laboratory, Institute for Solid State Physics, University of Tokyo, 106-1 Shirakata, Tokai, Ibaraki 319-1106 (Japan)]. E-mail: sibayama@issp.u-tokyo.ac.jp

    2006-05-31

    The structure of gamma-ray-irradiated {kappa}-carrageenan in aqueous solutions was investigated in terms of small-angle neutron scattering. The scattered intensity, I(q), of non-irradiated {kappa}-carrageenan solutions (5 wt%) was well described with an Ornstein-Zernike (OZ)-type function with the correlation length of 85 A, indicating that the {kappa}-carrageenan solution behaves just as a polymer solution in the semi-dilute regime. By increasing the irradiation dose (100 kGy), I(q) changed to a power-law function with the scattering exponent of -1.84. Further increase in dose results in a recovery of OZ-type function. This indicates that a progressive cleavage of {kappa}-carrageenan chains takes place randomly, leading to a self-similar structure at 100 kGy. This is followed by further segmentation of {kappa}-carrageenan chains.

  19. Magnetic particles studied with neutron depolarization and small-angle neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Rosman, R.

    1991-04-23

    Materials containing magnetic single-domain particles, referred to as `particulate media`, have been studied using neutron depolarization (ND) and small-angle neutron scattering (SANS). In a ND experiment the polarization vector of a polarized neutron beam is analyzed after transmission through a magnetic medium. Such an analysis in general yields the correlation length of variations in magnetic induction along the neutron path (denoted `magnetic correlation length`), mean orientation of these variations and mean magnetic induction. In a SANS experiment, information about nuclear and magnetic inhomogeneities in the medium is derived from the broadening of a generally unpolarized neutron beam due to scattering by these inhomogeneities. Spatial and magnetic microstructure of a variety of particulate media have been studied using ND and/or SANS, by determination of the magnetic or nuclear correlation length in these media in various magnetic states. This thesis deals with the ND theory and its application to particulate media. ND and SANS experiments on a variety of particulate media are discussed. (author). 178 refs., 97 figs., 8 tabs.

  20. Magnetic particles studied with neutron depolarization and small-angle neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Rosman, R.

    1991-04-23

    Materials containing magnetic single-domain particles, referred to as 'particulate media', have been studied using neutron depolarization (ND) and small-angle neutron scattering (SANS). In a ND experiment the polarization vector of a polarized neutron beam is analyzed after transmission through a magnetic medium. Such an analysis in general yields the correlation length of variations in magnetic induction along the neutron path (denoted 'magnetic correlation length'), mean orientation of these variations and mean magnetic induction. In a SANS experiment, information about nuclear and magnetic inhomogeneities in the medium is derived from the broadening of a generally unpolarized neutron beam due to scattering by these inhomogeneities. Spatial and magnetic microstructure of a variety of particulate media have been studied using ND and/or SANS, by determination of the magnetic or nuclear correlation length in these media in various magnetic states. This thesis deals with the ND theory and its application to particulate media. ND and SANS experiments on a variety of particulate media are discussed. (author). 178 refs., 97 figs., 8 tabs.

  1. Survey of background scattering from materials found in small-angle neutron scattering.

    Science.gov (United States)

    Barker, J G; Mildner, D F R

    2015-08-01

    Measurements and calculations of beam attenuation and background scattering for common materials placed in a neutron beam are presented over the temperature range of 300-700 K. Time-of-flight (TOF) measurements have also been made, to determine the fraction of the background that is either inelastic or quasi-elastic scattering as measured with a 3He detector. Other background sources considered include double Bragg diffraction from windows or samples, scattering from gases, and phonon scattering from solids. Background from the residual air in detector vacuum vessels and scattering from the 3He detector dome are presented. The thickness dependence of the multiple scattering correction for forward scattering from water is calculated. Inelastic phonon background scattering at small angles for crystalline solids is both modeled and compared with measurements. Methods of maximizing the signal-to-noise ratio by material selection, choice of sample thickness and wavelength, removal of inelastic background by TOF or Be filters, and removal of spin-flip scattering with polarized beam analysis are discussed.

  2. A neutron scattering study of triblock copolymer micelles

    Energy Technology Data Exchange (ETDEWEB)

    Gerstenberg, M.C.

    1997-11-01

    The thesis describes the neutron scattering experiments performed on poly(ethylene oxide)/poly(propylene oxide)/poly(ethylene oxide) triblock copolymer micelles in aqueous solution. The studies concern the non-ionic triblock copolymer P85 which consists of two outer segments of 25 monomers of ethylene oxide attached to a central part of 40 monomers of propylene oxide. The amphiphilic character of P85 leads to formation of various structures in aqueous solution such as spherical micelles, rod-like structures, and a BCC liquid-crystal mesophase of spherical micelles. The present investigations are centered around the micellar structures. In the first part of this thesis a model for the micelle is developed for which an analytical scattering form factor can be calculated. The micelle is modeled as a solid sphere with tethered Gaussian chains. Good agreement was found between small-angle neutron scattering experiments and the form factor of the spherical P85 micelles. Above 60 deg. C some discrepancies were found between the model and the data which is possibly due to an elongation of the micelles. The second part focuses on the surface-induced ordering of the various micellar aggregates in the P85 concentration-temperature phase diagram. In the spherical micellar phase, neutron reflection measurements indicated a micellar ordering at the hydrophilic surface of quartz. Extensive modeling was performed based on a hard sphere description of the micellar interaction. By convolution of the distribution of hard spheres at a hard wall, obtained from Monte Carlo simulations, and the projected scattering length density of the micelle, a numerical expression was obtained which made it possible to fit the data. The hard-sphere-hard-wall model gave an excellent agreement in the bulk micellar phase. However, for higher concentrations (25 wt % P85) close to the transition from the micellar liquid into a micellar cubic phase, a discrepancy was found between the model and the

  3. Down-scattered neutron imaging detector for areal density measurement of inertial confinement fusion.

    Science.gov (United States)

    Arikawa, Y; Yamanoi, K; Nakazato, T; Estacio, E S; Shimizu, T; Sarukura, N; Nakai, M; Hosoda, H; Norimatsu, T; Hironaka, Y; Azechi, H; Izumi, N; Murata, T; Fujino, S; Yoshida, H; Kamada, K; Usuki, Y; Suyama, T; Yoshikawa, A; Satoh, N; Kan, H

    2010-10-01

    A custom developed (6)Li glass scintillator (APLF80+3Pr) for down-scattered neutron diagnostics in inertial confinement fusion experiments is presented. (6)Li provides an enhanced sensitivity for down-scattered neutrons in DD fusion and its experimentally observed 5-6 ns response time fulfills the requirement for down-scattered neutron detectors. A time-of-flight detector operating in the current mode using the APLF80+3Pr was designed and its feasibility observing down-scattered neutrons was demonstrated. Furthermore, a prototype design for a down-scattered neutron imaging detector was also demonstrated. This material promises viability as a future down-scattered neutron detector for the National Ignition Facility.

  4. Down-scattered neutron imaging detector for areal density measurement of inertial confinement fusion

    Energy Technology Data Exchange (ETDEWEB)

    Arikawa, Y.; Yamanoi, K.; Nakazato, T.; Estacio, E. S.; Shimizu, T.; Sarukura, N.; Nakai, M.; Hosoda, H.; Norimatsu, T.; Hironaka, Y.; Azechi, H. [Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871 (Japan); Izumi, N. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States); Murata, T. [Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871 (Japan); Kumamoto University, 2-40-1 Kurokami, Kumamoto 860-8555 (Japan); Fujino, S. [Kyushu University, 744 Nishiku, Motooka, Fukuoka 819-0395 (Japan); Yoshida, H. [Ceramic Research Center of Nagasaki, Hiekoba, Hisami, Higashisonogi 859-3726 (Japan); Kamada, K.; Usuki, Y. [Furukawa Co. Ltd., 1-25-13 Kannondai, Tsukuba, Ibaraki 305-0856 (Japan); Suyama, T. [Tokuyama Co. Ltd., 3-3-1 Shibuyaku, Shibuya, Tokyo 150-8383 (Japan); Yoshikawa, A. [Tohoku University, 2-1-1 Katahira, Aoyou, Sendai, Miyagi 980-8577 (Japan); Satoh, N. [Hamamatsu Photonics K.K., 5000 Hiraguchi, Hamakitaku, Hamamatsu, Shizuoka 434-8601 (Japan); and others

    2010-10-15

    A custom developed {sup 6}Li glass scintillator (APLF80+3Pr) for down-scattered neutron diagnostics in inertial confinement fusion experiments is presented. {sup 6}Li provides an enhanced sensitivity for down-scattered neutrons in DD fusion and its experimentally observed 5-6 ns response time fulfills the requirement for down-scattered neutron detectors. A time-of-flight detector operating in the current mode using the APLF80+3Pr was designed and its feasibility observing down-scattered neutrons was demonstrated. Furthermore, a prototype design for a down-scattered neutron imaging detector was also demonstrated. This material promises viability as a future down-scattered neutron detector for the National Ignition Facility.

  5. Ni containing solid Kr bubbles studied with neutron depolarization and small-angle neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Rosman, R.; Rekveldt, M.T. (Interfacultair Reactor Inst., Delft Univ. of Technology (Netherlands))

    1991-07-01

    Neutron depolarization (ND) and small-angle neutron scattering (SANS) experiments on Ni containing solid Kr bubbles are presented and discussed. The aim of the measurements is to study the effect of the Kr bubbles on the local magnetization. For the first time ND measurements in relatively large fields up to 80kA/m could be performed. However, the ND results do not yield information about the Kr bubbles. The SANS patterns at applied fields larger than 400kA/m are isotropic and are in agreement with a high fraction of small (radius {approx equal} 1.5nm) Kr bubbles. Also a small fraction of larger (radius > or approx. 15nm) Kr bubbles or other nuclear inhomogeneities is likely to be present. The magnetic scattering is in agreement with a local magnetization which is affected by the demagnetization fields of these inhomogeneities. (orig.).

  6. Proton dynamics in bacterial spores, a neutron scattering investigation

    Directory of Open Access Journals (Sweden)

    Noue Alexandre Colas de la

    2015-01-01

    Full Text Available Results from first neutron scattering experiments on bacterial spores are reported. The elastic intensities and mean square displacements have a non-linear behaviour as function of temperature, which is in agreement with a model presenting more pronounced variations at around 330 K (57 ∘C and 400 K (127 ∘C. Based on the available literature on thermal properties of bacterial spores, mainly referring to differential scanning calorimetry, they are suggested to be associated to main endothermic transitions induced by coat and/or core bacterial response to heat treatment.

  7. Application of Incoherent Inelastic Neutron Scattering in Pharmaceutical Analysis

    DEFF Research Database (Denmark)

    Bordallo, Heloisa N.; A. Zakharov, Boris; Boidyreva, E.V.

    2012-01-01

    This study centers on the use of inelastic neutron scattering as an alternative tool for physical characterization of solid pharmaceutical drugs. On the basis of such approach, relaxation processes in the pharmaceutical compound phenacetin (p-ethoxyacetanilide, C(10)H(13)NO(2)) were evidenced...... contributes to understanding the relationships between intermolecular hydrogen bonds, intramolecular dynamics, and conformational flexibility in pharmaceuticals on a molecular level, which can help in evaluating phase stability with respect to temperature variations on processing or on storage, and is related...

  8. Neutron Imaging of Laser Melted SS316 Test Objects with Spatially Resolved Small Angle Neutron Scattering

    Directory of Open Access Journals (Sweden)

    Adam J. Brooks

    2017-12-01

    Full Text Available A novel neutron far field interferometer is explored for sub-micron porosity detection in laser sintered stainless steel alloy 316 (SS316 test objects. The results shown are images and volumes of the first quantitative neutron dark-field tomography at various autocorrelation lengths, ξ . In this preliminary work, the beam defining slits were adjusted to an uncalibrated opening of 0.5 mm horizontal and 5 cm vertical; the images are blurred along the vertical direction. In spite of the blurred attenuation images, the dark-field images reveal structural information at the micron-scale. The topics explored include: the accessible size range of defects, potentially 338 nm to 4.5 μ m, that can be imaged with the small angle scattering images; the spatial resolution of the attenuation image; the maximum sample dimensions compatible with interferometry optics and neutron attenuation; the procedure for reduction of the raw interferogram images into attenuation, differential phase contrast, and small angle scattering (dark-field images; and the role of neutron far field interferometry in additive manufacturing to assess sub-micron porosity.

  9. Neutron and light scattering studies of polymers adsorbed on laponite

    CERN Document Server

    Nelson, A R J

    2002-01-01

    The adsorption of poly(ethylene oxide) (PEO) and various poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (Pluronic) copolymers onto the synthetic clay Laponite, was investigated using Small Angle Neutron Scattering (SANS) and Dynamic Light Scattering (DLS). The Laponite particles are anisotropic, with a relatively high aspect ratio; but are the same order of magnitude in size as the polymer radius of gyration. Consequently, the particles present a radically different adsorption geometry compared to a locally planar interface, that is assumed by the majority of adsorption studies. The PEO homo-polymer formed thin layers, with the layer thickness being much smaller on the face than on the edge of the particle. Furthermore, the face thickness remained constant with increasing molecular weight, unlike the edge thickness, which grew with a small power law dependence on the molecular weight. Although the hydrodynamic thicknesses (DLS) were larger than those observed with SANS, the layer thicknesses ...

  10. Neutron scattering of a floating heavy water bridge

    Energy Technology Data Exchange (ETDEWEB)

    Fuchs, Elmar C [Wetsus, Center of Excellence for Sustainable Water Technology, Agora 1, 8900 CC Leeuwarden (Netherlands); Bitschnau, Brigitte [Institute of Physical and Theoretical Chemistry, Graz University of Technology, Rechbauerstrasse 12, 8010 Graz (Austria); Woisetschlaeger, Jakob [Institute of Thermal Turbomachnery and Machine Dynamics, Graz University of Technology, Inffeldgasse 25A, Graz (Austria); Maier, Eugen [Institute for Chemistry and Technology of Materials, Graz University of Technology, Stremayrgasse 16, 8010 Graz (Austria); Beuneu, Brigitte; Teixeira, Jose [Laboratoire Leon Brillouin, CEA-CNRS/IRAMIS, CEA/Saclay, 91191 Gif-sur-Yvette Cedex (France)

    2009-03-21

    When high voltage is applied to distilled water filled into two beakers close to each other, a water connection forms spontaneously, giving the impression of a floating water bridge (Fuchs et al 2007 J. Phys. D: Appl. Phys. 40 6112-4, 2008 J. Phys. D: Appl. Phys. 41 185502). This phenomenon is of special interest, since it comprises a number of phenomena currently tackled in modern water science. In this work, the first data on neutron scattering of a floating heavy water bridge are presented and possible interpretations are discussed. D{sub 2}O was measured instead of H{sub 2}O because of the very strong incoherent scattering of H. The obtained data support the 'bubble hypothesis' suggested earlier (Fuchs et al 2008).

  11. On the analysis of Deep Inelastic Neutron Scattering Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Blostein, J.J.; Dawidowski, J.; Granada, J.R. [Comision Nacional de Energia Atomica and CONICET, Centro Atomico Bariloche and Instituto Balseiro, Bariloche (Argentina)

    2001-03-01

    We analyze the different steps that must be followed for data processing in Deep Inelastic Neutron Scattering Experiments. Firstly we discuss to what extent multiple scattering effects can affect the measured peak shape, concluding the an accurate calculation of these effects must be performed to extract the desired effective temperature from the experimental data. We present a Monte Carlo procedure to perform these corrections. Next, we focus our attention on experiments performed on light nuclei. We examine cases in which the desired information is obtained from the observed peak areas, and we analyze the procedure to obtain an effective temperature from the experimental peaks. As a consequence of the results emerging from those cases we trace the limits of validity of the convolution formalism usually employed, and propose a different treatment of the experimental data for this kind of measurements. (author)

  12. Neutron-19C scattering: Towards including realistic interactions

    Science.gov (United States)

    Deltuva, A.

    2017-09-01

    Low-energy neutron-19C scattering is studied in the three-body n + n +18C model using a realistic nn potential and a number of shallow and deep n-18C potentials, the latter supporting deeply-bound Pauli-forbidden states that are projected out. Exact Faddeev-type three-body scattering equations for transition operators including two- and three-body forces are solved in the momentum-space partial-wave framework. Phase shift, inelasticity parameter, and cross sections are calculated. For the elastic n-19C scattering in the JΠ =0+ partial wave the signatures of the Efimov physics, i.e., the pole in the effective-range expansion and the elastic cross section minimum, are confirmed for both shallow and deep models, but with clear quantitative differences between them, indicating the importance of a proper treatment of deeply-bound Pauli-forbidden states. In contrast, the inelasticity parameter is mostly correlated with the asymptotic normalization coefficient of the 19C bound state. Finally, in the regime of very weak 19C binding and near-threshold (bound or virtual) excited 20C state the standard Efimovian behaviour of the n-19C scattering length and cross section was confirmed, resolving the discrepancies between earlier studies by other authors (Mazumdar et al., 2006 [20], Yamashita et al., 2007 [23]).

  13. Development of a scattering probability method for accurate vapor fraction measurements by neutron radiography

    CERN Document Server

    Joo, H

    1999-01-01

    Recent test results indicated drawbacks associated with the simple exponential attenuation method (SEAM) as currently applied to neutron radiography measurements to determine vapor fractions in a hydrogenous two-phase flow in a metallic conduit. The scattering component of the neutron beam intensity exiting the flow system is not adequately accounted for by SEAM, and this leads to inaccurate results. To properly account for the scattering effect, a neutron scattering probability method (SPM) is developed. The method applies a neutron-hydrogen scattering kernel to scattered thermal neutrons that leave the incident beam in narrow conduits but eventually show up elsewhere in the measurements. The SPM has been tested with known vapor (void) distributions within an acrylic disk and a water/vapor channel. The vapor (void) fractions deduced by SPM are in good agreement with the known exact values. Details of the scattering correction method and the test results are discussed.

  14. The fluctuating ribosome: thermal molecular dynamics characterized by neutron scattering

    Science.gov (United States)

    Zaccai, Giuseppe; Natali, Francesca; Peters, Judith; Řihová, Martina; Zimmerman, Ella; Ollivier, J.; Combet, J.; Maurel, Marie-Christine; Bashan, Anat; Yonath, Ada

    2016-11-01

    Conformational changes associated with ribosome function have been identified by X-ray crystallography and cryo-electron microscopy. These methods, however, inform poorly on timescales. Neutron scattering is well adapted for direct measurements of thermal molecular dynamics, the ‘lubricant’ for the conformational fluctuations required for biological activity. The method was applied to compare water dynamics and conformational fluctuations in the 30 S and 50 S ribosomal subunits from Haloarcula marismortui, under high salt, stable conditions. Similar free and hydration water diffusion parameters are found for both subunits. With respect to the 50 S subunit, the 30 S is characterized by a softer force constant and larger mean square displacements (MSD), which would facilitate conformational adjustments required for messenger and transfer RNA binding. It has been shown previously that systems from mesophiles and extremophiles are adapted to have similar MSD under their respective physiological conditions. This suggests that the results presented are not specific to halophiles in high salt but a general property of ribosome dynamics under corresponding, active conditions. The current study opens new perspectives for neutron scattering characterization of component functional molecular dynamics within the ribosome.

  15. Neutron scattering from the Kondo Insulator SmB6

    Science.gov (United States)

    Broholm, Collin

    A review of neutron scattering work probing the Kondo insulator SmB6 is presented with special emphasis on assessing the topology of the underlying strongly renormalized band structure. A 14 meV excition dominates the spectrum and is evidence of strong electron correlations [1]. Though the data generally supports the proposal that SmB6 is a topological Kondo insulator, specific heat and high-resolution neutron scattering data show a continuum of states well below the bulk transport gap, which enrich the problem and may connect to the recent surprising de Haas van Alpen results. ``Interaction Driven Subgap Spin Exciton in the Kondo Insulator SmB6,'' W. T. Fuhrman, J. Leiner, P. Nikolic, G. E. Granroth, M. B. Stone, M. D. Lumsden, L. DeBeer-Schmitt, P. A. Alekseev, J.-M. Mignot, S. M. Koohpayeh, P. Cottingham, W. Adam Phelan, L. Schoop, T. M. McQueen, and C. Broholm, Phys. Rev. Lett. 114, 036401 (2015). Supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Material Sciences and Engineering, under Grant No. DEFG02-08ER46544 and the Gordon and Betty Moore Foundation.

  16. Electron Scattering From High-Momentum Neutrons in Deuterium

    CERN Document Server

    Klimenko, A V; Ambrozewicz, P; Anghinolo, M; Asryan, G; Avakian, H; Bagdasaryan, H; Baillie, N; Ball, J P; Baltzell, N A; Barrow, S; Batourine, V; Battaglieri, M; Bedlinskiy, I; Bektasoglu, M; Bellis, M; Benmouna, N; Biselli, A S; Bltmann, S; Boiarinov, S; Bouchigny, S; Bradford, R; Branford, D; Brooks, W K; Burkert, V D; Butuceanu, C; Calarco, J R; Careccia, S L; Carman, D S; Cazes, A; Chen, S; Cole, P L; Coltharp, P; Cords, D; Corvisiero, P; Crabb, D; Cummings, J P; Dashyan, N B; De Sanctis, E; De Vita, R; Degtyarenko, P V; Denizli, H; Dennis, L; Dharmawardane, K V; Djalali, C; Dodge, G E; Donnelly, J; Doughty, D; Dugger, M; Dytman, S; Dzyubak, O P; Egiyan, H; Egiyan, K S; Elouadrhiri, L; Eugenio, P; Fatemi, R; Fedotov, G; Fersch, R G; Feuerbach, R J; Funsten, H; Garçon, M; Gavalian, G; Gilfoyle, G P; Giovanetti, K L; Girod, F X; Goetz, J T; Gonenc, A; Gordon, C I O; Gothe, R W; Grioen, K A; Guidal, M; Guillo, M; Guler, N; Guo, L; Gyurjyan, V; Hadjidakis, C; Hakobyan, R S; Hardie, J; Hersman, F W; Hicks, K; Hleiqawi, I; Holtrop, M; Hyde-Wright, C E; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Ito, M M; Jenkins, D; Jo, H S; Joo, K; Jüngst, H G; Kellie, J D; Khandaker, M; Kim, W; Klein, A; Klein, F J; Kossov, M; Kramer, L H; Kubarovski, V; Kuhn, S E; Kuleshov, S V; Kühn, J; Lachniet, J; Laget, J M; Langheinrich, J; Lawrence, D; Li, J; Livingston, K; McAleer, S; McKinnon, B; McNabb, J W C; Mecking, B A; Mehrabyan, S S; Melone, J J; Mestayer, M D; Meyer, C A; Mibe, T; Mikhailov, K; Minehart, R C; Mirazita, M; Miskimen, R; Mokeev, V; Morand, L; Morrow, S A; Mutchler, G S; Müller, J; Nadel-Turonski, P; Napolitano, J; Nasseripour, R; Niccolai, S; Niculescu, G; Niculescu, I; Niczyporuk, B B; Niyazov, R A; Nozar, M; O'Rielly, G V; Osipenko, M; Ostrovidov, A I; Park, K; Pasyuk, E; Paterson, C; Pierce, J; Pivnyuk, N; Pocanic, D; Pogorelko, O I; Pozdniakov, S; Preedom, B M; Price, J W; Prok, Y; Protopopescu, D; Raue, B A; Riccardi, G; Ricco, G; Ripani, M; Ritchie, B G; Ronchetti, F; Rosner, G; Rossi, P; Sabatie, F; Salgado, C; Santoro, J P; Sapunenko, V; Schumacher, R A; Serov, V S; Sharabyan, Yu G; Skabelin, A V; Smith, E S; Smith, L C; Sober, D I; Stavinsky, A V; Stepanyan, S; Stokes, B E; Stoler, P; Strauch, S; Taiuti, M; Tedeschi, D J; Thoma, U; Tkabladze, A; Tkachenko, S I; Todor, L; Tur, C; Ungaro, M; Vineyard, M F; Vlassov, A V; Weinstein, L B; Weygand, D P; Williams, M; Wolin, E; Wood, M H; Yegneswaran, A; Zana, L; Zhang, J; Zhao, B

    2006-01-01

    We report results from an experiment measuring the semi-inclusive reaction $d(e,e'p_s)$ where the proton $p_s$ is moving at a large angle relative to the momentum transfer. If we assume that the proton was a spectator to the reaction taking place on the neutron in deuterium, the initial state of that neutron can be inferred. This method, known as spectator tagging, can be used to study electron scattering from high-momentum (off-shell) neutrons in deuterium. The data were taken with a 5.765 GeV electron beam on a deuterium target in Jefferson Laboratory's Hall B, using the CLAS detector. A reduced cross section was extracted for different values of final-state missing mass $W^{*}$, backward proton momentum $\\vec{p}_{s}$ and momentum transfer $Q^{2}$. The data are compared to a simple PWIA spectator model. A strong enhancement in the data observed at transverse kinematics is not reproduced by the PWIA model. This enhancement can likely be associated with the contribution of final state interactions (FSI) that ...

  17. Double-Scatter Fast-Neutron Imaging for National Security Applications

    Science.gov (United States)

    Polack, John

    2017-09-01

    Fast neutron imaging based on two (or more) elastic scatters provides more event-by-event information on incident neutron energy and direction than imaging based on single-scatter events. However, the requirement of two scatters in different detectors means that this information comes at the cost of lower intrinsic efficiency. Sandia National Laboratories has been involved in the development of several double-scatter neutron imagers over the past decade, including the Neutron Scatter Camera and MINER (Mobile Imager of Neutrons for Emergency Responders). Recent work has been focused on developing uncertainty quantification techniques to help leverage the rich information carried by double-scatter events and provide quantitative decision metrics for detection and diagnostic applications. Work is also underway to develop a single-volume scatter camera, based on utilizing multiple neutron scatters in a single scintillator volume, which will mitigate the typical loss in efficiency suffered by double-scatter imagers. This talk will present a brief overview of this ongoing work, with a focus on simulated response characterization of both traditional double-scatter imagers and the single-volume scatter camera. Preferred name is Kyle (middle name).

  18. Wavelength-independent constant period spin-echo modulated small angle neutron scattering

    NARCIS (Netherlands)

    Sales, Morten; Plomp, J.; Habicht, Klaus; Tremsin, Anton; Bouwman, W.G.; Strobl, Markus

    2016-01-01

    Spin-Echo Modulated Small Angle Neutron Scattering (SEMSANS) in Time-of-Flight (ToF) mode has been shown to be a promising technique for measuring (very) small angle neutron scattering (SANS) signals and performing quantitative Dark-Field Imaging (DFI), i.e., SANS with 2D spatial resolution.

  19. Ten year's activity in the field of neutron scattering workshop

    Energy Technology Data Exchange (ETDEWEB)

    Hamaguchi, Yoshikazu [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2003-03-01

    'Neutron scattering' is in the frame of the 'Utilization of Research Reactor's of the FNCA (Forum for Nuclear Cooperation in Asia) project, which held the workshops from FY 1992. This report is a summary of the results and activities of neutron scattering workshops and sub-workshops since the start in FY 1992. (author)

  20. Analysis of neutron scattering data: Visualization and parameter estimation

    Energy Technology Data Exchange (ETDEWEB)

    Beauchamp, J.J.; Fedorov, V.; Hamilton, W.A.; Yethiraj, M.

    1998-09-01

    Traditionally, small-angle neutron and x-ray scattering (SANS and SAXS) data analysis requires measurements of the signal and corrections due to the empty sample container, detector efficiency and time-dependent background. These corrections are then made on a pixel-by-pixel basis and estimates of relevant parameters (e.g., the radius of gyration) are made using the corrected data. This study was carried out in order to determine whether treatment of the detector efficiency and empty sample cell in a more statistically sound way would significantly reduce the uncertainties in the parameter estimators. Elements of experiment design are shortly discussed in this paper. For instance, we studied the way the time for a measurement should be optimally divided between the counting for signal, background and detector efficiency. In Section 2 we introduce the commonly accepted models for small-angle neutron and x-scattering and confine ourselves to the Guinier and Rayleigh models and their minor generalizations. The traditional approaches of data analysis are discussed only to the extent necessary to allow their comparison with the proposed techniques. Section 3 describes the main stages of the proposed method: visual data exploration, fitting the detector sensitivity function, and fitting a compound model. This model includes three additive terms describing scattering by the sampler, scattering with an empty container and a background noise. We compare a few alternatives for the first term by applying various scatter plots and computing sums of standardized squared residuals. Possible corrections due to smearing effects and randomness of estimated parameters are also shortly discussed. In Section 4 the robustness of the estimators with respect to low and upper bounds imposed on the momentum value is discussed. We show that for the available data set the most accurate and stable estimates are generated by models containing double terms either of Guinier's or Rayleigh

  1. The neutron-deuteron elastic scattering angular distribution at 95 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Mermod, Philippe

    2004-04-01

    The neutron-deuteron elastic scattering differential cross section has been measured at 95 MeV incident neutron energy, with the Medley setup at TSL in Uppsala. The neutron-proton differential cross section has also been measured for normalization purposes. The data are compared with theoretical calculations to investigate the role of three-nucleon force effects.

  2. Collective dynamics in phospholipid bilayers investigated by inelastic neutron scattering: Exploring the dynamics of biological membranes with neutrons

    OpenAIRE

    Rheinstädter, M. C.; Ollinger, C.; Fragneto, G.; Salditt, T.

    2004-01-01

    We present the first inelastic neutron scattering study of the short wavelength dynamics in a phospholipid bilayer. We show that inelastic neutron scattering using a triple-axis spectrometer at the high flux reactor of the ILL yields the necessary resolution and signal to determine the dynamics of model membranes. The results can quantitatively be compared to recent Molecular Dynamics simulations. Reflectivity, in-plane correlations and the corresponding dynamics can be measured simultaneousl...

  3. Physics of frustrated systems: A neutron scattering study

    Science.gov (United States)

    Gasparovic, Goran

    Frustration refers to the inability of a system to simultaneously satisfy all interactions. The principal ingredients of frustration are (i) competition between interactions within the system, and (ii) conflicting constraints established by symmetry, or higher energy interactions. The behavior of frustrated systems is generally difficult to predict, and often results in novel cooperative states and phenomena. Frustration is common in disordered systems, in this dissertation, however, we focus on frustrated systems without quenched disorder. Effects of frustration tend to be pronounced when coupled with weak connectivity. Weak connectivity refers to a topology in which the order in one part of the system does not constrain the order in other parts. We have used neutron scattering to study structurally and magnetically frustrated systems, both strongly and weakly connected. In ZrW2O8 and Sc2(WO4) 3, anomalously large Negative Thermal Expansion (NTE) has been observed over a wide temperature range. Analysis indicates that the NTE effect in these materials is driven by folding of rigid units consisting of strongly bonded oxygen-metal polyhedra. Weak connectivity is manifested by structural under-constraint, which enables soft optical phonons. Using neutron scattering, we observed an unusually high density-of-states at low energies, and mapped the dispersion relations of the most intense phonon modes. While in conventional materials soft phonon modes typically signal an imminent structural phase transition, in NTE materials the transition is frustrated by the incompatibility between the crystal symmetry and the symmetry of the soft phonon modes. This results in the unusual NTE effect. RbFe(MoO4)2 is a frustrated, quasi-classical ( S = 5/2), quasi-two-dimensional Heisenberg antiferromagnet on a triangular lattice, with easy-plane anisotropy. In RbFe(MoO4)2, frustrated units (triangles) share edges, and are strongly connected. Although a long range magnetic order is

  4. X-ray, neutron, and electron scattering. Report of a materials sciences workshop

    Energy Technology Data Exchange (ETDEWEB)

    1977-08-01

    The ERDA Workshop on X-ray, Neutron, and Electron Scattering to assess needs and establish priorities for energy-related basic research on materials. The general goals of the Workshop were: (1) to review various energy technologies where x-ray, neutron, and electron scattering techniques might make significant contributions, (2) to identify present and future materials problems in the energy technologies and translate these problems into requirements for basic research by x-ray, neutron, and electron scattering techniques, (3) to recommend research areas utilizing these three scattering techniques that should be supported by the DPR Materials Sciences Program, and (4) to assign priorities to these research areas.

  5. Proceedings of a workshop on methods for neutron scattering instrumentation design

    Energy Technology Data Exchange (ETDEWEB)

    Hjelm, R.P. [ed.] [Los Alamos National Lab., NM (United States)

    1997-09-01

    The future of neutron and x-ray scattering instrument development and international cooperation was the focus of the workshop. The international gathering of about 50 participants representing 15 national facilities, universities and corporations featured oral presentations, posters, discussions and demonstrations. Participants looked at a number of issues concerning neutron scattering instruments and the tools used in instrument design. Objectives included: (1) determining the needs of the neutron scattering community in instrument design computer code and information sharing to aid future instrument development, (2) providing for a means of training scientists in neutron scattering and neutron instrument techniques, and (3) facilitating the involvement of other scientists in determining the characteristics of new instruments that meet future scientific objectives, and (4) fostering international cooperation in meeting these needs. The scope of the meeting included: (1) a review of x-ray scattering instrument design tools, (2) a look at the present status of neutron scattering instrument design tools and models of neutron optical elements, and (3) discussions of the present and future needs of the neutron scattering community. Selected papers were abstracted separately for inclusion to the Energy Science and Technology Database.

  6. Direct Observation of Neutron Scattering in BC408 Scintillator for Comparison with SImulation

    Science.gov (United States)

    Rogers, W. F.; Boone, J. E.; Wantz, A.; Frank, N.; Kuchera, A. N.; Mosby, S.; Thoennessen, M.; MoNA Collaboration

    2017-09-01

    Monte Carlo simulation provides an important tool for the interpretation of neutron scattering data in the Modular Neutron Array (MoNA) and the Large multi-Institutional Scintillator Array (LISA), each located at the NSCL facility at MSU and consisting of 144 stacked 2-m long organic plastic scintillator bar detectors. Energy and trajectory for unbound state decay neutrons are determined by time of flight and location of first light produced in the array. While most neutrons scattering elastically from protons and inelastically from C nuclei produce light above detector threshold, those scattered elastically from C remain below threshold (``dark scatter''), altering neutron trajectories, thus decreasing energy and momentum resolution. To test the accuracy of our Geant4/MENATE_R simulations, we observed neutrons scattering from 16 MoNA bars arranged in two stack geometries at the LANSCE facility at Los Alamos National Laboratory. Spallation neutrons ranging in energy from 0.5 to 800 MeV emerged from a 3 mm collimator in the 90m shed on WNR flight path 4FP15L and struck the array along a well defined path. Results for neutron hit multiplicity, scattering dynamics, and dark scatter redirection are compared with simulation. Work supported by NSF Grant PHY-1744043.

  7. The small angle neutron scattering study on the segmented polyurethane

    Energy Technology Data Exchange (ETDEWEB)

    Sudirman; Gunawan; Prasetyo, S.M.; Karo Karo, A.; Lahagu, I.M.; Darwinto, Tri [Materials Science Research Center, National Nuclear Energy Agency, Serpong, Tangerang (Indonesia)

    1999-10-01

    The distance between hard segment (HS) and soft segment (SS) of segmented polyurethane have been determined using the Small Angle Neutron Scattering (SANS) technique. The segmented Polyurethanes (SPU) are linear multiblock copolymers, which include elastomer thermoplastic. SPU consist of hard segment and soft segment, each has tendency to make a group with similar type to form a domain. The soft segments used were polypropylene glycol (PPG) and 4,4 diphenylmethane diisocyanate (MDI), while l,4 butanediol (BD) was used as hard segment. The characteristic of SPU depends on its phase structure which is affected by several factors, such as type of chemical formula and the composition of the HS and SS, solvent as well as the synthesizing process. The samples used in this study were SPU56 and SPU68. Based on the appearance of SANS profile, it was obtained that domain distances are 12.32 nm for the SPU56 and 19 nm for the SPU68. (author)

  8. Elementary scattering theory for X-ray and neutron users

    CERN Document Server

    Sivia, D S

    2011-01-01

    The opportunities for doing scattering experiments at synchrotron and neutron facilities have grown rapidly in recent years and are set to continue to do so into the foreseeable future. This text provides a basic understanding of how these techniques enable the structure and dynamics of materials to be studied at the atomic and molecular level. Although mathematics cannot be avoided in a theoretical discussion, the aim has been to write a book that most scientists will still find approachable. To this end, the first two chapters are devoted to providing a tutorial background in the mathematics and physics that are implicitly assumed in other texts. Thereafter, the philosophy has been one of keeping things as simple as possible.

  9. A small angle neutron scattering study of thermoplastic elastomer

    Energy Technology Data Exchange (ETDEWEB)

    Sutiarso; Edy Giri, R. Putra; Andon, Insani; Sudirman; Sudaryanto [Materials Science Research Centre, National Atomic Energy Agency, Jakarta (Indonesia)

    1998-10-01

    A bilateral scientific cooperation, in the small angle neutron scattering has been agreed upon between CIAE, China and BATAN, Indonesia as well as MINT Malaysia. As stated in the agreed proposal that the objective of this cooperation, in the initial stage (stage-1), was to have a regional intercomparison measurements of SANS instruments in order to determine their characteristic/performance. Therefore, this report is supposed to describe the progress in the SANS instrument development of each country involved during the period of 1996/97 and some activities related to the SANS instrument. Since, up to now, we have not yet received any progresses reported from either China or Malaysia, this report will describe the progress of SANS`s activities in BATAN only. (author)

  10. Neutron scattering study of water confined in periodic mesoporous organosilicas

    Science.gov (United States)

    Levy, Esthy; Kay Chan, Lok; Yu, Dehong; Marek Koza, Michael; Mastai, Yitzhak; Ford, R. C.; Li, Jichen

    2010-07-01

    A series of quasi-elastic neutron scattering measurements were performed using IN6 at the Institute Laue Langevin for a mesoporous organosilica material with phenyl functions, called phenyltriethoxysilane (PTES). The aim of the experiment was to study the diffusion dynamics of nano-scale water clusters inside the hydrophobic pores as a function of temperature and hydration. By fitting the Debye-Waller factor, the data show clearly the different behavior between water, both inside and outside the hydrophobic pores, which resembles bulk water. The mean thermal displacement of the external water increases with T almost linearly up to 353 K, while the internal water quickly reaches the maximum at T˜323 K, indicating the confinement by an averaged pore diameter of the porous organosilica.

  11. Neutron scattering studies on chromatin higher-order structure

    Energy Technology Data Exchange (ETDEWEB)

    Graziano, V.; Gerchman, S.E.; Schneider, D.K.; Ramakrishnan, V. [Brookhaven National Laboratory, Upton, NY (United States)

    1994-12-31

    We have been engaged in studies of the structure and condensation of chromatin into the 30nm filament using small-angle neutron scattering. We have also used deuterated histone H1 to determine its location in the chromatin 30nm filament. Our studies indicate that chromatin condenses with increasing ionic strength to a limiting structure that has a mass per unit length of 6-7 nucleosomes/11 nm. They also show that the linker histone H1/H5 is located in the interior of the chromatin filament, in a position compatible with its binding to the inner face of the nucleosome. Analysis of the mass per unit length as a function of H5 stoichiometry suggests that 5-7 contiguous nucleosomes need to have H5 bound before a stable higher order structure can exist.

  12. Quasielastic neutron scattering study of silver selenium halides

    CERN Document Server

    Major, A G; Barnes, A C; Howells, W S

    2002-01-01

    Both silver chalcogenides (Ag sub 2 S, Ag sub 2 Se, and Ag sub 2 Te) and silver halides (AgCl, AgBr, and AgI) are known to be fast-ion solids in which the silver ions can diffuse quickly in a sublattice formed by the other ions. To clarify whether mixtures of these materials (such as Ag sub 3 SeI) possess comparable properties and whether a systematic dependence on the cation-to-anion ratio can be observed, some of these mixtures were studied by quasielastic neutron scattering both in the solid and the liquid phases. To identify the diffusion mechanisms and constants, a new data-analysis method based on a two-dimensional maximum-likelihood fit is proposed. This method has the potential to give more reliable information on the diffusion mechanism than the traditional Bayesian method. (orig.)

  13. The Manuel Lujan Jr. Neutron Scattering Center (LANSCE) experiment reports 1993 run cycle. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Farrer, R.; Longshore, A. [comps.

    1995-06-01

    This year the Manuel Lujan Jr. Neutron Scattering Center (LANSCE) ran an informal user program because the US Department of Energy planned to close LANSCE in FY1994. As a result, an advisory committee recommended that LANSCE scientists and their collaborators complete work in progress. At LANSCE, neutrons are produced by spallation when a pulsed, 800-MeV proton beam impinges on a tungsten target. The proton pulses are provided by the Clinton P. Anderson Meson Physics Facility (LAMPF) accelerator and a associated Proton Storage Ring (PSR), which can Iter the intensity, time structure, and repetition rate of the pulses. The LAMPF protons of Line D are shared between the LANSCE target and the Weapons Neutron Research (WNR) facility, which results in LANSCE spectrometers being available to external users for unclassified research about 80% of each annual LAMPF run cycle. Measurements of interest to the Los Alamos National Laboratory (LANL) may also be performed and may occupy up to an additional 20% of the available beam time. These experiments are reviewed by an internal program advisory committee. This year, a total of 127 proposals were submitted. The proposed experiments involved 229 scientists, 57 of whom visited LANSCE to participate in measurements. In addition, 3 (nuclear physics) participating research teams, comprising 44 scientists, carried out experiments at LANSCE. Instrument beam time was again oversubscribed, with 552 total days requested an 473 available for allocation.

  14. Neutron scattering studies of three one-dimensional antiferromagnets

    CERN Document Server

    Kenzelmann, M

    2001-01-01

    observed in the disordered phase of spin-1/2 chains. The magnetic order of the one-dimensional spin-1/2 XY antiferromagnet Cs sub 2 CoCl sub 4 was investigated using neutron diffraction. The magnetic structure has an ordering wave-vector (0, 0.5, 0.5) for T < 217 mK and the magnetic structure is a non-linear structure with the magnetic moments at a small angle to the b axis. Above a field of H = 2.1 T the magnetic order collapses in an apparent first order phase transition, suggesting a transition to a spin-liquid phase. Low-dimensional magnets with low-spin quantum numbers are ideal model systems for investigating strongly interacting macroscopic quantum ground states and their non-linear spin excitations. This thesis describes neutron scattering experiments of three one-dimensional low-spin antiferromagnets where strong quantum fluctuations lead to highly-correlated ground states and unconventional cooperative spin excitations. The excitation spectrum of the antiferromagnetic spin-1 Heisenberg chain CsNi...

  15. A United Effort for Crystal Growth, Neutron Scattering, and X-ray Scattering Studies of Novel Correlated Electron Materials

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young S. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2015-02-12

    The research accomplishments during the award involved experimental studies of correlated electron systems and quantum magnetism. The techniques of crystal growth, neutron scattering, x-ray scattering, and thermodynamic & transport measurements were employed, and graduate students and postdoctoral research associates were trained in these techniques.

  16. Direct Observation of Neutron Scattering in MoNA Scintillator Detectors

    Science.gov (United States)

    Rogers, W. F.; Mosby, S.; Frank, N.; Kuchera, A. N.; Thoennessen, M.; MoNA Collaboration

    2017-01-01

    Monte Carlo simulations provide an important tool for the interpretation of neutron scattering data in the MoNA and LISA arrays at NSCL. Neutron energy and trajectory are determined by time of flight and position of first light produced in the array. Neutrons elastically scattered from H and inelastically from C typically produce light above detector threshold, while those elastically scattered from C produce light below threshold (``dark scattering'') and are redirected in flight, thus lowering energy and trajectory resolution. In order to test the effectiveness of our Geant4/MENATE_R simulations, we conducted an experiment at the LANSCE facility at Los Alamos National Laboratory to observe scattering of individual neutrons with well defined energy and trajectory in 16 MoNA detector bars arranged in two different stack geometries. Neutrons with energies ranging from 0.5 to 800 MeV emerged from a 3 mm collimator in the 90m shed on the WNR 4FP15L flight path to enter the array at a well defined point. Several features of neutron scattering are compared with simulation predictions, including hit multiplicity, scattering angle, mean distance between scatters, and the effect of dark scatter redirection. Results to date will be presented. Work supported by NSF Grant PHY-1506402.

  17. Scattering studies of large scale structures at the ultra small angle neutron scattering instrument S18

    Science.gov (United States)

    Hainbuchner, M.; Baron, M.; Lo Celso, F.; Triolo, A.; Triolo, R.; Rauch, H.

    2002-02-01

    In recent years ultra small angle neutron scattering (USANS) has developed into a powerful standard method for large scale structure investigations. The upgraded instrument S18 at the ILL's 58 MW high flux reactor is operated routinely with increasing beam time demand. The performance of the instrument and its abilities will be discussed in this paper. A peak to background ratio better than 10 5 is reached using Agamalian's tail reduction method. A q-range from 2.10 -5 up to 5.10 -2 Å-1 can be covered. This allows a clear overlap with standard pinhole SANS instruments. The new way collecting scattering data logarithmically equidistant in q-space saves measuring time. This allows measuring times of about 1.5 h for strong scattering specimens with reasonable statistics. We will present an overview of recent experiments which have been performed in co-operation with different groups from the international user community. This work comprises of structure investigations of petroliferous sedimentary rocks showing fractal scattering behaviour and time resolved USANS studies of the dynamics of hydration of cement paste. Concerning soft matter structures, Pirelli rubber nanocomposites have been investigated. In addition, time resolved measurement on a D 2O solution of a PPO-PEO-PPO block copolymer (Reverse Pluronic 25R5) and the dynamics of phase separation of methyl-hydroxy-propyl cellulose (MHPC) have been studied using a sample temperature control system.

  18. Forge-Hardened TiZr Null-Matrix Alloy for Neutron Scattering under Extreme Conditions

    Directory of Open Access Journals (Sweden)

    Takuo Okuchi

    2015-12-01

    Full Text Available For neutron scattering research that is performed under extreme conditions, such as high static pressures, high-strength metals that are transparent to the neutron beam are required. The diffraction of the neutron beam by the metal, which follows Bragg’s law, can be completely removed by alloying two metallic elements that have coherent scattering lengths with opposite signs. An alloy of Ti and Zr, which is known as a TiZr null-matrix alloy, is an ideal combination for such purposes. In this study, we increased the hardness of a TiZr null-matrix alloy via extensive mechanical deformation at high temperatures. We successfully used the resulting product in a high-pressure cell designed for high-static-pressure neutron scattering. This hardened TiZr null-matrix alloy may play a complementary role to normal TiZr alloy in future neutron scattering research under extreme conditions.

  19. Resolution effects and analysis of small-angle neutron scattering data

    DEFF Research Database (Denmark)

    Pedersen, J.S.

    1993-01-01

    A discussion of the instrumental smearing effects for small-angle neutron scattering (SANS) data sets is given. It is shown that these effects can be described by a resolution function, which describes the distribution of scattering vectors probed for the nominal values of the scattering vector. ...

  20. Measurement of very small hydrogen content in zirconium alloys by measuring thermal neutron incoherent scattering

    CERN Document Server

    Choi, Y N; Lee, C H; Oh, H S; Park, S D; Somenkov, V A

    2002-01-01

    In neutron-scattering experiments, the incoherent scattering contributes to the background signal, which is an unwelcome property of matter. Among natural nuclei, the hydrogen nucleus (proton) has a remarkably large value of incoherent neutron scattering cross section. Therefore, a very small amount of hydrogen in a material could be analyzed by measuring the neutron incoherent scattering of the material. The hydrogen content of a metal or semiconductor is a matter of concern because it can affect significantly the physical, mechanical or chemical properties of materials although the amount of hydrogen is very small. In this study, the neutron incoherent scattering was measured using a 1-D position-sensitive detector at 1.835 A. Estimated detection limits are about 5 and 2 mu g/g for 10-min and 1-h measurements, respectively. Using the calibration data obtained by measurement of artificial samples (zircaloy+polypropylene films), the relative amounts of hydrogen in three commercial zircaloy samples were estima...

  1. PREFACE: 7th Meeting of the Spanish Neutron Scattering Association (SETN)

    Science.gov (United States)

    Pérez-Landazábal, J. I.; Recarte, V.

    2015-11-01

    The VII th Meeting of the Spanish Neutron Scattering Association was held on the campus of the Public University of Navarra (UPNa) in Pamplona (Spain) during 22-25 June 2014. It was the seventh edition of a series of biennial meetings that began in San Sebastian in 2002, which followed the meetings of Puerto de La Cruz (2004), Jaca (2006), Sant Feliu de Guixols (2008), Gijón (2010) and Segovia (2012). It is the largest meeting and discussion forum for Spanish scientific users of neutron scattering techniques, whatever the branch of science or technology development their research activity concerns. Throughout these years, the Spanish community of neutron techniques has been consolidating, increasing every year both in the number of users and in the diversity of techniques and topics analyzed. In this sense, the series of biennial meetings of the Society aims to give visibility and summarize the activity taking place in this field. Ongoing with the initiative undertaken in the last two editions, some selected works shown in the conference are published in this edition of Journal of Physics: Conference Series. The conference consisted of plenary lectures issued by relevant researchers in neutron science techniques, as well as invited lectures in which the most significant recent results achieved by Spanish scientists from fundamental science to applied technology were shown. To encourage the participation of as many research groups as possible and in particular young researchers, oral and poster presentations were also included. The VII th SETN meeting was organized by the Physics Department of the Public University of Navarra in collaboration with the Spanish Society for Neutron Techniques (SETN, Sociedad Española de Técnicas Neutrónicas). The meeting attracted around 70 participants from all over the country and foreign researchers were also invited to the conference. We want to emphasize the excellent quality of the presentations and want to thank the support

  2. Geometry Survey of the Time-of-Flight Neutron-Elastic Scattering (Antonella) Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Oshinowo, Babatunde O. [Fermilab; Izraelevitch, Federico [Buenos Aires U.

    2016-10-17

    The Antonella experiment is a measurement of the ionization efficiency of nuclear recoils in silicon at low energies [1]. It is a neutron elastic scattering experiment motivated by the search for dark matter particles. In this experiment, a proton beam hits a lithium target and neutrons are produced. The neutron shower passes through a collimator that produces a neutron beam. The beam illuminates a silicon detector. With a certain probability, a neutron interacts with a silicon nucleus of the detector producing elastic scattering. After the interaction, a fraction of the neutron energy is transferred to the silicon nucleus which acquires kinetic energy and recoils. This kinetic energy is then dissipated in the detector producing ionization and thermal energy. The ionization produced is measured with the silicon detector electronics. On the other hand, the neutron is scattered out of the beam. A neutron-detector array (made of scintillator bars) registers the neutron arrival time and the scattering angle to reconstruct the kinematics of the neutron-nucleus interaction with the time-of-flight technique [2]. In the reconstruction equations, the energy of the nuclear recoil is a function of the scattering angle with respect to the beam direction, the time-of-flight of the neutron and the geometric distances between components of the setup (neutron-production target, silicon detector, scintillator bars). This paper summarizes the survey of the different components of the experiment that made possible the off-line analysis of the collected data. Measurements were made with the API Radian Laser Tracker and I-360 Probe Wireless. The survey was completed at the University of Notre Dame, Indiana, USA in February 2015.

  3. Effects of Hot-Spot Geometry on Backscattering and Down-Scattering Neutron Spectra

    Science.gov (United States)

    Mohamed, Z. L.; Mannion, O. M.; Forrest, C. J.; Knauer, J. P.; Anderson, K. S.; Radha, P. B.

    2017-10-01

    The measured neutron spectrum produced by a fusion experiment plays a key role in inferring observable quantities. One important observable is the areal density of an implosion, which is inferred by measuring the scattering of neutrons. This project seeks to use particle-transport simulations to model the effects of hot-spot geometry on backscattering and down-scattering neutron spectra along different lines of sight. Implosions similar to those conducted at the Laboratory of Laser Energetics are modeled by neutron transport through a DT plasma and a DT ice shell using the particle transport codes MCNP and IRIS. Effects of hot-spot geometry are obtained by ``detecting'' scattered neutrons along different lines of sight. This process is repeated for various hot-spot geometries representing known shape distortions between the hot spot and the shell. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  4. Small-angle neutron scattering study of sodium cholate and sodium ...

    Indian Academy of Sciences (India)

    angle neutron scattering study of sodium cholate and sodium deoxycholate interacting micelles in aqueous medium. J Santhanalakshmi G Shantha Lakshmi V K Aswal P S Goyal. Physical and Theoretical Volume 113 Issue 1 February 2001 pp 55- ...

  5. Progress report on neutron scattering research (April 1, 1998 - March 31, 1999)

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Jun-ichi; Fujiwara, Satoru; Aizawa, Kazuya [eds.] [Advanced Science Research Center (Tokai Site), Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan)

    2000-03-01

    The present issue summarizes research progress in neutron scattering at Japan Atomic Energy Research Institute (JAERI) by utilizing the research reactor (JRR-3M) during the period between April 1, 1998 and March 31, 1999. (author)

  6. Neutron and photon (light) scattering on solitons in the quasi-one-dimensional magnetics

    CERN Document Server

    Abdulloev, K O

    1999-01-01

    The general expression we have found earlier for the dynamics form-factor is used to analyse experiments on the neutron and photon (light) scattering by the gas of solitons in quasi-one-dimensional magnetics (Authors)

  7. Progress report on neutron scattering research. April 1, 2001 - March 31, 2002

    Energy Technology Data Exchange (ETDEWEB)

    Katano, Susumu; Koizumi, Satoshi; Matsuda, Masaaki (eds.) [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2002-11-01

    This issue summarizes research progress in neutron scattering at Japan Atomic Energy Research Institute (JAERI) by utilizing the research reactor JRR-3M during the period between April 1, 2001 and March 31, 2002. (author)

  8. Neutron scattering and diffraction instrument for structural study on biology in Japan

    Energy Technology Data Exchange (ETDEWEB)

    Niimura, Nobuo [Japan Atomic Energy Research Inst., Ibaraki-ken (Japan)

    1994-12-31

    Neutron scattering and diffraction instruments in Japan which can be used for structural studies in biology are briefly introduced. Main specifications and general layouts of the instruments are shown.

  9. Progress report on neutron scattering research. April 1, 1999 - March 31, 2000

    Energy Technology Data Exchange (ETDEWEB)

    Fujiwara, Satoru; Aizawa, Kazuya; Katano, Susumu (eds.) [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-03-01

    This issue summarizes research progress in neutron scattering at Japan Atomic Energy Research Institute (JAERI) by utilizing the research reactor (JRR-3M) during the period between April 1, 1999 and March 31, 2000. (author)

  10. Temperature-dependent structural and functional features of a hyperthermostable enzyme using elastic neutron scattering

    NARCIS (Netherlands)

    Koutsopoulos, S; van der Oost, J; Norde, W

    2005-01-01

    The dynamic behavior of an endoglucanase from the hyperthermophilic microorganism Pyrococcus furiosus was investigated using elastic neutron scattering. The temperature dependence of the atomic motions was correlated with conformational. and functional characteristics of the enzyme. The onset of

  11. Status of a facility for measuring nuclear recoils by neutron scattering from cryogenic particle detectors

    Science.gov (United States)

    van den Putte, M. J. J.; Hoess, C.; Giles, T. J.; Angrave, L.; Booth, N. E.; Cooper, S.; Esposito, E.; Gaitskell, R. J.; Houwman, E. P.; Salmon, G. L.; Wänninger, S.

    1996-02-01

    We are setting up a dedicated neutron-scattering facility in order to study the response of cryogenic detectors to nuclear recoils in preparation for dark matter searches. The design and status of the facility are presented.

  12. Status of a facility for measuring nuclear recoils by neutron scattering from cryogenic particle detectors

    Energy Technology Data Exchange (ETDEWEB)

    Van den Putte, M.J.J. [Oxford Univ. (United Kingdom). Dept. of Physics; Hoess, C. [Oxford Univ. (United Kingdom). Dept. of Physics; Giles, T.J. [Oxford Univ. (United Kingdom). Dept. of Physics; Angrave, L. [Oxford Univ. (United Kingdom). Dept. of Physics; Booth, N.E. [Oxford Univ. (United Kingdom). Dept. of Physics; Cooper, S. [Oxford Univ. (United Kingdom). Dept. of Physics; Esposito, E. [Oxford Univ. (United Kingdom). Dept. of Physics; Gaitskell, R.J. [Oxford Univ. (United Kingdom). Dept. of Physics; Houwman, E.P. [Oxford Univ. (United Kingdom). Dept. of Physics; Salmon, G.L. [Oxford Univ. (United Kingdom). Dept. of Physics; Waenninger, S. [Oxford Univ. (United Kingdom). Dept. of Physics

    1996-02-11

    We are setting up a dedicated neutron-scattering facility in order to study the response of cryogenic detectors to nuclear recoils in preparation for dark matter searches. The design and status of the facility are presented. (orig.).

  13. Directional Stand-off Detection of Fast Neutrons and Gammas Using Angular Scattering Distributions

    Energy Technology Data Exchange (ETDEWEB)

    Vanier P. e.; Dioszegi, I.; Salwen, C.; Forman, L.

    2009-10-25

    We have investigated the response of a DoubleScatter Neutron Spectrometer (DSNS) for sources at long distances (gr than 200 meters). We find that an alternative method for analyzing double scatter data avoids some uncertainties introduced by amplitude measurements in plastic scintillators.Time of flight is used to discriminate between gamma and neutron events, and the kinematic distributions of scattering angles are assumed to apply. Non-relativistic neutrons are most likely to scatter at 45°, while gammas with energies greater than 2 MeV are most likely to be forward scattered. The distribution of scattering angles of fission neutrons arriving from a distant point source generates a 45° cone, which can be back-projected to give the source direction. At the same time, the distribution of Compton-scattered gammas has a maximum in the forward direction, and can be made narrower by selecting events that deposit minimal energy in the first scattering event. We have further determined that the shape of spontaneous fission neutron spectra at ranges gr than 110 m is still significantly different from thecosmic ray background.

  14. Small angle neutron scattering study of lysozyme solutions

    Science.gov (United States)

    Boué, F.; Lefaucheux, F.; Robert, M. C.; Rosenman, I.

    1993-10-01

    In order to investigate how macromolecular aggregation proceeds for obtaining nucleation and crystal growth, a series of hen egg white (HEW) lysozyme solutions representative of a large supersaturation range have been investigated by small angle neutron scattering (SANS). In all these solutions, the signal well corresponds to species of radii of gyration Rg below 50 Å. Moreover, the effective values Rg are compatible with a rather monodisperse distribution of species the size of which increases when the supersaturation increases; for example, saturated solutions correspond to dimer populations. The largest size which has been identified corresponds to octomers which seems a limit beyond which nucleation and growth occur. The growth units are larger than dimers and probably correspond to tetramers or octomers. SANS allows one to study kinetic aspects. We observe that when a given supersaturation is quickly established, the radius of gyration increases with time. In the light of these results, it appears that SANS affords a powerful tool to study aggregation phenomena occurring in the metastable zone.

  15. Thermal neutron scattering law calculations using ab initio molecular dynamics

    Science.gov (United States)

    Wormald, Jonathan; Hawari, Ayman I.

    2017-09-01

    In recent years, methods for the calculation of the thermal scattering law (i.e. S(α,β), where α and β are dimensionless momentum and energy transfer variables, respectively) were developed based on ab initio lattice dynamics (AILD) and/or classical molecular dynamics (CMD). While these methods are now mature and efficient, further advancement in the application of such atomistic techniques is possible using ab initio molecular dynamics (AIMD) methods. In this case, temperature effects are inherently included in the calculation, e.g. phonon density of states (DOS), while using ab initio force fields that eliminate the need for parameterized semi-empirical force fields. In this work, AIMD simulations were performed to predict the phonon spectra as a function of temperature for beryllium and graphite, which are representative nuclear reactor moderator and reflector materials. Subsequently, the calculated phonon spectra were utilized to predict S(α,β) using the LEAPR module of the NJOY code. The AIMD models of beryllium and graphite were 5 × 5 × 5 crystal unit cells (250 atoms and 500 atoms respectively). Electronic structure calculations for the prediction of Hellman-Feynman forces were performed using density functional theory with a GGA exchange correlation functional and corresponding core electron pseudopotentials. AIMD simulations of 1000-10,000 time-steps were performed with the canonical ensemble (NVT thermostat) for several temperatures between 300 K and 900 K. The phonon DOS were calculated as the power spectrum of the AIMD predicted velocity autocorrelation functions. The resulting AIMD phonon DOS and corresponding inelastic thermal neutron scattering cross sections at 300 K, where anharmonic effects are expected to be small, were found to be in reasonable agreement with the results generated using traditional AILD. This illustrated the validity of the AIMD approach. However, since the impact of the temperature on the phonon DOS (e.g. broadening of

  16. Perspectives of extreme sample environment in neutron scattering ...

    Indian Academy of Sciences (India)

    @hmi.de. Abstract. Because neutrons can penetrate bulky pieces of matter, increasingly complex sample environment is requested by the users of neutron beams. This corresponds to the ever-growing complexity of the scientific problems ...

  17. Some applications of polarized inelastic neutron scattering in ...

    Indian Academy of Sciences (India)

    5232 ... powerful tool for the investigation of materials in the field of condensed matter physics. Nowadays polarized neutrons find application in various research fields ... in fundamental physics to test time-invariance properties of neutrons etc.

  18. The Manuel Lujan, Jr. Neutron Scattering Center LANSCE experiment reports 1989 run cycle

    Energy Technology Data Exchange (ETDEWEB)

    Hyer, D.K.; DiStravolo, M.A. (comps.)

    1990-10-01

    This report contains a listing and description of experiments carried on at the LANSCE neutron scattering facility in the following areas: High Density Powder Diffraction; Neutron Powder Diffractometer, (NPD); Single Crystal Diffractometer, (SCD); Low-Q Diffractometer, (LQD); Surface Profile Analysis Reflectometer, (SPEAR); Filter Difference Spectrometer, (FDS); and Constant-Q Spectrometer.

  19. Invisible detergents for structure determination of membrane proteins by small-angle neutron scattering

    DEFF Research Database (Denmark)

    Midtgaard, Søren Roi; Darwish, Tamim A.; Pedersen, Martin Cramer

    2018-01-01

    A novel and generally applicable method for determining structures of membrane proteins in solution via small-angle neutron scattering (SANS) is presented. Common detergents for solubilizing membrane proteins were synthesized in isotope-substituted versions for utilizing the intrinsic neutron sca...

  20. Mantid—Data analysis and visualization package for neutron scattering and μ SR experiments

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, O. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire (United Kingdom); Tessella Ltd., Abingdon, Oxfordshire (United Kingdom); Bilheux, J.C.; Borreguero, J.M. [Neutron Data Analysis and Visualization, Oak Ridge National Laboratory, Oak Ridge, TN (United States); Buts, A. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire (United Kingdom); Campbell, S.I. [Neutron Data Analysis and Visualization, Oak Ridge National Laboratory, Oak Ridge, TN (United States); Chapon, L. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire (United Kingdom); Institut Laue-Langevin, Grenoble (France); Doucet, M. [Neutron Data Analysis and Visualization, Oak Ridge National Laboratory, Oak Ridge, TN (United States); Draper, N. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire (United Kingdom); Tessella Ltd., Abingdon, Oxfordshire (United Kingdom); Ferraz Leal, R. [Institut Laue-Langevin, Grenoble (France); Gigg, M.A. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire (United Kingdom); Tessella Ltd., Abingdon, Oxfordshire (United Kingdom); Lynch, V.E. [Neutron Data Analysis and Visualization, Oak Ridge National Laboratory, Oak Ridge, TN (United States); Markvardsen, A. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire (United Kingdom); Mikkelson, D.J.; Mikkelson, R.L. [University of Wisconsin-Stout, Menomonie, WI (United States); Neutron Data Analysis and Visualization, Oak Ridge National Laboratory, Oak Ridge, TN (United States); Miller, R. [Computing and Computational Science Directorate, Oak Ridge National Laboratory, Oak Ridge, TN (United States); Palmen, K.; Parker, P.; Passos, G.; Perring, T.G. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire (United Kingdom); Peterson, P.F. [Neutron Data Analysis and Visualization, Oak Ridge National Laboratory, Oak Ridge, TN (United States); and others

    2014-11-11

    The Mantid framework is a software solution developed for the analysis and visualization of neutron scattering and muon spin measurements. The framework is jointly developed by software engineers and scientists at the ISIS Neutron and Muon Facility and the Oak Ridge National Laboratory. The objectives, functionality and novel design aspects of Mantid are described.

  1. The structure of fillers, polymers and their interfaces in polymer composites using neutron scattering methods

    Energy Technology Data Exchange (ETDEWEB)

    Hjelm, R.P.

    1998-12-01

    The neutron scattering methods, small-angle neutron scattering and neutron reflectometry, provide information on the structure of polymer composite materials that is not available from other structural probes. The unique capabilities of these methods derive from three factors. First, the length scales probed correspond to polymer conformation, molecular and domain scales and to the characteristic sizes of many fillers. Second, neutrons are able to penetrate relatively thick samples, allowing bulk samples to be measured, and enabling buried interfaces to be studied. This characteristic also allows for the construction of special sample containment needed for studying materials under stress, extremes in pressure and temperature, etc. Third, neutrons readily distinguish between different light elements, and between different isotopes of the same element. The ability to distinguish between hydrogen and deuterium is particularly important in this regard. New ways of exploiting the capabilities of neutrons are opening up with the development of improved sources and instruments in the US and elsewhere. In this talk the author will discuss the basic concepts that give rise to the unique capabilities of neutron scattering, giving several examples of the uses of neutron scattering techniques in the study of polymer composites. The examples will include the morphology of fillers, polymer binders and matrices, interfaces and defect structures.

  2. Leading neutron energy and pT distributions in deep inelastic scattering and photoproduction at HERA

    CERN Document Server

    Chekanov, S; Abt, I; Adamczyk, L; Adamus, M; Adler, V; Allfrey, P D; Antonelli, S; Antonioli, P; Antonov, A; Arneodo, M; Bamberger, A; Barakbaev, A N; Barbagli, G; Bari, G; Barreiro, F; Bartsch, D; Basile, M; Behrens, U; Bell, M A; Bellagamba, L; Bellan, P; Bertolin, A; Bhadra, S; Bindi, M; Bloch, I; Blohm, C; Bold, T; Bonato, A; Boos, E G; Borras, K; Boscherini, D; Boutle, S K; Brock, I; Brook, N H; Brownson, E; Brugnera, R; Bruni, A; Bruni, G; Brzozowska, B; Brümmer, N; Bussey, P J; Butterworth, J M; Bylsma, B; Büttner, C; Caldwell, A; Capua, M; Carlin, R; Catterall, C D; Chwastowski, J; Ciborowski, J; Ciesielski, R; Cifarelli, L; Cindolo, F; Cole, J E; Contin, A; Cooper-Sarkar, A M; Coppola, N; Corradi, M; Corriveau, F; Cottrell, A; Cui, Y; D'Agostini, G; Dal Corso, F; Danielson, T; De Favereau, J; De Pasquale, S; Del Peso, J; Dementiev, R K; Derrick, M; Devenish, R C E; Dobur, D; Dolgoshein, B A; Dossanov, A; Doyle, A T; Dunne, W; Durkin, L S; Dusini, S; Eisenberg, Y; Ermolov, P F; Eskreys, A; Estrada; Everett, A; Fazio, S; Ferrando, J; Ferrero, M I; Figiel, J; Foster, B; Foudas, C; Fourletov, S; Fourletova, J; Fry, C; Gabareen, A; Galas, A; Gallo, E; Garfagnini, A; Geiser, A; Gialas, I; Gil, M; Giller, I; Gladilin, L K; Gladkov, D; Glasman, C; Goers, S; Gosau, T; Grabowska-Bold, I; Gregor, I; Grigorescu, G; Grzelak, G; Gwenlan, C; Göttlicher, P; Haas, T; Hain, W; Hamatsu, R; Hart, J C; Hartmann, H; Hartner, G; Heath, G P; Hilger, E; Hochman, D; Holm, U; Hori, R; Horn, C; Iacobucci, G; Ibrahim, Z A; Iga, Y; Ingbir, R; Jakob, H P; Jechow, M; Jiménez, M; Jones, T W; Jüngst, M; Kagawa, S; Kahle, B; Kaji, H; Kamaluddin, B; Kananov, S; Karshon, U; Karstens, F; Kataoka, M; Katkov, I I; Kcira, D; Keramidas, A; Khein, L A; Kim, J Y; Kind, O M; Kisielewska, D; Kitamura, S; Klanner, R; Klein, U; Koffeman, E; Kollar, D; Kooijman, P; Korcsak-Gorzo, K; Korzhavina, I A; Kotanski, A; Kowalski, H; Kulinski, P; Kuze, M; Kuzmin, V A; Kötz, U; Labarga, L; Lee, A; Levchenko, B B; Levy, A; Limentani, S; Ling, T Y; Liu, C; Lobodzinska, E; Lohmann, W; Lohrmann, E; Loizides, J H; Long, K R; Longhin, A; Lukasik, J; Lukina, O Yu; Luzniak, P; Löhr, B; Ma, K J; Magill, S; Malka, J; Mankel, R; Margotti, A; Marini, G; Martin, J F; Mastroberardino, A; Matsumoto, T; Mattingly, M C K; Melzer-Pellmann, I A; Menary, S; Miglioranzi, S; Monaco, V; Montanari, A; Morris, J D; Musgrave, B; Nagano, K; Namsoo, T; Nania, R; Nicholass, D; Nigro, A; Ning, Y; Noor, U; Notz, D; Nowak, R J; Nuncio-Quiroz, A E; Oh, B Y; Okazaki, N; Olkiewicz, K; Ota, O; Patel, S; Paul, E; Pavel, N; Pawlak, J M; Pelfer, P G; Pellegrino, A; Piotrzkowski, K; Plucinsky, P P; Pokrovskiy, N S; Polini, A; Proskuryakov, A S; Przybycien, M; Raval, A; Reeder, D D; Ren, Z; Renner, R; Repond, J; Ri, Y D; Rinaldi, L; Roberfroid, V; Robertson, A; Ron, E; Rosin, M; Rubinsky, I; Ruspa, M; Ryan, P; Sacchi, R; Salehi, H; Samson, U; San, R; Sartorelli, G; Savin, A A; Saxon, D H; Schioppa, M; Schlenstedt, S; Schleper, P; Schmidke, W B; Schneekloth, U; Schonberg, V; Schörner-Sadenius, T; Sciulli, F; Shcheglova, L M; Shehzadi, R; Shimizu, S; Skillicorn, I O; Slominski, W; Smith, W H; Soares, M; Solano, A; Son, D; Sosnovtsev, V; Spiridonov, A; Stadie, H; Stanco, L; Standage, J; Stifutkin, A; Stopa, P; Straub, P B; Suchkov, S; Susinno, G; Suszycki, L; Sutiak, J; Sutton, M R; Sztuk, J; Szuba, D; Szuba, J; Tapper, A D; Targett-Adams, C; Tassi, E; Tawara, T; Terron, J; Theedt, T; Tiecke, H; Tokushuku, K; Tsurugai, T; Turcato, M; Tymieniecka, T; Ukleja, A; Ukleja, J; Uribe-, C; Vlasov, N N; Vázquez, M; Walczak, R; Walsh, R; Wan-Abdullah, W A T; Whitmore, J J; Whyte, J; Wichmann, K; Wick, K; Wiggers, L; Wing, M; Wlasenko, M; Wolf, G; Wolfe, H; Wrona, K; Yagues-Molina, A G; Yamada, S; Yamazaki, Y; Yoshida, R; Youngman, C; Zambrana, M; Zarnecki, A F; Zaw, I; Zeuner, W; Zhautykov, B O; Zhou, C; Zichichi, A; Zotkin, D S; Zotkin, S A

    2007-01-01

    The production of energetic neutrons in $ep$ collisions has been studied with the ZEUS detector at HERA. The neutron energy and $p_T^2$ distributions were measured with a forward neutron calorimeter and tracker in a $40 \\pb^{-1}$ sample of inclusive deep inelastic scattering (DIS) data and a $6 \\pb^{-1}$ sample of photoproduction data. The neutron yield in photoproduction is suppressed relative to DIS for the lower neutron energies and the neutrons have a steeper $p_T^2$ distribution, consistent with the expectation from absorption models. The distributions are compared to HERA measurements of leading protons. The neutron energy and transverse-momentum distributions in DIS are compared to Monte Carlo simulations and to the predictions of particle exchange models. Models of pion exchange incorporating absorption and additional secondary meson exchanges give a good description of the data.

  3. Scattered and (n,2n) neutrons as a measure of areal density in ICF capsules

    CERN Document Server

    Wilson, D C; Disdier, L; Houry, M; Bourgade, J L; Murphy, T J

    2002-01-01

    The fraction of low-energy neutrons created from 14 MeV neutrons by elastic scattering and (n,2n) reactions on D and T has been proposed as a measure of the areal density (radial integral of density) of ICF targets. In simple situations the fraction of neutrons between 9.4 (the upper energy of T+T neutrons) and 13 MeV (below the Doppler broadened 14.1 MeV peak) is proportional to the at the time of neutron production. This ratio does not depend upon the temperature of the fuel, as does the number of reaction-in-flight neutrons. The ratio of neutrons elastically scattered at a specific energy (e.g. 13 MeV) to the total number of neutrons can be measured along different lines of sight. The ratio of two perpendicular measurements provides a quantitative measure of asymmetry. A detector can be placed inside the target chamber to measure these low-energy neutrons. If it is close enough to the target that measurements are made before the 14 MeV neutrons reach the chamber wall, gamma rays can be a negligible back...

  4. Pulsed Neutron Scattering Studies of Strongly Fluctuating solids, Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Collin Broholm

    2006-06-22

    The conventional description of a solid is based on a static atomic structure with small amplitude so-called harmonic fluctuations about it. This is a final technical report for a project that has explored materials where fluctuations are sufficiently strong to severely challenge this approach and lead to unexpected and potentially useful materials properties. Fluctuations are enhanced when a large number of configurations share the same energy. We used pulsed spallation source neutron scattering to obtain detailed microscopic information about structure and fluctuations in such materials. The results enhance our understanding of strongly fluctuating solids and their potential for technical applications. Because new materials require new experimental techniques, the project has also developed new techniques for probing strongly fluctuating solids. Examples of material that were studied are ZrW2O8 with large amplitude molecular motion that leads to negative thermal expansion, NiGa2S4 where competing interactions lead to an anomalous short range ordered magnet, Pr1- xBixRu2O7 where a partially filled electron shell (Pr) in a weakly disordered environment produces anomalous metallic properties, and TbMnO3 where competing interactions lead to a magneto-electric phase. The experiments on TbMnO3 exemplify the relationship between research funded by this project and future applications. Magneto-electric materials may produce a magnetic field when an electric field is applied or vise versa. Our experiments have clarified the reason why electric and magnetic polarization is coupled in TbMnO3. While this knowledge does not render TbMnO3 useful for applications it will focus the search for a practical room temperature magneto-electric for applications.

  5. Diffuse neutron scattering study of Cu2−xSe

    DEFF Research Database (Denmark)

    Cava, R. J.; Andersen, Niels Hessel; Clausen, Kurt Nørgaard

    1986-01-01

    We have measured the diffuse neutron scattering in the hkk plane for Cu2Se and Cu1.8Se at 180°C and 51°C, respectively, in the cubic antifluorite type phase. The diffuse scattering shows significant structure, indicative of correlated short range mobile ion ordering. The short range order is found...

  6. The neutron-deuteron scattering problem in the framework of the Faddeev formalism

    Science.gov (United States)

    Belov, P. A.; Yakovlev, S. L.

    2017-11-01

    The three-body Faddeev equations in the configuration space are solved numerically for study of the neutron-deuteron scattering process above the breakup threshold. The amplitudes for the binary scattering process and breakup are obtained by the developed asymptotic approach.

  7. Critical neutron scattering from the Heisenberg ferromagnets EuO and EuS

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage; Dietrich, O. W.; Passell, L.

    1972-01-01

    The magnetic neutron scattering from isotopically enriched powders of EuO and EuS near their Curie temperatures has been studied. Results of the critical exponents for the static properties in standard notation were * Thumbnail image of Spin wave scattering at T...

  8. Elastic and inelastic neutron scattering cross sections for fission reactor applications

    Energy Technology Data Exchange (ETDEWEB)

    Hicks, S. F.; Combs, B.; Downes, L.; Girgis, J.; Kersting, L. J.; Lueck, C. J.; McDonough, P. J.; Schniederjan, J.; Sidwell, L.; Sigillito, A. J. [Department of Physics, University of Dallas, Irving TX 75019 (United States); Chakraborty, A.; Crider, B. P.; Kumar, A.; McEllistrem, M. T.; Peters, E. E.; Prados-Estevz, F. M. [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506 (United States); Vanhoy, J. R.; Watts, D. [Department of Physics, United States Naval Academy, Annapolis MD 21402 (United States); Yates, S. W. [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506 (United States) and Department of Chemistry, University of Kentucky, Lexington, KY 40506 (United States)

    2013-04-19

    Nuclear data important for the design and development of the next generation of light-water reactors and future fast reactors include neutron elastic and inelastic scattering cross sections on important structural materials, such as Fe, and on coolant materials, such as Na. These reaction probabilities are needed since neutron reactions impact fuel performance during irradiations and the overall efficiency of reactors. While neutron scattering cross sections from these materials are available for certain incident neutron energies, the fast neutron region, particularly above 2 MeV, has large gaps for which no measurements exist, or the existing uncertainties are large. Measurements have been made at the University of Kentucky Accelerator Laboratory to measure neutron scattering cross sections on both Fe and Na in the region where these gaps occur and to reduce the uncertainties on scattering from the ground state and first excited state of these nuclei. Results from measurements on Fe at incident neutron energies between 2 and 4 MeV will be presented and comparisons will be made to model calculations available from data evaluators.

  9. Elastic incoherent neutron scattering operating by varying instrumental energy resolution: principle, simulations, and experiments of the resolution elastic neutron scattering (RENS).

    Science.gov (United States)

    Magazù, Salvatore; Migliardo, Federica; Benedetto, Antonio

    2011-10-01

    The main aim of this paper is to present the scientific case of the resolution elastic neutron scattering (RENS) method that is based on the collection of elastic neutron scattering intensity as a function of the instrumental energy resolution and that is able to extract information on the system dynamical properties from an elastic signal. In this framework, it is shown that in the measured elastic scattering law, as a function of the instrumental energy resolution, an inflection point occurs when the instrumental energy resolution intersects the system relaxation time, and in an equivalent way, a transition in the temperature behavior of the measured elastic scattering law occurs when the characteristic system relaxation time crosses the instrumental energy resolution time. With regard to the latter, an operative protocol to determine the system characteristic time by different elastic incoherent neutron scattering (EINS) thermal scans at different instrumental energy resolutions is also proposed. The proposed method, hence, is not primarily addressed to collect the measured elastic scattering intensity with a great accuracy, but rather relies on determining an inflection point in the measured elastic scattering law versus instrumental energy resolution. The RENS method is tested both numerically and experimentally. As far as numerical simulations are concerned, a simple model system for which the temperature behavior of the relaxation time follows an Arrhenius law, while its scattering law follows a Gaussian behavior, is considered. It is shown that the system relaxation time used as an input for the simulations coincides with the one obtained by the RENS approach. Regarding the experimental findings, due to the fact that a neutron scattering spectrometer working following the RENS method has not been constructed yet, different EINS experiments with different instrumental energy resolutions were carried out on a complex model system, i.e., dry and D(2)O hydrated

  10. Neutron elastic scattering on lead at 3.0 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Chavez, E.; Huerta, A.; Ortiz, M.E.; Rodriguez, P.; Favela, F.; Marin, D. [lFUNAM, 04510 Mexico D.F. (Mexico); Moreno, E.; Murillo, G.; Policroniades, R.; Varela, A. [Laboratorio del Acelerador, INlN, AP 18-1027, Mexico D.F. (Mexico); Barron P, L. [Arizona State University, P.O. Box 871504 Tempe, AZ 85287-1504 (United States)

    2007-12-15

    Recent interest on precise information of the elastic scattering of fast (MeV) neutrons on {sup 208}Pb revealed the lack of sufficient experimental information. In this work we present new data obtained at the EN-Tandem Accelerator Laboratory of the 'Instituto Nacional de Investigaciones Nucleares' (ININ). A tagged mono-energetic flux of neutrons is generated through the D(d,n){sup 3}He reaction by detecting and identifying the conjugated Helium particles. The neutron 'cone' produced this way is directed towards a {sup nat}Pb target. The angular distribution of the scattered neutrons is measured between five and twenty degrees relative to the neutron direction by an array of plastic scintillators. Comparison with the previous data and optical model calculations is presented. Future perspectives are discussed. (Author)

  11. Measurement of the Neutron Radius of 208Pb Through Parity-Violation in Electron Scattering

    CERN Document Server

    Abrahamyan, S; Albataineh, H; Aniol, K; Armstrong, D S; Armstrong, W; Averett, T; Babineau, B; Barbieri, A; Bellini, V; Beminiwattha, R; Benesch, J; Benmokhtar, F; Bielarski, T; Boeglin, W; Camsonne, A; Canan, M; Carter, P; Cates, G D; Chen, C; Chen, J -P; Hen, O; Cusanno, F; Dalton, M M; De Leo, R; de Jager, K; Deconinck, W; Decowski, P; Deng, X; Deur, A; Dutta, D; Etile, A; Flay, D; Franklin, G B; Friend, M; Frullani, S; Fuchey, E; Garibaldi, F; Gasser, E; Gilman, R; Giusa, A; Glamazdin, A; Gomez, J; Grames, J; Gu, C; Hansen, O; Hansknecht, J; Higinbotham, D W; Holmes, R S; Holmstrom, T; Horowitz, C J; Hoskins, J; Huang, J; Hyde, C E; Itard, F; Jen, C -M; Jensen, E; Jin, G; Johnston, S; Kelleher, A; Kliakhandler, K; King, P M; Kowalski, S; Kumar, K S; Leacock, J; Leckey, J; Lee, J H; LeRose, J J; Lindgren, R; Liyanage, N; Lubinsky, N; Mammei, J; Mammoliti, F; Margaziotis, D J; Markowitz, P; McCreary, A; McNulty, D; Mercado, L; Meziani, Z -E; Michaels, R W; Mihovilovic, M; Muangma, N; Muñoz-Camacho, C; Nanda, S; Nelyubin, V; Nuruzzaman, N; Oh, Y; Palmer, A; Parno, D; Paschke, K D; Phillips, S K; Poelker, B; Pomatsalyuk, R; Posik, M; Puckett, A J R; Quinn, B; Rakhman, A; Reimer, P E; Riordan, S; Rogan, P; Ron, G; Russo, G; Saenboonruang, K; Saha, A; Sawatzky, B; Shahinyan, A; Silwal, R; Sirca, S; Slifer, K; Solvignon, P; Souder, P A; Sperduto, M L; Subedi, R; Suleiman, R; Sulkosky, V; Sutera, C M; Tobias, W A; Troth, W; Urciuoli, G M; Waidyawansa, B; Wang, D; Wexler, J; Wilson, R; Wojtsekhowski, B; Yan, X; Yao, H; Ye, Y; Ye, Z; Yim, V; Zana, L; Zhan, X; Zhang, J; Zhang, Y; Zheng, X; Zhu, P

    2012-01-01

    We report the first measurement of the parity-violating asymmetry A_PV in the elastic scattering of polarized electrons from 208Pb. A_PV is sensitive to the radius of the neutron distribution (Rn). The result A_PV = 0.656 \\pm 0.060 (stat) \\pm 0.013 (syst) corresponds to a difference between the radii of the neutron and proton distributions Rn - Rp = 0.33 +0.16 -0.18 fm and provides the first electroweak observation of the neutron skin which is expected in a heavy, neutron-rich nucleus.

  12. Inelastic scattering of fast neutrons on Fe-56; Inelastische Streuung schneller Neutronen an {sup 56}Fe

    Energy Technology Data Exchange (ETDEWEB)

    Beyer, Roland

    2014-11-24

    The relevant reaction cross sections for the nuclear transmutation will be measured at the neutron flight time facility nELBE in Dresden-Rossendorf. Transmutation by fast neutron irradiation is supposed to reduce the radiotoxicity of high-level radioactive wastes. The thesis is aimed to measure the inelastic neutron scattering cross sections of Fe-56 using a new double flight-time method. With combined plastic and BaF2 scintillation detectors for the first time the emitted neutrons and photons are observed in coincidence.

  13. Neutron scattering studies of the dynamics of biopolymer-water systems using pulsed-source spectrometers

    Energy Technology Data Exchange (ETDEWEB)

    Middendorf, H.D. [Univ. of Oxford (United Kingdom); Miller, A. [Stirling Univ., Stirling (United Kingdom)

    1994-12-31

    Energy-resolving neutron scattering techniques provide spatiotemporal data suitable for testing and refining analytical models or computer simulations of a variety of dynamical processes in biomolecular systems. This paper reviews experimental work on hydrated biopolymers at ISIS, the UK Pulsed Neutron Facility. Following an outline of basic concepts and a summary of the new instrumental capabilities, the progress made is illustrated by results from recent experiments in two areas: quasi- elastic scattering from highly hydrated polysaccharide gels (agarose and hyaluronate), and inelastic scattering from vibrational modes of slightly hydrated collagen fibers.

  14. Behavior of aqueous Tetrabutylammonium bromide - a combined approach of microscopic simulation and neutron scattering

    CERN Document Server

    Bhowmik, Debsindhu

    2016-01-01

    Aqueous solution of tetrabutylammonium bromide is studied by quasi-elastic neutron scattering, to give information on the dynamic modes involving the ions present. Using a careful combination of two techniques, time-of-flight (TOF) and neutron spin echo (NSE), we de- couple the dynamic information in both the coherently and incoherently scattered signal from this system. We take advantage of the different intensity ratio of the two signals, as detected by each of the techniques, to achieve this decoupling. By using heavy water as the sol- vent, the tetrabutylammonium cation is the only hydrogen-containing species in the system and gives rise to a significant incoherent scattered intensity. The dynamic analysis of the incoherent signal (measured by TOF) leads to a translational diffusion coefficient of the cation as that is in good agreement with previous NMR, neutron scattering and tracer diffusion measurements. The dynamic analysis of the coherent signal observed at wave-vectors < 0.6 angstrom^(-1) (measu...

  15. Investigations of homologous disaccharides by elastic incoherent neutron scattering and wavelet multiresolution analysis

    Energy Technology Data Exchange (ETDEWEB)

    Magazù, S.; Migliardo, F. [Dipartimento di Fisica e di Scienze della Terra dell’, Università degli Studi di Messina, Viale F. S. D’Alcontres 31, 98166 Messina (Italy); Vertessy, B.G. [Institute of Enzymology, Hungarian Academy of Science, Budapest (Hungary); Caccamo, M.T., E-mail: maccamo@unime.it [Dipartimento di Fisica e di Scienze della Terra dell’, Università degli Studi di Messina, Viale F. S. D’Alcontres 31, 98166 Messina (Italy)

    2013-10-16

    Highlights: • Innovative multiresolution wavelet analysis of elastic incoherent neutron scattering. • Elastic Incoherent Neutron Scattering measurements on homologues disaccharides. • EINS wavevector analysis. • EINS temperature analysis. - Abstract: In the present paper the results of a wavevector and thermal analysis of Elastic Incoherent Neutron Scattering (EINS) data collected on water mixtures of three homologous disaccharides through a wavelet approach are reported. The wavelet analysis allows to compare both the spatial properties of the three systems in the wavevector range of Q = 0.27 Å{sup −1} ÷ 4.27 Å{sup −1}. It emerges that, differently from previous analyses, for trehalose the scalograms are constantly lower and sharper in respect to maltose and sucrose, giving rise to a global spectral density along the wavevector range markedly less extended. As far as the thermal analysis is concerned, the global scattered intensity profiles suggest a higher thermal restrain of trehalose in respect to the other two homologous disaccharides.

  16. On measuring the neutron coherent scattering length with ultrahigh ...

    Indian Academy of Sciences (India)

    to account for the neutron beam refraction at the sample-ambient interfaces, to infer the correct bc from the observed phase. The formula for the phase used hitherto is approxi- mate and would significantly overestimate bc. The refractive index for neutrons can thus be determined to a phenomenal precision of a few parts in ...

  17. Investigating Structure and Dynamics of Proteins in Amorphous Phases Using Neutron Scattering

    Directory of Open Access Journals (Sweden)

    Maria Monica Castellanos

    2017-01-01

    Full Text Available In order to increase shelf life and minimize aggregation during storage, many biotherapeutic drugs are formulated and stored as either frozen solutions or lyophilized powders. However, characterizing amorphous solids can be challenging with the commonly available set of biophysical measurements used for proteins in liquid solutions. Therefore, some questions remain regarding the structure of the active pharmaceutical ingredient during freezing and drying of the drug product and the molecular role of excipients. Neutron scattering is a powerful technique to study structure and dynamics of a variety of systems in both solid and liquid phases. Moreover, neutron scattering experiments can generally be correlated with theory and molecular simulations to analyze experimental data. In this article, we focus on the use of neutron techniques to address problems of biotechnological interest. We describe the use of small-angle neutron scattering to study the solution structure of biological molecules and the packing arrangement in amorphous phases, that is, frozen glasses and freeze-dried protein powders. In addition, we discuss the use of neutron spectroscopy to measure the dynamics of glassy systems at different time and length scales. Overall, we expect that the present article will guide and prompt the use of neutron scattering to provide unique insights on many of the outstanding questions in biotechnology.

  18. Neutron scattering studies on magnetic excitations in complex ordered manganites

    Energy Technology Data Exchange (ETDEWEB)

    Senff, D.

    2007-09-15

    This thesis deals with magnetic excitations in three different Manganese oxides, single-layered LaSrMnO{sub 4}, charge- and orbital-ordered La{sub 1/2}Sr{sub 3/2}MnO{sub 4}, and multiferroic TbMnO{sub 3}, which are studied by means of inelastic neutron scattering. The properties of the first system, LaSrMnO{sub 4}, are governed by the complex interplay of orbital, spin, and lattice degrees of freedom typical for the physics of manganites. The magnetic low-temperature behavior is quite unusual, and the comprehensive analysis of the spin-wave spectrum of LaSrMnO{sub 4} suggests a heterogenous ground state with ferromagnetic orbital polarons embedded in an antiferromagnetic background. The doped system La{sub 1/2}Sr{sub 3/2}MnO{sub 4} exhibits a stable charge- and orbital-ordered state, which today is discussed very controversially, as it is of great relevance for the colossal increase of electric conductivity at the metal-insulator transition in perovskite manganites. Analyzing the spin-wave dispersion of the ordered state, we find an excellent agreement with classical predictions by Goodenough and reject a recent alternative proposal. The different strength of the ferromagnetic and antiferromagnetic exchange in the CE-type ordering leads to the conclusion that the magnetic state has to be considered as a weak AFM coupling of stable FM elements. This thesis is further supported by the thermal evolution of the ordered state, revealing anisotropic correlations and the close competition of FM and AFM correlations above the Neel transition, as well as by the doping dependence of the charge- and orbital-ordered state, which is interpreted on the basis of a different response of the magnetic system with respect to additional electrons or holes. In the orthorhombic perovskite TbMnO{sub 3} the electric polarization is closely coupled to the magnetic degrees of freedom via a complex, non-collinear magnetic ordering. Precisely characterizing the different magnon excitations

  19. Neutron scattering studies of low dimensional magnetic systems

    DEFF Research Database (Denmark)

    Hansen, Ursula Bengård

    formodelling waviness in McStas and discuss its eects on a simple neutron guide system.ESS is expected to have specialised neutron optics tailor made for the specic requirementsof each instrument. One common feature for several of the instruments is thatsmaller samples and more complex sample environment...... been using the ray tracing softwareMcStas to investigate both the eect of waviness in neutron guides and a specialisedfocusing guide system.The simulation of waviness was motivated by the fact that the current waviness implementationin McStas yielded unphysical results. Here, I present a new algorithm...

  20. Elastic and Inelastic Neutron Scattering with a C7LYC Array

    Science.gov (United States)

    Wilson, G. L.; Brown, T.; Chowdhury, P.; Doucet, E.; Lister, C. J.; D'Olympia, N.; Devlin, M.; Mosby, S.

    2015-10-01

    A scintillator array of 16 1'' ×1'' Cs2LiYCl6 (CLYC) detectors has been commissioned for low energy nuclear science. Standard CLYC crystals detect both gamma rays and neutrons rays with excellent pulse shape discrimination, with thermal neutrons detected via the 6Li(n, α)t reaction. Our discovery of spectroscopy-grade response of CLYC for fast neutrons via the 35Cl(n,p) reaction, with a pulse height resolution of under 10 % in the < 8 MeV range, led to our present array of 7Li enriched C7LYC detectors, where the large thermal neutron response is essentially eliminated. While the intrinsic efficiency of C7LYC for fast neutron detection is low, the array can be placed near the target since a long TOF arm is no longer needed for neutron energy measurement, thus recovering efficiency through increased solid angle coverage. The array was recently deployed at Los Alamos to test its capability in measuring differential scattering cross sections as a function of energy for 56Fe and 238U. The incident energy from a white neutron source was measured via TOF, and the scattered neutron energy via the pulse height. Techniques, analysis and first results will be discussed. Supported by the NNSA Stewardship Science Academic Alliance Program under Grant DE-NA00013008.

  1. Cold Neutron Focusing Multiple Biconcave Lenses and Anti-Gravity Prisms for 40m Small Angle Neutron Scattering Instrument

    Energy Technology Data Exchange (ETDEWEB)

    Sim, Jun-Bo; Choi, Sung-Min [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2007-07-01

    Small angle neutron scattering (SANS) instrument with long flight path is a very powerful tool to investigate the structures of various nanoscale materials. Currently, a new 40m SANS instrument is under development to be installed at HANARO, which will be one of the key facilities for nano-characterization in Korea. To enhance the measurement capability of the 40m SANS, especially in the low Q region, cold neutron focusing and cancellation of gravity effects using multiple biconcave lenses and prisms are suggested. In this paper, we present recent Monte Carlo simulation studies on the refractive focusing and anti-gravity optics.

  2. Distributed data processing and analysis environment for neutron scattering experiments at CSNS

    CERN Document Server

    Tian, H L; Yan, L L; Tang, M; Hu, L; Zhao, D X; Qiu, Y X; Zhang, H Y; Zhuang, J; Du, R

    2016-01-01

    China Spallation Neutron Source (CSNS) is the first high performance pulsed neutron source in China, which will meet the increasing fundamental research and technique applications demands in the domestic and oversea. A new distributed data processing and analysis environment has been developed, which has generic functionalities for neutron scattering experiments. The environment consists of three parts, an object-oriented data processing framework adopting a data centered architecture, a communication and data caching system based on C/S paradigm, and a data analysis and visualization software providing the 2D/3D experimental data display. This environment will be widely applied in CSNS for live data processing and virtual neutron scattering experiments based on Monte Carlo methods.

  3. Precision Measurement of the n-3He Incoherent Scattering Length Using Neutron Interferometry

    CERN Document Server

    Huber, M G; Black, T C; Chen, W C; Gentile, T R; Hussey, D S; Pushin, D; Wietfeldt, F E; Yang, L

    2008-01-01

    We report the first measurement of the low-energy neutron-3He incoherent scattering length using neutron interferometry: b_i' = (-2.417 +/- 0.012 statistical +/- 0.014 systematic) fm. It is in slight disagreement with the only previous measurement of this quantity by Zimmer, et al., b_i' = (-2.365 +/- 0.020) fm, which used a very different technique, pseudomagnetic spin rotation. The neutron-3He scattering lengths are important for testing and developing nuclear potential models that include three nucleon forces, effective field theories for few-body nuclear systems, and for understanding quantum excitations in liquid helium. This work demonstrates the first use of a polarized nuclear target in a neutron interferometer.

  4. Solution structure of a short dna fragment studied by neutron scattering

    DEFF Research Database (Denmark)

    Lederer, H.; May, R. P.; Kjems, Jørgen

    1986-01-01

    The solution structure of a DNA fragment of 130 base pairs and known sequence has been investigated by neutron small-angle scattering. In 0.1 M NaCl, the overall structure of the DNA fragment which contains the strong promoter A1 of the Escherichia coli phage T7 agrees with that expected for B......-DNA. The neutron scattering curve is well fitted by that of a rigid rod with a length of 44 nm and a diameter of 2 nm. The result were confirmed by quasi-elastic light scattering and analytical centrifugation. The neutron measurements in H2O and D2O buffer reveal a cross-sectional in homogeneity not detected by X...

  5. Report on the workshop on Monte Carlo simulation of neutron scattering instruments

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, R.K.

    1998-01-09

    The main purpose of this workshop was to reach a consensus concerning the desired features of a general computer program for source-to-detector Monte Carlo simulation of neutron scattering instruments. A second goal was to decide on a strategy for achieving this and to begin to portion out the tasks involved to avoid duplication of efforts among the various groups. The meeting was organized by Kent Crawford (Argonne National Laboratory) and attended by representatives of all the major US neutron scattering facilities and several of the European neutron scattering facilities. This document is a summary of the discussions that took place during the workshop. A copy of the meeting schedule is attached, as well as a list of participants.

  6. Frozen concentration fluctuations in a poly(N-isopropyl acrylamide) gel studied by neutron spin echo and small-angle neutron scattering

    CERN Document Server

    Koizumi, S; Richter, D; Schwahn, D; Faragó, B; Annaka, M

    2002-01-01

    By employing neutron spin echo and small-angle neutron scattering, we determined the structure factor of the frozen concentration fluctuations on nano-length scales in a swollen poly(N-isopropyl acrylamide) gel. The frozen contribution, showing a plateau at the low scattering wavenumber q (0.02 A sup - sup 1), is intimately related to the abnormal butterfly scattering pattern appearing at low q under deformation. (orig.)

  7. Measurement of neutron inelastic scattering cross section of {sup 238}U

    Energy Technology Data Exchange (ETDEWEB)

    Miura, Takako; Baba, Mamoru; Ibaraki, Masanobu; Sanami, Toshiya; Win, Than; Hirasawa, Yoshitaka; Matsuyama, Shigeo; Hirakawa, Naohiro [Tohoku Univ., Sendai (Japan)

    1998-03-01

    Neutron scattering from the 0{sup +}, 2{sup +} (1-st) and 4{sup +} (2nd) levels of {sup 238}U was measured for incident energies between 0.4 and 0.85 MeV at the Tohoku University 4.5 MV Dynamitron facility, using the time-of-flight (TOF) method with monoenergetic pulsed neutrons by the {sup 7}Li(p,n) reaction. The results are presented in comparison with other experimental data and evaluated data. (author)

  8. Neutron scattering and the 30 S ribosomal subunit of E. coli

    Energy Technology Data Exchange (ETDEWEB)

    Moore, P.B.; Engelman, D.M.; Langer, J.A.; Ramakrishnan, V.R.; Schindler, D.G.; Schoenborn, B.P.; Sillers, I.Y.; Yabuki, S.

    1982-01-01

    This paper reviews the progress made in the study of the internal organization of the 30 S ribosomal subunit of E. coli by neutron scattering since 1975. A map of that particle showing the position of 14 of the subunit's 21 proteins is presented, and the methods currently used for collecting and analyzing such data are discussed. Also discussed is the possibility of extending the interpretation of neutron mapping data beyond the limits practical today. 30 references, 5 figures.

  9. Neutron Scattering and the 30 S Ribosomal Subunit of E. Coli

    Science.gov (United States)

    Moore, P. B.; Engelman, D. M.; Langer, J. A.; Ramakrishnan, V. R.; Schindler, D. G.; Schoenborn, B. P.; Sillers, I. Y.; Yabuki, S.

    1982-06-01

    This paper reviews the progress made in the study of the internal organization of the 30 S ribosomal subunit of E. coli by neutron scattering since 1975. A map of that particle showing the position of 14 of the subunit's 21 proteins is presented, and the methods currently used for collecting and analyzing such data are discussed. Also discussed is the possibility of extending the interpretation of neutron mapping data beyond the limits practical today.

  10. Finite-element method for multigroup neutron transport: anisotropic scattering in 1-D slab geometry

    Energy Technology Data Exchange (ETDEWEB)

    Riyait, N.S.; Ackroyd, R.T.

    1987-01-01

    Proof-tests on 1-D multigroup neutron transport problems are reported for strong anisotropic scattering. These tests have been undertaken as part of the validation of the 3-D multigroup finite-element transport code FELTRAN for anisotropic scattering media. To illustrate the treatment of within-group and intergroup anisotropic scattering in the finite-element method the relevant theory is outlined. Ingroup scattering is checked using the backward-forward-isotropic (BFI) scattering law for source and eigenvalue problems. With this law anisotropic scattering problems can be transformed into equivalent isotropic scattering problems. In this way the well-validated isotropic scattering version of FELTRAN is used to validate the anisotropic version. Intergroup scattering effects are checked by solving few-group source problems for P/sub 1/ and P/sub 3/ scattering and the BFI scattering law. For P/sub 1/ and P/sub 3/ scattering checks are made with the discrete-ordinate finite-difference code ANISN and the spherical harmonics finite-difference code MARC/PN. For the BFI scattering law comparison is made with two-group exact solutions of Williams (1985) for 1-D systems.

  11. Studies of parity and time reversal symmetries in neutron scattering from165Ho

    Science.gov (United States)

    Haase, D. G.; Gould, C. R.; Koster, J. E.; Roberson, N. R.; Seagondollar, L. W.; Soderstrum, J. P.; Schneider, M. B.; Zhu, X.

    1988-12-01

    We describe searches for parity and time reversal violations in the scattering of polarized neutrons from polarized and aligned165Ho targets. We have completed a search with 7.1 and 11.0 MeV neutrons for PoddTodd terms in the elastic scattering forward amplitude of the form s. ( I×K), where s is the neutron spin, I is the target spin and k is the neutron momentum vector. The target was a single crystal of holmium, polarized horizontally along its b axis by a 1 Tesla magnetic field. The neutrons were polarized vertically. Differences in the neutron transmission were measured for neutrons with spins parallel (antiparallel) to I×k. The P,T violating analyzing powers were found to be consistent with zero at the few 10-3 level: ρP,T(7.1 MeV)=-0.88 (±2.02) x 10-3, ρP,T(11.0 MeV)=-0.4 (±2.88) x 10-3. We have also attempted to find enhancements with MeV neutrons in P-violation due to the term s k. We are preparing an aligned target cryostat for investigations of PevenTodd terms {bd(Ik)(I×k)s} in neutron scattering. The target will be a single crystal cylinder of165Ho cooled to 100 mK in a bath of liquid helium and rotated by a shaft from a room temperature stepping motor. The cylinder will be oriented vertically and the alignment ( c) axis oriented horizontally. Warming or rotation of the sample allows one to separate effects that mimic the sought-after time reversal violating term.

  12. Application of Small-Angle Neutron and X-ray Scattering in Determining Lipid Bilayer Structure

    Science.gov (United States)

    Pan, Jianjun; Heberle, Frederick A.; Kucerka, Norbert; Tristram-Nagle, Stephanie; Szymanski, Michelle; Koepfinger, Mary; Katsaras, John

    2012-02-01

    Accurately determining lipid structure in biologically relevant fluid bilayers is not straightforward. We have recently developed a hybrid experimental/computational technique (i.e., the scattering density profile, or SDP model), which exploits the fact that neutron and X-ray scattering are sensitive to different bilayer thicknesses - the large difference in neutron scattering length density (SLD) between proteated lipid and deuterated water defines the overall bilayer thickness, while X-ray scattering resolves the headgroup-headgroup distance due to the large scattering contrast between the electron-rich phosphate groups and the hydrocarbon/aqueous medium. A key step in the SDP analysis is the use of MD simulations to parse the lipid molecule into fragments whose volume probability distributions follow simple analytical functional forms. Given the appropriate atomic scattering lengths, these volume probabilities can simultaneously predict both the neutron and X-ray SLD profiles, and hence the scattering form factors. Structural results for commonly used phosphatidylcholine and phosphatidylglycerol lipids will be given.

  13. Differential Cross Sections for Neutron Elastic and Inelastic Scattering on 23Na

    Directory of Open Access Journals (Sweden)

    Vanhoy J.R.

    2014-03-01

    Full Text Available Measurements of neutron elastic and inelastic scattering from 23Na have been performed for sixteen incident neutron energies above 1.5 MeV with the 7-MV University of Kentucky Accelerator using the 3H(p,n reaction as the neutron source. These measurements were complemented by γ-ray excitation functions using the (n,n'γ reaction. The time-of-flight technique is employed for background reduction in both neutron and γ- ray measurements and for determining the energy of the scattered neutrons. Cross section determinations support fuel cycle and structural materials research and development. Previous reaction model evaluations [1] relied primarily on total cross sections and four (n,n0 and (n,n1 angular distributions in the En = 5 to 9 MeV range. The inclusion of more inelastic channels at lower neutron energies provides additional information on direct couplings between elastic and inelastic scattering as a function of angular momentum transfer. Reaction model calculations examining direct collective and statistical properties were performed.

  14. Inelastic neutron scattering cross-section measurements on 7Li and 63,65Cu

    Science.gov (United States)

    Nyman, Markus; Belloni, Francesca; Ichinkhorloo, Dagvadorj; Pirovano, Elisa; Plompen, Arjan; Rouki, Chariklia

    2017-09-01

    The γ-ray production cross section for the 477.6-keV transition in 7Li following inelastic neutron scattering has been measured from the reaction threshold up to 18 MeV. This cross section is interesting as a possible standard for other inelastic scattering measurements. The experiment was conducted at the Geel Electron LINear Accelerator (GELINA) pulsed white neutron source with the Gamma Array for Inelastic Neutron Scattering (GAINS) spectrometer. Previous measurements of this cross section are reviewed and compared with our results. Recently, this cross section has also been calculated using the continuum discretized coupled-channels (CDCC) method. Experiments for studying neutrinoless double-β decay (2β0ν) or other very rare processes require greatly reducing the background radiation level (both intrinsic and external). Copper is a common shielding and structural material, used extensively in experiments such as COBRA, CUORE, EXO, GERDA, and MAJORANA. Understanding the background contribution arising from neutron interactions in Cu is important when searching for very weak experimental signals. Neutron inelastic scattering on natCu was investigated with GAINS. The results are compared with previous experimental data and evaluated nuclear data libraries.

  15. Precision measurement of the n-4He scattering length using neutron interferometry

    Science.gov (United States)

    Huber, M. G.; Arif, M.; Jacobson, D. L.; Pushin, D. A.; Abutaleb, M. O.; Black, T. C.; Shahi, C. B.; Wietfeldt, F. E.

    2010-11-01

    The NIST neutron interferometer and optics facility (NIOF) is currently performing a precision measurement of the n-4He scattering length to less than 0.3% relative uncertainty. A neutron interferometer consists of a perfect silicon crystal machined such that there are three separate blades on a common base. Neutrons entering the interferometer are Bragg diffracted in the blades to produce two spatially separate yet coherent beam paths much like an optical Mach-Zehnder interferometer. A sample placed in one of the beam paths of the interferometer causes a phase difference between the two paths. This phase difference is directly related to the sample's scattering length. Neutron scattering lengths are one parameter that can be predicted using advanced theoretical models describing two and three nucleon interactions. In an effort to provide tests and/or benchmarks of these theoretical models, the NIOF has already performed precision measurements of neutron scattering lengths to less than 1% relative uncertainty in several low Z gases: H, D, 3He, and polarized 3He. A preliminary result of this work will be given.

  16. Inelastic neutron scattering cross-section measurements on 7Li and 63,65Cu

    Directory of Open Access Journals (Sweden)

    Nyman Markus

    2017-01-01

    Full Text Available The γ-ray production cross section for the 477.6-keV transition in 7Li following inelastic neutron scattering has been measured from the reaction threshold up to 18 MeV. This cross section is interesting as a possible standard for other inelastic scattering measurements. The experiment was conducted at the Geel Electron LINear Accelerator (GELINA pulsed white neutron source with the Gamma Array for Inelastic Neutron Scattering (GAINS spectrometer. Previous measurements of this cross section are reviewed and compared with our results. Recently, this cross section has also been calculated using the continuum discretized coupled-channels (CDCC method. Experiments for studying neutrinoless double-β decay (2β0ν or other very rare processes require greatly reducing the background radiation level (both intrinsic and external. Copper is a common shielding and structural material, used extensively in experiments such as COBRA, CUORE, EXO, GERDA, and MAJORANA. Understanding the background contribution arising from neutron interactions in Cu is important when searching for very weak experimental signals. Neutron inelastic scattering on natCu was investigated with GAINS. The results are compared with previous experimental data and evaluated nuclear data libraries.

  17. Note on the elastic-scattering of few-MeV neutrons from elemental calcium

    Energy Technology Data Exchange (ETDEWEB)

    Smith, A.B.; Guenther, P.T.

    1982-03-01

    Neutron differential-elastic-scattering cross sections of elemental calcium are measured from < 1.5 to 4.0 MeV at intervals of approx. = 50 to 100 keV. Scattering angles are distributed between 20 and 160/sup 0/. Incident-neutron energy resolutions are approximately 50 to 100 keV. The experimental results are compared with values given in ENDF/B-V and are examined in the context of shielding applications. An optical potential is deduced from the measured values and its possible implications are discussed.

  18. Turn-key module for neutron scattering with sub-micro-eV resolution.

    Energy Technology Data Exchange (ETDEWEB)

    Georgii, R.; Brandl, G.; HauBler, W.; Tischendorf, A.; Pfleiderer, C.; Boni, P.; Arend, N.; Keller, T.; Lal, J. (Biosciences Division); ( MSD); (Technische Univ. Munchen); (JCNS); (MPI-FKE)

    2011-02-18

    We report the development of a compact turn-key module that boosts the resolution in quasielastic neutron scattering by several orders of magnitude down to the low sub-micro-eV range. It is based on a pair of neutron resonance spin flippers that generate a well defined temporal intensity modulation, also known as Modulation of IntEnsity by Zero Effort (MIEZE). The module may be used under versatile conditions, in particular, in applied magnetic fields and for depolarizing and incoherently scattering samples. We demonstrate the power of MIEZE in studies of the helimagnetic order in MnSi under applied magnetic fields.

  19. Neutron Scattering from Heisenberg Ferromagnets EuO and EuS

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage; Dietrich, O. W.; Passell, L.

    1976-01-01

    Neutron scattering has been used to study the magnetic ordering process in the isotropic exchange coupled ferromagnets EuO and EuS. Quantities investigated include the critical coefficients B and F+ and the critical exponents β, ν, and γ describing respectively the temperature dependence of the r......Neutron scattering has been used to study the magnetic ordering process in the isotropic exchange coupled ferromagnets EuO and EuS. Quantities investigated include the critical coefficients B and F+ and the critical exponents β, ν, and γ describing respectively the temperature dependence...

  20. Distributed data processing and analysis environment for neutron scattering experiments at CSNS

    Science.gov (United States)

    Tian, H. L.; Zhang, J. R.; Yan, L. L.; Tang, M.; Hu, L.; Zhao, D. X.; Qiu, Y. X.; Zhang, H. Y.; Zhuang, J.; Du, R.

    2016-10-01

    China Spallation Neutron Source (CSNS) is the first high-performance pulsed neutron source in China, which will meet the increasing fundamental research and technique applications demands domestically and overseas. A new distributed data processing and analysis environment has been developed, which has generic functionalities for neutron scattering experiments. The environment consists of three parts, an object-oriented data processing framework adopting a data centered architecture, a communication and data caching system based on the C/S paradigm, and data analysis and visualization software providing the 2D/3D experimental data display. This environment will be widely applied in CSNS for live data processing.

  1. International Conference on Surface X-ray and Neutron Scattering (SXNS-11)

    Energy Technology Data Exchange (ETDEWEB)

    Michael J. Bedzyk

    2011-06-17

    The 11th International Surface X-ray and Neutron Scattering (SXNS) Conference was held on July 13-17, 2010, on the Northwestern University (NU) campus, in Evanston Illinois and hosted by the NU Materials Research Science and Engineering Center. This biennial conference brought together a community of 164 attendees from 16 countries. The field now makes use of a broad range of new experimental capabilities that have been made possible through the development of increasingly brilliant X-ray and neutron sources around the world, including third generation synchrotron sources, neutron reactor and spallation sources, as well as the recent development of X-ray lasers.

  2. Collective dynamics in phospholipid bilayers investigated by inelastic neutron scattering: exploring the dynamics of biological membranes with neutrons

    Science.gov (United States)

    Rheinstädter, M. C.; Ollinger, C.; Fragneto, G.; Salditt, T.

    2004-07-01

    We present the first inelastic neutron scattering study of the short wavelength dynamics in a phospholipid bilayer. We show that inelastic neutron scattering using a triple-axis spectrometer at the high-flux reactor of the ILL yields the necessary resolution and signal to determine the dynamics of model membranes. The results can quantitatively be compared to recent Molecular Dynamics simulations. Reflectivity, in-plane correlations and the corresponding dynamics can be measured simultaneously to gain a maximum amount of information. With this technique, complete dispersion relations can be measured with a high-energy resolution. Structure and dynamics in phospholipid bilayers, and the relation between them, can be studied on a molecular length scale.

  3. Low-angle polarized neutron and X-ray scattering from magnetic nanolayers and nanostructures

    CERN Document Server

    Paul, Amitesh

    2017-01-01

    This research monograph presents the latest results related to the characterization of low dimensional systems. Low-angle polarized neutron scattering and X-ray scattering at grazing incidence are used as the two main techniques to explore various physical phenomena of these systems. Special focus is put on systems like thin film transition metal and rare-earth layers, oxide heterostructures, hybrid systems, self-assembled nanostructures and self-diffusion.  Readers will gain in-depth knowledge about the usage of specular scattering and off-specular scattering techniques. Investigation of in-plane and out-of-plane structures and magnetism with vector magnetometric information is illustrated comprehensively. The book caters to a wide audience working in the field of nano-dimensional magnetic systems and the neutron and X-ray reflectometry community in particular.

  4. Collective excitations of normal liquid 4He, at 3.1 K, studied by neutron inelastic scattering

    DEFF Research Database (Denmark)

    Schou Pedersen, K.; Carneiro, K.

    1980-01-01

    Neutron inelastic scattering from normal liquid 4He at T=3.1 K and wave vectors in the region 0.2......Neutron inelastic scattering from normal liquid 4He at T=3.1 K and wave vectors in the region 0.2...

  5. Hydrogen dynamics in Na3AlH6: A combined density functional theory and quasielastic neutron scattering study

    DEFF Research Database (Denmark)

    Zsigmond, G.; Manoshin, S.; Lieutenant, K.

    2007-01-01

    Handling of polarization became very important in simulations of neutron scattering. One of the very comprehensive and open-source neutron simulation package, VITESS, has been intensely involved in polarized neutron simulations. Several examples will be shown here. Another similar package NISP al...

  6. Investigation of thermally induced anion disorder in fluorites using neutron scattering techniques

    DEFF Research Database (Denmark)

    Hutchings, M T; Clausen, Kurt Nørgaard; Dickens, M H

    1984-01-01

    the coherent diffuse quasielastic neutron scattering from single crystals of three such fluorite compounds PbF2, SrCl2 and CaF2, was investigated. The diffuse scattering intensity, and its energy width, increases with temperature into the fast-ion phase, and when integrated over energy transfer the intensity...... anion Frenkel interstitials, anion vacancies and relaxed anions has been developed which satisfactorily accounts for the distribution of intensity....

  7. The measurement of self-diffusion coefficients in liquid metals with quasielastic neutron scattering

    OpenAIRE

    Meyer, A.

    2015-01-01

    Quasielastic incoherent neutron scattering (QENS) has proven to be a versatile tool to study self diffusion of atoms in liquid metals. Here it is shown, that coherent contributions to the signal in the small q limit appear as a flat and energy independent constant to the QENS signal in single-component liquid metals even for systems with a small incoherent scattering cross section, like aluminum. Container-less processing via electromagnetic or electrostatic levitation devices, especially des...

  8. Coherent Scattering Investigations at the Spallation Neutron Source: a Snowmass White Paper

    CERN Document Server

    Akimov, D; Barbeau, P; Barton, P; Bolozdynya, A; Cabrera-Palmer, B; Cavanna, F; Cianciolo, V; Collar, J; Cooper, R J; Dean, D; Efremenko, Y; Etenko, A; Fields, N; Foxe, M; Figueroa-Feliciano, E; Fomin, N; Gallmeier, F; Garishvili, I; Gerling, M; Green, M; Greene, G; Hatzikoutelis, A; Henning, R; Hix, R; Hogan, D; Hornback, D; Jovanovic, I; Hossbach, T; Iverson, E; Klein, S R; Khromov, A; Link, J; Louis, W; Lu, W; Mauger, C; Marleau, P; Markoff, D; Martin, R D; Mueller, P; Newby, J; Orrell, J; O'Shaughnessy, C; Pentilla, S; Patton, K; Poon, A W; Radford, D; Reyna, D; Ray, H; Scholberg, K; Sosnovtsev, V; Tayloe, R; Vetter, K; Virtue, C; Wilkerson, J; Yoo, J; Yu, C H

    2013-01-01

    The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory, Tennessee, provides an intense flux of neutrinos in the few tens-of-MeV range, with a sharply-pulsed timing structure that is beneficial for background rejection. In this white paper, we describe how the SNS source can be used for a measurement of coherent elastic neutrino-nucleus scattering (CENNS), and the physics reach of different phases of such an experimental program (CSI: Coherent Scattering Investigations at the SNS).

  9. EVALUATION OF NEUTRON SCATTERING CORRECTION USING THE SEMI-EMPIRICAL METHOD AND THE SHADOW-CONE METHOD FOR THE NEUTRON FIELD OF THE KOREA ATOMIC ENERGY RESEARCH INSTITUTE.

    Science.gov (United States)

    Lee, Seung Kyu; Kim, Sang I; Lee, Jungil; Chang, Insu; Kim, Jang-Lyul; Kim, Hyoungtaek; Kim, Min Chae; Kim, Bong-Hwan

    2017-10-19

    When neutron survey metres are calibrated in neutron fields, the results for room- and air-scattered neutrons vary according to the distance from the source and the size, shape and construction of the neutron calibration room. ISO 8529-2 recommends four approaches for correcting these effects: the shadow-cone method, semi-empirical method, generalised fit method and reduced-fitting method. In this study, neutron scattering effects are evaluated and compared using the shadow-cone and semi-empirical methods for the neutron field of the Korea Atomic Energy Research Institute (KAERI). The neutron field is constructed using a 252Cf neutron source positioned in the centre of the neutron calibration room. To compare the neutron scattering effects using the two correction methods, measurements and simulations are performed using respectively KAERI's Bonner sphere spectrometer (BBS) and Monte Carlo N-Particle code at twenty different positions. Neutron spectra are measured by a europium-activated lithium iodide [6LiI(Eu)] scintillator in combination with the BBS. The calibration factors obtained using each methods show good agreement within 1.1%. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  10. Neutron and photon scattering properties of high density concretes used in radiation therapy facilities: A Monte Carlo study

    Science.gov (United States)

    Mesbahi, Asghar; Khaldari, Rezvan

    2017-09-01

    In the current study the neutron and photon scattering properties of some newly developed high density concretes (HDCs) were calculated by using MCNPX Monte Carlo code. Five high-density concretes including Steel-Magnetite, Barite, Datolite-Galena, Ilmenite-ilmenite, Magnetite-Lead with the densities ranging from 5.11 g/cm3 and ordinary concrete with density of 2.3 g/cm3 were studied in our simulations. The photon beam spectra of 4 and 18 MV from Varian linac and neutron spectra of clinical 18 MeV photon beam was used for calculations. The fluence of scattered photon and neutron from all studied concretes was calculated in different angles. Overall, the ordinary concrete showed higher scattered photons and Datolite-Galena concrete (4.42 g/cm3) had the lowest scattered photons among all studied concretes. For neutron scattering, fluence at the angle of 180 was higher relative to other angles while for photons scattering fluence was maximum at 90 degree. The scattering fluence for photons and neutrons was dependent on the angle and composition of concrete. The results showed that the fluence of scattered photons and neutrons changes with the composition of high density concrete. Also, for high density concretes, the variation of scattered fluence with angle was very pronounced for neutrons but it changed slightly for photons. The results can be used for design of radiation therapy bunkers.

  11. Comparison of neutron scattering and DFM capacitance instruments ...

    African Journals Online (AJOL)

    2012-03-20

    Mar 20, 2012 ... Soil water evaporation is an important parameter that needs to be accurately measured for the design of water-efficient agricultural systems. With this study, the abilities of the DFM capacitance probes and a neutron water meter (NWM) to ..... for calibration and the remaining half were used to validate the.

  12. Recent neutron scattering research and development in India

    Indian Academy of Sciences (India)

    technological importance. Thermal neutron has certain special properties that enable,. e.g., selective viewing of parts of an organic molecule, hydrogen or water in materials, investigations on minerals and ceramics, and microscopic and mesoscopic characterization of bulk samples. The national facility comprises of eight ...

  13. Comparison of neutron scattering and DFM capacitance instruments ...

    African Journals Online (AJOL)

    Soil water evaporation is an important parameter that needs to be accurately measured for the design of water-efficient agricultural systems. With this study, the abilities of the DFM capacitance probes and a neutron water meter (NWM) to measure evaporation from the soil surface were compared. Measured evaporation was ...

  14. Life at extreme conditions: Neutron scattering studies of biological ...

    Indian Academy of Sciences (India)

    The short review concentrates on recent work performed at the neutrons in biology laboratories of the Institut Laue Langevin and Institut de Biologie Structurale in Grenoble. Extremophile organisms have been discovered that require extreme conditions of temperature, pressure or solvent environment for survival.

  15. Neutron scattering studies of biological molecules suggest that ...

    Indian Academy of Sciences (India)

    Abstract. The short review concentrates on recent work performed at the neutrons in biology laboratories of the Institut Laue Langevin and Institut de Biologie Structurale in Grenoble. Extremophile organisms have been discovered that require extreme condi- tions of temperature, pressure or solvent environment for survival.

  16. Monte Carlo simulations of down-scattered neutron and knock-on deuteron spectra in deuterium-tritium capsule implosions

    Science.gov (United States)

    Zhao, Bin; Zheng, Jian

    2013-12-01

    A Monte Carlo particle tracking (MCPT) code has been developed and coupled to hydrodynamic simulations to generate and track primary and scattered neutrons in addition to scattered charged particles by post-processing. This code uses one dimensional (1-D) deuterium-tritium implosion profiles, and the computed down-scattered neutron and knock-on deuteron spectra are analyzed for different areal densities. The mixing effects on the spectra of down-scattered neutron and knock-on deuteron are also investigated. The implementation of the numerical scheme is analyzed, and the particle splitting technique is adopted, which is proven to efficiently reduce computational effort.

  17. An automated analysis workflow for optimization of force-field parameters using neutron scattering data

    Science.gov (United States)

    Lynch, Vickie E.; Borreguero, Jose M.; Bhowmik, Debsindhu; Ganesh, Panchapakesan; Sumpter, Bobby G.; Proffen, Thomas E.; Goswami, Monojoy

    2017-07-01

    Large-scale simulations and data analysis are often required to explain neutron scattering experiments to establish a connection between the fundamental physics at the nanoscale and data probed by neutrons. However, to perform simulations at experimental conditions it is critical to use correct force-field (FF) parameters which are unfortunately not available for most complex experimental systems. In this work, we have developed a workflow optimization technique to provide optimized FF parameters by comparing molecular dynamics (MD) to neutron scattering data. We describe the workflow in detail by using an example system consisting of tRNA and hydrophilic nanodiamonds in a deuterated water (D2O) environment. Quasi-elastic neutron scattering (QENS) data show a faster motion of the tRNA in the presence of nanodiamond than without the ND. To compare the QENS and MD results quantitatively, a proper choice of FF parameters is necessary. We use an efficient workflow to optimize the FF parameters between the hydrophilic nanodiamond and water by comparing to the QENS data. Our results show that we can obtain accurate FF parameters by using this technique. The workflow can be generalized to other types of neutron data for FF optimization, such as vibrational spectroscopy and spin echo.

  18. Investigation of phonon-like excitation in hydrated protein powders by neutron scattering

    Science.gov (United States)

    Chu, Xiang-Qiang (Rosie); Mamontov, Eugene; O'Neill, Hugh; Zhang, Qiu; Kolesnikov, Alexander

    2013-03-01

    Detecting the phonon dispersion relations in proteins is essential for understanding the intra-protein dynamical behavior. Such study has been attempted by X-ray in recent years. However, for such detections, neutrons have significant advantages in resolution and time-efficiency compare to X-rays. Traditionally the collective motions of atoms in protein molecules are hard to detect using neutrons, because of high incoherent scattering background from intrinsic hydrogen atoms in the protein molecules. The recent availability of a fully deuterated green fluorescent protein (GFP) synthesized by the Bio-deuteration Lab at ORNL opens new possibilities to probe collective excitations in proteins using inelastic neutron scattering. Using a direct time-of-flight Fermi chopper neutron spectrometer, we obtained a full map of the meV phonon-like excitations in the fully deuterated protein. The Q range of the observed excitations corresponds to the length scale close to the size of the secondary structures of proteins and reflects the collective intra-protein motions. Our results show that hydration of GFP seems to harden, not soften, the collective motions. This result is counterintuitive but in agreement with the observations by previous neutron scattering experiments. Sample preparation was supported by facilities operated by the Center for Structural Molecular Biology at ORNL which is supported by the U.S. DOE, Office of Science, Office of Biological and Environmental Research Project ERKP291.

  19. Small-angle neutron scattering study of a dense microemulsion system formed with an ionic liquid

    Energy Technology Data Exchange (ETDEWEB)

    Kang, T. [Biology and Soft Matter Division; Oak Ridge National Laboratory; Oak Ridge; USA; Qian, S. [Biology and Soft Matter Division; Oak Ridge National Laboratory; Oak Ridge; USA; Smith, G. S. [Biology and Soft Matter Division; Oak Ridge National Laboratory; Oak Ridge; USA; Do, C. [Biology and Soft Matter Division; Oak Ridge National Laboratory; Oak Ridge; USA; Heller, W. T. [Biology and Soft Matter Division; Oak Ridge National Laboratory; Oak Ridge; USA

    2017-01-01

    The structure of the microemulsion formed with an Ionic Liquid (IL) in specific systematic composition series has been investigated by small-angle neutron scattering to understand how the IL can be used to tune the structure and properties of microemulsions.

  20. Study of water diffusion on single-supported bilayer lipid membranes by quasielastic neutron scattering

    DEFF Research Database (Denmark)

    Bai, M.; Miskowiec, A.; Hansen, F. Y.

    2012-01-01

    High-energy-resolution quasielastic neutron scattering has been used to elucidate the diffusion of water molecules in proximity to single bilayer lipid membranes supported on a silicon substrate. By varying sample temperature, level of hydration, and deuteration, we identify three different types...

  1. Progress report on neutron scattering research (April 1, 1997 - March 31, 1998)

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Jun-ichi; Fujiwara, Satoru; Aizawa, Kazuya [eds.

    1999-02-01

    The present issue summarizes research progress in neutron scattering at Japan Atomic Energy Research Institute (JAERI) by utilizing the research reactor (JRR-3M) during the period between April 1, 1997 and March 31, 1998. The 76 papers are indexed individually. (J.P.N.)

  2. Exploring lipid dynamics in photosensitive membranes by quasielastic neutron scattering techniques

    DEFF Research Database (Denmark)

    Shen, Chen; Peters, Judith; Pieper, Jörg

    consisting a well- known 1-palmitoyl-2-oleoyl-sn-phosphatidyl-choline (POPC) matrix and embedded azo-chol. Lipid dynamics upon presence of azo-chol in either of the two conformations was studied at four temperatures by quasielastic neutron scattering experiments. The results involve dynamics of POPC...

  3. A small-angle neutron scattering study of cholic acid-based organogel systems

    NARCIS (Netherlands)

    Willemen, H.M.; Marcelis, A.T.M.; Sudhölter, E.J.R.; Bouwman, W.G.; Deme, B.; Terech, P.

    2004-01-01

    Small-angle neutron scattering measurements were performed on some cholic acid-based gel systems in order to gain detailed information about the network structure. The presence of thin fibers with a radius of about 10-20 Å was found for various gelators. Two types of interaction between different

  4. Hydrogen rotational and translational diffusion in calcium borohydride from quasielastic neutron scattering and DFT

    DEFF Research Database (Denmark)

    Blanchard, Didier; Riktor, M.D.; Maronsson, Jon Bergmann

    2010-01-01

    Hydrogen dynamics in crystalline calcium borohydride can be initiated by long-range diffusion or localized motion such as rotations, librations, and vibrations. Herein, the rotational and translational diffusion were studied by quasielastic neutron scattering (QENS) by using two instruments with ...

  5. A small angle neutron scattering study on the mixtures of pluronic ...

    Indian Academy of Sciences (India)

    Abstract. Small angle neutron scattering (SANS) experiments have been carried out on the micellar solutions containing mixtures of a hydrophobic triblock copoly- mer (L121, EO5PO68EO5) and a hydrophobic anionic surfactant (AOT, sodium bis(2- ethylhexyl)sulphosuccinate) in water with varying ratio (R) of AOT to L121 ...

  6. Small-angle neutron scattering study of aggregate structures of multi ...

    Indian Academy of Sciences (India)

    The aggregate structures of a set of novel single-chain surfactants bearing one, two and three pyridinium headgroups have been studied using small-angle neutron scattering (SANS). It is found that the nature of aggregate structures of these cationic surfactants depend on the number of headgroups present in the ...

  7. Small-angle neutron and dynamic light scattering study of gelatin ...

    Indian Academy of Sciences (India)

    The state of intermolecular aggregates and that of folded gelatin molecules could be characterized by dynamic laser light and small-angle neutron scattering experiments, which implied spontaneous segregation of particle sizes preceding coacervation, which is a liquid-liquid phase transition phenomenon. Dynamic light ...

  8. Benchmarking a first-principles thermal neutron scattering law for water ice with a diffusion experiment

    Science.gov (United States)

    Holmes, Jesse; Zerkle, Michael; Heinrichs, David

    2017-09-01

    The neutron scattering properties of water ice are of interest to the nuclear criticality safety community for the transport and storage of nuclear materials in cold environments. The common hexagonal phase ice Ih has locally ordered, but globally disordered, H2O molecular orientations. A 96-molecule supercell is modeled using the VASP ab initio density functional theory code and PHONON lattice dynamics code to calculate the phonon vibrational spectra of H and O in ice Ih. These spectra are supplied to the LEAPR module of the NJOY2012 nuclear data processing code to generate thermal neutron scattering laws for H and O in ice Ih in the incoherent approximation. The predicted vibrational spectra are optimized to be representative of the globally averaged ice Ih structure by comparing theoretically calculated and experimentally measured total cross sections and inelastic neutron scattering spectra. The resulting scattering kernel is then supplied to the MC21 Monte Carlo transport code to calculate time eigenvalues for the fundamental mode decay in ice cylinders at various temperatures. Results are compared to experimental flux decay measurements for a pulsed-neutron die-away diffusion benchmark.

  9. Progress report on neutron scattering research (April 1, 1996 - March 31, 1997)

    Energy Technology Data Exchange (ETDEWEB)

    Ishii, Yoshinobu; Suzuki, Jun-ichi; Fujiwara, Satoru [eds.

    1997-10-01

    This issue summarizes research progress in neutron scattering at Japan Atomic Energy Research Institute (JAERI) by utilizing the research reactor (JRR-3M) mainly during the period between April 1, 1996 and March 31, 1997. The 57 of the presented papers are indexed individually. (J.P.N.)

  10. Reversible membrane reorganizations during photosynthesis in vivo: revealed by small-angle neutron scattering

    DEFF Research Database (Denmark)

    Nagy, Gergely; Posselt, Dorthe; Kovacs, Laszlo

    2011-01-01

    In the present study, we determined characteristic repeat distances of the photosynthetic membranes in living cyanobacterial and eukaryotic algal cells, and in intact thylakoid membranes isolated from higher plants with time-resolved small-angle neutron scattering. This non-invasive technique rev...

  11. Velocity-Autocorrelation Function in Liquids, Deduced from Neutron Incoherent Scattering Results

    DEFF Research Database (Denmark)

    Carneiro, Kim

    1976-01-01

    The Fourier transform p(ω) of the velocity-autocorrelation function is derived from neutron incoherent scattering results, obtained from the two liquids Ar and H2. The quality and significance of the results are discussed with special emphasis on the long-time t-3/2 tail, found in computer...

  12. Neutron scattering study of the incommensurate high-field phase of CuGeO3

    DEFF Research Database (Denmark)

    Rønnow, H.M.; Enderle, M.; McMorrow, D.F.

    2000-01-01

    CuGeO3 is a good realization of a spin-Peierls system. Using neutron scattering, we have investigated the transition from the dimerized spin-Peierls phase to an incommensurately modulated high-field phase. The incommensurate period has been measured for fields up to 14.5 T and is found...

  13. Application of small-angle neutron scattering (SANS) to the study of coal porosity

    Energy Technology Data Exchange (ETDEWEB)

    Tricker, M.J.; Grint, A.; Audley, G.J.; Church, S.M. (British Petroleum Co. Ltd., Sunbury-on-Thames); Rainey, V.S.; Wright, C.J. (UKAEA Atomic Energy Research Establishment, Harwell)

    1983-09-01

    Pore size distribution functions of coals of different rank obtained from small-angle neutron scattering data are quantitatively consistent with data obtained from adsorption measurements. The agreement will provide a firm foundation for using SANS to probe coal porosity under conditions where conventional gas adsorption techniques are inappropriate.

  14. Application of small-angle neutron scattering (SANS) to the study of coal porosity

    Energy Technology Data Exchange (ETDEWEB)

    Tricker, M.J.; Grint, A.; Audley, G.J.; Church, S.M.; Rainey, V.S.; Wright, C.J.

    1983-09-01

    Pore size distribution functions of coals of different rank obtained from small-angle neutron scattering data are quantitatively consistent with data obtained from adsorption measurements. The agreement will provide a firm foundation for using SANS to probe coal porosity under conditions where conventional gas adsorption techniques are inappropriate. (14 refs.)

  15. Neutron Scattering Studies of the Ionic Conductor LiI D2O

    DEFF Research Database (Denmark)

    Andersen, N. H.; Kjems, Jørgen; Poulsen, Finn Willy

    1982-01-01

    The structural properties of the ionic conductor LiID2O have been studied by neutron scattering. The cubic room temperature α-phase, Pm3m, is disordered both with respect to the occupation of the Li+-positions and to the orientations of the water molecules. A first order phase transition from the α...

  16. Apple II direct memory access interface to acquire neutron scattering time of flight spectra

    Science.gov (United States)

    Cilloco, F.; Ippoliti, A.; Sacchetti, F.

    1990-07-01

    A data acquisition system designed to acquire time of flight spectra in neutron scattering experiments is described. The system is completely hardware, so that even employing a relatively slow clock (1 MHz) it is adequate to work at 300 kHz with no loss of information.

  17. Neutron scattering studies of Cd1−xMnxTe

    DEFF Research Database (Denmark)

    Giebultowicz, T.; Lebech, Bente; Buras, B

    1984-01-01

    The diluted magnetic (‘‘semimagnetic’’) semiconductor Cd1–xMnxTe reveals intriguing spin glass properties. In this paper, the results of neutron scattering studies of Cd1–xMnxTe are presented. The low‐temperature spin correlations have been studied for several single crystal samples in the compos...

  18. Changes in the hydration structure of imidazole upon protonation: Neutron scattering and molecular simulations

    Czech Academy of Sciences Publication Activity Database

    Duboué-Dijon, Elise; Mason, Philip E.; Fischer, H. E.; Jungwirth, Pavel

    2017-01-01

    Roč. 146, č. 18 (2017), č. článku 185102. ISSN 0021-9606 R&D Projects: GA ČR(CZ) GBP208/12/G016 Institutional support: RVO:61388963 Keywords : imidazole protonation * molecular dynamics * neutron scattering Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.965, year: 2016

  19. Total neutron scattering: The key to the local and medium range ...

    Indian Academy of Sciences (India)

    pattern, however, contains structural information over all length scales, and it can be used to obtain a complete structural ... discussion of the PDF method, its formalism and many more applications can be found in [5]. 2. ... the high resolution instrument NPDF at the Lujan Neutron Scattering Center and the PDF below was ...

  20. Neutron scattering study of the excitation spectrum of solid helium at ...

    Indian Academy of Sciences (India)

    October 2008 physics pp. 673–678. Neutron scattering study of the excitation spectrum of solid helium at ultra-low temperatures. ELIZABETH BLACKBURN1, JOHN GOODKIND1, SUNIL K SINHA1,∗,. COLLIN BROHOLM2, JOHN COPLEY3 and ROSS ERWIN3. 1University of California San Diego, La Jolla, CA 92093-0319, ...

  1. A Novel Scanning Land Mine Detector Based on the Technique of Neutron Back Scattering Imaging

    NARCIS (Netherlands)

    Bom, V.; Osman, A.M.; Monem, A.M.A.

    2008-01-01

    The neutron back-scattering (NBS) technique is a well established method to find hydrogen in objects. It can be applied in land mine detection taking advantage of the fact that land mines are abundant in hydrogen. The NBS technique is suitable for land mine scanning e.g., seeking for land mines with

  2. Quasi-elastic neutron scattering study of the mobility of methane in microporous silica

    NARCIS (Netherlands)

    Benes, Nieck Edwin; Jobic, Herve; Verweij, H.

    2001-01-01

    The dynamics of translation and rotation of methane in microporous bulk silica have been studied with quasi-elastic neutron scattering. At T=200 K the self-diffusion coefficient of translation is DS=1.1×10−8 m2 s−1 with an estimated activation energy of 4 kJ mol−1. Any variation of DS with occupancy

  3. Neutron Scattering from the Heisenberg Ferromagnets EuO and EuS

    DEFF Research Database (Denmark)

    Dietrich, O. W.; Als-Nielsen, Jens Aage; Passell, L.

    1976-01-01

    Inelastic neutron scattering has been used to investigate the spin dynamics of the isotropic Heisenberg ferromagnet EuO over a wide range of wave vectors and over a temperature range extending from 0.14 to 1.9TC. Below the ordering temperature spin-wave renormalization is found to agree well...

  4. Small angle neutron scattering study of U(VI) third phase formation ...

    Indian Academy of Sciences (India)

    It was observed that third phase formation takes place due to the formation of. UO2(NO3)2.DHDECMP reverse micelles in the dodecane phase. SANS data obtained were interpreted with particle interaction model using Baxter sticky spheres model. Keywords. Small angle neutron scattering; U(VI); third phase; DHDECMP.

  5. Time-reversal invariance violation measurement using polarized neutron scattering from polarized xenon

    CERN Document Server

    Chu, Pinghan

    2014-01-01

    We proposed to use polarized neutrons scattering from a hyperpolarized 131Xe gaseous target in order to measure time-reversal violation effect in baryon processes with nucleons. This article provides a brief introduction, historical review, and possible methods to construct a hyperpolarized 131Xe gaseous target.

  6. Fine Structure Discussion of Parity-Nonconserving Neutron Scattering at Epithermal Energies

    OpenAIRE

    Hussein, M. S.; Kerman, A. K.; Lin, C-Y

    1994-01-01

    The large magnitude and the sign correlation effect in the parity non-conserving resonant scattering of epithermal neutrons from $^{232}$Th is discussed in terms of a non-collective $2p-1h$ local doorway model. General conclusions are drawn as to the probability of finding large parity violation effects in other regions of the periodic table.

  7. Extracting hadron-neutron scattering amplitudes from hadron-proton and hadron-deuteron measurements

    Science.gov (United States)

    Franco, V.

    1977-01-01

    A method is presented for extracting hadron-neutron scattering amplitudes from hadron-proton and hadron-deuteron measurements within the framework of the Glauber approximation. This method, which involves the solution of a linear integral equation, is applied to pn collisions between 15 and 275 GeV/c. Effects arising from inelastic intermediate states are estimated.

  8. Measurement of leading neutron production in deep-inelastic scattering at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Aaron, F.D. [National Inst. for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Bucharest Univ. (Romania). Faculty of Physics; Alexa, C. [National Inst. for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Alimujiang, K. [DESY, Hamburg (DE)] (and others)

    2009-10-15

    The production of leading neutrons, where the neutron carries a large fraction x{sub L} of the incoming proton's longitudinal momentum, is studied in deep-inelastic positron-proton scattering at HERA. The data were taken with the H1 detector in the years 2006 and 2007 and correspond to an integrated luminosity of 122 pb{sup -1}. The semi-inclusive cross section is measured in the phase space defined by the photon virtuality 6neutron transverse momentum p{sub T}<0.2 GeV. The leading neutron structure function, F{sub 2}{sup LN(3)} (Q{sup 2},x,x{sub L}), and the fraction of deep-inelastic scattering events containing a leading neutron are studied as a function of Q{sup 2}, x and x{sub L}. Assuming that the pion exchange mechanism dominates leading neutron production, the data provide constraints on the shape of the pion structure function. (orig.)

  9. Measurement of Leading Neutron Production in Deep-Inelastic Scattering at HERA

    CERN Document Server

    Aaron, F.D.; Alimujiang, K.; Andreev, V.; Antunovic, B.; Backovic, S.; Baghdasaryan, A.; Barrelet, E.; Bartel, W.; Begzsuren, K.; Belousov, A.; Bizot, J.C.; Boudry, V.; Bozovic-Jelisavcic, I.; Bracinik, J.; Brandt, G.; Brinkmann, M.; Brisson, V.; Bruncko, D.; Bunyatyan, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A.J.; Cantun Avila, K.B.; Cerny, K.; Cerny, V.; Chekelian, V.; Cholewa, A.; Contreras, J.G.; Coughlan, J.A.; Cozzika, G.; Cvach, J.; Dainton, J.B.; Daum, K.; Deak, M.; Delcourt, B.; Delvax, J.; De Wolf, E.A.; Diaconu, C.; Dodonov, V.; Dossanov, A.; Dubak, A.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eliseev, A.; Elsen, E.; Falkiewicz, A.; Favart, L.; Fedotov, A.; Felst, R.; Feltesse, J.; Ferencei, J.; Fischer, D.-J.; Fleischer, M.; Fomenko, A.; Gabathuler, E.; Gayler, J.; Ghazaryan, Samvel; Glazov, A.; Glushkov, I.; Goerlich, L.; Gogitidze, N.; Gouzevitch, M.; Grab, C.; Greenshaw, T.; Grell, B.R.; Grindhammer, G.; Habib, S.; Haidt, D.; Helebrant, C.; Henderson, R.C.W.; Hennekemper, E.; Henschel, H.; Herbst, M.; Herrera, G.; Hildebrandt, M.; Hiller, K.H.; Hoffmann, D.; Horisberger, R.; Hreus, T.; Jacquet, M.; Janssen, X.; Jonsson, L.; Jung, Andreas Werner; Jung, H.; Kapichine, M.; Katzy, J.; Kenyon, I.R.; Kiesling, C.; Klein, M.; Kleinwort, C.; Kluge, T.; Knutsson, A.; Kogler, R.; Kostka, P.; Kraemer, M.; Krastev, K.; Kretzschmar, J.; Kropivnitskaya, A.; Kruger, K.; Kutak, K.; Landon, M.P.J.; Lange, W.; Lastovicka-Medin, G.; Laycock, P.; Lebedev, A.; Lendermann, V.; Levonian, S.; Li, G.; Lipka, K.; Liptaj, A.; List, B.; List, J.; Loktionova, N.; Lopez-Fernandez, R.; Lubimov, V.; Lytkin, L.; Makankine, A.; Malinovski, E.; Marage, P.; Marti, Ll.; Martyn, H.-U.; Maxfield, S.J.; Mehta, A.; Meyer, A.B.; Meyer, H.; Meyer, H.; Meyer, J.; Mikocki, S.; Milcewicz-Mika, I.; Moreau, F.; Morozov, A.; Morris, J.V.; Mozer, Matthias Ulrich; Mudrinic, M.; Muller, K.; Murin, P.; Naumann, Th.; Newman, P.R.; Niebuhr, C.; Nikiforov, A.; Nikitin, D.; Nowak, G.; Nowak, K.; Olsson, J.E.; Osman, S.; Ozerov, D.; Pahl, P; Palichik, V.; Panagoulias, I.; Pandurovic, M.; Papadopoulou, Th.; Pascaud, C.; Patel, G.D.; Pejchal, O.; Perez, E.; Petrukhin, A.; Picuric, I.; Piec, S.; Pitzl, D.; Placakyte, R.; Pokorny, B.; Polifka, R.; Povh, B.; Radescu, V.; Rahmat, A.J.; Raicevic, N.; Raspiareza, A.; Ravdandorj, T.; Reimer, P.; Rizvi, E.; Robmann, P.; Roland, B.; Roosen, R.; Rostovtsev, A.; Rotaru, M.; Ruiz Tabasco, J.E.; Rusakov, S.; Salek, D.; Sankey, D.P.C.; Sauter, M.; Sauvan, E.; Schmitt, S.; Schoeffel, L.; Schoning, A.; Schultz-Coulon, H.-C.; Sefkow, F.; Shaw-West, R.N.; Shtarkov, L.N.; Shushkevich, S.; Sloan, T.; Smiljanic, Ivan; Soloviev, Y.; Sopicki, P.; South, D.; Spaskov, V.; Specka, Arnd E.; Staykova, Z.; Steder, M.; Stella, B.; Stoicea, G.; Straumann, U.; Sunar, D.; Sykora, T.; Tchoulakov, V.; Thompson, G.; Thompson, P.D.; Toll, T.; Tomasz, F.; Tran, T.H.; Traynor, D.; Trinh, T.N.; Truol, P.; Tsakov, I.; Tseepeldorj, B.; Turnau, J.; Urban, K.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vargas Trevino, A.; Vazdik, Y.; Vinokurova, S.; Volchinski, V.; von den Driesch, M.; Wegener, D.; Wissing, Ch.; Wunsch, E.; Zacek, J.; Zalesak, J.; Zhang, Z.; Zhokin, A.; Zimmermann, T.; Zohrabyan, H.; Zomer, F.

    2010-01-01

    The production of leading neutrons, where the neutron carries a large fraction x_L of the incoming proton's longitudinal momentum, is studied in deep-inelastic positron-proton scattering at HERA. The data were taken with the H1 detector in the years 2006 and 2007 and correspond to an integrated luminosity of 122 pb^{-1}. The semi-inclusive cross section is measured in the phase space defined by the photon virtuality 6 < Q^2 < 100 GeV^2, Bjorken scaling variable 1.5x10^{-4} < x < 3x10^{-2}, longitudinal momentum fraction 0.32 < x_L < 0.95 and neutron transverse momentum p_T < 0.2 GeV. The leading neutron structure function, F_2^{LN(3)}(Q^2,x,x_L), and the fraction of deep-inelastic scattering events containing a leading neutron are studied as a function of Q^2, x and x_L. Assuming that the pion exchange mechanism dominates leading neutron production, the data provide constraints on the shape of the pion structure function.

  10. Testing Monte Carlo Simulations for Neutron Scattering in MoNA

    Science.gov (United States)

    Hamann, A.; Garrett, S.; Seagren, T.; Taylor, N. E.; Rogers, W. F.; MoNA Collaboration

    2015-10-01

    Monte Carlo simulations provide an important tool for nuclear physics research, both in preparing for experiments, and in interpreting experimental data. The Modular Neutron Array (MoNA) and the Large area multi-Institutional Scintillator Array (LISA) are used in conjunction with the Sweeper Magnet and charged particle detector chamber at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University to study the properties of exotic, neutron-rich nuclei. We use simulations to model our BC408 scintillator detectors and extract physics results from experimental data. We have developed specific simulations in preparation for an experiment we will conduct at the Los Alamos Neutron Science Center (LANSCE), where we will direct a well-defined neutron beam onto a cluster of 16 MoNA detector bars and observe the scattering patterns of single neutrons. Simulations enable us to study the predicted light output generated by individual neutron scattering channels from Carbon and Hydrogen. The data we will generate in the LANSCE experiment will provide a large experimental database with which to test the reliability of our simulations. This is important since our understanding of nuclei far from stability is becoming increasingly reliant on simulations. this work supported by NSF Grants PHY-1101745 and PHY-1506402.

  11. Fast-neutron total and scattering cross sections of sup 58 Ni and nuclear models

    Energy Technology Data Exchange (ETDEWEB)

    Smith, A.B.; Guenther, P.T.; Whalen, J.F. (Argonne National Lab., IL (United States)); Chiba, S. (Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment)

    1991-07-01

    The neutron total cross sections of {sup 58}Ni were measured from {approx} 1 to > 10 MeV using white-source techniques. Differential neutron elastic-scattering cross sections were measured from {approx} 4.5 to 10 MeV at {approx} 0.5 MeV intervals with {ge} 75 differential values per distribution. Differential neutron inelastic-scattering cross sections were measured, corresponding to fourteen levels with excitations up to 4.8 MeV. The measured results, combined with relevant values available in the literature, were interpreted in terms of optical-statistical and coupled-channels model using both vibrational and rotational coupling schemes. The physical implications of the experimental results nd their interpretation are discussed in the contexts of optical-statistical, dispersive-optical, and coupled-channels models. 61 refs.

  12. Effect of anisotropic scattering in neutronics analysis of BWR assembly

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, Toshikazu [Division of Sustainable Energy and Environmental Engineering, Graduate School of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka 565-0571 (Japan)]. E-mail: takeda@nucl.eng.osaka-u.ac.jp; Okamoto, Toshiki [Division of Sustainable Energy and Environmental Engineering, Graduate School of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka 565-0571 (Japan); Inoue, Akira [Division of Sustainable Energy and Environmental Engineering, Graduate School of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka 565-0571 (Japan); Kosaka, Shinya [TEPCO Systems Corporation, 2-37-28 Eitai, Koutou-ku, Tokyo 135-0034 (Japan); Ikeda, Hideaki [TEPCO Systems Corporation, 2-37-28 Eitai, Koutou-ku, Tokyo 135-0034 (Japan)

    2006-11-15

    The anisotropic scattering effect to keff is studied for UO{sub 2} and MOX fueled BWR assemblies. The anisotropic scattering effect increases the assembly k {sub {infinity}} by 0.44% {delta}k for the UO{sub 2} assembly with 0% void fraction, and by 0.21% {delta}k for the MOX assembly with 0% void fraction. This is because the anisotropic scattering effect flattens the intra-assembly thermal flux, and the absorption rate in the surrounding water gap is decreased, but the absorption rates in the MOX fuel rods are increased compared to the UO{sub 2} rods. Therefore, the total decrease in absorption rates in the UO{sub 2} assembly is relatively large, and the k {sub {infinity}} is increased in the UO{sub 2} assembly. The dependence of the anisotropic scattering effect on the void fraction is investigated, and the significant difference of 0.62% {delta}k/k is found for the 0% and the 80% void fractions. The BWR assemblies with Gd rods are also considered. Furthermore, the usefulness of the transport cross section is investigated, and it is found that the transport cross section gives reasonable anisotropic scattering effect, though not satisfactory.

  13. Derivation of Inter-Atomic Force Constants of Cu2O from Diffuse Neutron Scattering Measurement

    Directory of Open Access Journals (Sweden)

    T. Makhsun

    2013-04-01

    Full Text Available Neutron scattering intensity from Cu2O compound has been measured at 10 K and 295 K with High Resolution Powder Diffractometer at JRR-3 JAEA. The oscillatory diffuse scattering related to correlations among thermal displacements of atoms was observed at 295 K. The correlation parameters were determined from the observed diffuse scattering intensity at 10 and 295 K. The force constants between the neighboring atoms in Cu2O were estimated from the correlation parameters and compared to those of Ag2O

  14. An automated analysis workflow for optimization of force-field parameters using neutron scattering data

    Energy Technology Data Exchange (ETDEWEB)

    Lynch, Vickie E.; Borreguero, Jose M. [Neutron Data Analysis & Visualization Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831 (United States); Bhowmik, Debsindhu [Computational Sciences & Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831 (United States); Ganesh, Panchapakesan; Sumpter, Bobby G. [Center for Nanophase Material Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831 (United States); Computational Sciences & Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831 (United States); Proffen, Thomas E. [Neutron Data Analysis & Visualization Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831 (United States); Goswami, Monojoy, E-mail: goswamim@ornl.gov [Center for Nanophase Material Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831 (United States); Computational Sciences & Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831 (United States)

    2017-07-01

    Graphical abstract: - Highlights: • An automated workflow to optimize force-field parameters. • Used the workflow to optimize force-field parameter for a system containing nanodiamond and tRNA. • The mechanism relies on molecular dynamics simulation and neutron scattering experimental data. • The workflow can be generalized to any other experimental and simulation techniques. - Abstract: Large-scale simulations and data analysis are often required to explain neutron scattering experiments to establish a connection between the fundamental physics at the nanoscale and data probed by neutrons. However, to perform simulations at experimental conditions it is critical to use correct force-field (FF) parameters which are unfortunately not available for most complex experimental systems. In this work, we have developed a workflow optimization technique to provide optimized FF parameters by comparing molecular dynamics (MD) to neutron scattering data. We describe the workflow in detail by using an example system consisting of tRNA and hydrophilic nanodiamonds in a deuterated water (D{sub 2}O) environment. Quasi-elastic neutron scattering (QENS) data show a faster motion of the tRNA in the presence of nanodiamond than without the ND. To compare the QENS and MD results quantitatively, a proper choice of FF parameters is necessary. We use an efficient workflow to optimize the FF parameters between the hydrophilic nanodiamond and water by comparing to the QENS data. Our results show that we can obtain accurate FF parameters by using this technique. The workflow can be generalized to other types of neutron data for FF optimization, such as vibrational spectroscopy and spin echo.

  15. Studying Kinetics with Neutrons Prospects for Time-Resolved Neutron Scattering

    CERN Document Server

    Eckold, Götz; Nagler, Stephen E

    2010-01-01

    Neutrons are extremely versatile probes for investigating structure and dynamics in condensed matter. Due to their large penetration depth, they are ideal for in-situ measurements of samples situated in sophisticated and advanced environments. The advent of new high-intensity neutron sources and instruments, as well as the development of new real-time techniques, allows the tracking of transformation processes in condensed matter on a microscopic scale. The present volume provides a review of the state of the art of this new and exciting field of kinetics with neutrons

  16. New evaluation of thermal neutron scattering libraries for light and heavy water

    Directory of Open Access Journals (Sweden)

    Marquez Damian Jose Ignacio

    2017-01-01

    Full Text Available In order to improve the design and safety of thermal nuclear reactors and for verification of criticality safety conditions on systems with significant amount of fissile materials and water, it is necessary to perform high-precision neutron transport calculations and estimate uncertainties of the results. These calculations are based on neutron interaction data distributed in evaluated nuclear data libraries. To improve the evaluations of thermal scattering sub-libraries, we developed a set of thermal neutron scattering cross sections (scattering kernels for hydrogen bound in light water, and deuterium and oxygen bound in heavy water, in the ENDF-6 format from room temperature up to the critical temperatures of molecular liquids. The new evaluations were generated and processable with NJOY99 and also with NJOY-2012 with minor modifications (updates, and with the new version of NJOY-2016. The new TSL libraries are based on molecular dynamics simulations with GROMACS and recent experimental data, and result in an improvement of the calculation of single neutron scattering quantities. In this work, we discuss the importance of taking into account self-diffusion in liquids to accurately describe the neutron scattering at low neutron energies (quasi-elastic peak problem. To improve modeling of heavy water, it is important to take into account temperature-dependent static structure factors and apply Sköld approximation to the coherent inelastic components of the scattering matrix. The usage of the new set of scattering matrices and cross-sections improves the calculation of thermal critical systems moderated and/or reflected with light/heavy water obtained from the International Criticality Safety Benchmark Evaluation Project (ICSBEP handbook. For example, the use of the new thermal scattering library for heavy water, combined with the ROSFOND-2010 evaluation of the cross sections for deuterium, results in an improvement of the C/E ratio in 48 out of

  17. New evaluation of thermal neutron scattering libraries for light and heavy water

    Science.gov (United States)

    Marquez Damian, Jose Ignacio; Granada, Jose Rolando; Cantargi, Florencia; Roubtsov, Danila

    2017-09-01

    In order to improve the design and safety of thermal nuclear reactors and for verification of criticality safety conditions on systems with significant amount of fissile materials and water, it is necessary to perform high-precision neutron transport calculations and estimate uncertainties of the results. These calculations are based on neutron interaction data distributed in evaluated nuclear data libraries. To improve the evaluations of thermal scattering sub-libraries, we developed a set of thermal neutron scattering cross sections (scattering kernels) for hydrogen bound in light water, and deuterium and oxygen bound in heavy water, in the ENDF-6 format from room temperature up to the critical temperatures of molecular liquids. The new evaluations were generated and processable with NJOY99 and also with NJOY-2012 with minor modifications (updates), and with the new version of NJOY-2016. The new TSL libraries are based on molecular dynamics simulations with GROMACS and recent experimental data, and result in an improvement of the calculation of single neutron scattering quantities. In this work, we discuss the importance of taking into account self-diffusion in liquids to accurately describe the neutron scattering at low neutron energies (quasi-elastic peak problem). To improve modeling of heavy water, it is important to take into account temperature-dependent static structure factors and apply Sköld approximation to the coherent inelastic components of the scattering matrix. The usage of the new set of scattering matrices and cross-sections improves the calculation of thermal critical systems moderated and/or reflected with light/heavy water obtained from the International Criticality Safety Benchmark Evaluation Project (ICSBEP) handbook. For example, the use of the new thermal scattering library for heavy water, combined with the ROSFOND-2010 evaluation of the cross sections for deuterium, results in an improvement of the C/E ratio in 48 out of 65

  18. Optimizing Neutron Thermal Scattering Effects in very High Temperature Reactors. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Hawari, Ayman [North Carolina State Univ., Raleigh, NC (United States). Dept. of Nuclear Engineering; Ougouag, Abderrafi [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2014-07-08

    This project aims to develop a holistic understanding of the phenomenon of neutron thermalization in the VHTR. Neutron thermalization is dependent on the type and structure of the moderating material. The fact that the moderator (and reflector) in the VHTR is a solid material will introduce new and interesting considerations that do not apply in other (e.g. light water) reactors. The moderator structure is expected to undergo radiation induced changes as the irradiation (or burnup) history progresses. In this case, the induced changes in structure will have a direct impact on many properties including the neutronic behavior. This can be easily anticipated if one recognizes the dependence of neutron thermalization on the scattering law of the moderator. For the pebble bed reactor, it is anticipated that the moderating behavior can be tailored, e.g. using moderators that consist of composite materials, which could allow improved optimization of the moderator-to-fuel ratio.

  19. Time-resolved small-angle neutron scattering of a micelle-to-vesicle transition

    Energy Technology Data Exchange (ETDEWEB)

    Egelhaaf, S.U. [Institut Max von Laue - Paul Langevin (ILL), 38 -Grenoble (France); Schurtenberger, P. [Eidgenoessische Technische Hochschule, Zurich (Switzerland)

    1997-04-01

    Amphiphilic molecules spontaneously self-assemble in solution to form a variety of aggregates. Only limited information is available on the kinetics of the structural transitions as well as on the existence of non-equilibrium or metastable states. Aqueous mixtures of lecithin and bile salt are very interesting biological model-systems which exhibit a spontaneous transition from polymer-like mixed micelles to vesicles upon dilution. The small-angle neutron scattering (SANS) instrument D22, with its very high neutron flux and the broad range of scattering vectors covered in a single instrumental setting, allowed us for the first time to perform time-resolved scattering experiments in order to study the micelle-to-vesicle transition. The temporal evolution of the aggregate structures were followed and detailed information was obtained even on molecular length-scales. (author). 5 refs.

  20. Calibration and absolute normalization procedure of a new Deep Inelastic Neutron Scattering spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez Palomino, L.A.; Blostein, J.J. [Consejo Nacional de Investigaciones Cientificas y Tecnicas, Centro Atomico Bariloche and Instituto Balseiro, Comision Nacional de Energia Atomica, Universidad Nacional de Cuyo, 8400 Bariloche (Argentina); Dawidowski, J., E-mail: javier@cab.cnea.gov.ar [Consejo Nacional de Investigaciones Cientificas y Tecnicas, Centro Atomico Bariloche and Instituto Balseiro, Comision Nacional de Energia Atomica, Universidad Nacional de Cuyo, 8400 Bariloche (Argentina)

    2011-08-01

    We describe the calibration process of a new Deep Inelastic Neutron Scattering (DINS) spectrometer, recently implemented at the Bariloche Electron LINAC (Argentina), consisting in the determination of the incident neutron spectrum, dead-time and electronic delay of the data acquisition line, and detector bank efficiency. For this purpose, samples of lead, polyethylene and graphite of different sizes were employed. Their measured spectra were corrected by multiple scattering, attenuation and detector efficiency effects, by means of an ad hoc Monte Carlo code. We show that the corrected spectra are correctly scaled with respect to the scattering power of the tested materials within a 2% of experimental error, thus allowing us to define an experimental constant that links the arbitrary experimental scale (number of recorded counts per monitor counts) with the involved cross-sections. The present work also serves to analyze the existence of possible sources of systematic errors.

  1. Neutron diffraction and quasielastic neutron scattering studies of films of intermediate-length alkanes adsorbed on a graphite surface

    Science.gov (United States)

    Diama, Armand

    Over the past several years, we have conducted a variety of elastic neutron diffraction and quasielastic neutron scattering experiments to study the structure and the dynamics of films of two intermediate-length alkane molecules (C nH2n+2), adsorbed on a graphite basal-plane surface. The two molecules are the normal alkane n-tetracosane [n-CH 3(CH2)22CH3] and the branched alkane squalane (C30H62 or 2, 6, 10, 15, 19, 23-hexamethyltetracosane) whose carbon backbone is the same length as teteracosane. The temperature dependence of the monolayer structure of tetracosane and squalane was investigated using elastic neutron diffraction and evidence of two phase transitions was observed. Both the low-coverage tetracosane (C 24H50) and squalane (C30H62) monolayers have crystalline-to-"smectic" and "smectic"-to-isotropic fluid phase transitions upon heating. The diffusive motion in the tetracosane and squalane monolayers has been investigated by quasielastic neutron scattering. Two different quasielastic neutron scattering spectrometers at the Center for Neutron Research, National Institute of Standards and Technology (NIST) have been used. The spectrometers differ in both their dynamic range and energy resolution allowing molecular motions to be investigated on time scales in the range 10-13--10 -9 s. On these time scales, we observe evidence of translational, rotational, and intermolecular diffusive motions in the tetracosane and squalane monolayers. We conclude that the molecular diffusive motion in the two monolayers is qualitatively similar. Thus, despite the three methyl sidegroups at each end of the squalane molecule, its monolayer structure, phase transitions, and dynamics are qualitatively similar to that of a monolayer of the unbranched tetracosane molecules. With the higher resolution spectrometer at NIST, we have also investigated the molecular diffusive motion in multilayer tetracosane films. The analysis of our measurements indicates slower diffusive motion in

  2. EXPERIENCE WITH COLLABORATIVE DEVELOPMENT FOR THE SPALLATION NEUTRON SOURCE FROM A PARTNER LAB PERSPECTIVE.

    Energy Technology Data Exchange (ETDEWEB)

    HOFF, L.T.

    2005-10-10

    Collaborative development and operation of large physics experiments is fairly common. Less common is the collaborative development or operation of accelerators. A current example of the latter is the Spallation Neutron Source (SNS). The SNS project was conceived as a collaborative effort between six DOE facilities. In the SNS case, the control system was also developed collaboratively. The SNS project has now moved beyond the collaborative development phase and into the phase where Oak Ridge National Lab (ORNL) is integrating contributions from collaborating ''partner labs'' and is beginning accelerator operations. In this paper, the author reflects on the benefits and drawbacks of the collaborative development of an accelerator control system as implemented for the SNS project from the perspective of a partner lab.

  3. Recent neutron scattering research and development in India

    Indian Academy of Sciences (India)

    ... development laboratory are located at APSARA reactor. All the instruments including the detectors and electronics have been developed within BARC. A new powder diffractometer (PD-3) is being developed by UGC-DAE-CSR. The national facility is utilized in collaboration with various universities and other institutions.

  4. Nuclear structure of 76Se from inelastic neutron scattering measurements

    Science.gov (United States)

    Mukhopadhyay, Sharmistha

    2017-09-01

    The low-lying, low-spin levels of 76Se were studied with the (n,n' γ) reaction. Gamma-ray excitation function measurements were performed at incident neutron energies from 2.0 to 3.5 MeV, and γ-ray angular distributions were measured at neutron energies of 2.4, 3.0 and 3.7 MeV. From these measurements, level spins, level lifetimes, γ-ray intensities, and multipole mixing ratios were determined. Interpreting the nuclear structure of the stable Se nuclei is challenging, with shape transitions, shape coexistence, and triaxiality in evidence. The low-lying structure of 76Se appears to be the most vibrational of the Se isotopes, with a two-phonon (0+, 2+, 4+) triplet of collective states. In addition to these clearly collective excitations, we have identified and characterized a 4+ ->2+ ->0+ cascade of two E 2 transitions built on the first excited 0+ state at 1122 keV. The picture for 76Se thus differs from 72Se and 74Se, and indicates that the configuration mixing of this coexisting band is less than exhibited in the other Se nuclei. Comparison of the low-lying level schemes of 76Ge and 76Se, the double-beta decay daughter, shows a marked difference. This material is based upon work supported by the U.S. National Science Foundation under Grant No. PHY-1606890.

  5. Design of a facility for the in situ measurement of catalytic reaction by neutron scattering spectroscopy

    Science.gov (United States)

    Tan, Shuai; Cheng, Yongqiang; Daemen, Luke L.; Lutterman, Daniel A.

    2018-01-01

    Catalysis is a critical enabling science for future energy needs. The next frontier of catalysis is to evolve from catalyst discovery to catalyst design, and for this next step to be realized, we must develop new techniques to better understand reaction mechanisms. To do this, we must connect catalytic reaction rates and selectivities to the kinetics, energetics, and dynamics of individual elementary steps and relate these to the structure and dynamics of the catalytic sites involved. Neutron scattering spectroscopies offer unique capabilities that are difficult or impossible to match by other techniques. The current study presents the development of a compact and portable instrumental design that enables the in situ investigation of catalytic samples by neutron scattering techniques. The developed apparatus was tested at the Spallation Neutron Source (SNS) in Oak Ridge National Laboratory and includes a gas handling panel that allows for computer hookups to control the panel externally and online measurement equipment such as coupled GC-FID/TCD (Gas Chromatography-Flame Ionization Detector/Thermal Conductivity Detector) and MS (Mass Spectrometry) to characterize offgassing while the sample is in the neutron scattering spectrometer. This system is flexible, modular, compact, and portable enabling its use for many types of gas-solid and liquid-solid reactions at the various beamlines housed at the SNS.

  6. Nondestructive Evaluation on Hydrided LWR Fuel Cladding by Small Angle Incoherent Neutron Scattering of Hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Yong [ORNL; Qian, Shuo [ORNL; Littrell, Ken [ORNL; Parish, Chad M [ORNL; Bell, Gary L [ORNL; Plummer, Lee K [ORNL

    2013-01-01

    A non-destructive neutron scattering method was developed to precisely measure the uptake of total hydrogen in nuclear grade Ziraloy-4 cladding. The hydriding apparatus consists of a closed stainless steel vessel that contains Zr alloy specimens and H gas. By controlling the initial H gas pressure in the vessel and the temperature profile, target H concentrations from tens of ppm to a few thousands of wppm have been successfully achieved. Following H charging, the H content of the hydrided specimens was measured using the vacuum hot extraction method (VHE), by which the samples with desired H concentration were selected for the neutron study. Small angle neutron incoherent scattering (SANIS) were performed in the High Flux Isotope Reactor at Oak Ridge national Laboratory (ORNL). Our study indicates that a very small amount ( 20 ppm) H in commercial Zr cladding can be measured very accurately in minutes for a wide range of H concentration by a nondestructive method. The H distribution in a tube sample was obtained by scaling the neutron scattering rate with a factor, which is determined by calibration process with direct chemical analysis method on the specimen. This scale factor can be used for future test with unknown H concentration, thus provide a nondestructive method for absolute H concentration determination.

  7. Small angle neutron scattering study of two nonionic surfactants in ...

    Indian Academy of Sciences (India)

    I(q)qr sin(qr)dq which yields the pair distance distribution function p(r), where r is the distance in real space. The point, at which the p(r) falls to zero, is indicative of the particle maximum dimension. 3. Results and discussion. Few scattering curves of C14E7+D2O as a function of temperature for concentration c = 0.17% ...

  8. The Prospect of Neutron Scattering In the 21st Century: A Powerful Tool for Materials Research

    Directory of Open Access Journals (Sweden)

    E. Kartini

    2007-07-01

    Full Text Available Over the last 60 years research reactors (RRs have played an important role in technological and socio-economical development of mankind, such as radioisotope production for medicine, industry, research and education. Neutron scattering has been widely used for research and development in materials science. The prospect of neutron scattering as a powerful tool for materials research is increasing in the 21st century. This can be seen from the investment of several new neutron sources all over the world such as the Spallation Neutron Source (SNS in USA, the Japan Proton Accelerator Complex (JPARC in Japan, the new OPAL Reactor in Australia, and some upgrading to the existing sources at ISIS, Rutherford Appleton Laboratory, UK; Institute of Laue Langevin (ILL in Grenoble, France and Berlin Reactor, Germany. Developing countries with moderate flux research reactor have also been involved in this technique, such as India, Malaysia and Indonesia. The Siwabessy Multipurpose Reactor in Serpong, Indonesia that also produces thermal neutron has contributed to the research and development in the Asia Pacific Region. However, the international joint research among those countries plays an important role on optimizing the results.

  9. Review of the Lujan neutron scattering center: basic energy sciences prereport February 2009

    Energy Technology Data Exchange (ETDEWEB)

    Hurd, Alan J [Los Alamos National Laboratory; Rhyne, James J [Los Alamos National Laboratory; Lewis, Paul S [Los Alamos National Laboratory

    2009-01-01

    The Lujan Neutron Scattering Center (Lujan Center) at LANSCE is a designated National User Facility for neutron scattering and nuclear physics studies with pulsed beams of moderated neutrons (cold, thermal, and epithermal). As one of five experimental areas at the Los Alamos Neutron Science Center (LANSCE), the Lujan Center hosts engineers, scientists, and students from around the world. The Lujan Center consists of Experimental Room (ER) 1 (ERl) built by the Laboratory in 1977, ER2 built by the Office of Basic Energy Sciences (BES) in 1989, and the Office Building (622) also built by BES in 1989, along with a chem-bio lab, a shop, and other out-buildings. According to a 1996 Memorandum of Agreement (MOA) between the Defense Programs (DP) Office of the National Nuclear Security Agency (NNSA) and the Office of Science (SC, then the Office of Energy Research), the Lujan Center flight paths were transferred from DP to SC, including those in ERI. That MOA was updated in 2001. Under the MOA, NNSA-DP delivers neutron beam to the windows of the target crypt, outside of which BES becomes the 'landlord.' The leveraging nature of the Lujan Center on the LANSCE accelerator is a substantial annual leverage to the $11 M BES operating fund worth approximately $56 M operating cost of the linear accelerator (LINAC)-in beam delivery.

  10. Measurements of elastic scattering cross sections of carbon, iron and lead for 75 MeV Neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Ibaraki, Masanobu; Baba, Mamoru; Nauchi, Yasushi; Miura, Takako; Hirasawa, Yoshitaka; Hirakawa, Naohiro [Department of Quantum Science and Energy Engineering, Tohoku University, Sendai, Miyagi (Japan); Nakashima, Hiroshi; Meigo, Shin-ichiro; Tanaka, Susumu

    1999-03-01

    We have performed the measurements of elastic scattering cross sections of carbon, iron and lead for 75 MeV neutrons using a {sup 7}Li(p, n) quasi-monoenergetic neutron source. Elastically scattered neutrons were measured with a time of flight method (TOF) using five liquid scintillation detectors. The data were obtained at 25 laboratory angles between 2.6deg and 53.0deg. The experimental data were compared with the neutron cross section libraries, systematics used in cascade/transport codes and optical model calculations. (author)

  11. Preparation and characterisation of magnetic nanostructured samples for inelastic neutron scattering experiments

    Energy Technology Data Exchange (ETDEWEB)

    Kreuzpaintner, Wolfgang

    2010-06-22

    Recent advances in thin-film structuring techniques have generated significant interest in the dynamics of spin waves in magnetic nanostructures and the possible use of inelastic neutron scattering (INS) for their investigation. This thesis describes the design and implementation, at GKSS Research Centre, of equipment for preparation of large and laterally submicron and nanometre structured magnetic samples for such future INS experiments. After a brief resume on spin waves in nanostructures, the development work on new purpose-designed equipment, including high vacuum (HV) argon ion beam milling and ultra high vacuum (UHV) e-beam evaporation setups, is described. Ni nanodot as well as Ni and novel Gd nanowire samples were prepared using combinations of sputter deposition, laser interference lithography, argon ion beam milling, e-beam evaporation and self organisation techniques. With reference to sample preparation, epitaxial growth studies for Ni on Si(100) substrate were performed, resulting in the development of a new deposition process, which by thermal tuning allows for the direct epitaxial growth of Ni on Si with unprecedented crystalline quality. The results of various characterisation experiments on the prepared nanostructured samples, including Scanning Electron Microscopy (SEM), microprobe analysis, Atomic and Magnetic Force Microscopy (AFM/MFM), Vibrating Sample Magnetometry (VSM), X-ray Diffraction (XRD) and Reflectivity (XRR), unpolarised and Polarised Neutron Scattering (PNR) and off-specular scattering by X-rays and neutrons using rocking scans and Time-Of-Flight Grazing Incidence Small Angle Neutron Scattering (TOF-GISANS), together with various analysis procedures such as Distorted-Wave Born Approximation (DWBA), are reported. The analysis of a Gd nanowire sample by TOF-GISANS led to a novel evaluation technique which in comparison with single wavelength methods allows portions of reciprocal space to be scanned without changing the angle of

  12. Monte Carlo simulations of neutron-scattering instruments using McStas

    DEFF Research Database (Denmark)

    Nielsen, K.; Lefmann, K.

    2000-01-01

    Monte Carlo simulations have become an essential tool for improving the performance of neutron-scattering instruments, since the level of sophistication in the design of instruments is defeating purely analytical methods. The program McStas, being developed at Rise National Laboratory, includes...... an extension language that makes it easy to adapt it to the particular requirements of individual instruments, and thus provides a powerful and flexible tool for constructing such simulations. McStas has been successfully applied in such areas as neutron guide design, flux optimization, non-Gaussian resolution...

  13. Phonons in Solid Hydrogen and Deuterium Studied by Inelastic Coherent Neutron Scattering

    DEFF Research Database (Denmark)

    Nielsen, Mourits

    1973-01-01

    Phonon dispersion relations have been measured by coherent neutron scattering in solid para-hydrogen and ortho-deuterium. The phonon energies are found to be nearly equal in the two solids, the highest energy in each case lying close to 10 meV. The pressure and temperature dependence of the phonon...... energies have been measured in ortho-deuterium and the lattice change determined by neutron diffraction. When a pressure of 275 bar is applied, the phonon energies are increased by about 10%, and heating the crystal to near the melting point decreases them by about 7%. The densities of states, the specific...

  14. Analysing neutron scattering data using McStas virtual experiments

    Energy Technology Data Exchange (ETDEWEB)

    Udby, L., E-mail: udby@fys.ku.d [University of Copenhagen, Nanoscience and Escience Centers, Niels Bohr Institute, Universitetsparken 5, DK-2100 (Denmark); Willendrup, P.K.; Knudsen, E. [Riso National Laboratory for Sustainable Energy, Technical University of Denmark, Materials Research Division, Frederiksborgvej 399, DK-4000 (Denmark); Niedermayer, Ch. [Laboratory for Neutron Scattering, Paul Scherrer Institute, 5232 Villigen PSI (Switzerland); Filges, U. [Laboratory for Developments and Methods, Paul Scherrer Institute, 5232 Villigen PSI (Switzerland); Christensen, N.B. [Riso National Laboratory for Sustainable Energy, Technical University of Denmark, Materials Research Division, Frederiksborgvej 399, DK-4000 (Denmark); Farhi, E. [Institut Laue-Langevin, 6, rue Jules Horowitz, F-38042 Grenoble Cedex 9 (France); Wells, B.O. [Department of Physics, University of Connecticut, 2152 Hillside Road, U-3046, CT 06269-3046 (United States); Lefmann, K. [University of Copenhagen, Nanoscience and Escience Centers, Niels Bohr Institute, Universitetsparken 5, DK-2100 (Denmark); ESS, University of Lund, St. Algatan 4 (Sweden)

    2011-04-01

    With the intention of developing a new data analysis method using virtual experiments we have built a detailed virtual model of the cold triple-axis spectrometer RITA-II at PSI, Switzerland, using the McStas neutron ray-tracing package. The parameters characterising the virtual instrument were carefully tuned against real experiments. In the present paper we show that virtual experiments reproduce experimentally observed linewidths within 1-3% for a variety of samples. Furthermore we show that the detailed knowledge of the instrumental resolution found from virtual experiments, including sample mosaicity, can be used for quantitative estimates of linewidth broadening resulting from, e.g., finite domain sizes in single-crystal samples.

  15. Backward-forward reaction asymmetry of neutron elastic scattering on deuterium

    Science.gov (United States)

    Pirovano, E.; Beyer, R.; Junghans, A. R.; Nankov, N.; Nolte, R.; Nyman, M.; Plompen, A. J. M.

    2017-02-01

    A new measurement of the angular distribution of neutron elastic scattering on deuterium was carried out at the neutron time-of-flight facility nELBE. The backward-forward asymmetry of the reaction was investigated via the direct detection of neutrons scattered at the laboratory angle of 15∘ and 165∘ from a polyethylene sample enriched with deuterium. In order to extend the measurement to neutron energies below 1 MeV, 6Li glass scintillators were employed. The data were corrected for the background and the multiple scattering in the target, the events due to scattering on deuterium were separated from those due to carbon, and the ratio of the differential cross section at 15∘ and 165∘ was determined. The results, covering the energy range from 200 keV to 2 MeV, were found to be in agreement with the theoretical predictions calculated by Canton et al. [Eur. Phys. J. A 14, 225 (2002)], 10.1140/epja/i2001-10122-3 and by Golak et al. [Eur. Phys. J. A 50, 177 (2014)], 10.1140/epja/i2014-14177-7. The comparison with the evaluated nuclear data libraries indicated CENDL-3.1, JEFF-3.2, and JENDL-4.0 as the evaluations that best describe the asymmetry of n -d scattering. ENDF/B-VII.1 is compatible with the data for energies below 700 keV, but above the backward to forward ratio is higher than measured. ROSFOND-2010 and BROND-2.2 resulted to have little compatibility with the data.

  16. Neutron scattering. Annual progress report 1997; Neutronenstreuung. Annual progress report 1997

    Energy Technology Data Exchange (ETDEWEB)

    Allenspach, P.; Boeni, B.; Fischer, P.; Furrer, A. [Eidgenoessische Technische Hochschule, Zurich (Switzerland). Lab. fuer Neutronenstreuung

    1998-02-01

    The present progress report describes the scientific and technical activities obtained by LNS staff members in 1997. It also includes the work performed by external groups at our CRG instruments D1A and IN3 at the ILL Grenoble. Due to the outstanding properties of neutrons and x-rays the research work covered many areas of science and materials research. The highlight of the year 1997 was certainly the production of neutrons at the new spallation neutron source SINQ. From July to November, SINQ was operating for typically two days/week and allowed the commissioning of four instruments at the neutron guide system: - the triple-axis spectrometer Druechal, - the powder diffractometer DMC, - the double-axis diffractometer TOPSI, the polarised triple-axis spectrometer TASP. These instruments are now fully operational and have already been used for condensed matter studies, partly in cooperation with external groups. Five further instruments are in an advanced state, and their commissioning is expected to occur between June and October 1998: - the high-resolution powder diffractometer HRPT, - the single-crystal diffractometer TriCS, - the time-of-flight spectrometer FOCUS, - the reflectometer AMOR, - the neutron optical bench NOB. Together with the small angle neutron scattering facility SANS operated by the spallation source department, all these instruments will be made available to external user groups in the future. (author) figs., tabs., refs.

  17. Secondary relaxation in two engineering thermoplastics by neutron scattering and dielectric spectroscopy

    CERN Document Server

    Arrese, S; Alegria, A; Colmenero, J; Frick, B

    2002-01-01

    We present a preliminary investigation of the dynamics of glassy polycarbonate (PC) and polysulfone (PSF) by means of quasielastic neutron scattering and dielectric spectroscopy. Whereas the consideration of pure phenylene ring pi-flips is enough to explain the momentum-transfer (Q) dependence of the inelastic intensity measured for PSF, in the case of PC the Q dependence of both the coherent and the incoherent scattering functions reveal the existence in this polymer of some more complex motion of the phenylene ring. On the other hand, the similarity of the energy landscapes deduced from the different techniques points to a closely related molecular origin for all the relaxation/motions observed. (orig.)

  18. Small-angle neutron scattering from poly(NIPA-co-AMPS) gels

    DEFF Research Database (Denmark)

    Travas-Sejdic, J.; Easteal, A.; Knott, R.

    2000-01-01

    The microstructure of the poly( N-isopropylacrylamide-co-acrylamido- 2-methyl-1-propane sulphonic acid) gel, poly( NIPA-co-AMPS), was investigated as a function of temperature and cross-link density using the small angle neutron scattering technique. The sample temperature was varied in the range...... 30 to 55C. Two different behaviours of poly( NIPA-co-AMPS) gels were observed. At low temperature (30C), the magnitude of the scattered intensity increased with cross-link density suggesting that additional cross-links introduced more inhomogeneities in the gel network. At high temperatures the trend...

  19. Neutron Scattering Studies of Pre-Transitional Effects in Solid-Solid Phase Transformations

    Energy Technology Data Exchange (ETDEWEB)

    Shapiro, S. M.

    1999-06-30

    Neutron scattering studies have played a fundamental role in understanding solid-solid phase transformations, particularly in studying the lattice dynamical behavior associated with precursor effects. A review of the studies performed on solids exhibiting Martensitic transformations is given below. The mode softening and associated elastic diffuse scattering, previously observed in NiAl alloys, will be discussed as well as more recent work on Ni{sub 2}MnGa, a system exhibiting magnetic order as well as a Martensitic transformation. Also, new results on the precursor effects in ordered and disordered FePt alloys will be presented.

  20. Quasielastic Diffuse Neutron Scattering from Fluorites in the Fast Ion Phase

    DEFF Research Database (Denmark)

    Clausen, K.; Hayes, W.; Hutchings, M.T

    1981-01-01

    Quasielastic diffuse coherent neutron scattering arising from the dynamically disordered anions in CaF2 and PbF2 has been investigated as the temperature is increased into the fast ion phase. The characteristic variation with scattering vector Image of the integrated intensity, S(Image ), can...... be accounted for by a model in which the most probable instantaneous configuration of the defective anions is a cluster centered at the mid-point of nearest-neighbour regular anion sites. The observed S(Image ,ω) is Lorentzian in ω and the width has a marked increase with temperature....

  1. Impact of anisotropic atomic motions in proteins on powder-averaged incoherent neutron scattering intensities

    Science.gov (United States)

    Kneller, Gerald R.; Chevrot, Guillaume

    2012-12-01

    This paper addresses the question to which extent anisotropic atomic motions in proteins impact angular-averaged incoherent neutron scattering intensities, which are typically recorded for powder samples. For this purpose, the relevant correlation functions are represented as multipole series in which each term corresponds to a different degree of intrinsic motional anisotropy. The approach is illustrated by a simple analytical model and by a simulation-based example for lysozyme, considering in both cases the elastic incoherent structure factor. The second example shows that the motional anisotropy of the protein atoms is considerable and contributes significantly to the scattering intensity.

  2. Oxygen Monolayers Adsorbed on Graphite Studied by Neutron Scattering

    DEFF Research Database (Denmark)

    Nielsen, Mourits; McTague, J. P.

    1979-01-01

    The phase diagram of absorbed films of O2 molecules on (002) surfaces of graphite has been measured in the range of densities from submonolayer to 1.6 monolayer. This system is particularly interesting because it orders magnetically below 11.9 K for dense monolayer and higher coverages. This magn......The phase diagram of absorbed films of O2 molecules on (002) surfaces of graphite has been measured in the range of densities from submonolayer to 1.6 monolayer. This system is particularly interesting because it orders magnetically below 11.9 K for dense monolayer and higher coverages....... This magnetic order is observed both through the antiferromagnetic-superstructure-Bragg reflection as well as through the accompanying magnetostrictive distortion which is seen as a splitting of the nuclear Bragg scattering peak. In all, three distinct two-dimensionally ordered phases have been found, each...

  3. Ab initio simulations and neutron scattering studies of structure and dynamics in PdH

    CERN Document Server

    Totolici, I E

    2001-01-01

    The work presented in this PhD thesis is concerned with the interpretation of the neutron scattering measurements from the palladium hydrogen system by means of ab initio electronic structure calculations. The motivation of performing such calculations was due to recent neutron scattering studies on this system that showed a strong directional dependence to the dynamical structure factor together with a complex dependence on energy. Here we attempt to describe the origin of these features by ab initio simulations of the dynamical structure factor. The method assumes an adiabatic separation of the motion of the proton and palladium atoms. The proton wave functions are calculated by a direct solution of the associated single-particle Schroedinger equation using a plane wave basis set method and a mapping of the adiabatic surface. The Fourier components of the adiabatic potential are obtained from LDA pseudopotential calculations. Using Fermi's golden rule within the Born approximation we were then able to calcu...

  4. Molecular Dynamics and Neutron Scattering Studies of Mixed Solutions of Caffeine and Pyridine in Water.

    Science.gov (United States)

    Tavagnacco, Letizia; Mason, Philip E; Neilson, George W; Saboungi, Marie-Louise; Cesàro, Attilio; Brady, John W

    2017-11-01

    Insight into the molecular interactions of homotactic and heterotactic association of caffeine and pyridine in aqueous solution is given based on both experimental and simulation studies. Caffeine is about 5 times more soluble in a 3 m aqueous pyridine solution than it is in pure water (an increase from ~0.1 m to 0.5 m). At this elevated concentration the system becomes suitable for neutron scattering study. Caffeine-pyridine interactions were studied by neutron scattering and molecular dynamics simulations, allowing a detailed characterization of the spatial and orientational structure of the solution. It was found that while pyridine-caffeine interactions are not as strong as caffeine-caffeine interactions, the pyridine-caffeine interactions still significantly disrupted caffeine-caffeine stacking. The alteration of the caffeine-caffeine stacking, occasioned by the presence of pyridine molecules in solution and the consequent formation of heterotactic interactions, leads to the experimentally-detected increase in caffeine solubility.

  5. Neutron scattering study of 36 Ar monolayer films adsorbed on graphite

    DEFF Research Database (Denmark)

    Taub, H.; da Costa Carneiro, Kim; Kjems, Jørgen

    1977-01-01

    Diffraction of neutrons from 36 Ar monolayers adsorbed on graphite basal planes indicates that an ordered, two-dimensional (2D) triangular lattice is formed at low temperature. The lattice constant is found to be slightly larger than that of the bulk 3D solid but significantly smaller than...... surfaces at low temperatures) are observed to decrease smoothly above 40 K, falling from 100 to 15 Å at 80 K. Little if any positional order remains at temperatures where the nearest-neighbor distance in the monolayer matches that of a registered √3×√3 phase. The spectrum of neutrons inelastically...... scattered from 36 Ar monolayers in the nominally in-plane configuration can be reasonably well described at low temperatures by a 2D harmonic-phonon model while the scattering in the out-of-plane configuration seems to be best represented in terms of a resonant coupling of the monolayer film to out...

  6. Neutron scattering study of adsorption in porous MCM-41 silica{sup 1}

    Energy Technology Data Exchange (ETDEWEB)

    Brown, R.J.C. [Queen' s Univ., Chemistry Dept., Kingston, ON (Canada); Evans, M.J.B. [Royal Military Coll., Dept. of Chemistry and Chemical Engineering, Kingston, ON (Canada); Tun, Z., E-mail: zin.tun@nrc.gc.ca [Canadian Neutron Beam Centre, National Research Council Canada, Chalk River, ON (Canada)

    2010-10-15

    Adsorption of n-pentane on MCM-41 silica has been studied by neutron scattering on both the adsorption and desorption isotherms. Adsorption takes place without hysteresis in either the isotherm or the neutron scattering profile. Adsorption of contrast-matched pentane in porous MCM-41 silica at first increases the intensity of the (10) Bragg peak but reduces the (11) and (20) peaks, and as the pores are filled the intensities of all Bragg peaks are reduced to zero. The SANS background has a 1/Q dependence, typical of a material prepared with templates of one-dimensional character (cylinders). The initial increase of (10) intensity allows estimation of the cylindrical pore diameter to be 37 AÅ based on the variation of form factor as a function of the cylinder radius. (author)

  7. Neutron Scattering in Hydrogenous Moderators, Studied by Time Dependent Reaction Rate Method

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, L.G.; Moeller, E.; Purohit, S.N.

    1966-03-15

    The moderation and absorption of a neutron burst in water, poisoned with the non-1/v absorbers cadmium and gadolinium, has been followed on the time scale by multigroup calculations, using scattering kernels for the proton gas and the Nelkin model. The time dependent reaction rate curves for each absorber display clear differences for the two models, and the separation between the curves does not depend much on the absorber concentration. An experimental method for the measurement of infinite medium reaction rate curves in a limited geometry has been investigated. This method makes the measurement of the time dependent reaction rate generally useful for thermalization studies in a small geometry of a liquid hydrogenous moderator, provided that the experiment is coupled to programs for the calculation of scattering kernels and time dependent neutron spectra. Good agreement has been found between the reaction rate curve, measured with cadmium in water, and a calculated curve, where the Haywood kernel has been used.

  8. A new small-angle neutron scattering spectrometer at China Mianyang research reactor

    Science.gov (United States)

    Peng, Mei; Sun, Liangwei; Chen, Liang; Sun, Guangai; Chen, Bo; Xie, Chaomei; Xia, Qingzhong; Yan, Guanyun; Tian, Qiang; Huang, Chaoqiang; Pang, Beibei; Zhang, Ying; Wang, Yun; Liu, Yaoguang; Kang, Wu; Gong, Jian

    2016-02-01

    A new pinhole small-angle neutron scattering (SANS) spectrometer, installed at the cold neutron source of the 20 MW China Mianyang Research Reactor (CMRR) in the Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, has been put into use since 2014. The spectrometer is equipped with a multi-blade mechanical velocity selector, a multi-beam collimation system, and a two-dimensional He-3 position sensitive neutron detector. The q-range of the spectrometer covers from 0.01 nm-1 to 5.0 nm-1. In this paper, the design and characteristics of the SANS spectrometer are described. The q-resolution calculations, together with calibration measurements of silver behenate and a dispersion of nearly monodisperse poly-methyl-methacrylate nanoparticles indicate that our SANS spectrometer has a good performance and is now in routine service.

  9. Tagged spectator deep-inelastic scattering off the deuteron as a tool to study neutron structure

    Directory of Open Access Journals (Sweden)

    Cosyn Wim

    2016-01-01

    Full Text Available We give an overview of a model to describe deep-inelastic scattering (DIS off the deuteron with a spectator proton, based on the virtual nucleon approximation (VNA. The model accounts for the final-state interactions (FSI of the DIS debris with the spectator proton. Values of the rescattering cross section are obtained by fits to high-momentum spectator data. By using the so-called “pole extrapolation” method, free neutron structure functions can be obtained by extrapolating low-momentum spectator proton data to the on-shell neutron pole. We apply this method to the BONuS data set and find a surprising Bjorken x dependence, indicating a possible rise of the neutron to proton structure function ratio at high x.

  10. Magnetic design of a spin-echo small-angle neutron-scattering instrument

    CERN Document Server

    Uca, O; Rekveldt, M T

    2003-01-01

    In a spin-echo small-angle neutron scattering instrument dipole magnets and guide field coils are used. The homogeneity of the fields should be sufficient to have linear labeling of the height with precession. Furthermore, the instrument must have a homogenous line integral over the beam cross-section. It is shown that line integral inhomogeneities are directly connected to field components perpendicular to the main field. The design parameters of these magnetic units of the setup are calculated.

  11. Functional materials analysis using in situ and in operando X-ray and neutron scattering.

    Science.gov (United States)

    Peterson, Vanessa K; Papadakis, Christine M

    2015-03-01

    In situ and in operando studies are commonplace and necessary in functional materials research. This review highlights recent developments in the analysis of functional materials using state-of-the-art in situ and in operando X-ray and neutron scattering and analysis. Examples are given covering a number of important materials areas, alongside a description of the types of information that can be obtained and the experimental setups used to acquire them.

  12. Functional materials analysis using in situ and in operando X-ray and neutron scattering

    Directory of Open Access Journals (Sweden)

    Vanessa K. Peterson

    2015-03-01

    Full Text Available In situ and in operando studies are commonplace and necessary in functional materials research. This review highlights recent developments in the analysis of functional materials using state-of-the-art in situ and in operando X-ray and neutron scattering and analysis. Examples are given covering a number of important materials areas, alongside a description of the types of information that can be obtained and the experimental setups used to acquire them.

  13. Functional materials analysis using in situ and in operando X-ray and neutron scattering

    Science.gov (United States)

    Peterson, Vanessa K.; Papadakis, Christine M.

    2015-01-01

    In situ and in operando studies are commonplace and necessary in functional materials research. This review highlights recent developments in the analysis of functional materials using state-of-the-art in situ and in operando X-ray and neutron scattering and analysis. Examples are given covering a number of important materials areas, alongside a description of the types of information that can be obtained and the experimental setups used to acquire them. PMID:25866665

  14. Characterization of conformational properties of protein/trehalose/water system by neutron scattering

    CERN Document Server

    Brandt, A; Mangione, A; Migliardo, F; Vertessy, B G

    2002-01-01

    In this contribution we report results of a small-angle neutron scattering (SANS) investigation of dUTPase/D sub 2 O solutions. Data were collected by the V4 spectrometer at the BENSC facility (Berlin, Germany). The results allow us to characterize the conformational properties of the protein in solution as a function of temperature and in the presence of trehalose, a disaccharide with a noticeable bioprotective action. (orig.)

  15. Interface and surface formation in self-assembled polymer multilayers by off-specular neutron scattering

    CERN Document Server

    Lauter-Pasyuk, V; Toperverg, B P; Petrenko, A; Aksenov, V; Schubert, D; Schreiber, J; Burcin, M

    2002-01-01

    Free-surface and interface properties of a polystyrene-polybuthylmethacrylate multilayer film are studied by neutron specular reflection and off-specular scattering. Experimental data collected over a broad range of incoming and outgoing wave vectors are fitted by a theoretical model that delivers a set of parameters characterizing the state of the outermost layer as well as the conformal roughness of the interfaces. (orig.)

  16. Small angle X-ray and neutron scattering from solutions of biological macromolecules

    CERN Document Server

    Svergun, Dmitri I; May, Roland P; Timmins, Peter A

    2013-01-01

    In this book, following the presentation of the basics of scattering from isotropic macromolecular solutions, modern instrumentation, experimental practice and advanced analysis techniques are explained. Advantages of X-rays (rapid data collection, small sample volumes) and of neutrons (contrast variation by hydrogen/deuterium exchange) are specifically highlighted. Examples of applications of the technique to different macromolecular systems are considered with specific emphasis on the synergistic use of SAXS/SANS with other structural, biophysical and computational techniques.

  17. A Study of the Spin Structure on the Neutron in Deep Inelastic Scattering of Polarized Electrons on Polarized Neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Spengos, M

    2004-01-06

    The internal spin structure of the neutron, was studied in deep inelastic scattering of longitudinally polarized electrons from a polarized {sup 3}He target in the End Station A of the Stanford Linear Accelerator Center (SLAC). The spin asymmetry of the neutron was measured at energies between 19 and 26 GeV in the range 0.03 {le} x {le} 0.06 at an average Q{sup 2} of 2 (GeV/c){sup 2}. The results are in agreement with a new measurement of the asymmetry by SMC within their six times larger uncertainties. The spin dependent structure function g{sub 1}(x) for the neutron was determined from the asymmetry measurement and, its integral over x is found to be {integral}g{sub 1}{sup n}(x)dx = -0.038 {+-} 0.009. This result is 2.7 standard deviations from the Ellis-Jaffe Sum Rule and combined with the EMC results from the proton in very good agreement with the Bjorken Sum Rule. In the Quark Parton Model (QPM), in conjunction with the weak coupling constants F and D, from baryon decay, the result implies that the quarks contribute approximately 32% of the nucleon helicity. Finally, different ways of evolving the data, based on various theoretical models, is attempted and future aspects for spin physics, with emphasis at spin physics at SLAC, are discussed.

  18. Neutron scattering to study membrane systems: from lipid vesicles to living cells.

    Energy Technology Data Exchange (ETDEWEB)

    Myles, Dean A A [ORNL; Standaert, Robert F. [ORNL; Stanley, Christopher B. [ORNL; Cheng, Xiaolin [ORNL; Elkins, James G. [ORNL; Katsaras, John [ORNL; Qian, Shuo [ORNL; Nickels, Jonathan D. [ORNL; Chatterjee, Sneha [ORNL

    2017-03-01

    The existence and role of lateral lipid organization in biological membranes has been studied and contested for more than 30 years. Lipid domains, or rafts, are hypothesized as scalable compartments in biological membranes, providing appropriate physical environments to their resident membrane proteins. This implies that lateral lipid organization is associated with a range of biological functions, such as protein co-localization, membrane trafficking, and cell signaling, to name just a few. Neutron scattering techniques have proven to be an excellent tool to investigate these structural features in model lipids, and more recently, in living cells. I will discuss our recent work using neutrons to probe the structure and mechanical properties in model lipid systems and our current efforts in using neutrons to probe the structure and organization of the bilayer in a living cell. These efforts in living cells have used genetic and biochemical strategies to generate a large neutron scattering contrast, making the membrane visible. I will present our results showing in vivo bilayer structure and discuss the outlook for this approach.

  19. Method for improving the angular resolution of a neutron scatter camera

    Science.gov (United States)

    Mascarenhas, Nicholas; Marleau, Peter; Gerling, Mark; Cooper, Robert Lee; Mrowka, Stanley; Brennan, James S.

    2012-12-25

    An instrument that will directly image the fast fission neutrons from a special nuclear material source wherein the neutron detection efficiency is increased has been described. Instead of the previous technique that uses a time-of-flight (TOF) between 2 widely spaced fixed planes of neutron detectors to measure scatter neutron kinetic energy, we now use the recoil proton energy deposited in the second of the 2 scatter planes which can now be repositioned either much closer together or further apart. However, by doubling the separation distance between the 2 planes from 20 cm to a distance of 40 cm we improved the angular resolution of the detector from about 12.degree. to about 10.degree.. A further doubling of the separation distance to 80 cm provided an addition improvement in angular resolution of the detector to about 6.degree. without adding additional detectors or ancillary electronics. The distance between planes also may be dynamically changed using a suitable common technique such as a gear- or motor-drive to toggle between the various positions. The angular resolution of this new configuration, therefore, is increased at the expanse of detection sensitivity. However, the diminished sensitivity may be acceptable for those applications where the detector is able to interrogate a particular site for an extended period.

  20. Estimation of quantum correlations in magnetic materials by neutron scattering data

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ben-Qiong, E-mail: losenq@caep.cn [Key Laboratory of Neutron Physics, Institute of Nuclear Physics and Chemistry, CAEP, Mianyang 621900 (China); Wu, Lian-Ao, E-mail: lianaowu@gmail.com [Department of Theoretical Physics and History of Science, The Basque Country University (EHU/UPV), PO Box 644, 48080 Bilbao (Spain); IKERBASQUE, Basque Foundation for Science, 48011 Bilbao (Spain); Zeng, Guo-Mo [College of Physics, Jilin University, Changchun 130012 (China); Song, Jian-Ming; Luo, Wei; Lei, Yang; Sun, Guang-Ai; Chen, Bo; Peng, Shu-Ming [Key Laboratory of Neutron Physics, Institute of Nuclear Physics and Chemistry, CAEP, Mianyang 621900 (China)

    2014-10-24

    We demonstrate that inelastic neutron scattering technique can be used to indirectly detect and measure the macroscopic quantum correlations quantified by both entanglement and discord in a quantum magnetic material, VODPO{sub 4}⋅1/2 D{sub 2}O. The amount of quantum correlations is obtained by analyzing the neutron scattering data of magnetic excitations in isolated V{sup 4+} spin dimers. Our quantitative analysis shows that the critical temperature of this material can reach as high as T{sub c}=82.5 K, where quantum entanglement drops to zero. Significantly, quantum discord can even survive at T{sub c}=300 K and may be used in room temperature quantum devices. Taking into account the spin–orbit (SO) coupling, we also predict theoretically that entanglement can be significantly enhanced and the critical temperature T{sub c} increases with the strength of spin–orbit coupling. - Highlights: • We predict macroscopic quantum correlations in VODPO{sub 4} ⋅ 0.5D{sub 2}O by analyzing neutron scattering experimental data. • The critical temperature of VODPO{sub 4} ⋅ 0.5D{sub 2}O can reach as high as 82.5 K, where entanglement drops to 0. • Quantum discord can even survive at room temperature. • Entanglement can be enhanced and the critical temperature increases with the strength of DM interaction.

  1. The role of momentum transfer during incoherent neutron scattering is explained by the energy landscape model.

    Science.gov (United States)

    Frauenfelder, Hans; Young, Robert D; Fenimore, Paul W

    2017-05-16

    We recently introduced a model of incoherent quasielastic neutron scattering (QENS) that treats the neutrons as wave packets of finite length and the protein as a random walker in the free energy landscape. We call the model ELM for "energy landscape model." In ELM, the interaction of the wave packet with a proton in a protein provides the dynamic information. During the scattering event, the momentum [Formula: see text] is transferred by the wave packet to the struck proton and its moiety, exerting the force [Formula: see text] The resultant energy [Formula: see text] is stored elastically and returned to the neutron as it exits. The energy is given by [Formula: see text], where [Formula: see text] is the ambient temperature and [Formula: see text] ([Formula: see text] 91 K Å) is a new elastobaric coefficient. Experiments yield the scattering intensity (dynamic structure factor) [Formula: see text] as a function of [Formula: see text] and [Formula: see text] To test our model, we use published data on proteins where only thermal vibrations are active. ELM competes with the currently accepted theory, here called the spatial motion model (SMM), which explains [Formula: see text] by motions in real space. ELM is superior to SMM: It can explain the experimental angular and temperature dependence, whereas SMM cannot do so.

  2. Antiferromagnetism, crystal fields and hybridisation in UxY1-xPd3 studied by neutron scattering

    DEFF Research Database (Denmark)

    Bull, M.J.; McEwen, K.A.; Eccleston, R.S.

    1999-01-01

    We summarise our UxY1-xPd3 inelastic neutron scattering experiments and present new neutron diffraction results for a single crystal of U0.45Y0.55Pd3. Long-range antiferromagnetic order is unambiguously observed below T-N = 22.5 K. in contrast, no long-range order is found in polycrystalline...

  3. Neutron production from beam-modifying devices in a modern double scattering proton therapy beam delivery system

    Science.gov (United States)

    Pérez-Andújar, Angélica; Newhauser, Wayne D; DeLuca, Paul M

    2014-01-01

    In this work the neutron production in a passive beam delivery system was investigated. Secondary particles including neutrons are created as the proton beam interacts with beam shaping devices in the treatment head. Stray neutron exposure to the whole body may increase the risk that the patient develops a radiogenic cancer years or decades after radiotherapy. We simulated a passive proton beam delivery system with double scattering technology to determine the neutron production and energy distribution at 200 MeV proton energy. Specifically, we studied the neutron absorbed dose per therapeutic absorbed dose, the neutron absorbed dose per source particle and the neutron energy spectrum at various locations around the nozzle. We also investigated the neutron production along the nozzle's central axis. The absorbed doses and neutron spectra were simulated with the MCNPX Monte Carlo code. The simulations revealed that the range modulation wheel (RMW) is the most intense neutron source of any of the beam spreading devices within the nozzle. This finding suggests that it may be helpful to refine the design of the RMW assembly, e.g., by adding local shielding, to suppress neutron-induced damage to components in the nozzle and to reduce the shielding thickness of the treatment vault. The simulations also revealed that the neutron dose to the patient is predominated by neutrons produced in the field defining collimator assembly, located just upstream of the patient. PMID:19147903

  4. The hydrogen anomaly in neutron Compton scattering: new experiments and a quantitative theoretical explanation

    Science.gov (United States)

    Karlsson, E. B.; Hartmann, O.; Chatzidimitriou-Dreismann, C. A.; Abdul-Redah, T.

    2016-08-01

    No consensus has been reached so far about the hydrogen anomaly problem in Compton scattering of neutrons, although strongly reduced H cross-sections were first reported almost 20 years ago. Over the years, this phenomenon has been observed in many different hydrogen-containing materials. Here, we use yttrium hydrides as test objects, YH2, YH3, YD2 and YD3, Y(H x D1-x )2 and Y(H x D1-x )3, for which we observe H anomalies increasing with transferred momentum q. We also observe reduced deuteron cross-sections in YD2 and YD3 and have followed those up to scattering angles of 140° corresponding to high momentum transfers. In addition to data taken using the standard Au-197 foils for neutron energy selection, the present work includes experiments with Rh-103 foils and comparisons were also made with data from different detector setups. The H and D anomalies are discussed in terms of the different models proposed for their interpretation. The ‘electron loss model’ (which assumes energy transfer to excited electrons) is contradicted by the present data, but it is shown here that exchange effects in scattering from two or more protons (or deuterons) in the presence of large zero-point vibrations, can explain quantitatively the reduction of the cross-sections as well as their q-dependence. Decoherence processes also play an essential role. In a scattering time representation, shake-up processes can be followed on the attosecond scale. The theory also shows that large anomalies can appear only when the neutron coherence lengths (determined by energy selection and detector geometry) are about the same size as the distance between the scatterers.

  5. Branch Point Withdrawal in Elongational Startup Flow by Time-Resolved Small Angle Neutron Scattering

    KAUST Repository

    Ruocco, N.

    2016-05-27

    We present a small angle neutron scattering (SANS) investigation of a blend composed of a dendritic polymer and a linear matrix with comparable viscosity in start-up of an elongational flow at Tg + 50. The two-generation dendritic polymer is diluted to 10% by weight in a matrix of a long well-entangled linear chains. Both components consist of mainly 1,4-cis-polyisoprene but differ in isotopic composition. The resulting scattering contrast is sufficiently high to permit time-resolved measurements of the system structure factor during the start-up phase and to follow the retraction processes involving the inner sections of the branched polymer in the nonlinear deformation response. The outer branches and the linear matrix, on the contrary, are in the linear deformation regime. The linear matrix dominates the rheological signature of the blend and the influence of the branched component can barely be detected. However, the neutron scattering intensity is predominantly that of the (branched) minority component so that its dynamics is clearly evident. In the present paper, we use the neutron scattering data to validate the branch point withdrawal process, which could not be unambiguously discerned from rheological measurements in this blend. The maximal tube stretch that the inner branches experience, before the relaxed outer arm material is incorporated into the tube is determined. The in situ scattering experiments demonstrate for the first time the leveling-off of the strain as the result of branch point withdrawal and chain retraction directly on the molecular level. We conclude that branch point motion in the mixture of architecturally complex polymers occurs earlier than would be expected in a purely branched system, presumably due to the different topological environment that the linear matrix presents to the hierarchically deep-buried tube sections. © 2016 American Chemical Society.

  6. Design of the Next Generation Target at the Lujan Neutron Scattering Center, LANSCE

    Energy Technology Data Exchange (ETDEWEB)

    Ferres, Laurent [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); National Graduate School of Engineering and Research Center (ENSICAEN), Caen (France)

    2016-08-03

    Los Alamos National Laboratory (LANL) supports scientific research in many diverse fields such as biology, chemistry, and nuclear science. The Laboratory was established in 1943 during the Second World War to develop nuclear weapons. Today, LANL is one of the largest laboratories dedicated to nuclear defense and operates an 800 MeV proton linear accelerator for basic and applied research including: production of high- and low-energy neutrons beams, isotope production for medical applications and proton radiography. This accelerator is located at the Los Alamos Neutron Science Center (LANSCE). The work performed involved the redesign of the target for the low-energy neutron source at the Lujan Neutron Scattering Center, which is one of the facilities built around the accelerator. The redesign of the target involves modeling various arrangements of the moderator-reflector-shield for the next generation neutron production target. This is done using Monte Carlo N-Particle eXtended (MCNPX), and ROOT analysis framework, a C++ based-software, to analyze the results.

  7. Coherent deeply virtual Compton scattering off 3He and neutron generalized parton distributions

    Directory of Open Access Journals (Sweden)

    Rinaldi Matteo

    2014-06-01

    Full Text Available It has been recently proposed to study coherent deeply virtual Compton scattering (DVCS off 3He nuclei to access neutron generalized parton distributions (GPDs. In particular, it has been shown that, in Impulse Approximation (IA and at low momentum transfer, the sum of the quark helicity conserving GPDs of 3He, H and E, is dominated by the neutron contribution. This peculiar result makes the 3He target very promising to access the neutron information. We present here the IA calculation of the spin dependent GPD H See Formula in PDF of 3He. Also for this quantity the neutron contribution is found to be the dominant one, at low momentum transfer. The known forward limit of the IA calculation of H See Formula in PDF , yielding the polarized parton distributions of 3He, is correctly recovered. The extraction of the neutron information could be anyway non trivial, so that a procedure, able to take into account the nuclear effects encoded in the IA analysis, is proposed. These calculations, essential for the evaluation of the coherent DVCS cross section asymmetries, which depend on the GPDs H,E and H See Formula in PDF , represent a crucial step for planning possible experiments at Jefferson Lab.

  8. Charge-dependent conformations and dynamics of pamam dendrimers revealed by neutron scattering and molecular dynamics

    Science.gov (United States)

    Wu, Bin

    Neutron scattering and fully atomistic molecular dynamics (MD) are employed to investigate the structural and dynamical properties of polyamidoamine (PAMAM) dendrimers with ethylenediamine (EDA) core under various charge conditions. Regarding to the conformational characteristics, we focus on scrutinizing density profile evolution of PAMAM dendrimers as the molecular charge of dendrimer increases from neutral state to highly charged condition. It should be noted that within the context of small angle neutron scattering (SANS), the dendrimers are composed of hydrocarbon component (dry part) and the penetrating water molecules. Though there have been SANS experiments that studied the charge-dependent structural change of PAMAM dendrimers, their results were limited to the collective behavior of the aforementioned two parts. This study is devoted to deepen the understanding towards the structural responsiveness of intra-molecular polymeric and hydration parts separately through advanced contrast variation SANS data analysis scheme available recently and unravel the governing principles through coupling with MD simulations. Two kinds of acids, namely hydrochloric and sulfuric acids, are utilized to tune the pH condition and hence the molecular charge. As far as the dynamical properties, we target at understanding the underlying mechanism that leads to segmental dynamic enhancement observed from quasielstic neutron scattering (QENS) experiment previously. PAMAM dendrimers have a wealth of potential applications, such as drug delivery agency, energy harvesting medium, and light emitting diodes. More importantly, it is regarded as an ideal system to test many theoretical predictions since dendrimers conjugate both colloid-like globular shape and polymer-like flexible chains. This Ph.D. research addresses two main challenges in studying PAMAM dendrimers. Even though neutron scattering is an ideal tool to study this PAMAM dendrimer solution due to its matching temporal and

  9. PREFACE: 6th Meeting of the Spanish Neutron Scattering Association (SETN2012)

    Science.gov (United States)

    2014-11-01

    The bi-annual Meeting of the Spanish Neutron Scattering Association, VI RSETN, took place in the magnificent world heritage ancient city of Segovia, Spain, from 24-27 June 2012, at the historical building ''Palacio de Mansilla''. It was the sixth in a series of successful scientific meetings, beginning in 2002 (San Sebastián), and followed by conferences in Puerto de la Cruz (Canary Islands, 2004), Jaca (Aragón, 2006), Sant Feliú de Guixols (Cataluña, 2008) and Gijón (Asturias, 2010). The conference covered a broad range of topics related to the use of neutron scattering techniques, from soft matter and biosciences to magnetism, condensed matter as well as advanced neutron instrumentation and applications. In addition to those topics, Spanish scientists working at neutron facilities reported recent upgrades of neutron instruments. The VI RSETN was organized by a group of research scientists belonging to different institutions in Madrid: CSIC, Universidad Complutense and Universidad Politécnica de Madrid, in cooperation with the Spanish Society for Neutron Techniques (SETN, 'Sociedad Española de Técnicas Neutrónicas'). The meeting attracted around 90 participants. The total number of oral presentations was 36, including plenary and invited talks, both from domestic and foreign speakers. In addition, the number of posters was around 20. The success of the VI RSETN was due to the efforts of many colleagues involved at all stages of the meeting. We would like to thank the scientific committee, the local organizing committee, the chairs of the conference sessions as well as all the reviewers who agreed generously to help with the process. We would also like to emphasize the excellent scientific quality of all the presentations and posters, and we thank the support received from our sponsors (SETN, ICMM-CSIC, ESS-Bilbao, ILL, Carburos Metálicos), which was really important for the conference success. Finally, we hope that the readers will enjoy the 28

  10. Structural Significance of Lipid Diversity as Studied by Small Angle Neutron and X-ray Scattering.

    Science.gov (United States)

    Kučerka, Norbert; Heberle, Frederick A; Pan, Jianjun; Katsaras, John

    2015-09-21

    We review recent developments in the rapidly growing field of membrane biophysics, with a focus on the structural properties of single lipid bilayers determined by different scattering techniques, namely neutron and X-ray scattering. The need for accurate lipid structural properties is emphasized by the sometimes conflicting results found in the literature, even in the case of the most studied lipid bilayers. Increasingly, accurate and detailed structural models require more experimental data, such as those from contrast varied neutron scattering and X-ray scattering experiments that are jointly refined with molecular dynamics simulations. This experimental and computational approach produces robust bilayer structural parameters that enable insights, for example, into the interplay between collective membrane properties and its components (e.g., hydrocarbon chain length and unsaturation, and lipid headgroup composition). From model studies such as these, one is better able to appreciate how a real biological membrane can be tuned by balancing the contributions from the lipid's different moieties (e.g., acyl chains, headgroups, backbones, etc.).

  11. Structural Significance of Lipid Diversity as Studied by Small Angle Neutron and X-ray Scattering

    Directory of Open Access Journals (Sweden)

    Norbert Kučerka

    2015-09-01

    Full Text Available We review recent developments in the rapidly growing field of membrane biophysics, with a focus on the structural properties of single lipid bilayers determined by different scattering techniques, namely neutron and X-ray scattering. The need for accurate lipid structural properties is emphasized by the sometimes conflicting results found in the literature, even in the case of the most studied lipid bilayers. Increasingly, accurate and detailed structural models require more experimental data, such as those from contrast varied neutron scattering and X-ray scattering experiments that are jointly refined with molecular dynamics simulations. This experimental and computational approach produces robust bilayer structural parameters that enable insights, for example, into the interplay between collective membrane properties and its components (e.g., hydrocarbon chain length and unsaturation, and lipid headgroup composition. From model studies such as these, one is better able to appreciate how a real biological membrane can be tuned by balancing the contributions from the lipid’s different moieties (e.g., acyl chains, headgroups, backbones, etc..

  12. Neutron scattering studies of crude oil viscosity reduction with electric field

    Science.gov (United States)

    Du, Enpeng

    Small-angle neutron scattering (SANS) is a very powerful laboratory technique for micro structure research which is similar to the small angle X-ray scattering (SAXS) and light scattering for microstructure investigations in various materials. In small-angle neutron scattering (SANS) technique, the neutrons are elastically scattered by changes of refractive index on a nanometer scale inside the sample through the interaction with the nuclei of the atoms present in the sample. Because the nuclei of all atoms are compact and of comparable size, neutrons are capable of interacting strongly with all atoms. This is in contrast to X-ray techniques where the X-rays interact weakly with hydrogen, the most abundant element in most samples. The SANS refractive index is directly related to the scattering length density and is a measure of the strength of the interaction of a neutron wave with a given nucleus. It can probe inhomogeneities in the nanometer scale from 1nm to 1000nm. Since the SANS technique probes the length scale in a very useful range, this technique provides valuable information over a wide variety of scientific and technological applications, including chemical aggregation, defects in materials, surfactants, colloids, ferromagnetic correlations in magnetism, alloy segregation, polymers, proteins, biological membranes, viruses, ribosome and macromolecules. Quoting the Nobel committee, when awarding the prize to C. Shull and B. Brockhouse in 1994: "Neutrons tell you where the atoms are and what the atoms do". At NIST, there is a single beam of neutrons generated from either reactor or pulsed neutron source and selected by velocity selector. The beam passes through a neutron guide then scattered by the sample. After the sample chamber, there are 2D gas detectors to collect the elastic scattering information. SANS usually uses collimation of the neutron beam to determine the scattering angle of a neutron, which results in an even lower signal-to-noise ratio for

  13. Leading neutron energy and p{sub T} distributions in deep inelastic scattering and photoproduction at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

    2007-02-15

    The production of energetic neutrons in ep collisions has been studied with the ZEUS detector at HERA. The neutron energy and p{sub T}{sup 2} distributions were measured with a forward neutron calorimeter and tracker in a 40 pb{sup -1} sample of inclusive deep inelastic scattering (DIS) data and a 6 pb{sup -1} sample of photoproduction data. The neutron yield in photoproduction is suppressed relative to DIS for the lower neutron energies and the neutrons have a steeper p{sub T}{sup 2} distribution, consistent with the expectation from absorption models. The distributions are compared to HERA measurements of leading protons. The neutron energy and transverse-momentum distributions in DIS are compared to Monte Carlo simulations and to the predictions of particle exchange models. Models of pion exchange incorporating absorption and additional secondary meson exchanges give a good description of the data. (orig.)

  14. Small-angle neutron scattering studies from solutions of bovine nasal cartilage proteoglycan

    Science.gov (United States)

    Patel, A.; Stivala, S. S.; Damle, S. P.; Gregory, J. D.; Bunick, G. J.; Uberbacher, E. C.

    1986-02-01

    Small-angle neutron scattering, SANS, of the proteoglycan subunit of bovine nasal cartilage in 0.15 N LiC1 at 25°C yielded the radius of gyration, R g, radius of gyration of the cross-section, R q, persistence length, a *, and the molecular weight, M. The following values were obtained: M = 3.9 × 10 6, R g = 745 Å, R q = 34.6 Å and a * = 35.2 Å. These values compare favorably with those that were obtained from small angle X-ray scattering, SAXS, of a similar extract. The scattering curve of the proteoglycan subunit in D 2O showed a characteristic broad peak in the specified angular range similar to that observed from SAXS, thus confirming the polyelectrolyte nature of the proteoglycan.

  15. Use of Small-Angle Neutron Scattering in Testing the Stability of Ferrofluids

    CERN Document Server

    Balasoiu, M; Avdeev, M V; Aksenov, V L; Khokhryakov, A A; Bica, L D; Hasegan, D; Török, G; Rosta, L

    2004-01-01

    Stability of ferrofluids - colloidal solutions of magnetic particles covered with surfactants - is the main characteristic that determines the possibility to exploit ferrofluids in different industrial and biomedical applications. Small-angle neutron scattering (SANS) can be effectively used to reveal the aggregation and its change with time in ferrofluids under the action of magnetic field. Despite the fact that in most cases the detailed description of scattering is complicated, one can judge whether a ferrofluid is stable or not by simple analysis of changes in the mean scattering intensity. The advantages of SANS are that industrial samples can be tested without any additional modifications, as well as the real-time experiments with any magnetic load can be easily performed. Examples for a number of ferrofluids are given.

  16. Polymer boosting effect in the droplet phase studied by small-angle neutron scattering

    CERN Document Server

    Frielinghaus, H; Allgaier, J; Richter, D; Jakobs, B; Sottmann, T; Strey, R

    2002-01-01

    Small-angle neutron-scattering experiments were performed in order to obtain the six partial scattering functions of a droplet microemulsion containing water, decane, C sub 1 sub 0 E sub 4 surfactant and PEP sub 5 -PEO sub 8 sub 0. We systematically varied the contrast around the polymer contrast, where only the polymer becomes visible, and we also measured bulk and film contrasts. With the singular value decomposition method we could extract the desired six partial scattering functions from the 15 measured spectra. We find a sphere-shell-shell structure of the droplets, where the innermost sphere consists of oil, the middle shell of surfactant and the outer shell is a depletion zone where the polymer is almost not present. (orig.)

  17. Quark structure of the nucleon and angular asymmetry of proton-neutron hard elastic scattering.

    Science.gov (United States)

    Granados, Carlos G; Sargsian, Misak M

    2009-11-20

    We investigate an asymmetry in the angular distribution of hard elastic proton-neutron scattering with respect to the 90 degrees center of mass scattering angle and demonstrate that it's magnitude is related to the helicity-isospin symmetry of the quark wave function of the nucleon. Our estimate of the asymmetry within the quark-interchange model of hard scattering demonstrates that the quark wave function of a nucleon based on the exact SU(6) symmetry predicts an angular asymmetry opposite to that of experimental observations. We found that the quark wave function based on the diquark picture of the nucleon produces a correct asymmetry. Comparison with the data allowed us to show that the vector diquarks contribute around 10% in the nucleon wave function and they are in negative phase relative to the scalar diquarks. These observations are essential in constraining QCD models of a nucleon.

  18. Neutron scattering in the proximate quantum spin liquid α-RuCl3

    Science.gov (United States)

    Banerjee, Arnab; Yan, Jiaqiang; Knolle, Johannes; Bridges, Craig A.; Stone, Matthew B.; Lumsden, Mark D.; Mandrus, David G.; Tennant, David A.; Moessner, Roderich; Nagler, Stephen E.

    2017-06-01

    The Kitaev quantum spin liquid (KQSL) is an exotic emergent state of matter exhibiting Majorana fermion and gauge flux excitations. The magnetic insulator α-RuCl3 is thought to realize a proximate KQSL. We used neutron scattering on single crystals of α-RuCl3 to reconstruct dynamical correlations in energy-momentum space. We discovered highly unusual signals, including a column of scattering over a large energy interval around the Brillouin zone center, which is very stable with temperature. This finding is consistent with scattering from the Majorana excitations of a KQSL. Other, more delicate experimental features can be transparently associated with perturbations to an ideal model. Our results encourage further study of this prototypical material and may open a window into investigating emergent magnetic Majorana fermions in correlated materials.

  19. Proton elastic scattering from tin isotopes at 295 MeV and systematic change of neutron density distributions

    CERN Document Server

    Terashima, S; Takeda, H; Ishikawa, T; Itoh, M; Kawabata, T; Murakami, T; Uchida, M; Yasuda, Y; Yosoi, M; Zenihiro, J; Yoshida, H P; Noro, T; Ishida, T; Asaji, S; Yonemura, T

    2008-01-01

    Cross sections and analyzing powers for proton elastic scattering from $^{116,118,120,122,124}$Sn at 295 MeV have been measured for a momentum transfer of up to about 3.5 fm$^{-1}$ to deduce systematic changes of the neutron density distribution. We tuned the relativistic Love-Franey interaction to explain the proton elastic scattering of a nucleus whose density distribution is well known. Then, we applied this interaction to deduce the neutron density distributions of tin isotopes. The result of our analysis shows the clear systematic behavior of a gradual increase in the neutron skin thickness of tin isotopes with mass number.

  20. Nobel Prize in Physics 1994 "for pioneering contributions to the development of neutron scattering techniques for studies of condensed matter" : Bertram N. Brockhouse and Clifford G. Shull

    CERN Multimedia

    1995-01-01

    Prof. C. G. Shull presents "Early development of neutron scattering". A description of the early experiments and instrumentation problems starting in 1946 that led to the use of neutron scattering as a tool in augmenting and extending x-ray scattering from materials.

  1. Measurement of 56Fe activity produced in inelastic scattering of neutrons created by cosmic muons in an iron shield.

    Science.gov (United States)

    Krmar, M; Jovančević, N; Nikolić, D

    2012-01-01

    We report on the study of the intensities of several gamma lines emitted after the inelastic scattering of neutrons in (56)Fe. Neutrons were produced via nuclear processes induced by cosmic muons in the 20tons massive iron cube placed at the Earth's surface and used as a passive shield for the HPGe detector. Relative intensities of detected gamma lines are compared with the results collected in the same iron shield by the use of the (252)Cf neutrons. Assessment against the published data from neutron scattering experiments at energies up to 14MeV is also provided. It allowed us to infer the qualitative information about the average energy of muon-created neutrons in the iron shield. Copyright © 2011 Elsevier Ltd. All rights reserved.

  2. Cryogen Free Ultra-Low Temperature Cryostat for Neutron Scattering Experiments

    Science.gov (United States)

    Downa, R. B. E.; Kirichek, O.; Manuel, P.; Keeping, J.; Bowden, Z. A.

    Most ultra-low temperature (below 1K) experiments at advanced neutron facilities are based on dilution and 3He refrigerator inserts used with Orange cryostats, or similar systems. However recent increases in liquid helium costs; caused by global helium supply problems, has raised significant concern about the affordability of such cryostats. Here we present the design and test results of a cryogen free top-loading cryostat which provides neutron scattering sample environment within the temperature range 1.25 - 300 K. The high cooling power of the cryostat 0.23 W at 1.9 K enables the operation of a dilution refrigerator insert in a continuous regime; which expands the low temperature margin of the temperature range to 35 mK. The cooling time of the dilution refrigerator insert is similar to one operated in an Orange cryostat. The main performance criteria such as base temperature, cooling power, and circulation rate are compatible with the technical specification of a standard dilution refrigerator. In fact the system offers operating parameters very similar to those of an Orange cryostat, but without the complication of cryogens. The first scientific results obtained in an ultra-low temperature neutron scattering experiment with this system are also going to be discussed.

  3. Neutron Scattering in Chemistry: Experiments, Models and Statistical Description of Physical Phenomena

    Science.gov (United States)

    Ramirez Cuesta, Timmy

    Incoherent inelastic neutron scattering spectroscopy is a very powerful technique that requires the use of ab-initio models to interpret the experimental data. Albeit not exact the information obtained from the models gives very valuable insight into the dynamics of atoms in solids and molecules, that, in turn, provides unique access to the vibrational density of states. It is extremely sensitive to hydrogen since the neutron cross section of hydrogen is the largest of all chemical elements. Hydrogen, being the lightest element highlights quantum effects more pronounced than the rest of the elements.In the case of non-crystalline or disordered materials, the models provide partial information and only a reduced sampling of possible configurations can be done at the present. With very large computing power, as exascale computing will provide, a new opportunity arises to study these systems and introduce a description of statistical configurations including energetics and dynamics characterization of configurational entropy. As part of the ICE-MAN project, we are developing the tools to manage the workflows, visualize and analyze the results. To use state of the art computational methods and most neutron scattering that using atomistic models for interpretation of experimental data This work is supported by the Laboratory Directed Research and Development (LDRD 8237) program of the UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy.

  4. Liquid 1-propanol studied by neutron scattering, near-infrared, and dielectric spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sillrén, P.; Matic, A.; Karlsson, M. [Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg (Sweden); Koza, M.; Maccarini, M.; Fouquet, P. [Institut Laue Langevin, 6, rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9 (France); Götz, M.; Bauer, Th.; Gulich, R.; Lunkenheimer, P.; Loidl, A. [Experimental Physics V, University of Augsburg, 86135 Augsburg (Germany); Mattsson, J. [School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom); Gainaru, C.; Vynokur, E.; Schildmann, S.; Bauer, S.; Böhmer, R. [Fakultät für Physik, Technische Universität Dortmund, 44221 Dortmund (Germany)

    2014-03-28

    Liquid monohydroxy alcohols exhibit unusual dynamics related to their hydrogen bonding induced structures. The connection between structure and dynamics is studied for liquid 1-propanol using quasi-elastic neutron scattering, combining time-of-flight and neutron spin-echo techniques, with a focus on the dynamics at length scales corresponding to the main peak and the pre-peak of the structure factor. At the main peak, the structural relaxation times are probed. These correspond well to mechanical relaxation times calculated from literature data. At the pre-peak, corresponding to length scales related to H-bonded structures, the relaxation times are almost an order of magnitude longer. According to previous work [C. Gainaru, R. Meier, S. Schildmann, C. Lederle, W. Hiller, E. Rössler, and R. Böhmer, Phys. Rev. Lett. 105, 258303 (2010)] this time scale difference is connected to the average size of H-bonded clusters. The relation between the relaxation times from neutron scattering and those determined from dielectric spectroscopy is discussed on the basis of broad-band permittivity data of 1-propanol. Moreover, in 1-propanol the dielectric relaxation strength as well as the near-infrared absorbance reveal anomalous behavior below ambient temperature. A corresponding feature could not be found in the polyalcohols propylene glycol and glycerol.

  5. Magnetic neutron scattering resonance of high-¤Tc¤ superconductors in external magnetic fields: An SO(5) study

    DEFF Research Database (Denmark)

    Mortensen, Asger; Rønnow, Henrik Moodysson; Bruus, Henrik

    2000-01-01

    The magnetic resonance at 41 meV observed in neutron scattering studies of YBa2Cu3O7 holds a key position in the understanding of high-T-c, superconductivity. Within the SO(5) model for superconductivity and antiferromagnetism, we have calculated the effect of an applied magnetic field...... space we find that (i) the scattering amplitude is zero at (pi/a,pi/a), (ii) the resonance peak is split into a ring with radius pi/d centered at (pi/a, pi/a), d being the vortex lattice constant, and consequently, (iii) the splitting pi/d scales with the magnetic field as root B....... on the neutron scattering cross section of the magnetic resonance. In the presence of Abrikosov vortices, the neutron scattering cross section shows clear signatures of not only the fluctuations in the superconducting order parameter psi, but also the modulation of the phase of psi due to vortices. In reciprocal...

  6. Measurement of the inelastic neutron scattering cross section of 56Fe

    Directory of Open Access Journals (Sweden)

    Nolte R.

    2010-10-01

    Full Text Available At the superconducting electron linear accelerator ELBE at Forschungszentrum Dresden-Rossendorf the neutron time-of-flight facility nELBE has become operational. Fast neutrons in the energy range from 200 keV to 10 MeV are produced by the pulsed electron beam from ELBE impinging on a liquid lead circuit as a radiator. The short beam pulses of 10 ps provide the basis for an excellent time resolution for neutron time-of-flight experiments, giving an energy resolution of about <1% at 1 MeV with a short flight path of 5 m. By means of a “double-time-of-flight” setup the (n,nâγ cross section to the first excited state of 56Fe has been measured over the whole energy range without knowledge about cross sections of higher-lying levels. Plastic scintillators were used to detect the inelastically scattered neutron and BaF2 detectors to detect the correlated γ-ray.

  7. Production of bacterial cellulose with controlled deuterium-hydrogen substitution for neutron scattering studies.

    Science.gov (United States)

    O'Neill, Hugh; Shah, Riddhi; Evans, Barbara R; He, Junhong; Pingali, Sai Venkatesh; Chundawat, Shishir P S; Jones, A Daniel; Langan, Paul; Davison, Brian H; Urban, Volker

    2015-01-01

    Isotopic enrichment of biomacromolecules is a widely used technique that enables the investigation of the structural and dynamic properties to provide information not accessible with natural abundance isotopic composition. This study reports an approach for deuterium incorporation into bacterial cellulose. A media formulation for growth of Acetobacter xylinus subsp. sucrofermentans and Gluconacetobacter hansenii was formulated that supports cellulose production in deuterium (D) oxide. The level of D incorporation can be varied by altering the ratio of deuterated and protiated glycerol used during cell growth in the D2O-based growth medium. Spectroscopic analysis and mass spectrometry show that the level of deuterium incorporation is high (>90%) for the perdeuterated form of bacterial cellulose. The small-angle neutron scattering profiles of the cellulose with different amounts of D incorporation are all similar indicating that there are no structural changes in the cellulose due to substitution of deuterium for hydrogen. In addition, by varying the amount of deuterated glycerol in the media it was possible to vary the scattering length density of the deuterated cellulose. The ability to control deuterium content of cellulose extends the range of experiments using techniques such as neutron scattering to reveal information about the structure and dynamics of cellulose, and its interactions with other biomacromolecules as well as synthetic polymers used for development of composite materials. © 2015 Elsevier Inc. and UT-Battelle, LLC, Contract no. DE-AC05-00OR22725. All rights reserved.

  8. Measurements of residual strains in ceramic-elastomer composites with diffuse scattering of polarized neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Zajac, Wojciech [H. Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences, Radzikowskiego 152, 31-342 Krakow (Poland)], E-mail: Wojciech.Zajac@ifj.edu.pl; Boczkowska, Anna; Babski, Kamil; Kurzydlowski, Krzysztof J. [Warsaw University of Technology, Faculty of Materials Science and Engineering, Woloska 141, 02-507 Warsaw (Poland); Deen, Pascale P. [Institute Laue-Langevin, 6 rue Jules Horowitz, 38000 Grenoble (France)

    2008-12-15

    An experiment of diffuse scattering (also referred to as wide-angle neutron scattering) of polarized neutrons with polarization analysis was performed in order to detect residual strains in ceramic-elastomer composites of porous SiO{sub 2} and poly(urea-urethane) elastomers. Two ceramics, with pore sizes of 20 and 70 {mu}m, and two elastomers, with hard/soft segments molar ratios of H/S = 0.25 and 1.5, were selected for composite fabrication. The use of polarization analysis made it possible to detect and study very weak coherent scattering peaks from the elastomer synthesized inside SiO{sub 2} ceramics. Residual strains were detected and measured based on interatomic distances in the SiO{sub 2}+ H/S = 1.5 composite but not in the SiO{sub 2}+ H/S = 0.25. The reason is sought in soft domains being ordered in the H/S = 0.25 elastomer as opposed to the H/S = 1.5 one.

  9. A neutron scattering study on the stability of trehalose mycolates under thermal stress

    Energy Technology Data Exchange (ETDEWEB)

    Migliardo, F., E-mail: fmigliardo@unime.it [Department of Physics, University of Messina, Viale D’Alcontres 31, 98166 Messina (Italy); Salmeron, C.; Bayan, N. [Laboratoire de Microbiologie Moléculaire et Cellulaire, IBBMC, Bat 430, Université de Paris Sud XI, 15 rue Georges Clémenceau, 91405 Orsay Cedex (France)

    2013-10-16

    Highlights: ► Neutron scattering measurements have been performed on mycolate water mixtures. ► A comparison with lecithin lipid water mixtures has been carried out. ► Mycolates show a lower mobility and flexibility compared to lecithin. ► The observed peculiarities of mycolic acids could be ascribed to trehalose. ► The results could justify the high resistance to thermal stress of mycobacteria. - Abstract: The present paper is focused on the study of the dynamics of mycolic acids, which are fundamental components of the outer membrane (mycomembrane) of Mycobacterium tuberculosis. An elastic neutron scattering study of mycolic acid/H{sub 2}O and lecithin/H{sub 2}O mixtures as a function of temperature and exchanged wavevector Q has been carried out. This study provides an effective way for characterizing the dynamical properties, furnishing a set of parameters characterizing the different flexibility and rigidity of the investigated lipids. The behavior of the elastically scattered intensity profiles and the derived mean square displacements as a function of temperature shows a more marked temperature dependence for lecithin lipids in comparison with mycolic acids, so revealing a higher thermal stability of these latter. These findings could be useful for understanding the dynamics-function relation in the mycomembrane and then to relate it to the low permeability and high resistance of mycobacteria to many antibiotics.

  10. Internal dynamics of F-actin and myosin subfragment-1 studied by quasielastic neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Matsuo, Tatsuhito [Quantum Beam Science Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Arata, Toshiaki [Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Oda, Toshiro [Graduate School of Science, University of Hyogo, Kamigori-cho, Ako-gun, Hyogo 678-1297 (Japan); Nakajima, Kenji; Ohira-Kawamura, Seiko; Kikuchi, Tatsuya [Neutron Science Section, J-PARC Center, Tokai, Ibaraki 319-1195 (Japan); Fujiwara, Satoru, E-mail: fujiwara.satoru@jaea.go.jp [Quantum Beam Science Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan)

    2015-04-10

    Various biological functions related to cell motility are driven by the interaction between the partner proteins, actin and myosin. To obtain insights into how this interaction occurs, the internal dynamics of F-actin and myosin subfragment-1 (S1) were characterized by the quasielastic neutron scattering measurements on the solution samples of F-actin and S1. Contributions of the internal motions of the proteins to the scattering spectra were separated from those of the global macromolecular diffusion. Analysis of the spectra arising from the internal dynamics showed that the correlation times of the atomic motions were about two times shorter for F-actin than for S1, suggesting that F-actin fluctuates more rapidly than S1. It was also shown that the fraction of the immobile atoms is larger for S1 than for F-actin. These results suggest that F-actin actively facilitates the binding of myosin by utilizing the more frequent conformational fluctuations than those of S1. - Highlights: • We studied the internal dynamics of F-actin and myosin S1 by neutron scattering. • The correlation times of the atomic motions were smaller for F-actin than for S1. • The fraction of the immobile atoms was also smaller for F-actin than for S1. • Our results suggest that mobility of atoms in F-actin is higher than that in S1. • We propose that high flexibility of F-actin facilitates the binding of myosin.

  11. Outline of spallation neutron source engineering

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Noboru [Center for Neutron Science, Tokai Research Establishment, Japan Atomic Energy Research Institute, Tokai, Ibaraki (Japan)

    2001-01-01

    Slow neutrons such as cold and thermal neutrons are unique probes which can determine structures and dynamics of condensed matter in atomic scale. The neutron scattering technique is indispensable not only for basic sciences such as condensed matter research and life science, but also for basic industrial technology in 21 century. It is believed that to survive in the science-technology competition in 21 century would be almost impossible without neutron scattering. However, the intensity of neutrons presently available is much lower than synchrotron radiation sources, etc. Thus, R and D of intense neutron sources become most important. The High-Intensity Proton Accelerator Project is now being promoted jointly by Japan Atomic Energy Research Institute and High Energy Accelerator Research Organization, but there has so far been no good text which covers all the aspects of pulsed spallation neutron sources. The present review was prepare aiming at giving a better understanding on pulsed spallation neutron sources not only to neutron source researchers but also more widely to neutron scattering researchers and accelerator scientists in this field. The contents involve, starting from what is neutron scattering and what neutrons are necessary for neutron scattering, what is the spallation reaction, how to produce neutrons required for neutron scattering more efficiently, target-moderator-reflector neutronics and its engineering, shielding, target station, material issues, etc. The author have engaged in R and D of pulsed apallation neutron sources and neutron scattering research using them over 30 years. The present review is prepared based on the author's experiences with useful information obtained through ICANS collaboration and recent data from the JSNS (Japanese Spallation Neutron Source) design team. (author)

  12. Advanced sources and optical components for the McStas neutron scattering instrument simulation package

    DEFF Research Database (Denmark)

    Farhi, E.; Monzat, C.; Arnerin, R.

    2014-01-01

    We present new McStas components Virtual_mcnp_input and Virtual_tripoli4_input, Virtual_mcnp_output and Virtual_tripoli_output to be used as interface for the MCNP and Tripoli neutron transport codes. Similarly, the new Lens component can be used to describe any refracting material set......-up, including lenses and prisms. A new library for McStas adds the ability to describe any geometrical arrangement as a set of polygons. This feature has been implemented in most sample scattering components such as Single_crystal, Incoherent, Isotropic_Sqw (liquids/amorphous/powder), PowderN as well...... as in Guide_anyshape component for reflecting or absorbing complex set-up. The PSD_Detector component models a neutron absorbing gas volume, taking into account for instance the penetration depth and the associated parallax effect, the charge cloud generated at the absorption location. This gas volume can...

  13. Gracing incidence small angle neutron scattering of incommensurate magnetic structures in MnSi thin films

    Energy Technology Data Exchange (ETDEWEB)

    Wiedemann, Birgit; Pfleiderer, Christian; Boeni, Peter [Physik Department, Technische Universitaet Muenchen (Germany); Zhang, Shilei; Hesjedal, Thorsten [Clarendon Laboratory, Department of Physics, University of Oxford (United Kingdom); Khaydukov, Yury; Soltwedel, Olaf; Keller, Thomas [Max-Planck-Institut fuer Festkoerperforschung (Germany); Max Planck Society, Outstation at FRM-II (Germany); Muehlbauer, Sebastian [Forschungsneutronenquelle Heinz Maier Leibnitz, Technische Universitaet Muenchen (Germany); Chacon, Alfonso [Physik Department, Technische Universitaet Muenchen (Germany); Forschungsneutronenquelle Heinz Maier Leibnitz, Technische Universitaet Muenchen (Germany)

    2015-07-01

    The topological stability of skyrmions in bulk samples of MnSi and the observation of spin transfer torque effects at ultra-low current densities have generated great interest in skyrmions in chiral magnets as a new route towards next generation spintronics devices. Yet, the formation of skyrmions in MBE grown thin films of MnSi reported in the literature is highly controversial. We report gracing incidence small angle neutron scattering (GISANS) of the magnetic order in selected thin films of MnSi grown by state of the art MBE techniques. In combination with polarised neutron reflectometry (PNR) and magnetisation measurements of the same samples our data provide direct reciprocal space information of the incommensurate magnetic order, clarifying the nature of magnetic phase diagram.

  14. Universality in the Neutron-^{19}C Scattering Using Finite-Range Separable Interactions

    Science.gov (United States)

    Shalchi, M. A.; Yamashita, M. T.; Hadizadeh, M. R.; Frederico, T.; Tomio, Lauro

    2017-03-01

    We report a study on the low-energy properties of the elastic s-wave scattering of a neutron ( n) in the carbon isotope ^{19}C near the critical condition for the occurrence of an excited Efimov state in the three-body n- n-^{18}C system. For the separation energy of the two halo neutrons in ^{20}C we use the available experimental data. We also investigate to which extent the universal scaling laws, strictly valid in the zero-range limit, will survive when using finite-range interactions. By allowing to vary the n-^{18}C binding energy, a scaling behavior for the real and imaginary parts of the s-wave phase-shift δ _0 is verified, emerging some universal characteristics given by the pole-position of k\\cot (δ _0^R) and effective-range parameters.

  15. Exploration of deeply virtual Compton scattering on the neutron in the Hall A of Jefferson Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Mazouz, Malek [Joseph Fourier Univ., Grenoble (France)

    2006-12-08

    Generalized Parton Distributions (GPDs) are universal functions which provide a comprehensive description of hadron properties in terms of quarks and gluons. Deeply Virtual Compton Scattering (DVCS) is the simplest hard exclusive process involving GPDs. In particular, the DVCS on the neutron is mostly sensitive to E, the less constrained GPD, wich allows to access to the quark angular momentum. The first dedicated DVCS experiment on the neutron ran in the Hall A of Jefferson Lab in fall 2004. The high luminosity of the experiment and the resulting background rate recquired specific devices which are decribed in this document. The analysis methods and the experiment results, leading to preliminary constraints on the GPD E, are presented.

  16. Structure and dynamics of nanoemulsions: Insights from combining dynamic and static neutron scattering

    Science.gov (United States)

    Hoffmann, I.; Heunemann, P.; Farago, B.; Grillo, I.; Holderer, O.; Päch, M.; Gradzielski, M.

    2012-12-01

    Despite their lack of thermodynamical stability, nanoemulsions can show a remarkable degree of kinetic stability. Among the various different preparation methods the phase-inversion concentration method is particularly interesting as it occurs spontaneously. Here we investigate such a system composed of a surfactant, cosurfactant, and oil that upon dilution with water forms long time metastable oil-in-water nanoemulsion droplets. The dynamics of the amphiphilic monolayers and its elastic properties is important for their stability and therefore the monolayer dynamics have been investigated by neutron spin echo (NSE). Despite the difficulties arising from the inherently polydisperse nature and the large number of different components necessarily contained in commercial nanoemulsion formulations, information concerning the membrane rigidity was extracted from the combination of small angle neutron scattering and NSE and several different formulations are compared. These results show that small amounts of different admixed ionic surfactants can modify the monolayer rigidity substantially and similarly effects of surface bound polyelectrolytes have been evaluated.

  17. Initial characterization of mudstone nanoporosity with small angle neutron scattering using caprocks from carbon sequestration sites.

    Energy Technology Data Exchange (ETDEWEB)

    McCray, John (Colorado School of Mines); Navarre-Sitchler, Alexis (Colorado School of Mines); Mouzakis, Katherine (Colorado School of Mines); Heath, Jason E.; Dewers, Thomas A.; Rother, Gernot (Oak Ridge National Laboratory)

    2010-11-01

    Geological carbon sequestration relies on the principle that CO{sub 2} injected deep into the subsurface is unable to leak to the atmosphere. Structural trapping by a relatively impermeable caprock (often mudstone such as a shale) is the main trapping mechanism that is currently relied on for the first hundreds of years. Many of the pores of the caprock are of micrometer to nanometer scale. However, the distribution, geometry and volume of porosity at these scales are poorly characterized. Differences in pore shape and size can cause variation in capillary properties and fluid transport resulting in fluid pathways with different capillary entry pressures in the same sample. Prediction of pore network properties for distinct geologic environments would result in significant advancement in our ability to model subsurface fluid flow. Specifically, prediction of fluid flow through caprocks of geologic CO{sub 2} sequestration reservoirs is a critical step in evaluating the risk of leakage to overlying aquifers. The micro- and nanoporosity was analyzed in four mudstones using small angle neutron scattering (SANS). These mudstones are caprocks of formations that are currently under study or being used for carbon sequestration projects and include the Marine Tuscaloosa Group, the Lower Tuscaloosa Group, the upper and lower shale members of the Kirtland Formation, and the Pennsylvanian Gothic shale. Total organic carbon varies from <0.3% to 4% by weight. Expandable clay contents range from 10% to {approx}40% in the Gothic shale and Kirtland Formation, respectively. Neutrons effectively scatter from interfaces between materials with differing scattering length density (i.e. minerals and pores). The intensity of scattered neutrons, I(Q), where Q is the scattering vector, gives information about the volume of pores and their arrangement in the sample. The slope of the scattering data when plotted as log I(Q) vs. log Q provides information about the fractality or geometry of

  18. Measured Neutron Spectra and Dose Equivalents From a Mevion Single-Room, Passively Scattered Proton System Used for Craniospinal Irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Howell, Rebecca M., E-mail: rhowell@mdanderson.org [Department of Radiation Physics, The University of Texas M. D. Anderson Cancer Center, Houston, Texas (United States); Burgett, Eric A.; Isaacs, Daniel [Department of Nuclear Engineering, Idaho State University, Pocatello, Idaho (United States); Price Hedrick, Samantha G.; Reilly, Michael P.; Rankine, Leith J.; Grantham, Kevin K.; Perkins, Stephanie; Klein, Eric E. [Department of Radiation Oncology, Washington University, St. Louis, Missouri (United States)

    2016-05-01

    Purpose: To measure, in the setting of typical passively scattered proton craniospinal irradiation (CSI) treatment, the secondary neutron spectra, and use these spectra to calculate dose equivalents for both internal and external neutrons delivered via a Mevion single-room compact proton system. Methods and Materials: Secondary neutron spectra were measured using extended-range Bonner spheres for whole brain, upper spine, and lower spine proton fields. The detector used can discriminate neutrons over the entire range of the energy spectrum encountered in proton therapy. To separately assess internally and externally generated neutrons, each of the fields was delivered with and without a phantom. Average neutron energy, total neutron fluence, and ambient dose equivalent [H* (10)] were calculated for each spectrum. Neutron dose equivalents as a function of depth were estimated by applying published neutron depth–dose data to in-air H* (10) values. Results: For CSI fields, neutron spectra were similar, with a high-energy direct neutron peak, an evaporation peak, a thermal peak, and an intermediate continuum between the evaporation and thermal peaks. Neutrons in the evaporation peak made the largest contribution to dose equivalent. Internal neutrons had a very low to negligible contribution to dose equivalent compared with external neutrons, largely attributed to the measurement location being far outside the primary proton beam. Average energies ranged from 8.6 to 14.5 MeV, whereas fluences ranged from 6.91 × 10{sup 6} to 1.04 × 10{sup 7} n/cm{sup 2}/Gy, and H* (10) ranged from 2.27 to 3.92 mSv/Gy. Conclusions: For CSI treatments delivered with a Mevion single-gantry proton therapy system, we found measured neutron dose was consistent with dose equivalents reported for CSI with other proton beamlines.

  19. The performance of neutron scattering spectrometers at a long-pulse spallation source

    Energy Technology Data Exchange (ETDEWEB)

    Pynn, R.

    1997-06-01

    In this document the author considers the performance of a long pulse spallation source for those neutron scattering experiments that are usually performed with a monochromatic beam at a continuous wave (CW) source such as a nuclear reactor. The first conclusion drawn is that comparison of the performance of neutron scattering spectrometers at CW and pulsed sources is simpler for long-pulsed sources than it is for the short-pulse variety. Even though detailed instrument design and assessment will require Monte Carlo simulations (which have already been performed at Los Alamos for SANS and reflectometry), simple arguments are sufficient to assess the approximate performance of spectrometers at an LPSS and to support the contention that a 1 MW long-pulse source can provide attractive performance, especially for instrumentation designed for soft-condensed-matter science. Because coupled moderators can be exploited at such a source, its time average cold flux is equivalent to that of a research reactor with a power of about 15 MW, so only a factor of 4 gain from source pulsing is necessary to obtain performance that is comparable with the ILL. In favorable cases, the gain from pulsing can be even more than this, approaching the limit set by the peak flux, giving about 4 times the performance of the ILL. Because of its low duty factor, an LPSS provides the greatest performance gains for relatively low resolution experiments with cold neutrons. It should thus be considered complementary to short pulse sources which are most effective for high resolution experiments using thermal or epithermal neutrons.

  20. Direct comparison of elastic incoherent neutron scattering experiments with molecular dynamics simulations of DMPC phase transitions

    Energy Technology Data Exchange (ETDEWEB)

    Aoun, Bachir; Pellegrini, Eric; Trapp, Marcus; Natali, Francesca; Cantù, Laura; Brocca, Paola; Gerelli, Yuri; Demé, Bruno; Marek Koza, Michael; Johnson, Mark; Peters, Judith

    2016-04-01

    Neutron scattering techniques have been employed to investigate 1,2-dimyristoyl-sn-glycero-3- phosphocholine (DMPC) membranes in the form of multilamellar vesicles (MLVs) and deposited, stacked multilamellar-bilayers (MLBs), covering transitions from the gel to the liquid phase. Neutron diffraction was used to characterise the samples in terms of transition temperatures, whereas elastic incoherent neutron scattering (EINS) demonstrates that the dynamics on the sub-macromolecular length-scale and pico- to nano-second time-scale are correlated with the structural transitions through a discontinuity in the observed elastic intensities and the derived mean square displacements. Molecular dynamics simulations have been performed in parallel focussing on the length-, time- and temperature-scales of the neutron experiments. They correctly reproduce the structural features of the main gel-liquid phase transition. Particular emphasis is placed on the dynamical amplitudes derived from experiment and simulations. Two methods are used to analyse the experimental data and mean square displacements. They agree within a factor of 2 irrespective of the probed time-scale, i.e. the instrument utilized. Mean square displacements computed from simulations show a comparable level of agreement with the experimental values, albeit, the best match with the two methods varies for the two instruments. Consequently, experiments and simulations together give a consistent picture of the structural and dynamical aspects of the main lipid transition and provide a basis for future, theoretical modelling of dynamics and phase behaviour in membranes. The need for more detailed analytical models is pointed out by the remaining variation of the dynamical amplitudes derived in two different ways from experiments on the one hand and simulations on the other.

  1. Virtual neutron scattering experiments - Training and preparing students for large-scale facility experiments

    Directory of Open Access Journals (Sweden)

    Julie Hougaard Overgaard

    2016-11-01

    Full Text Available Dansk Vi beskriver, hvordan virtuelle eksperimenter kan udnyttes i et læringsdesign ved at forberede de studerende til hands-on-eksperimenter ved storskalafaciliteter. Vi illustrerer designet ved at vise, hvordan virtuelle eksperimenter bruges på Niels Bohr Institutets kandidatkursus om neutronspredning. I den sidste uge af kurset, rejser studerende til et storskala neutronspredningsfacilitet for at udføre neutronspredningseksperimenter. Vi bruger studerendes udsagn om deres oplevelser til at argumentere for, at arbejdet med virtuelle experimenter forbereder de studerende til at engagere sig mere frugtbart med eksperimenter ved at lade dem fokusere på fysikken og relevante data i stedet for instrumenternes funktion. Vi hævder, at det er, fordi de kan overføre deres erfaringer med virtuelle eksperimenter til rigtige eksperimenter. Vi finder dog, at læring stadig er situeret i den forstand, at kun kendskab til bestemte eksperimenter overføres. Vi afslutter med at diskutere de muligheder, som virtuelle eksperimenter giver. English We describe how virtual experiments can be utilized in a learning design that prepares students for hands-on experiments at large-scale facilities. We illustrate the design by showing how virtual experiments are used at the Niels Bohr Institute in a master level course on neutron scattering. In the last week of the course, students travel to a large-scale neutron scattering facility to perform real neutron scattering experiments. Through student interviews and survey answers, we argue, that the virtual training prepares the students to engage more fruitfully with experiments by letting them focus on physics and data rather than the overwhelming instrumentation. We argue that this is because they can transfer their virtual experimental experience to the real-life situation. However, we also find that learning is still situated in the sense that only knowledge of particular experiments is transferred. We proceed to

  2. Dynamics of Different Functional Parts of Bacteriorhodopsin: H-2H Labeling and Neutron Scattering

    Science.gov (United States)

    Reat, Valerie; Patzelt, Heiko; Ferrand, Michel; Pfister, Claude; Oesterhelt, Dieter; Zaccai, Giuseppe

    1998-04-01

    We show that dynamics of specific amino acids within a protein can be characterized by neutron spectroscopy and hydrogen-deuterium labeling, and we present data on the motions of a selected set of groups within bacteriorhodopsin (BR), the retinal-based proton pump in the purple membrane of halophilic Archaea. Elastic incoherent neutron scattering experiments allow the definition of motions in the nano- to picosecond time scale and have revealed a dynamical transition from a harmonic to a softer, anharmonic atomic fluctuation regime in the global behavior of proteins. Biological activity in proteins is correlated with this transition, suggesting that flexibility is required for function. Elastic incoherent neutron scattering is dominated by H atom scattering, and to study the dynamics of a selected part of BR, fully deuterated purple membrane with BR containing H-retinal, H-tryptophan, and H-methionine was prepared biosynthetically in Halobacterium salinarum. These amino acids cluster in the functional center of the protein. In contrast to the protein globally, the thermal motions of the labeled atoms were found to be shielded from solvent melting effects at 260 K. Above this temperature, the labeled groups appear as more rigid than the rest of the protein, with a significantly smaller mean square amplitude of motion. These experimental results quantify the dynamical heterogeneity of BR (which meets the functional requirements of global flexibility), on the one hand, to allow large conformational changes in the molecule and of a more rigid region in the protein, on the other, to control stereo-specific selection of retinal conformations.

  3. A high resolution, inelastic neutron scattering investigation of tunnelling methyl groups in aspirin

    Science.gov (United States)

    Johnson, M. R.; Frick, B.; Trommsdorff, H. P.

    1996-08-01

    The tunnel frequency of protonated methyl groups in aspirin has been measured, by inelastic neutron scattering, at 2 K, to be 1.22 μeV. This result and the temperature dependence up to 42 K are in poor agreement with NMR measurements of deuterated methyl groups which conclude that the rotational potential is purely three-fold symmetric. The discrepancy is attributed to a six-fold contribution in the rotational potential for which justification is provided by a calculation of the rotational potential based on the room temperature crystal structure.

  4. Non-Linear Rheological Properties and Neutron Scattering Investigation on Dilute Ring-Linear Blends

    DEFF Research Database (Denmark)

    Pyckhout-Hintzen, W.; Bras, A.R.; Wischnewski, A.

    Linear and non-linear Rheology on dilute blends of polystyrene ring polymers in linear matrix is combined with Small Angle Neutron Scattering (SANS) investigations. In this way 2 different entanglement interactions become clear. After stretching the samples to different hencky strains up to 2...... with interpenetrating linear chains. At the same time the non-linear rheological and mechanical data fit to a non-affine slip-tube model as for moderately crosslinked networks and to interchain pressure models or a modified non-linear Doi-Edwards description for the observed strain hardening during the extensional...

  5. Neutron Scattering for Materials Science. Materials Research Society Symposium Proceedings, Volume 166

    Science.gov (United States)

    1990-01-01

    investigated by elas- tic diffuse neutron scattering. The diffuse intensity showed maxima which are attributed to the flat portions of the Fermi...should have a width in the - order of kBT" " 80meV, whereas the energy resolution is 0.8meV (FWHM). Iowever, the quasielas- tic width vanishes in the...0.6 3 Ni-6.5 at.Z Al-9.6 at.Z Mo 0 4 , Ni-6.1 atZ Al-9.4 at.Z Mo 0 Mt. no$. Soc. Symp. Proc. Vol. 166. 1990 Mateas Reeamh ocIety 256 EXPERIMENTAL

  6. Study of chemically unfolded {beta}-casein by means of small-angle neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Aschi, Adel [Laboratoire de Physique de la Matiere Molle, Faculte des Sciences de Tunis, Campus Universitaire, 1060, Tunis (Tunisia)]. E-mail: aschi13@yahoo.fr; Gharbi, Abdelhafidh [Laboratoire de Physique de la Matiere Molle, Faculte des Sciences de Tunis, Campus Universitaire, 1060, Tunis (Tunisia); Daoud, Mohamed [Service de Physique de l' Etat Condense. CEA Saclay. 91191 Gif-sur-Yvette cedex (France); Douillard, Roger [Equipe de Biochimie des Macromolecules Vegetales, Centre de Recherche Agronomique, 2Esplanade R. Garros, BP 224, 51686 Reims cedex 2 (France); Calmettes, Patrick [Laboratoire Leon Brillouin, CEA Saclay, 91191 Gif-sur-Yvette cedex (France)

    2007-01-01

    {beta}-casein is a flexible amphiphilic milk protein which forms an unfolded conformation in presence of very high denaturant concentrations. The structure of {beta}-casein formed at the bulk was studied by small-angle neutron scattering (SANS). The value of the second virial coefficient of the protein solutions indicates that the interactions between the polypeptide chain and solvent are repulsive. The protein conformation is similar to an excluded volume chain. The corresponding values of the contour length, L, the statistical length, b and the apparent radius of the chain cross-section, R{sub c} are given.

  7. The structure of P85 pluronic block copolymer micelles determined by small-angle neutron scattering

    DEFF Research Database (Denmark)

    Pedersen, J.S.; Gerstenberg, M.C.

    2003-01-01

    The symmetric triblock copolymer Pluronic P85 with EO(25)PO(40)EO(25) has been studied by small-angle neutron scattering (SANS) at 50 and 60 degreesC at concentrations of 0.25-10 wt.% in D(2)O. The data are analyzed by a model based on Monte Carlo simulations. The micelles are modeled as having...... a spherical core of poly(propylene oxide) (PPO) with some water surrounded by a corona of the poly(ethylene oxide) (PEO) block. The latter are non-interacting and obey Gaussian statistics, but are expelled from the core region. The analysis shows that the micelles are fairly concentration and temperature...

  8. Multiferroic phase of doped delafossite CuFeO2 identified using inelastic neutron scattering

    Science.gov (United States)

    Haraldsen, Jason T.; Ye, Feng; Fishman, Randy S.; Fernandez-Baca, Jamie A.; Yamaguchi, Yasuhiro; Kimura, Kenta; Kimura, Tsuyoshi

    2010-07-01

    We report inelastic neutron scattering measurements that provide a distinct dynamical “fingerprint” for the multiferroic ground state of 3.5% Ga-doped CuFeO2 . The complex ground state is stabilized by the displacement of the oxygen atoms, which contribute to the multiferroic coupling predicted in the “spin-driven” model. By comparing the observed and calculated spectrum of spin excitations, we conclude that the magnetic ground state is a distorted screw-type spin configuration with a distribution of turn angles.

  9. Cylindrical aggregates of chlorophylls studied by small-angle neutron scatter

    Energy Technology Data Exchange (ETDEWEB)

    Worcester, D.L. [Univ. of Missouri, Columbus, MO (United States); Katz, J.J. [Argonne National Laboratory, IL (United States)

    1994-12-31

    Neutron small-angle scattering has demonstrated tubular chlorophyll aggregates formed by self-assembly of a variety of chlorophyll types in nonpolar solvents. The size and other properties of the tubular aggregates can be accounted for by stereochemical properties of the chlorophyll molecules. Features of some of the structures are remarkably similar to light harvesting chlorophyll complexes in vivo, particularly for photosynthetic bacteria. These nanotube chlorophyll structures may have applications as light harvesting biomaterials where efficient energy transfer occurs from an excited state which is highly delocalized.

  10. Numerical generalized vibration density of states evaluation for inelastic neutron scattering in solid matter

    CERN Document Server

    Kazmianec, V; Aranghel, D

    2002-01-01

    A computational method for improved evaluation of the generalized vibration density of states (GVDS) is proposed. It is based on Fast Fourier Transform (FPT) technique and gives the possibility for more precise analyses of the neutron double differential scattering cross section. The method was applied to zirconium hydride investigation. The results were presented for ZrH sub 1 sub . sub 6 U sub 0 sub . sub 3 sub 2 sample at various temperatures on time-of-flight (TOF) Spectrometry at IBR-2 reactor of JINR-Dubna and were compared to GVDS values obtained by traditional single-phonon approximation method

  11. A Neutron Scattering Study of Lattice Dynamics of HgTe and HgSe

    DEFF Research Database (Denmark)

    Kepa, H.; Giebultowicz, T.; Buras, B.

    1982-01-01

    The dispersion relations for the acoustic and optic phonons in HgTe and for the acoustic phonons in HgSe were determined by neutron inelastic scattering in three high symmetry directions. The effect of the free-carrier screening of the long-range electric field of LO phonons in HgTe was observed........ The formalism of the rigid ion model is used for numerical calculations of the phonon dispersion relations and the phonon densities of states in HgTe and HgSe....

  12. Analysis of the Quasi-Elastic Scattering of Neutrons in Hydrogenous Liquids

    Energy Technology Data Exchange (ETDEWEB)

    Porohit, S.N. [Nuclear Science and Engineering Dept., Rensselaer Polytechnique Inst., Troy, NY (United States)

    1966-11-15

    A critical discussion of the quasi-elastic scattering of neutrons by incoherent (hydrogenous) liquids is presented. Using the line shape expression a comparative discussion of several phenomenological models has been carried out. Extension of the Singwi-Sjoelander zero phonon expression, for the jump-diffusion model, so as to include the one phonon expression has also been given. For a delayed diffusion model a complete treatment of S(K, {omega}) is presented. Along the lines of the macroscopic diffusion cooling, a microscopic diffusion cooling effect in fluids is speculated.

  13. Dynamics of flexible counter-ions in conducting polyaniline a quasielastic neutron-scattering study

    CERN Document Server

    Bee, M; Djurado, D; Marque, D; Combet, J; Rannou, P; Dufour, B

    2002-01-01

    Conducting polyaniline protonated with sulphonic flexible counter-ions was investigated by quasielastic incoherent neutron scattering. In addition to their role in electrical properties, the flexible counter-ions also increase the elasticity of the samples. As in the case of more rigid counter-ions, polymer chains appear as very stiff objects whose dynamics is completely outside the investigated time scale. Conversely, the counter-ion dynamics was proved to be of major importance in charge transport since a dynamical transition is observed precisely in the temperature range where the electronic properties change from a metallic to a semiconducting regime. (orig.)

  14. Characterization of 'strong-fragile' behaviour of glass-forming aqueous solutions by neutron scattering

    CERN Document Server

    Branca, C; Galli, G; Magazù, S; Maisano, G; Migliardo, F

    2002-01-01

    Neutron-scattering measurements have been performed on trehalose/H sub 2 O and sucrose/H sub 2 O mixtures by using the spectrometer MIBEMOL at the Laboratoire Leon Brillouin (LLB, Saclay) as a function of temperature and concentration. In order to characterize the different rigidities of both the disaccharide/H sub 2 O mixtures, we have evaluated the R sub 1 (T sub g) parameter connected to the 'strong-fragile' classification of the systems according to Angell's nomenclature. (orig.)

  15. Methyl group dynamics in a glass and its crystalline counterpart by neutron scattering

    CERN Document Server

    Moreno, A J; Colmenero, J; Frick, B

    2002-01-01

    Methyl group dynamics in the same sample of sodium acetate trihydrate in crystalline and glassy states have been investigated by neutron scattering. Measurements have been carried out in the whole temperature range covering the crossover from rotational tunneling to classical hopping. The results in the crystalline sample have been analyzed according to the usual single-particle model, while those in the glass were analyzed in terms of a broad Gaussian distribution of single-particle potentials, with a standard deviation of 205 K. The average barrier in the glass (417 K) takes, within the experimental error, the same value as the unique barrier in the crystal. (orig.)

  16. Small-Angle Neutron Scattering Measurements of Magnetic Cluster Sizes in Magnetic Recording Disks

    Energy Technology Data Exchange (ETDEWEB)

    Toney, Michael F

    2003-06-17

    We describe Small Angle Neutron Scattering measurements of the magnetic cluster size distributions for several longitudinal magnetic recording media. We find that the average magnetic cluster size is slightly larger than the average physical grain size, that there is a broad distribution of cluster sizes, and that the cluster size is inversely correlated to the media signal-to-noise ratio. These results show that intergranular magnetic coupling in these media is small and they provide empirical data for the cluster-size distribution that can be incorporated into models of magnetic recording.

  17. A neutron scattering study on the stability of trehalose mycolates under thermal stress

    Science.gov (United States)

    Migliardo, F.; Salmeron, C.; Bayan, N.

    2013-10-01

    The present paper is focused on the study of the dynamics of mycolic acids, which are fundamental components of the outer membrane (mycomembrane) of Mycobacterium tuberculosis. An elastic neutron scattering study of mycolic acid/H2O and lecithin/H2O mixtures as a function of temperature and exchanged wavevector Q has been carried out. This study provides an effective way for characterizing the dynamical properties, furnishing a set of parameters characterizing the different flexibility and rigidity of the investigated lipids. The behavior of the elastically scattered intensity profiles and the derived mean square displacements as a function of temperature shows a more marked temperature dependence for lecithin lipids in comparison with mycolic acids, so revealing a higher thermal stability of these latter. These findings could be useful for understanding the dynamics-function relation in the mycomembrane and then to relate it to the low permeability and high resistance of mycobacteria to many antibiotics.

  18. Structural defects in SiC single crystals studied by small-angle neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Nasir Khan, M. [Physics Research Division, PINSTECH, P.O. Nilore, Islamabad (Pakistan)]. E-mail: nasir@pinstech.org.pk; Bashir, J. [Physics Research Division, PINSTECH, P.O. Nilore, Islamabad (Pakistan); Seong, Baek-Seok [Korea Atomic Energy Research Institute, P.O. Box 105, Yusong, Daejeon 305-600 (Korea, Republic of); Lee, Chang-Hee [Korea Atomic Energy Research Institute, P.O. Box 105, Yusong, Daejeon 305-600 (Korea, Republic of)

    2006-11-15

    Growth-induced structural defects such as hollow core super screw dislocation known as micropipes in silicon carbide single crystals grown by sublimation method are investigated. Electron microscopy as well as small-angle neutron scattering (SANS) techniques were used to resolve these defects in sizes. For SANS, scattering signals in the momentum transfer range 0.1-2.2 nm{sup -1} were recorded. This corresponds for the periodic structure to length scale from 3 to 60 nm approximately. Isotropic patterns were analyzed using spherical-shell model. The analyses showed that the small spherical defects are within a volume fraction less than 5% in these crystals. The change in the growth process such as growth rate and atmosphere showed no significant change in the sizes of these defects but has an effect on the distribution of these defects.

  19. Small Angle Neutron Scattering for the Detection of Branching in Worm-Like Micellar Systems

    Science.gov (United States)

    Vogtt, Karsten; Rai, Durgesh; Beaucage, Gregory

    2014-03-01

    Micellar solutions can exhibit a broad variety of phase structure as a function of counter ion content, surfactant concentration, and the presence of ternary components. Under some conditions extended cylindrical structures that display persistence and other chain features of polymers are produced. These worm-like micelles (WLMs) can form branched structures that dynamically change under shear and even in quiescent conditions. The rheology of these branched WLMs is strongly dependent on migration of the branch points, and the dynamics of branch formation and removal. We have recently developed a scattering model for branched polyolefins and other topologically complex materials that can quantify the branching density, branch length, branch functionality and the hyperbranch (branch-on-branch) content of polymers. Using small angle neutron scattering these parameters are determined for model emulsions with varying surfactant and salt concentrations.

  20. Level Lifetimes in 94Zr from DSAM Measurements following Inelastic Neutron Scattering

    Directory of Open Access Journals (Sweden)

    Yates S. W.

    2014-03-01

    Full Text Available The lifetime of the second 2+ state in 94Zr was redetermined by the Doppler-shift attenuation method following inelastic neutron scattering (DSAM-INS from metallic Zr and ZrO2 samples of natural isotopic abundance. The new value for the level lifetime differs significantly from the previously published value, with the new lifetime found to be roughly twice that value. A reanalysis of the original γ-ray data from the enriched 94ZrO2 sample failed to expose the source of this discrepancy; however, powder X-ray diffraction and scanning electron microscopy performed on each scattering sample, including the enriched sample used previously, provide clues to an explanation and reveal the role of the chemical properties of the sample material in DSAM-INS lifetime determinations.

  1. Specular and off-specular neutron scattering from solid-supported glycolipid membrane multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Schneck, Emanuel; Tanaka, Motomu [Physikalisch-Chemisches Institut, Universitaet Heidelberg (Germany); Rehfeldt, Florian [Lehrstuhl fuer Biophysik E22, Technische Universitaet Muenchen (Germany); Deme, Bruno [Institut Laue-Langevin, Grenoble (France); Gege, Christian; Schmidt, Richard [Fachbereich Chemie, Universitaet Konstanz (Germany)

    2008-07-01

    Solid-supported glycolipid membrane multilayers, acting as well-defined model systems for the study of saccharide-mediated inter-membrane interactions, were studied by specular and off-specular neutron scattering. Experiments were carried out at controlled temperatures and humidities, as well as under bulk water using a self-developed liquid cell. Force-distance relationships were recorded by measuring at various osmotic pressures. Mechanical properties of the studied membranes (i.e. bending moduli and inter-membrane compression moduli) were extracted by comparing scattering signals to reciprocal space maps simulated in the framework of smectic crystal theory. The results demonstrate that distinct variations in the oligosaccharide headgroup structures of the glycolipid molecules can result in significant changes in bending modulus and inter-membrane interactions.

  2. In situ shape and distance measurements in neutron scattering and diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Fujiwara, Satoru; Mendelson, R.A. [Univ. of California, San Francisco, CA (United States)

    1994-12-31

    Neutron scattering combined with selective isotopic labeling and contrast matching is useful for obtaining in situ structural information about a selected particle, or particles, in a macromolecular complex. The observed intensities, however, may be distorted by inter-complex interference and by scattering-length-density fluctuations of the (otherwise) contrast-matched portions. Methods have been proposed to cancel out such distortions (Hoppe`s method, the Statistical Labeling Method, and the Triple Isotopic Substitution Method). With these methods as well as related unmixed-sample methods, structural information about the selected particles can be obtained without these distortions. We have generalized these methods so that, in addition to globular particles in solution, they can be applied to in situ structures of systems having underlying symmetry and/or net orientation as well. The information obtainable from such experiments is discussed.

  3. Neutron-Scattering Study of Spin Waves in the Ferrimagnet RbNiF3

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage; Birgeneau, R. J.; Guggenheim, H. J.

    1972-01-01

    by a 180° antiferromagnetic exchange between nearest-neighbor A, B spins and a 90° ferromagnetic exchange between nearest-neighbor B spins. In this paper we report a detailed inelastic-neutron-scattering study of the spin waves in RbNiF3 both at low temperatures and through Tc. The magnetic unit cell......-magnon Raman scattering. At higher temperatures it is found that the c-axis acoustic magnons renormalize like the magnetization, whereas the high-lying optic modes are nearly temperature independent. This leads one to the physical picture in which RbNiF3 at high temperatures is viewed as a set of strongly...

  4. Small angle neutron scattering study on short and long chain phosphatidylcholine mixture in trehalose solution

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Hiroshi [Department of Physics, Gunma University, Maebashi, Gunma (Japan)

    2001-03-01

    Trehalose protects cells and proteins against various stresses due to low temperatures or dryness. In order to clarify the molecular mechanism of cryoprotective function of trehalose, we have studied the interaction between trehalose and phosphatidylcholine (PC) which is a main lipid component of cell membranes. In this study, the structural change of a binary PC mixture by the presence of trehalose was investigated by means of small angle neutron scattering. The PC binary mixture studied contains dihexanoyl-PC (diC{sub 6}PC) and dihexadecy-PC (DHPC). The former has short hydrocarbon chains and the latter has long hydrocarbon chains. The scattering profiles from the DHPC/diC{sub 6}PC mixture were changed, depending on trehalose concentrations. This change can be interpreted as suggesting that the presence of trehalose reduces the interfacial area between water and PCs. (author)

  5. Proceedings of the 182nd basic science seminar (The workshop on neutron structural biology ) 'New frontiers of structural biology advanced by solution scattering'

    Energy Technology Data Exchange (ETDEWEB)

    Fujiwara, Satoru (ed.) [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-03-01

    182nd advanced science seminar (the workshop on neutron structural biology) was held in February 9-10, 2000 at Tokai. Thirty-six participants from universities, research institutes, and private companies took part in the workshop, and total of 24 lectures were given. This proceedings collects abstracts, the figures and tables, which the speakers used in their lectures. The proceedings contains two reviews from the point of view of x-ray and neutron scatterings, and six subjects (21 papers) including neutron and x-ray scattering in the era of structure genomics, structural changes detected with solution scattering, a new way in structural biology opened by neutron crystallography and neutron scattering, x-ray sources and detectors, simulation and solution scattering, and neutron sources and detectors. (Kazumata, Y.)

  6. Characterization of Nanocellulose Using Small-Angle Neutron, X-ray, and Dynamic Light Scattering Techniques.

    Science.gov (United States)

    Mao, Yimin; Liu, Kai; Zhan, Chengbo; Geng, Lihong; Chu, Benjamin; Hsiao, Benjamin S

    2017-02-16

    Nanocellulose extracted from wood pulps using TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-mediated oxidation and sulfuric acid hydrolysis methods was characterized by small-angle neutron scattering (SANS), small-angle X-ray scattering (SAXS), and dynamic light scattering (DLS) techniques. The dimensions of this nanocellulose (TEMPO-oxidized cellulose nanofiber (TOCN) and sulfuric acid hydrolyzed cellulose nanocrystal (SACN)) revealed by the different scattering methods were compared with those characterized by transmission electron microscopy (TEM). The SANS and SAXS data were analyzed using a parallelepiped-based form factor. The width and thickness of the nanocellulose cross section were ∼8 and ∼2 nm for TOCN and ∼20 and ∼3 nm for SACN, respectively, where the fitting results from SANS and SAXS profiles were consistent with each other. DLS was carried out under both the VV mode with the polarizer and analyzer parallel to each other and the HV mode having them perpendicular to each other. Using rotational and translational diffusion coefficients obtained under the HV mode yielded a nanocellulose length qualitatively consistent with that observed by TEM, whereas the length derived by the translational diffusion coefficient under the VV mode appeared to be overestimated.

  7. Charge Symmetry Breaking In Neutron Proton Scattering To Deuteron And Neutral Pion Close To Threshold

    CERN Document Server

    Reitzner, S D

    2001-01-01

    The charge symmetry breaking (CSB) experiment using the CHARGEX facility and the SASP magnetic spectrometer at TRIUMF has measured the forward-backward scattering asymmetry (Afb) for np→dπ 0 at a neutron beam energy of 279.5 MeV. This reaction is sensitive to contributions not present in elastic scattering and therefore will complement previous measurements of CSB. Contributions to CSB in np→dπ 0 are predicted to be an order of magnitude greater than those found for elastic scattering. These contributions, which include η − π 0 and η′ − π0 mixing and the u - d quark mass difference in pion- nucleon scattering, are predicted to give values for Afb that range from (−35 to +60) × 10−4. A fb can be non-zero only if charge-symmetry is violated. Due to the nature of the observable and the realities of the experiment, Afb is obtained from a χ2 minimization procedure which compares data w...

  8. Joint small-angle X-ray and neutron scattering data analysis of asymmetric lipid vesicles.

    Science.gov (United States)

    Eicher, Barbara; Heberle, Frederick A; Marquardt, Drew; Rechberger, Gerald N; Katsaras, John; Pabst, Georg

    2017-04-01

    Low- and high-resolution models describing the internal transbilayer structure of asymmetric lipid vesicles have been developed. These models can be used for the joint analysis of small-angle neutron and X-ray scattering data. The models describe the underlying scattering length density/electron density profiles either in terms of slabs or through the so-called scattering density profile, previously applied to symmetric lipid vesicles. Both models yield structural details of asymmetric membranes, such as the individual area per lipid, and the hydrocarbon thickness of the inner and outer bilayer leaflets. The scattering density profile model, however, comes at a cost of increased computational effort but results in greater structural resolution, showing a slightly lower packing of lipids in the outer bilayer leaflet of ∼120 nm diameter palmitoyl-oleoyl phosphatidyl-choline (POPC) vesicles, compared to the inner leaflet. Analysis of asymmetric dipalmitoyl phosphatidylcholine/POPC vesicles did not reveal evidence of transbilayer coupling between the inner and outer leaflets at 323 K, i.e. above the melting transition temperature of the two lipids.

  9. Development of a One-Dimensional Small-Angle Neutron Scattering Instrument at the University of Illinois TRIGA Reactor Laboratory

    Science.gov (United States)

    Monti, D. A.; Guillermo, N. R.; Hulin, M. J.; Heuser, B. J.; Toreja, A.; Moschetti, T. L.

    1996-03-01

    A small-angle neutron scattering instrument with slit-smeared geometry (1-D SANS) has been constructed at the University of Illinois 1.5 MWatt TRIGA reactor. This facility falls under the general heading of "low-flux research reactors" which typically are not used for neutron scattering research. Low-flux reactors can support neutron scattering research under certain conditions, however. 1-D SANS using elastically-bent crystal optics is one such example [Popovici, et al. (1995). J. Phys. Chem. Solids 56, 1425-1431]. Our instrument uses a pyrolytic graphite pre-monochromator and two elastically-bent Si wafers, all in a (+,+,-) configuration. Instrumental performance including low-angle resolution, on-sample intensity, resolution variability, and cross-section measurement capability will be presented.

  10. Relaxation dynamics of lysozyme in solution under pressure: Combining molecular dynamics simulations and quasielastic neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Calandrini, V. [Centre de Biophysique Moleculaire, Rue Charles Sadron, 45071 Orleans (France); Synchrotron Soleil, L' Orme de Merisiers, B.P. 48, 91192 Gif-sur-Yvette (France); Hamon, V. [Centre de Biophysique Moleculaire, Rue Charles Sadron, 45071 Orleans (France); Hinsen, K. [Centre de Biophysique Moleculaire, Rue Charles Sadron, 45071 Orleans (France); Synchrotron Soleil, L' Orme de Merisiers, B.P. 48, 91192 Gif-sur-Yvette (France); Calligari, P. [Centre de Biophysique Moleculaire, Rue Charles Sadron, 45071 Orleans (France); Institut Laue-Langevin, 6 Rue Jules Horowitz, B.P. 156, 38042 Grenoble (France); Laboratoire Leon Brillouin, CEA Saclay, 91191 Gif-sur-Yvette (France); Bellissent-Funel, M.-C. [Laboratoire Leon Brillouin, CEA Saclay, 91191 Gif-sur-Yvette (France); Kneller, G.R. [Centre de Biophysique Moleculaire, Rue Charles Sadron, 45071 Orleans (France); Synchrotron Soleil, L' Orme de Merisiers, B.P. 48, 91192 Gif-sur-Yvette (France)], E-mail: kneller@cnrs-orleans.fr

    2008-04-18

    This paper presents a study of the influence of non-denaturing hydrostatic pressure on the relaxation dynamics of lysozyme in solution, which combines molecular dynamics simulations and quasielastic neutron scattering experiments. We compare results obtained at ambient pressure and at 3 kbar. Experiments have been performed at pD 4.6 and at a protein concentration of 60 mg/ml. For both pressures we checked the monodispersity of the protein solution by small angle neutron scattering. To interpret the simulation results and the experimental data, we adopt the fractional Ornstein-Uhlenbeck process as a model for the internal relaxation dynamics of the protein. On the experimental side, global protein motions are accounted for by the model of free translational diffusion, neglecting the much slower rotational diffusion. We find that the protein dynamics in the observed time window from about 1 to 100 ps is slowed down under pressure, while its fractal characteristics is preserved, and that the amplitudes of the motions are reduced by about 20%. The slowing down of the relaxation is reduced with increasing q-values, where more localized motions are seen.

  11. Dynamics of supercooled confined water measured by deep inelastic neutron scattering

    Science.gov (United States)

    De Michele, Vincenzo; Romanelli, Giovanni; Cupane, Antonio

    2018-02-01

    In this paper, we present the results of deep inelastic neutron scattering (DINS) measurements on supercooled water confined within the pores (average pore diameter 20 Å) of a disordered hydrophilic silica matrix obtained through hydrolysis and polycondensation of the alkoxide precursor Tetra-Methyl-Ortho-Silicate via the sol-gel method. Experiments were performed at two temperatures (250 K and 210 K, i.e., before and after the putative liquid-liquid transition of supercooled confined water) on a "wet" sample with hydration h 40% w/w, which is high enough to have water-filled pores but low enough to avoid water crystallization. A virtually "dry" sample at h 7% was also investigated to measure the contribution of the silica matrix to the neutron scattering signal. As is well known, DINS measurements allow the determination of the mean kinetic energy and the momentum distribution of the hydrogen atoms in the system and therefore, allow researchers to probe the local structure of supercooled confined water. The main result obtained is that at 210 K the hydrogen mean kinetic energy is equal or even slightly higher than at 250 K. This is at odds with the predictions of a semiempirical harmonic model recently proposed to describe the temperature dependence of the kinetic energy of hydrogen in water. This is a new and very interesting result, which suggests that at 210 K, the water hydrogens experience a stiffer intermolecular potential than at 250 K. This is in agreement with the liquid-liquid transition hypothesis.

  12. Ligand-induced dynamical change of G-protein-coupled receptor revealed by neutron scattering

    Science.gov (United States)

    Shrestha, Utsab R.; Bhowmik, Debsindhu; Mamontov, Eugene; Chu, Xiang-Qiang

    Light activation of the visual G-protein-coupled receptor rhodopsin leads to the significant change in protein conformation and structural fluctuations, which further activates the cognate G-protein (transducin) and initiates the biological signaling. In this work, we studied the rhodopsin activation dynamics using state-of-the-art neutron scattering technique. Our quasi-elastic neutron scattering (QENS) results revealed a broadly distributed relaxation rate of the hydrogen atom in rhodopsin on the picosecond to nanosecond timescale (beta-relaxation region), which is crucial for the protein function. Furthermore, the application of mode-coupling theory to the QENS analysis uncovers the subtle changes in rhodopsin dynamics due to the retinal cofactor. Comparing the dynamics of the ligand-free apoprotein, opsin versus the dark-state rhodopsin, removal of the retinal cofactor increases the relaxation time in the beta-relaxation region, which is due to the possible open conformation. Moreover, we utilized the concept of free-energy landscape to explain our results for the dark-state rhodopsin and opsin dynamics, which can be further applied to other GPCR systems to interpret various dynamic behaviors in ligand-bound and ligand-free protein.

  13. Small-angle neutron-scattering studies of cobalt(II) organophosphorus polymers in deuteriobenzene

    Energy Technology Data Exchange (ETDEWEB)

    Thiyagarajan, P.; Diamond, H.; Danesi, P.R.; Horwitz, E.P.

    1987-12-16

    Bis(2,4,4-trimethylpentyl)phosphinic acid, an extractant used to separate cobalt from nickel by solvent extraction, can form polymers when bound to large amounts of cobalt(II). The size and shape of these polymers have been measured by small-angle neutron scattering. The polymers form long thin chains, approximately 550 A long and about 9 A in radius. In some preparations, although the lengths were similar, the measured average cross-sectional radii were slightly larger, implying some cross-linking. The Co(II) polymers formed from the homologous series phosphoric acid bis(2-ethylhexyl) ester, (2-ethylhexyl)phosphonic acid 2-ethylhexyl ester, and bis(2-ethylhexyl)phosphinic acid were also measured. The first member of this series produced long thin rodlike polymers of constant cross-sectional radius (10 A) and variable lengths; the phosphonic and phosphinic extractants produced smaller polymers whose neutron scattering did not conform to a cylindrical model. 21 references, 5 figures, 6 tables.

  14. Multiferroic phase of doped delafossite CuFeO2 identified using inelastic neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Haraldsen, Jason T [ORNL; Ye, Feng [ORNL; Fishman, Randy Scott [ORNL; Fernandez-Baca, Jaime A [ORNL; Yamaguchi, Y. [Osaka University; Kimura, K. [Osaka University; Kimura, T. [Osaka University

    2010-01-01

    Multiferroic materials allow the electric polarization to be controlled by switching the direction of magnetic ordering and consequently offer prospects for many new technological applications [1 4]. Because multiferroic behavior has been found in materials that exhibit complex (non-collinear and incommensurate) magnetic order, it is essential to know the spin arrangement of the ground states in these materials [4 9]. In many cases, elastic neutron scattering measurements alone are not sufficient to distinguish among several potential complex magnetic states. We report inelastic neutron scattering (INS) measurements that provide a distinct dynamical fingerprint for the multiferroic ground state of 3.5% Ga-doped CuFeO2. The complex ground state is stabilized by the displacement of the oxygen atoms [10], which are also responsible for the multiferroic coupling predicted by Arima [8]. By comparing the observed and calculated spectrum of spin excitations, we conclude that the magnetic ground state is a distorted screwtype spin configuration. The exchange interactions that stabilize this structure are consistent with those obtained from inelastic measurements [11, 12] on undoped CuFeO2.

  15. Hydrogen adsorption in HKUST-1: a combined inelastic neutron scattering and first-principles study

    Science.gov (United States)

    Brown, Craig M.; Liu, Yun; Yildirim, Taner; Peterson, Vanessa K.; Kepert, Cameron J.

    2009-05-01

    Hydrogen adsorption in high surface area nanoporous coordination polymers has attracted a great deal of interest in recent years due to the potential applications in energy storage. Here we present combined inelastic neutron scattering measurements and detailed first-principles calculations aimed at unraveling the nature of hydrogen adsorption in HKUST-1 (Cu3(1,3,5-benzenetricarboxylate)2), a metal-organic framework (MOF) with unsaturated metal centers. We reveal that, in this system, the major contribution to the overall binding comes from the classical Coulomb interaction which is not screened due to the open metal site; this explains the relatively high binding energies and short H2-metal distances observed in MOFs with exposed metal sites as compared to traditional ones. Despite the short distances, there is no indication of an elongation of the H-H bond for the bound H2 molecule at the metal site. We find that both the phonon and rotational energy levels of the hydrogen molecule are closely similar, making the interpretation of the inelastic neutron scattering data difficult. Finally, we show that the orientation of H2 has a surprisingly large effect on the binding potential, reducing the classical binding energy by almost 30%. The implication of these results for the development of MOF materials for better hydrogen storage is discussed.

  16. Insights into molecular architecture of terpenes using small angle neutron scattering

    Science.gov (United States)

    Rai, Durgesh K.; Annamraju, Aparna; Pingali, Sai Venkatesh; O'Neill, Hugh M.; Mewalal, Ritesh; Gunter, Lee E.; Tuskan, Gerald A.

    Understanding macromolecular architectures is vital to engineering prospective terpene candidates for advanced biofuels. Eucalyptus plants store terpenes in specialized cavity-like structures in the leaves called oil glands, which comprises of volatile (VTs) and non-volatile (NVTs) terpenes. Using small-angle neutron scattering, we have investigated the structure and phase behavior of the supramolecular assembly formed by Geranyl beta-D-glucoside (GDG), a NVT and compare the results with that of beta-octyl glucoside (BOG). The formation of micellar structures was observed in the concentration range of 0.5-5 v/v% in water using small angle neutron scattering (SANS) where Schultz sphere model was used in quantifying structural parameters of micelles. SANS studies determine that GDG and BOG behave like amphiphiles forming micellar structures in aqueous solution. The micelles swell upon addition of alpha-Pinene (AP) indicating partition to the core region of the micelles. The general behavior of the micellar growth after partitioning of AP to form thermodynamically stable sizes varies with the NVT concentration. Our studies reveal that the presence of steric hindrance in the GDG via the unsaturated bonds could help stabilize VTs inside the oil glands. LDRD project LOIS ID 7428, SNS, CSMB, HFIR, ORNL, DOE Office of Science User Facilities.

  17. Molecular mobility in Medicago truncatula seed during early stage of germination: Neutron scattering and NMR investigations

    Energy Technology Data Exchange (ETDEWEB)

    Falourd, Xavier [UR1268 Biopolymères Interactions Assemblages, INRA, F-44316 Nantes (France); Natali, Francesca [CNR-IOM-OGG, c/o Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9 (France); Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9 (France); Peters, Judith [Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9 (France); Université Joseph Fourier UFR PhITEM, BP 53, 38041 Grenoble Cedex 9 (France); Institut de Biologie Structurale, 41 rue Jules Horowitz, 38027 Grenoble Cedex 1 (France); Foucat, Loïc, E-mail: Loic.Foucat@nantes.inra.fr [UR1268 Biopolymères Interactions Assemblages, INRA, F-44316 Nantes (France)

    2014-01-15

    Highlights: • Neutron scattering and NMR approaches were used to characterize seed germination. • A parallel between macromolecular motions and water dynamics was established. • Freezing/thawing cycle revealed a hysteresis connected to the seed hydration level. - Abstract: First hours of Medicago truncatula (MT) seeds germination were investigated using elastic incoherent neutron scattering (EINS) and nuclear magnetic resonance (NMR), to follow respectively how macromolecular motions and water mobility evolve when water permeates into the seed. From EINS results, it was shown that there is an increase in macromolecular mobility with the water uptake. Changes in NMR relaxation parameters reflected microstructural changes associated with the recovery of the metabolic processes. The EINS investigation of the effect of temperature on macromolecular motions showed that there is a relationship between the amount of water in the seeds and the effect of freezing–thawing cycle. The NMR relaxometry results obtained at 253 K allowed establishing possible link between the freezing of water molecules tightly bound to macromolecules and their drastic motion restriction around 250 K, as observed with EINS at the highest water content.

  18. Neutron scattering studies of domain structures in type-II superconductor niobium

    Energy Technology Data Exchange (ETDEWEB)

    Reimann, Tommy; Schulz, Michael [Heinz Maier-Leibnitz Zentrum (MLZ), TU Muenchen, Garching (Germany); Physikdepartment E21, TU Muenchen, Garching (Germany); Muehlbauer, Sebastian [Heinz Maier-Leibnitz Zentrum (MLZ), TU Muenchen, Garching (Germany); Gruenzweig, Christian [Paul-Scherrer-Institut, Villigen (Switzerland); Boeni, Peter [Physikdepartment E21, TU Muenchen, Garching (Germany)

    2014-07-01

    In the intermediate mixed state (IMS) of a type II superconductor (SC), the sample splits up into Meissner domains and Shubnikov domains which carry the vortex lattice (VL). A detailed investigation of these domain patterns offers the possibility to study general characteristics of domain nucleation and morphology as well as the physical properties of vortex-vortex and vortex-pinning interactions. In this talk we show that ultra small angle neutron scattering (USANS) can be used for the identification of VL properties. We have studied the VL domain morphology in a Nb single crystal disc that exhibit strong vortex pinning. USANS is sensitive to structures with sizes up to 20 microns and is therefore capable to probe IMS domains which is not possible with the commonly used small angle neutron scattering (SANS). Furthermore, USANS averages over the whole sample and hence probes the bulk of the material in contrast to magneto optical methods. Our investigation on the IMS of Nb reveals a preferred domain size with a strong dependence on magnetic field and sample thickness. Surprisingly, the average domain size is nearly independent of the temperature in a field cooled measurement giving some hint on the nature of field expulsion in the IMS of samples with significant pinning.

  19. Atomistic modelling of scattering data in the Collaborative Computational Project for Small Angle Scattering (CCP-SAS)

    Energy Technology Data Exchange (ETDEWEB)

    Perkins, Stephen J.; Wright, David W.; Zhang, Hailiang; Brookes, Emre H.; Chen, Jianhan; Irving, Thomas C.; Krueger, Susan; Barlow, David J.; Edler, Karen J.; Scott, David J.; Terrill, Nicholas J.; King, Stephen M.; Butler, Paul D.; Curtis, Joseph E.

    2016-10-14

    The capabilities of current computer simulations provide a unique opportunity to model small-angle scattering (SAS) data at the atomistic level, and to include other structural constraints ranging from molecular and atomistic energetics to crystallography, electron microscopy and NMR. This extends the capabilities of solution scattering and provides deeper insights into the physics and chemistry of the systems studied. Realizing this potential, however, requires integrating the experimental data with a new generation of modelling software. To achieve this, the CCP-SAS collaboration (http://www.ccpsas.org/) is developing open-source, high-throughput and user-friendly software for the atomistic and coarse-grained molecular modelling of scattering data. Robust state-of-the-art molecular simulation engines and molecular dynamics and Monte Carlo force fields provide constraints to the solution structure inferred from the small-angle scattering data, which incorporates the known physical chemistry of the system. The implementation of this software suite involves a tiered approach in whichGenAppprovides the deployment infrastructure for running applications on both standard and high-performance computing hardware, andSASSIEprovides a workflow framework into which modules can be plugged to prepare structures, carry out simulations, calculate theoretical scattering data and compare results with experimental data.GenAppproduces the accessible web-based front end termedSASSIE-web, andGenAppandSASSIEalso make community SAS codes available. Applications are illustrated by case studies: (i) inter-domain flexibility in two- to six-domain proteins as exemplified by HIV-1 Gag, MASP and ubiquitin; (ii) the hinge conformation in human IgG2 and IgA1 antibodies; (iii) the complex formed between a hexameric protein Hfq and mRNA; and (iv) synthetic `bottlebrush' polymers.

  20. Monte Carlo study of neutron dose equivalent during passive scattering proton therapy

    Science.gov (United States)

    Zheng, Yuanshui; Newhauser, Wayne; Fontenot, Jonas; Taddei, Phil; Mohan, Radhe

    2007-08-01

    Stray radiation exposures are of concern for patients receiving proton radiotherapy and vary strongly with several treatment factors. The purposes of this study were to conservatively estimate neutron exposures for a contemporary passive scattering proton therapy system and to understand how they vary with treatment factors. We studied the neutron dose equivalent per therapeutic absorbed dose (H/D) as a function of treatment factors including proton energy, location in the treatment room, treatment field size, spread-out Bragg peak (SOBP) width and snout position using both Monte Carlo simulations and analytical modeling. The H/D value at the isocenter for a 250 MeV medium field size option was estimated to be 20 mSv Gy-1. H/D values generally increased with the energy or penetration range, fell off sharply with distance from the treatment unit, decreased modestly with the aperture size, increased with the SOBP width and decreased with the snout distance from the isocenter. The H/D values from Monte Carlo simulations agreed well with experimental results from the literature. The analytical model predicted H/D values within 28% of those obtained in simulations; this value is within typical neutron measurement uncertainties.

  1. The performance of neutron scattering spectrometers at a long-pulse spallation source

    Energy Technology Data Exchange (ETDEWEB)

    Pynn, R.

    1995-04-01

    The first conclusion the author wants to draw is that comparison of the performance of neutron scattering spectrometers at CW and pulsed sources is simpler for long-pulsed sources than it is for the short-pulse variety. Even though detailed instrument design and assessment will require Monte Carlo simulations (which have already been performed at Los Alamos for SANS and reflectometry), simple arguments are sufficient to assess the approximate performance of spectrometers at an LPSS and to support the contention that a 1 MW long-pulse source can provide attractive performance, especially for instrumentation designed for soft-condensed-matter science. Because coupled moderators can be exploited at such a source, its time average cold flux is equivalent to that of a research reactor with a power of about 15 MW, so only a factor of 4 gain from source pulsing is necessary to obtain performance that is comparable with the ILL. In favorable cases, the gain from pulsing can be even more than this, approaching the limit set by the peak flux, giving about 4 times the performance of the ILL. Because of its low duty factor, an LPSS provides the greatest performance gains for relatively low resolution experiments with cold neutrons. It should thus be considered complementary to short pulse sources which are most effective for high resolution experiments using thermal or epithermal neutrons.

  2. New instruments and science around SINQ. Lecture notes of the 4. summer school on neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Furrer, A. [ed.

    1996-11-01

    The spallation neutron source at PSI will be commissioned towards the end of this year together with a set of first generation instruments. This facility should then be available for the initial scientific work after spring next year. One of the main goals of this year`s summer school for neutron scattering was therefore the preparation of the potential customers at this facility for its scientific exploitation. In order to give them the - so to speak - last finish, we have dedicated the school to the discussion of the instruments at SINQ and their scientific potential. These proceedings are divided into two parts: Part A gives a complete description of the first-generation instruments and sample environment at SINQ. For all the instruments the relevant parameters for planning experiments are listed. Part A is completed by G. Bauer`s summary on experimental facilities and future developments at SINQ. Part B presents the lecture notes dealing with relevant applications of neutron based techniques in science and technology. The summary lecture by S.W. Lovesey is also included. (author) figs., tabs., refs.

  3. A new small-angle neutron scattering spectrometer at China Mianyang research reactor

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Mei, E-mail: pm740509@163.com; Sun, Liangwei; Chen, Liang; Sun, Guangai; Chen, Bo; Xie, Chaomei; Xia, Qingzhong; Yan, Guanyun; Tian, Qiang; Huang, Chaoqiang; Pang, Beibei; Zhang, Ying; Wang, Yun; Liu, Yaoguang; Kang, Wu; Gong, Jian

    2016-02-21

    A new pinhole small-angle neutron scattering (SANS) spectrometer, installed at the cold neutron source of the 20 MW China Mianyang Research Reactor (CMRR) in the Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, has been put into use since 2014. The spectrometer is equipped with a multi-blade mechanical velocity selector, a multi-beam collimation system, and a two-dimensional He-3 position sensitive neutron detector. The q-range of the spectrometer covers from 0.01 nm{sup −1} to 5.0 nm{sup −1}. In this paper, the design and characteristics of the SANS spectrometer are described. The q-resolution calculations, together with calibration measurements of silver behenate and a dispersion of nearly monodisperse poly-methyl-methacrylate nanoparticles indicate that our SANS spectrometer has a good performance and is now in routine service. - Highlights: • A new SANS spectrometer has been put into use since 2014 in China. • One MBR selector possesses a higher resolution compared with traditional selector is used. • The spectrometer has a good performance and is now in routinely service.

  4. Liquid-He-free 10-T superconducting magnet for neutron scattering

    CERN Document Server

    Katano, S; Metoki, N; Osakabe, T; Suzuki, J; Koike, Y; Ishii, Y

    2002-01-01

    A new type of superconducting magnet, which is directly cooled by two 4-K GM cryocoolers (i.e. liquid-He-free), has been developed for neutron-scattering experiments. The magnet consists of a split pair of a (Nb,Ti) sub 3 Sn inner coil and a NbTi outer coil. The gap between the coils is 29 mm, and the upper and lower coils are supported by three rings made of Al alloy (4.5, 7.5, and 8 mm in thickness) and a plate of Al alloy (42.5 in angle). The total thickness of the Al alloy in the neutron path is 52 mm, and the transmission of the beam is about 60% for neutrons with 20 meV. The room-temperature bore is 51 mm in diameter, and in this bore one of the sample-cooling systems (4-K cryocooler or liquid-He-free dilution refrigerator) is inserted. The maximum field of 10 T is very stably obtained. Some results on the magnetism of strongly correlated electron systems obtained with this cryomagnet are presented. (orig.)

  5. Monte-Carlo simulation of an ultra small-angle neutron scattering instrument based on Soller slits

    Energy Technology Data Exchange (ETDEWEB)

    Rieker, T. [Univ. of New Mexico, Albuquerque, NM (United States); Hubbard, P. [Sandia National Labs., Albuquerque, NM (United States)

    1997-09-01

    Monte Carlo simulations are used to investigate an ultra small-angle neutron scattering instrument for use at a pulsed source based on a Soller slit collimator and analyzer. The simulations show that for a q{sub min} of {approximately}le-4 {angstrom}{sup -1} (15 {angstrom} neutrons) a few tenths of a percent of the incident flux is transmitted through both collimators at q=0.

  6. Neutron Scattering and Diffraction Studies of Fluids and Fluid-Solid Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Cole, David R [ORNL; Herwig, Kenneth W [ORNL; Mamontov, Eugene [ORNL; Larese, John Z [ORNL

    2006-01-01

    There can be no disputing the fact that neutron diffraction and scattering have made a clear contribution to our current understanding of the structural and dynamical characteristics of liquid water and water containing dissolved ions at ambient conditions and to a somewhat lesser degree other state conditions involving a change in temperature and pressure. Indeed, a molecular-level understanding of how fluids (e.g., water, CO{sub 2}, CH{sub 4}, higher hydrocarbons, etc.) interact with and participate in reactions with other solid earth materials are central to the development of predictive models that aim to quantify a wide array of geochemical processes. In the context of natural systems, interrogation of fluids and fluid-solid interactions at elevated temperatures and pressures is an area requiring much more work, particularly for complex solutions containing geochemically relevant cations, anions, and other important dissolved species such as CO{sub 2} or CH{sub 4}. We have tried to describe a series of prototypical interfacial and surface problems using neutron scattering to stimulate the thinking of earth scientists interested applying some of these approaches to confined systems of mineralogical importance. Our ability to predict the molecular-level properties of fluids and fluid-solid interactions relies heavily on the synergism between experiments such as neutron diffraction or inelastic neutron scattering and molecular-based simulations. Tremendous progress has been made in closing the gap between experimental observations and predicted behavior based on simulations due to improvements in the experimental methodologies and instrumentation on the one hand, and the development of new potential models of water and other simple and complex fluids on the other. For example there has been an emergence of studies taking advantage of advanced computing power that can accommodate the demands of ab initio molecular dynamics. On the neutron instrumentation side

  7. Measurement of the Neutron Radius of 208Pb Through Parity Violation in Electron Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Saenboonruang, Kiadtisak [Univ. of Virginia, Charlottesville, VA (United States)

    2013-05-01

    In contrast to the nuclear charge densities, which have been accurately measured with electron scattering, the knowledge of neutron densities still lack precision. Previous model-dependent hadron experiments suggest the difference between the neutron radius, Rn, of a heavy nucleus and the proton radius, Rp, to be in the order of several percent. To accurately obtain the difference, Rn-Rp, which is essentially a neutron skin, the Jefferson Lab Lead (208Pb) Radius Experiment (PREX) measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from 208Pb at an energy of 1.06 GeV and a scattering angle of 5° . Since Z0 boson couples mainly to neutrons, this asymmetry provides a clean measurement of Rn with respect to Rp. PREX was conducted at the Jefferson lab experimental Hall A, from March to June 2010. The experiment collected a final data sample of 2x 107 helicity-window quadruplets. The measured parity-violating electroweak asymmetry APV = 0.656 ± 0.060 (stat) ± 0.014 (syst) ppm corresponds to a difference between the radii of the neutron and proton distributions, Rn-Rp = 0.33+0.16-0.18 fm and provides the first electroweak observation of the neutron skin as expected in a heavy, neutron-rich nucleus. The value of the neutron radius of 208Pb has important implications for models of nuclear structure and their application in atomic physics and astrophysics such as atomic parity non-conservation (PNC) and neutron stars.

  8. Spin-density correlations in the dynamic spin-fluctuation theory: Comparison with polarized neutron scattering experiments

    Energy Technology Data Exchange (ETDEWEB)

    Melnikov, N.B., E-mail: melnikov@cs.msu.su [Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Reser, B.I., E-mail: reser@imp.uran.ru [Miheev Institute of Metal Physics, Ural Branch of Russian Academy of Sciences, Ekaterinburg 620990 (Russian Federation); Paradezhenko, G.V., E-mail: gparadezhenko@cs.msu.su [Lomonosov Moscow State University, Moscow 119991 (Russian Federation)

    2016-08-01

    To study the spin-density correlations in the ferromagnetic metals above the Curie temperature, we relate the spin correlator and neutron scattering cross-section. In the dynamic spin-fluctuation theory, we obtain explicit expressions for the effective and local magnetic moments and spatial spin-density correlator. Our theoretical results are demonstrated by the example of bcc Fe. The effective and local moments are found in good agreement with results of polarized neutron scattering experiment over a wide temperature range. The calculated short-range order is small (up to 4 Å) and slowly decreases with temperature.

  9. Materials and Life Science Experimental Facility (MLF at the Japan Proton Accelerator Research Complex II: Neutron Scattering Instruments

    Directory of Open Access Journals (Sweden)

    Kenji Nakajima

    2017-11-01

    Full Text Available The neutron instruments suite, installed at the spallation neutron source of the Materials and Life Science Experimental Facility (MLF at the Japan Proton Accelerator Research Complex (J-PARC, is reviewed. MLF has 23 neutron beam ports and 21 instruments are in operation for user programs or are under commissioning. A unique and challenging instrumental suite in MLF has been realized via combination of a high-performance neutron source, optimized for neutron scattering, and unique instruments using cutting-edge technologies. All instruments are/will serve in world-leading investigations in a broad range of fields, from fundamental physics to industrial applications. In this review, overviews, characteristic features, and typical applications of the individual instruments are mentioned.

  10. Final report DOE Grant ''Development of focusing monochromators for neutron scattering instruments'' (DE-FG02-96ER45599)

    CERN Document Server

    Popovici, M P

    2000-01-01

    Bent crystal monochromators were developed for the neutron scattering community: (1) doubly focusing bulk silicon, for high-resolution neutron diffraction; (2) doubly focusing multi-wafer silicon, for residual stress instruments; (3) silicon-wafer: (a) with pneumatic spherical bending, (b) with mechanical cylindrical bending, (c) with mechanical two-dimensional bending, for high-resolution three-axis spectrometry; (4) doubly focusing multi-wafer silicon, for epithermal (eV range) neutrons; (5) doubly focusing composite pyrolytic graphite (low-cost), for high-flux applications.

  11. Neutron scattering shows a droplet of oleic acid at the center of the BAMLET complex.

    Science.gov (United States)

    Rath, Emma M; Duff, Anthony P; Gilbert, Elliot P; Doherty, Greg; Knott, Robert B; Church, W Bret

    2017-07-01

    The anti-cancer complex, Bovine Alpha-lactalbumin Made LEthal to Tumors (BAMLET), has intriguing broad-spectrum anti-cancer activity. Although aspects of BAMLET's anti-cancer mechanism are still not known, it is understood that it involves the oleic acid or oleate component of BAMLET being preferentially released into cancer cell membranes leading to increased membrane permeability and lysis. The structure of the protein component of BAMLET has previously been elucidated by small angle X-ray scattering (SAXS) to be partially unfolded and dramatically enlarged. However, the structure of the oleic acid component of BAMLET and its disposition with respect to the protein component was not revealed as oleic acid has the same X-ray scattering length density (SLD) as water. Employing the difference in the neutron SLDs of hydrogen and deuterium, we carried out solvent contrast variation small angle neutron scattering (SANS) experiments of hydrogenated BAMLET in deuterated water buffers, to reveal the size, shape, and disposition of the oleic acid component of BAMLET. Our resulting analysis and models generated from SANS and SAXS data indicate that oleic acid forms a spherical droplet of oil incompletely encapsulated by the partially unfolded protein component. This model provides insight into the anti-cancer mechanism of this cache of lipid. The model also reveals a protein component "tail" not associated with the oleic acid component that is able to interact with the tail of other BAMLET molecules, providing a plausible explanation of how BAMLET readily forms aggregates. Proteins 2017; 85:1371-1378. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  12. Arbitrary quadratures determination of the monoenergetic neutron density in an homogeneous finite sphere with isotropic scattering

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez G, J., E-mail: julian.sanchez@inin.gob.mx [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2015-09-15

    The solution of the so-called Canonical problems of neutron transport theory has been given by Case, who developed a method akin to the classical eigenfunction expansion procedure, extended to admit singular eigenfunctions. The solution is given as a set consisting of a Fredholm integral equation coupled with a transcendental equation, which has to be solved for the expansion coefficients by iteration. CASE's method make extensive use of the results of the theory of functions of a complex variable and many successful approaches to solve in an approximate form the above mentioned set have been reported in the literature. We present here an entirely different approach which deals with the canonical problems in a more direct and elementary manner. As far as we know, the original idea for the latter method is due to Carlvik who devised the escape probability approximation to the solution of the neutron transport equation in its integral form. In essence, the procedure consists in assuming a sectionally constant form of the neutron density that in turn yields a set of linear algebraic equations obeyed by the assumed constant values of the density. Very well established techniques of numerical analysis for the solution of integral equations consist in independent approaches that generalize the sectionally constant approach by assuming a sectionally low degree polynomial for the unknown function. This procedure also known as the arbitrary quadratures method is especially suited to deal with cases where the kernel of the integral equation is singular. The author wishes to present the results obtained with the arbitrary quadratures method for the numerical calculation of the monoenergetic neutron density in a critical, homogeneous sphere of finite radius with isotropic scattering. The singular integral equation obeyed by the neutron density in the critical sphere is introduced, an outline of the method's main features is given, and tables and graphs of the density

  13. Scaling analysis of bio-molecular dynamics derived from elastic incoherent neutron scattering experiments

    Energy Technology Data Exchange (ETDEWEB)

    Doster, W. [Physik-Department, Technische Universität München, D-85748 Garching (Germany); Nakagawa, H. [Jülich Centre for Neutron Science, Forschungszentrum Jülich GmbH, Outstation at MLZ, Lichtenbergstraße 1, 85747 Garching (Germany); Japan Atomic Energy Agency, Quantum Beam Science Directorate, Tokai, Ibaraki 319-1195 (Japan); Appavou, M. S. [Jülich Centre for Neutron Science, Forschungszentrum Jülich GmbH, Outstation at MLZ, Lichtenbergstraße 1, 85747 Garching (Germany)

    2013-07-28

    Numerous neutron scattering studies of bio-molecular dynamics employ a qualitative analysis of elastic scattering data and atomic mean square displacements. We provide a new quantitative approach showing that the intensity at zero energy exchange can be a rich source of information of bio-structural fluctuations on a pico- to nano-second time scale. Elastic intensity scans performed either as a function of the temperature (back-scattering) and/or by varying the instrumental resolution (time of flight spectroscopy) yield the activation parameters of molecular motions and the approximate structural correlation function in the time domain. The two methods are unified by a scaling function, which depends on the ratio of correlation time and instrumental resolution time. The elastic scattering concept is illustrated with a dynamic characterization of alanine-dipeptide, protein hydration water, and water-coupled protein motions of lysozyme, per-deuterated c-phycocyanin (CPC) and hydrated myoglobin. The complete elastic scattering function versus temperature, momentum exchange, and instrumental resolution is analyzed instead of focusing on a single cross-over temperature of mean square displacements at the apparent onset temperature of an-harmonic motions. Our method predicts the protein dynamical transition (PDT) at T{sub d} from the collective (α) structural relaxation rates of the solvation shell as input. By contrast, the secondary (β) relaxation enhances the amplitude of fast local motions in the vicinity of the glass temperature T{sub g}. The PDT is specified by step function in the elastic intensity leading from elastic to viscoelastic dynamic behavior at a transition temperature T{sub d}.

  14. Ordering phenomena in FeCo-films and Fe/Cr-multilayers: an X-ray and neutron scattering study

    Energy Technology Data Exchange (ETDEWEB)

    Nickel, B.

    2001-07-01

    The following topics are covered: critical phenomena in thin films, critical adsorption, finite size scaling, FeCo Ising model, kinematical scattering theory for thin films, FeCo thin films, growth and characterisation of single crystal FeCo thin films, X-ray study of ordering in FeCo films, antiferromagnetic coupling in Fe/Cr multilayers, neutron scattering on Fe/Cr multilayers (WL)

  15. The measurement of self-diffusion coefficients in liquid metals with quasielastic neutron scattering

    Directory of Open Access Journals (Sweden)

    Meyer Andreas

    2015-01-01

    Full Text Available Quasielastic incoherent neutron scattering (QENS has proven to be a versatile tool to study self diffusion of atoms in liquid metals. Here it is shown, that coherent contributions to the signal in the small q limit appear as a flat and energy independent constant to the QENS signal in single-component liquid metals even for systems with a small incoherent scattering cross section, like aluminum. Container-less processing via electromagnetic or electrostatic levitation devices, especially designed for QENS, enables the in-situ measurement on liquid metallic droplets of sizes between 5 mm to 10 mm in diameter. This gives access to the study of chemically reactive, refractory metallic melts and extends the accessible temperature range to undercoolings of several hundred Kelvin below the respective melting point. Compared to experiments using a thin-walled crucible giving hollow-cylindrical sample geometry it is shown that multiple scattering on levitated droplets is negligible for the analysis of the self-diffusion coefficient. QENS results of liquid germanium and 73germanium isotope mixtures, titanium, nickel, copper and aluminum are reviewed. The self-diffusion coefficients of these systems are best described by an Arrhenius-type temperature dependence around their respective melting points.

  16. Quasi-Elastic Neutron Scattering Studies of the Slow Dynamics of Supercooled and Glassy Aspirin

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yang [ORNL; Tyagi, M. [NCNR and University of Maryland; Mamontov, Eugene [ORNL; Chen, Sow-hsin H [ORNL

    2011-01-01

    Aspirin, also known as acetylsalicylic acid (ASA), is not only a wonderful drug, but also a good glass former. Therefore, it serves as an important molecular system to study the near-arrest and arrested phenomena. In this paper, a high-resolution quasi-elastic neutron scattering (QENS) technique is used to investigate the slow dynamics of supercooled liquid and glassy aspirin from 410 K down to 350 K. The measured QENS spectra can be analyzed with a stretched exponential model. We find that (i) the stretched exponent (Q) is independent of the wave vector transfer Q in the measured Q-range, and (ii) the structural relaxation time (Q) follows a power law dependence on Q. Consequently, the Q-independent structural relaxation time 0 can be extracted for each temperature to characterize the slow dynamics of aspirin. The temperature dependence of 0 can be fitted with the mode coupling power law, the Vogel-Fulcher-Tammann equation and a universal equation for fragile glass forming liquids recently proposed by M. Tokuyama in the measured temperature range. The calculated dynamic response function T(Q,t) using the experimentally determined self-intermediate scattering function of the hydrogen atoms of aspirin shows a direct evidence of the enhanced dynamic fluctuations as the aspirin is increasingly supercooled, in agreement with the fixed-time mean squared displacement x2 and non-Gaussian parameter 2 extracted from the elastic scattering.

  17. Quasi-elastic neutron scattering studies of the slow dynamics of supercooled and glassy aspirin

    Science.gov (United States)

    Zhang, Yang; Tyagi, Madhusudan; Mamontov, Eugene; Chen, Sow-Hsin

    2012-02-01

    Aspirin, also known as acetylsalicylic acid (ASA), is not only a wonderful drug, but also a good glass former. Therefore, it serves as an important molecular system to study the near-arrest and arrested phenomena. In this paper, a high-resolution quasi-elastic neutron scattering (QENS) technique is used to investigate the slow dynamics of supercooled liquid and glassy aspirin from 410 down to 350 K. The measured QENS spectra can be analyzed with a stretched exponential model. We find that (i) the stretched exponent β(Q) is independent of the wavevector transfer Q in the measured Q range and (ii) the structural relaxation time τ(Q) follows a power-law dependence on Q. Consequently, the Q-independent structural relaxation time τ0 can be extracted for each temperature to characterize the slow dynamics of aspirin. The temperature dependence of τ0 can be fitted with the mode-coupling power law, the Vogel-Fulcher-Tammann equation and a universal equation for fragile glass forming liquids recently proposed by Tokuyama in the measured temperature range. The calculated dynamic response function χT(Q, t) using the experimentally determined self-intermediate scattering function of the hydrogen atoms of aspirin shows direct evidence of the enhanced dynamic fluctuations as the aspirin is increasingly supercooled, in agreement with the fixed-time mean squared displacement langx2rang and the non-Gaussian parameter α2 extracted from the elastic scattering.

  18. Quasielastic neutron scattering study of large amplitude motions in molecular systems

    Energy Technology Data Exchange (ETDEWEB)

    Bee, M. [Univ. J. Fourier - Grenoble 1, Lab. de Spectrometrie Physique, Saint-Martin d`Heres (France)

    1996-12-31

    This lecture aims at giving some illustrations of the use of Incoherent Quasielastic Neutron Scattering in the investigation of motions of atoms or molecules in phases with dynamical disorder. The general incoherent scattering function is first recalled. Then the Elastic Incoherent Structure Factor is introduced. It is shown how its determination permits to deduce a particular dynamical model. Long-range translational diffusion is illustrated by some experiments carried out with liquids or with different chemical species intercalated in porous media. Examples of rotational motions are provided by solid phases where an orientational disorder of the molecules exists. The jump model is the most commonly used and yields simple scattering laws which can be easily handled. Highly disordered crystals require a description in terms of the isotropic rotational diffusion model. Many of the present studies are concerned with rather complicated systems. Considerable help is obtained either by using selectively deuterated samples or by carrying out measurements with semi-oriented samples. (author) 5 figs., 14 refs.

  19. The CIELO collaboration: Progress in international evaluations of neutron reactions on Oxygen, Iron, Uranium and Plutonium

    Directory of Open Access Journals (Sweden)

    Chadwick M.B.

    2017-01-01

    Full Text Available The CIELO collaboration has studied neutron cross sections on nuclides that significantly impact criticality in nuclear technologies – 16O, 56Fe, 235,8U and 239Pu – with the aim of improving the accuracy of the data and resolving previous discrepancies in our understanding. This multi-laboratory pilot project, coordinated via the OECD/NEA Working Party on Evaluation Cooperation (WPEC Subgroup 40 with support also from the IAEA, has motivated experimental and theoretical work and led to suites of new evaluated libraries that accurately reflect measured data and also perform well in integral simulations of criticality.

  20. The CIELO collaboration: Progress in international evaluations of neutron reactions on Oxygen, Iron, Uranium and Plutonium

    Science.gov (United States)

    Chadwick, M. B.; Capote, R.; Trkov, A.; Kahler, A. C.; Herman, M. W.; Brown, D. A.; Hale, G. M.; Pigni, M.; Dunn, M.; Leal, L.; Plompen, A.; Schillebeeck, P.; Hambsch, F.-J.; Kawano, T.; Talou, P.; Jandel, M.; Mosby, S.; Lestone, J.; Neudecker, D.; Rising, M.; Paris, M.; Nobre, G. P. A.; Arcilla, R.; Kopecky, S.; Giorginis, G.; Cabellos, O.; Hill, I.; Dupont, E.; Danon, Y.; Jing, Q.; Zhigang, G.; Tingjin, L.; Hanlin, L.; Xichao, R.; Haicheng, W.; Sin, M.; Bauge, E.; Romain, P.; Morillon, B.; Noguere, G.; Jacqmin, R.; Bouland, O.; De Saint Jean, C.; Pronyaev, V. G.; Ignatyuk, A.; Yokoyama, K.; Ishikawa, M.; Fukahori, T.; Iwamoto, N.; Iwamoto, O.; Kuneada, S.; Lubitz, C. R.; Palmiotti, G.; Salvatores, M.; Kodeli, I.; Kiedrowski, B.; Roubtsov, D.; Thompson, I.; Quaglioni, S.; Kim, H. I.; Lee, Y. O.; Koning, A. J.; Carlson, A.; Fischer, U.; Sirakov, I.

    2017-09-01

    The CIELO collaboration has studied neutron cross sections on nuclides that significantly impact criticality in nuclear technologies - 16O, 56Fe, 235,8U and 239Pu - with the aim of improving the accuracy of the data and resolving previous discrepancies in our understanding. This multi-laboratory pilot project, coordinated via the OECD/NEA Working Party on Evaluation Cooperation (WPEC) Subgroup 40 with support also from the IAEA, has motivated experimental and theoretical work and led to suites of new evaluated libraries that accurately reflect measured data and also perform well in integral simulations of criticality.

  1. The CIELO Collaboration: Progress in International Evaluations of Neutron Reactions on Oxygen, Iron, Uranium and Plutonium

    Energy Technology Data Exchange (ETDEWEB)

    Chadwick, M. B.; Capote, R.; Trkov, A.; Kahler, A. C.; Herman, M. W.; Brown, D. A.; Hale, G. M.; Pigni, M.; Dunn, M.; Leal, L.; Plompen, A.; Schillebeecks, P.; Hambsch, F. -J.; Kawano, T.; Talou, P.; Jandel, M.; Mosby, S.; Lestone, J.; Neudecker, D.; Rising, M.; Paris, M.; Nobre, G. P. A.; Arcilla, R.; Kopecky, S.; Giorginis, G.; Cabellos, O.; Hill, I.; Dupont, E.; Danon, Y.; Jing, Q.; Zhigang, G.; Tingjin, L.; Hanlin, L.; Xichao, R.; Haicheng, W.; Sin, M.; Bauge, E.; Romain, P.; Morillon, B.; Salvatores, M.; Jacqmin, R.; Bouland, O.; De Saint Jean, C.; Pronyaev, V. G.; Ignatyuk, A.; Yokoyama, K.; Ishikawa, M.; Fukahori, T.; Iwamoto, N.; Iwamoto, O.; Kuneada, S.; Lubitz, C. R.; Palmiotti, G.; Kodeli, I.; Kiedrowski, B.; Roubtsov, D.; Thompson, I.; Quaglioni, S.; Kim, H. I.; KLee, Y. O.; Koning, A. J.; Carlson, A.; Fischer, U.

    2016-11-01

    The CIELO collaboration has studied neutron cross sections on nuclides that significantly impact criticality in nuclear technologies - 16O, 56Fe, 235,8U and 239Pu - with the aim of reducing uncertainties and resolving previous discrepancies in our understanding. This multi-laboratory pilot project, coordinated via the OECD/NEA Working Party on Evaluation Cooperation (WPEC) Subgroup 40 with support also from the IAEA, has motivated experimental and theoretical work and led to suites of new evaluated libraries that accurately reflect measured data and also perform well in integral simulations of criticality.

  2. Measurement of the spin structure of the neutron using polarised deep inelastic scattering

    Science.gov (United States)

    Kaiser, Ralf Bernd

    The measurement of the spin structure function g1p of the proton and its integral Γ1p by the EMC experiment at C scERN in 1988 indicated that only 12% ± 17% of the proton spin is carried by quarks. This unexpected result-the so called 'spin crisis'-lead to a series of new experimental proposals. One of these, the H scERMES experiment, uses the polarised positron beam of the H scERA accelerator together with a polarised internal gas target of hydrogen, deuterium or 3He for the study of the spin structure of the nucleon. The scattered positrons and other products of the reaction are detected in a forward spectrometer with large acceptance. This thesis focuses on three topics, after a review of the relevant theory and an overview of the H scERMES experiment: The H scERMES transition radiation detector (TRD), which is used to distinguish high energy positrons from hadrons, the H scERMES particle identification (PID) system and the measurement of the spin structure function g1n of the neutron. The H scERMES TRD is the main Canadian contribution to the apparatus of the experiment. The H scERMES PID system allows the identification of positrons from deep inelastic scattering with an efficiency of 99% and a hadron contamination of less than 0.5%. The first physics result from the 1995 H scERMES data is the measurement of the spin structure function g1n(x) of the neutron. The value of the resulting integral Γ1n=∫01g1n(x)/ dx confirms previous measurements at SLAC and violates the Ellis-Jaffe sum rule by about one sigma. The contribution of the quarks to the spin of the neutron can be calculated in the framework of the quark parton model to be 37 ± 16%, indicating that less than half of the spin of the neutron is carried by quarks.

  3. Studies of magnetism with inelastic scattering of cold neutrons; Etudes de magnetisme realisees a l'aide de la diffusion inelastique de neutrons froids

    Energy Technology Data Exchange (ETDEWEB)

    Jacrot, B. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    Inelastic scattering of cold neutrons can be used to study some aspects of magnetism: spins waves, exchange integrals, vicinity of Curie point. After description of the experimental set-up, several experiments, in the fields mentioned above, are analysed. (author) [French] La technique de diffusion inelastique des neutrons froids est utilisee pour etudier certains aspects du magnetisme: ondes de spins, integrales d'echange, etude au voisinage du point de Curie, etc. Apres une description de l'appareillage, on analyse diverses experiences effectuees dans les domaines enumeres plus haut. (auteur)

  4. Structural characterization of a polymer substituted fullerene (flagellene) by small angle neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Affholter, K.A.; Bunick, G.J.; Wignall, G.D. [Oak Ridge National Lab., TN (United States); Desimone, J.M.; Hunt, M.O. Jr.; Menceloglu, Y.Z.; Samulski, E.T. [North Carolina Univ., Chapel Hill, NC (United States). Dept. of Chemistry

    1994-12-31

    Small-angle neutron scattering (SANS) can structurally characterize fullerenes in solvents with strong SANS contrast (e.g. CS{sub 2}). Deuterated solvents (e.g. toluene-d{sub 8}) have a high scattering length density (SLD), which is close to that of C{sub 60} and C{sub 70} moieties. Hence, there is virtually no SANS contrast with the solvent and these particles are practically ``invisible`` in such media. On the other hand, the negative scattering length of hydrogen means that the SLD of H{sup 1}-containing materials is much lower, so they have strong contrast with toluene-d{sub 8}. Thus, SANS makes it possible to study the size and shapes of modified buckyballs such as the polymer-substituted fullerenes, or flagellenes. These consist of C{sub 60} cores to which 1-4 polystryene chains (with a molecular weight, MW {approx_equal} 2000) are attached. The extrapolated cross section at zero angle of scatter [d{Sigma}/d{Omega}(0)] is a function of the number of pendant chains, so SANS can be used to assess the number of ``arms`` which are covalently attached to the fullerene ``sphere.`` Close agreement ({plus_minus}4%) between measured and calculated values of d{Sigma}/d{Omega}(0) along with independent estimates of the radius of gyration (R{sub g}) and second virial coefficient (A{sub 2}) for a calibration linear polystyrene sample serves as a cross check on the validity of this methodology.

  5. Structure and dynamics of polyelectrolyte complex coacervates studied by scattering of neutrons, X-rays, and light

    NARCIS (Netherlands)

    Spruijt, E.; Leermakers, F.A.M.; Fokkink, R.G.; Schweins, R.; Well, van A.A.; Cohen Stuart, M.A.; Gucht, van der J.

    2013-01-01

    We investigate the microscopic structure and density fluctuations of complex coacervates of flexible polyelectrolytes using scattering of neutrons, X-rays, and light. Poly(acrylic acid) and poly(N,N-dimethylaminoethyl methacrylate) offer a well-defined model system that allows for selective labeling

  6. Low-temperature dynamics of magnetic colloids studied by time-resolved small-angle neutron scattering

    NARCIS (Netherlands)

    Wiedenmann, A.; Keiderling, U.; Meissner, M.; Wallacher, D.; Gähler, R.; May, R.P.; Prévost, S.; Klokkenburg, M.; Erne, B.H.; Kohlbrecher, J.

    2008-01-01

    The dynamics of ordering and relaxation processes in magnetic colloids has been studied by means of stroboscopic small angle neutron scattering techniques in an oscillating magnetic field. Surfactant stabilized ferrofluids (FFs) of Fe3O4 and Co nanoparticles have been investigated as a function of

  7. Dipolar structures in magnetite ferrofluids studied with small-angle neutron scattering with and without applied magnetic field

    NARCIS (Netherlands)

    Klokkenburg, M.; Erne, B.H.; Wiedenmann, A.; Petukhov, A.V.; Philipse, A.P.

    2007-01-01

    Field-induced structure formation in a ferrofluid with well-defined magnetite nanoparticles with a permanent magnetic dipole moment was studied with small-angle neutron scattering (SANS) as a function of the magnetic interactions. The interactions were tuned by adjusting the size of the

  8. Structure dependence of final-state effects in deep inelastic neutron scattering: Quasiclassical theory

    Energy Technology Data Exchange (ETDEWEB)

    Silver, R.N.; Reiter, G.

    1987-03-01

    Using a quasiclassical approximation, we calculate the Q..-->..infinity limit of S(Q,..omega..) for finite potentials with a hard core. For yequivalentm(..omega..-h-dash-barQ/sup 2//2m)/h-dash-barQ, we find QS(Q,..omega..) equals a convolution of the impulse-approximation result F/sub IA/(y) with a ''final-state'' resolution function, R/sub FS/(y), which depends on the structure of the material through the radial distribution function g(r). For realistic g(r), R/sub FS/(y) has smaller full width at half maximum than the Hohenberg-Platzman prediction, zero second moment, and no Lorentzian wings. We compare with previous theoretical work, and we discuss the determination of momentum distributions in quantum solids and fluids from deep-inelastic neutron scattering data.

  9. Investigation of scaling laws by critical neutron scattering from beta-brass

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage

    1969-01-01

    Using a Cu65-Zn β-brass crystal, the critical scattering of neutrons has been studied, both above and below T c. The staggered susceptibilities χ vary as C+(T/Tc-1)-γ and C-(1-T/Tc)-γ ', respectively. It is found that γ=γ' within an accuracy of 3%, in agreement with the scaling hypothesis of static...... critical phenomena; and that C+/C-=5.46±0.05, in excellent agreement with the recent parametric representation theory of Schofield and in fair agreement with the results of series expansions by Essam and Hunter. For fixed q, a flat maximum is observed in the wave-vector-dependent susceptibility χ(q, T...

  10. Molecular mobility in Medicago truncatula seed during early stage of germination: Neutron scattering and NMR investigations

    Science.gov (United States)

    Falourd, Xavier; Natali, Francesca; Peters, Judith; Foucat, Loïc

    2014-01-01

    First hours of Medicago truncatula (MT) seeds germination were investigated using elastic incoherent neutron scattering (EINS) and nuclear magnetic resonance (NMR), to follow respectively how macromolecular motions and water mobility evolve when water permeates into the seed. From EINS results, it was shown that there is an increase in macromolecular mobility with the water uptake. Changes in NMR relaxation parameters reflected microstructural changes associated with the recovery of the metabolic processes. The EINS investigation of the effect of temperature on macromolecular motions showed that there is a relationship between the amount of water in the seeds and the effect of freezing-thawing cycle. The NMR relaxometry results obtained at 253 K allowed establishing possible link between the freezing of water molecules tightly bound to macromolecules and their drastic motion restriction around 250 K, as observed with EINS at the highest water content.

  11. Two-dimensional neutron scattering in a floating heavy water bridge

    Energy Technology Data Exchange (ETDEWEB)

    Fuchs, Elmar C [Wetsus, Centre of Excellence for Sustainable Water Technology, Agora 1, 8900 CC Leeuwarden (Netherlands); Baroni, Patrick; Noirez, Laurence [Laboratoire Leon Brillouin, CEA-CNRS/IRAMIS, CE-Saclay, 91191 Gif-sur-Yvette Cedex (France); Bitschnau, Brigitte [Institute of Physical and Theoretical Chemistry, Graz University of Technology, Rechbauerstrasse 12, 8010 Graz (Austria)

    2010-03-17

    When a high voltage is applied to pure water in two filled beakers kept close to each other, a connection forms spontaneously, giving the impression of a floating water bridge. This phenomenon is of special interest, since it comprises a number of phenomena currently tackled in modern water science. In this work, the first two-dimensional structural study of a floating heavy water bridge is presented as a function of the azimuthal angle. A small anisotropy in the angular distribution of the intensity of the first structural peak was observed, indicating a preferred orientation of a part of the D{sub 2}O molecules along the electric field lines without breaking the local tetrahedral symmetry. The experiment is carried out by neutron scattering on a D{sub 2}O bridge.

  12. Spiral spin state in high-temperature copper-oxide superconductors: Evidence from neutron scattering measurements

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    2005-01-01

    An effective spiral spin phase ground state provides a new paradigm for the high-temperature superconducting cuprates. It accounts for the recent neutron scattering observations of spin excitations regarding both the energy dispersion and the intensities, including the "universal" rotation by 45...... degrees around the resonance energy E-res. The intensity has a 2D character even in a single twin crystal. The value of E-res is related to the nesting properties of the Fermi surface. The excitations above E-res are shown to be due to in-plane spin fluctuations, a testable difference from the stripe...... model. The form of the exchange interaction function reveals the effects of the Fermi surface, and the unique shape predicts large quantum spin fluctuations in the ground state....

  13. Characterisation of creep cavitation damage in a stainless steel pressure vessel using small angle neutron scattering

    CERN Document Server

    Bouchard, P J; Treimer, W

    2002-01-01

    Grain-boundary cavitation is the dominant failure mode associated with initiation of reheat cracking, which has been widely observed in austenitic stainless steel pressure vessels operating at temperatures within the creep range (>450 C). Small angle neutron scattering (SANS) experiments at the LLB PAXE instrument (Saclay) and the V12 double-crystal diffractometer of the HMI-BENSC facility (Berlin) are used to characterise cavitation damage (in the size range R=10-2000 nm) in a variety of creep specimens extracted from ex-service plant. Factors that affect the evolution of cavities and the cavity-size distribution are discussed. The results demonstrate that SANS techniques have the potential to quantify the development of creep damage in type-316H stainless steel, and thereby link microstructural damage with ductility-exhaustion models of reheat cracking. (orig.)

  14. Development of a system for simultaneously generating triple extreme conditions for neutron scattering experiments

    Energy Technology Data Exchange (ETDEWEB)

    Ichimura, Shigeju [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-10-01

    We have developed new system available for controlling sample environment during the neutron scattering experiments. The system can simultaneously generate triple extreme conditions of low temperature, high magnetic field and high pressure. The system consists of : (1) a liquid-helium cryostat which enables the sample temperature range of 1.7 K to 200 K, (2) a superconducting magnet providing a vertical field up to 5 Tesla with antisymmetric split-coil geometry for polarized-beam experiments, and (3) a non-magnetic clamping high-pressure cell designed with the aim of generating hydrostatic pressure up to 2.5 Gpa. In the workshop, we will report the outline of the system and some results of performance tests using the system at JRR-3M of JAERI. (author)

  15. Local structure in ZrW2O8 from neutron total scattering

    Science.gov (United States)

    Tucker, Matthew G.; Keen, David A.; Evans, John S. O.; Dove, Martin T.

    2007-08-01

    The local structure of the low-temperature ordered phase of the negative thermal expansion (NTE) material ZrW2O8 has been investigated by reverse Monte Carlo (RMC) modelling of neutron total scattering data. The local structure is described using the instantaneous distributions of bond lengths and angles obtained from the RMC-derived models which are simultaneously consistent with the average crystal structure. These results, together with their variation with temperature, show that the majority of the mean squared displacements of the atoms are accounted for by rigid unit mode (RUM) motions of the ZrO6 octahedra and WO4 tetrahedra. The detailed structural description presented in this paper further supports the dominance of the basic RUM interpretation of NTE in ZrW2O8 where rigid ZrO6 and WO4 polyhedra are joined by flexible Zr-O-W linkages.

  16. An inert-gas furnace for neutron scattering measurements of internal stresses in engineering materials

    Science.gov (United States)

    Haynes, R.; Paradowska, A. M.; Chowdhury, M. A. H.; Goodway, C. M.; Done, R.; Kirichek, O.; Oliver, E. C.

    2012-04-01

    The ENGIN-X beamline is a dedicated engineering science facility at ISIS optimized for the measurement of strain, and thus stress, deep within crystalline materials using the atomic lattice planes as an atomic ‘strain gauge’. Internal stresses in materials have a considerable effect on material properties including fatigue resistance, fracture toughness and strength. The growing interest in properties of materials at high temperatures may be attributed to the dynamic development in technologies where materials are exposed to a high-temperature environment for example in the aerospace industry or fission and fusion nuclear reactors. This article describes in detail the design and construction of a furnace for neutron scattering measurements of internal stress in engineering materials under mechanical load and in elevated temperature environments, designed to permit a range of gases to provide a non-oxidizing atmosphere for hot samples.

  17. A cryogenic high pressure cell for inelastic neutron scattering measurements of quantum fluids and solids.

    Science.gov (United States)

    Carmichael, J R; Diallo, S O

    2013-01-01

    We present our new development of a high pressure cell for inelastic neutron scattering measurements of helium at ultra-low temperatures. The cell has a large sample volume of ~140 cm(3) and a working pressure of ~7 MPa, with a relatively thin wall-thickness (1.1 mm)--thanks to the high yield strength aluminum used in the design. Two variants of this cell have been developed. The first cell is permanently joined components using electron-beam welding and explosion welding, methods that have little or no impact on the global heat treatment of the cell. The second cell discussed has modular and interchangeable components, which includes a capacitance pressure gauge, that can be sealed using the traditional indium wire technique. The performance of the cells have been tested in recent measurements on superfluid liquid helium near the solidification line.

  18. mQfit, a new program for analyzing quasi-elastic neutron scattering data

    Directory of Open Access Journals (Sweden)

    Martinez Nicolas

    2015-01-01

    Full Text Available Analysis of Quasi-elastic Neutron Scattering (QENS data of complex systems such as biological or soft matter samples in a comprehensive and explicit way often requires great efforts. Most popular software only allows to fit spectra originating from one single instrument and does not permit to extract parameters from a model that is fitted simultaneously to data taken at different instrumental resolutions. We present here a new program, mQfit (multiple QENS dataset fitting, that enables to fit QENS data taken at different spectrometers (with typical resolutions between 0.01 and 0.1 meV and momentum transfer ranges. This allows drastically reducing the number of fitting parameters. The routine is implemented with a user friendly Graphical User's Interface (GUI, and freely available. As an example, we will present results obtained on E. coli bacterial pellets, and compare them to values published in the literature.

  19. Study of the Boson Peak and Fragility of Bioprotectant Glass-Forming Mixtures by Neutron Scattering

    Directory of Open Access Journals (Sweden)

    F. Migliardo

    2013-01-01

    Full Text Available The biological relevance of trehalose, glycerol, and their mixtures in several anhydrobiotic and cryobiotic organisms has recently promoted both experimental and simulation studies. In addition, these systems are employed in different industrial fields, such as pharmaceutical and cosmetic industries, as additives in mixtures for cryopreservation and in several formulations. This review article shows an overview of Inelastic Neutron Scattering (INS data, collected at different temperature values by the OSIRIS time-of-flight spectrometer at the ISIS Facility (Rutherford Appleton Laboratory, Oxford, UK and by the IN4 and IN6 spectrometers at the Institut Laue Langevin (ILL, Grenoble, France, on trehalose/glycerol mixtures as a function of the glycerol content. The data analysis allows determining the Boson peak behavior and discussing the findings in terms of fragility in relation to the bioprotective action of trehalose and glycerol.

  20. Refined model of the {Fe9} magnetic molecule from low-temperature inelastic neutron scattering studies

    Energy Technology Data Exchange (ETDEWEB)

    Engelhardt, Larry [Francis Marion University; Demmel, Franz [Rutherford Appleton Laboratory; Luban, Marshall [Ames Laboratory; Timco, Grigore A [The University of Manchester; Tuna, Floriana [The University of Manchester; Winpenny, Richard E [The University of Manchester

    2014-06-01

    We present a refined model of the {Fe9} tridiminished icosahedron magnetic molecule system. This molecule was originally modeled as being composed of two ({Fe3} and {Fe6}) clusters, with the Fe3+ ions within each cluster being coupled via exchange interactions, but with no coupling between the clusters. The present inelastic neutron scattering (INS) measurements were used to probe the low-lying energy spectrum of {Fe9}, and these results demonstrate that the previously published model of two uncoupled clusters is incomplete. To achieve agreement between the experiment and theory, we have augmented the model with relatively small exchange coupling between the clusters. A combination of Lanczos matrix diagonalization and quantum Monte Carlo simulations have been used to achieve good agreement between the experimental data and the improved model of the full {Fe9} system despite the complexity of this model (with Hilbert space dimension >107).

  1. Dynamics in poly vinyl alcohol (PVA) based hydrogel: Neutron scattering study

    Science.gov (United States)

    Prabhudesai, S. A.; Lawrence, Mathias B.; Mitra, S.; Desa, J. A. E.; Mukhopadhyay, R.

    2015-06-01

    Results of quasielastic neutron scattering measurements carried out on Poly Vinyl Alcohol (PVA) based hydrogels are reported here. PVA hydrogels are formed using Borax as a cross-linking agent in D2O solvent. This synthetic polymer can be used for obtaining the hydrogels with potential use in the field of biomaterials. The aim of this paper is to study the dynamics of polymer chain in the hydrogel since it is known that polymer mobility influences the kinetics of loading and release of drugs. It is found that the dynamics of hydrogen atoms in the polymer chain could be described by a model where the diffusion of hydrogen atoms is limited within a spherical volume of radius 3.3 Å. Average diffusivity estimated from the behavior of quasielastic width is found to be 1.2 × 10-5 cm2/sec.

  2. Neutron scattering studies on protein dynamics using the human myelin peripheral membrane protein P2

    Science.gov (United States)

    Laulumaa, Saara; Kursula, Petri; Natali, Francesca

    2015-01-01

    Myelin is a multilayered proteolipid membrane structure surrounding selected axons in the vertebrate nervous system, which allows the rapid saltatory conduction of nerve impulses. Deficits in myelin formation and maintenance may lead to chronic neurological disease. P2 is an abundant myelin protein from peripheral nerves, binding between two apposing lipid bilayers. We studied the dynamics of the human myelin protein P2 and its mutated P38G variant in hydrated powders using elastic incoherent neutron scattering. The local harmonic vibrations at low temperatures were very similar for both samples, but the mutant protein had increased flexibility and softness close to physiological temperatures. The results indicate that a drastic mutation of proline to glycine at a functional site can affect protein dynamics, and in the case of P2, they may explain functional differences between the two proteins.

  3. Neutron scattering studies on protein dynamics using the human myelin peripheral membrane protein P2

    Directory of Open Access Journals (Sweden)

    Laulumaa Saara

    2015-01-01

    Full Text Available Myelin is a multilayered proteolipid membrane structure surrounding selected axons in the vertebrate nervous system, which allows the rapid saltatory conduction of nerve impulses. Deficits in myelin formation and maintenance may lead to chronic neurological disease. P2 is an abundant myelin protein from peripheral nerves, binding between two apposing lipid bilayers. We studied the dynamics of the human myelin protein P2 and its mutated P38G variant in hydrated powders using elastic incoherent neutron scattering. The local harmonic vibrations at low temperatures were very similar for both samples, but the mutant protein had increased flexibility and softness close to physiological temperatures. The results indicate that a drastic mutation of proline to glycine at a functional site can affect protein dynamics, and in the case of P2, they may explain functional differences between the two proteins.

  4. Hydration-dependent dynamics of human telomeric oligonucleotides in the picosecond timescale: A neutron scattering study

    Science.gov (United States)

    Sebastiani, F.; Longo, M.; Orecchini, A.; Comez, L.; De Francesco, A.; Muthmann, M.; Teixeira, S. C. M.; Petrillo, C.; Sacchetti, F.; Paciaroni, A.

    2015-07-01

    The dynamics of the human oligonucleotide AG3(T2AG3)3 has been investigated by incoherent neutron scattering in the sub-nanosecond timescale. A hydration-dependent dynamical activation of thermal fluctuations in weakly hydrated samples was found, similar to that of protein powders. The amplitudes of such thermal fluctuations were evaluated in two different exchanged wave-vector ranges, so as to single out the different contributions from intra- and inter-nucleotide dynamics. The activation energy was calculated from the temperature-dependent characteristic times of the corresponding dynamical processes. The trends of both amplitudes and activation energies support a picture where oligonucleotides possess a larger conformational flexibility than long DNA sequences. This additional flexibility, which likely results from a significant relative chain-end contribution to the average chain dynamics, could be related to the strong structural polymorphism of the investigated oligonucleotides.

  5. Micelle structural studies on oil solubilization by a small-angle neutron scattering

    Science.gov (United States)

    Putra, Edy Giri Rachman; Seong, Baek Seok; Ikram, Abarrul

    2009-02-01

    A small-angle neutron scattering (SANS) technique was applied to reveal the micelle structural changes. The micelle structural changes of 0.3 M sodium dodecyl sulfate (SDS) concentration by addition of various oil, i.e. n-hexane, n-octane, and n-decane up to 60% (v/v) have been investigated. It was found that the size, aggregation number and the structures of the micelles changed exhibiting that the effective charge on the micelle decreases with an addition of oil. There was a small increase in minor axis of micelle while the correlation peak shifted to a lower momentum transfer Q and then to higher Q by a further oil addition.

  6. Hydration-dependent dynamics of human telomeric oligonucleotides in the picosecond timescale: A neutron scattering study

    Energy Technology Data Exchange (ETDEWEB)

    Sebastiani, F.; Comez, L.; Sacchetti, F. [Dipartimento di Fisica e Geologia, Università degli Studi di Perugia, Via A. Pascoli, 06123 Perugia (Italy); CNR, Istituto Officina dei Materiali, Unità di Perugia, c/o Dipartimento di Fisica e Geologia, Università di Perugia, 06123 Perugia (Italy); Longo, M. [Dipartimento di Fisica e Geologia, Università degli Studi di Perugia, Via A. Pascoli, 06123 Perugia (Italy); Elettra—Sincrotrone Trieste, 34149 Basovizza, Trieste (Italy); Orecchini, A.; Petrillo, C.; Paciaroni, A., E-mail: alessandro.paciaroni@fisica.unipg.it [Dipartimento di Fisica e Geologia, Università degli Studi di Perugia, Via A. Pascoli, 06123 Perugia (Italy); De Francesco, A. [CNR-IOM OGG c/o Institut Laue-Langevin, 71 Avenue des Martyrs, CS20156, 38042 Grenoble Cedex 9 (France); Muthmann, M. [Jülich Centre for Neutron Science, Forschungszentrum Jülich GmbH, Outstation at Heinz Maier-Leibnitz Zentrum, Lichtenbergstrasse 1, 85747 Garching (Germany); Teixeira, S. C. M. [EPSAM, Keele University, Staffordshire ST5 5BG (United Kingdom); Institut Laue–Langevin, 71 Avenue des Martyrs, CS20156, 38042 Grenoble Cedex 9 (France)

    2015-07-07

    The dynamics of the human oligonucleotide AG{sub 3}(T{sub 2}AG{sub 3}){sub 3} has been investigated by incoherent neutron scattering in the sub-nanosecond timescale. A hydration-dependent dynamical activation of thermal fluctuations in weakly hydrated samples was found, similar to that of protein powders. The amplitudes of such thermal fluctuations were evaluated in two different exchanged wave-vector ranges, so as to single out the different contributions from intra- and inter-nucleotide dynamics. The activation energy was calculated from the temperature-dependent characteristic times of the corresponding dynamical processes. The trends of both amplitudes and activation energies support a picture where oligonucleotides possess a larger conformational flexibility than long DNA sequences. This additional flexibility, which likely results from a significant relative chain-end contribution to the average chain dynamics, could be related to the strong structural polymorphism of the investigated oligonucleotides.

  7. The dynamics of water in hydrated white bread investigated using quasielastic neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Sjoestroem, J [Department of Applied Physics, Chalmers University of Technology, SE-41296 Goeteborg (Sweden); Kargl, F [Institute of Mathematical and Physical Sciences, University of Wales, Aberystwyth SY23 3BZ (United Kingdom); Fernandez-Alonso, F [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX (United Kingdom); Swenson, J [Department of Applied Physics, Chalmers University of Technology, SE-41296 Goeteborg (Sweden)

    2007-10-17

    The dynamics of water in fresh and in rehydrated white bread is studied using quasielastic neutron scattering (QENS). A diffusion constant for water in fresh bread, without temperature gradients and with the use of a non-destructive technique, is presented here for the first time. The self-diffusion constant for fresh bread is estimated to be D{sub s} = 3.8 x 10{sup -10} m{sup 2} s{sup -1} and the result agrees well with previous findings for similar systems. It is also suggested that water exhibits a faster dynamics than previously reported in the literature using equilibration of a hydration-level gradient monitored by vibrational spectroscopy. The temperature dependence of the dynamics of low hydration bread is also investigated for T = 280-350 K. The average relaxation time at constant momentum transfer (Q) shows an Arrhenius behavior in the temperature range investigated.

  8. X-ray Diffraction and Neutron Scattering Analysis of Natural and Synthetic Spider Silk Fibers

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Randolph [Utah State Univ., Logan, UT (United States)

    2013-11-11

    Spider silks have the potential to provide new bio-inspired materials for numerous applications in bioenergetics and products ranging from protective clothing to artificial ligaments and tendons. A number of spider silk genes have been cloned and sequenced by the Lewis laboratory revealing the basis for understanding the key elements of spider silk proteins with respect to their materials performance. In particular, specific amino acid motifs have been identified which have been conserved for over 125 million years in all spiders that use their silk to physically trap prey. The key element in taking the next step toward generating bio-based materials from spider silks will be to move from the current descriptive data to predictive knowledge. Current efforts are focused on mimicking spider silk through synthetic proteins. In developing synthetic silk fibers, we first need to understand the complete secondary and tertiary structure of natural silk so that we can compare synthetic constructs to the natural material. Being able to compare the structure on a single fiber level is critical to the future of molecular directed mimic development because we can vary mechanical properties by different spinning methods. The new generation of synchrotron x-ray diffraction and neutron beamlines will allow, for the first time, determination of the molecular structure of silk fibers and synthetic mimics. We propose an exciting new collaborative research team working jointly between Argonne National Laboratory, Arizona State U. and the University of Wyoming to address the ?characterization of synthetic and natural spider silk fibers using x-ray and neutron diffraction.? Thus these new methodologies will provide understanding of current fibers and determine changes needed to produce fibers with specific properties. The following specific aims are proposed: ? Synthesize spider silk fibers with molecular structures mimicking that of natural silks. Test the mechanic properties of these

  9. Static and quasi-elastic small angle neutron scattering on biocompatible ionic ferrofluids: magnetic and hydrodynamic interactions

    CERN Document Server

    Gazeau, F; Dubois, E; Perzynski, R

    2003-01-01

    We investigate the structure and dynamics of ionic magnetic fluids (MFs), based on ferrite nanoparticles, dispersed at pH approx 7 either in H sub 2 O or in D sub 2 O. Polarized and non-polarized static small angle neutron scattering (SANS) experiments in zero magnetic field allow us to study both the magnetic and the nuclear contributions to the neutron scattering. The magnetic interparticle attraction is probed separately from the global thermodynamic repulsion and compares well to direct magnetic susceptibility measurements. The magnetic interparticle correlation is in these fluid samples independent of the probed spatial scale. In contrast, a spatial dependence of the interparticle correlation is evidenced at large PHI by the nuclear structure factor. A model of magnetic interaction quantitatively explains the under-field anisotropy of the SANS nuclear contribution. In a quasi-elastic neutron spin-echo experiment, we probe the Brownian dynamics of translation of the nanoparticles in the range 1.3 sup<=...

  10. Neutron scattering studies of bio-polymer-water systems: solvent mobility and collective excitations

    Energy Technology Data Exchange (ETDEWEB)

    Middendorf, H.D. [Oxford Univ. (United Kingdom). Clarendon Lab.

    1995-12-31

    The understanding of bio-polymer-water interactions at the molecular level depends crucially on a good characterization of dissipative processes and on accurate model parameters derived from experiments. The fundamental interest of this study is the coupling between hard and soft degrees of freedom, the dynamics of hydrogen-bonded molecular components and the effect of hydration on collective modes. The experiments and results discussed in this paper demonstrate how neutron scattering provides new insights into the dynamics of hydrated biomolecules. The ability to do diffraction-cum-spectroscopy over a large Q,{omega}-range corresponding to the space and time scales of bio-polymer-water interactions opens new ways which can be exploited for testing and refining theoretical models and simulations. Outstanding assets of neutron techniques in this context are the capability to probe diffusive as well as cooperative processes over scale lengths from about 1 to a few angstroms, together with the possibility of varying scattering contrast between the constituents of a heterogeneous system. Two systems are considered: a globular, slightly hydrated protein (phycocyanin) and a highly hydrated network of polysaccharide fibers. The phycocyanin results draw attention to the fact that the energy landscape of a hydrated biomolecule is very complex. Some of the concepts and models used in theoretical work will need to be refined substantially in order to accommodate data from experimental techniques capable of providing genuine spatio-temporal information. The characterization of hydration phenomena by two or three discrete relaxation times is too simplistic and the two-state models are inadequate to describe protein hydration. (J.S.). 39 refs., 10 figs.

  11. Neutron-19C scattering: Emergence of universal properties in a finite range potential

    Science.gov (United States)

    Shalchi, M. A.; Yamashita, M. T.; Hadizadeh, M. R.; Frederico, T.; Tomio, Lauro

    2017-01-01

    The low-energy properties of the elastic s-wave scattering for the n-19C are studied near the critical condition for the occurrence of an excited Efimov state in n-n-18C. It is established to which extent the universal scaling laws, strictly valid in the zero-range limit, survive when finite range potentials are considered. By fixing the two-neutrons separation energy in 20C with available experimental data, it is studied the scaling of the real (δ0R) and imaginary parts of the s-wave phase-shift with the variation of the n-18C binding energy. We obtain some universal characteristics given by the pole-position of kcot ⁡ (δ0R) and effective-range parameters. By increasing the n-18C binding energy, it was verified that the excited state of 20C goes to a virtual state, resembling the neutron-deuteron behavior in the triton. It is confirmed that the analytical structure of the unitary cut is not affected by the range of the potential or mass asymmetry of the three-body system.

  12. Investigation of Monodisperse Dendrimeric Polysaccharide Nanoparticle Dispersions Using Small Angle Neutron Scattering

    Science.gov (United States)

    Atkinson, John; Nickels, Jonathan; Papp-Szabo, Erzsi; Katsaras, John; Dutcher, John

    2015-03-01

    Phytoglycogen is a highly branched polysaccharide that is very similar to the energy storage molecule glycogen. We have isolated monodisperse phytoglycogen nanoparticles from corn and these particles are attractive for applications in the cosmetic, food and beverage, and biomedical industries. Many of these promising applications are due to the special interaction between the nanoparticles and water, which results in: (1) high solubility; (2) low viscosity and high stability in aqueous dispersions; and (3) a remarkable capacity to sequester and retain water. Our rheology measurements indicate that the nanoparticles behave like hard spheres in water, with the viscosity diverging for concentrations >25% (w/w). Because of this, aqueous suspensions of phytoglycogen provide an ideal platform for detailed testing of theories of colloidal glasses and jamming. To further explore the interaction of the phytoglycogen particles and water, we have performed small angle neutron scattering (SANS) measurements on the Extended Q-Range SANS (EQ-SANS) diffractometer at the Spallation Neutron Source at Oak Ridge National Laboratory. Measurements performed on phytoglycogen dispersions in mixtures of hydrogenated and deuterated water have allowed us to determine the particle size and average particle spacing as a function of the phytoglycogen concentration in the limits of dilute and concentrated dispersions.

  13. Level lifetimes and the nuclear structure of 134,136Xe from inelastic neutron scattering

    Science.gov (United States)

    Peters, E. E.; Chakraborty, A.; Crider, B. P.; Ross, T. J.; Ashley, S. F.; Elhami, E.; Kumar, A.; Liu, S. H.; McEllistrem, M. T.; Mukhopadhyay, S.; Orce, J. N.; Prados-Estévez, F. M.; Yates, S. W.; Hicks, S. F.

    2017-09-01

    The level structures of 134,136Xe were studied with the inelastic neutron scattering reaction followed by γ-ray detection. Highly enriched solid XeF2 samples were used in the measurements. A number of level lifetimes were determined for the first time with the Doppler-shift attenuation method, and the low-lying excited states were characterized from this new spectroscopic information. In 134Xe, the third excited state, a tentative 0+ level, was verified. The 3- octupole phonon has been confirmed, and the complete negative-parity multiplet resulting from the ν (1h11 / 2 2d3 / 2) configuration has been tentatively identified for the first time in the N = 80 isotones. In 136Xe, a nucleus with a closed N = 82 neutron shell, several spins and parities of the states below 3 MeV in excitation energy have been firmly assigned for the first time, or have been re-assigned. New insights into the structures of these nuclei will be discussed. This material is based upon work supported by the U.S. National Science Foundation under Grant No. PHY-1606890.

  14. Mobility of water in Linde type A synthetic zeolites: an inelastic neutron scattering study

    Science.gov (United States)

    Corsaro, C.; Crupi, V.; Longo, F.; Majolino, D.; Venuti, V.; Wanderlingh, U.

    2005-12-01

    In the present work the effects produced by cation substitution on the dynamics of water in Linde type A (LTA) synthetic zeolites were investigated by means of inelastic neutron spectroscopy (INS). In particular, we performed measurements on fully hydrated Na-A and Mg-exchanged-A zeolites. The collected INS spectra showed two broad bands due to the vibrational (water-cation and hydrogen bond stretch) and librational (rock, twist and wag) modes of water. To quantitatively assign these various modes, the spectra were decomposed into Gaussian components and compared with the INS spectra of ice and of water in other zeolites. The observed shifts of the band positions for different temperatures were discussed. In particular, a slight shift of the three librational modes towards higher frequencies with increasing temperature was revealed for both samples. The hydrogen bond stretching and librational modes of water in Na-A and Mg50-A zeolites shift to lower frequencies with respect to ice. Furthermore, in the case of Mg50-A zeolite, we observed a shift upwards in frequency of librational bands with respect to Na-A zeolite. The obtained results were discussed in relation to our previous elastic and quasi-elastic neutron scattering (ENS and QENS respectively) measurements on the same samples.

  15. Present status and plans for upgrading the Lujan neutron scattering center

    Energy Technology Data Exchange (ETDEWEB)

    Rhyne, James J [LANSCE-LC

    2010-01-01

    The Lujan Center, part of the LANSCE accelerator complex at Los Alamos National Laboratory, operates a comprehensive neutron scattering facility for the U.S. Department of Energy that serves approximately 300 users per year. This paper will discuss the current instruments and status of the facility and also focus on the plans for a major upgrade of the Center including new instruments and enhancements to specific existing instruments. The instrument suite currently includes two reflectometers (one with full polarization), an engineering diffraction machine, a diffractometer specialized to pair-distribution analysis, 2 general purpose powder diffractometers, and 2 inelastic spectrometers. To complement these spectrometers, a full range of pressure, temperature, and magnetic field sample environments is available for users. As part of the planning for a forthcoming enhancement of Lujan Center, a series of workshops have been held over the past year to encourage user input to the design for new instruments as well as major upgrades of existing machines. Many of the planned facilities are designed to take advantage of the Lujan Center 20 Hz pulse repetition rate and cold source moderators, both of which are beneficial for high-resolution instruments using long neutron wavelengths.

  16. Neutron Scattering at the Intersection of Heart Health Science and Biophysics

    Directory of Open Access Journals (Sweden)

    Drew Marquardt

    2015-06-01

    Full Text Available There is an urgent quest for improved heart health. Here, we review how neutron radiation can provide insight into the molecular basis of heart health. Lower cholesterol, a daily intake of aspirin and supplemental vitamin E are argued to all improve heart health. However, the mechanisms behind these common regimens, and others, are not entirely understood. It is not clear why a daily intake of aspirin can help some people with heart disease, and the benefits of vitamin E in the treatment of reperfusion injury have been heavily debated. The molecular impact of cholesterol in the body is still a hot topic. Neutron scattering experiments present a unique opportunity for biophysicists attempting to address these problems. We review some recently published studies that are advancing our understanding of how cholesterol, vitamin E and aspirin work at the molecular level, by studying the impact of these molecules on the cell membrane. These insights engage the broader health science community with new ways of thinking about these molecules.

  17. Neutron diffraction and micro-Raman scattering studies on rare-earth carbide halides

    Science.gov (United States)

    Henn, R. W.; Strach, T.; Kremer, R. K.; Simon, A.

    1998-12-01

    Neutron-diffraction experiments on powder samples and micro-Raman scattering investigations on single crystals of the layered compounds R2CxHal2, (R=Y, Gd, x=1,2, and Hal=Br, I) have been performed in order to study their static and dynamic lattice properties. For the superconductors Y2C2I2 (Tc=9.97 K) and Y2C2Br2 (Tc=5.04 K), the C-C atomic distances were obtained with high accuracy from neutron-diffraction experiments between T=1.5 and 270 K. The expected Raman-active phonons were determined from a factor-group analysis of the crystal structures. In the monocarbide Y2CBr2, the Raman-active phonons of the heavy-ion sublattices have been observed. In the dicarbide compounds R2C2Hal2, additionally, the stretching and tilting modes of the dimeric C2 units were clearly identified by analyzing spectra from natC and 13C substituted samples. The influence of the quasimolecular C2 unit on the electronic properties in the R2C2Hal2 compounds and its interaction with the surrounding metal atom octahedra is discussed.

  18. High-resolution inelastic neutron scattering and neutron powder diffraction study of the adsorption of dihydrogen by the Cu(II) metal-organic framework material HKUST-1

    Science.gov (United States)

    Callear, Samantha K.; Ramirez-Cuesta, Anibal J.; David, William I. F.; Millange, Franck; Walton, Richard I.

    2013-12-01

    We present new high-resolution inelastic neutron scattering (INS) spectra (measured using the TOSCA and MARI instruments at ISIS) and powder neutron diffraction data (measured on the diffractometer WISH at ISIS) from the interaction of the prototypical metal-organic framework HKUST-1 with various dosages of dihydrogen gas. The INS spectra show direct evidence for the sequential occupation of various distinct sites for dihydrogen in the metal-organic framework, whose population is adjusted during increasing loading of the guest. The superior resolution of TOSCA reveals subtle features in the spectra, not previously reported, including evidence for split signals, while complementary spectra recorded on MARI present full information in energy and momentum transfer. The analysis of the powder neutron patterns using the Rietveld method shows a consistent picture, allowing the crystallographic indenisation of binding sites for dihydrogen, thus building a comprehensive picture of the interaction of the guest with the nanoporous host.

  19. Spin-Echo Small Angle Neutron Scattering analysis of liposomes and bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Heijkamp, Leon F van; Sevcenco, Ana-Maria; Abou, Diane; Luik, Remko van; Krijger, Gerard C; Schepper, Ignatz M de; Wolterbeek, Bert; Bouwman, Wim G [Faculty of Applied Sciences, Department of Radiation, Radionuclides and Reactors, Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands); Hagedoorn, Peter-Leon [Faculty of Applied Sciences, Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft (Netherlands); Koning, Gerben A, E-mail: l.f.vanheijkamp@tudelft.n, E-mail: w.g.bouwman@tudelft.n [Laboratory Experimental Surgical Oncology, Section Surgical Oncology, Department of Surgery, Erasmus Medical Center, POBox 1738, 3000 DR Rotterdam (Netherlands)

    2010-10-01

    Two types of liposomes, commonly used in drug delivery studies, and E. coli bacteria, all prepared in H{sub 2}O, were resuspended in D{sub 2}O and measured with Small Angle Spin-Echo Neutron Scattering (SESANS). Modeling was performed using correlation functions for solid spheres and hollow spheres. The signal strength and curve shape were more indicative of hollow particles, indicating that the H{sub 2}O-D{sub 2}O exchange occurred too fast to be observed with the available time resolution. Fitting the particle diameter and membrane thickness of the hollow sphere model to the data, gave results which were in good agreement with Dynamic Light Scattering (DLS) data and literature, showing as a proof-of-principle that SESANS is able to investigate such systems. SESANS may become a good alternative to conventional tritium studies or a tool with which to study intracellular vesicle transport phenomena, with possible in vivo applications. Calculations show that a substantial change in numbers of a mixed system of small and large biological particles should be observable. A possible application is the destruction by external means of great numbers of liposomes in the presence of tumor cells for triggered drug release in cancer treatment. Since SESANS is both non-invasive and non-destructive and can handle relatively thick samples, it could be a useful addition to more conventional techniques.

  20. Monomeric Amyloid Beta Peptide in Hexafluoroisopropanol Detected by Small Angle Neutron Scattering.

    Directory of Open Access Journals (Sweden)

    Bo Zhang-Haagen

    Full Text Available Small proteins like amyloid beta (Aβ monomers are related to neurodegenerative disorders by aggregation to insoluble fibrils. Small angle neutron scattering (SANS is a nondestructive method to observe the aggregation process in solution. We show that SANS is able to resolve monomers of small molecular weight like Aβ for aggregation studies. We examine Aβ monomers after prolonged storing in d-hexafluoroisopropanol (dHFIP by using SANS and dynamic light scattering (DLS. We determined the radius of gyration from SANS as 1.0±0.1 nm for Aβ1-40 and 1.6±0.1 nm for Aβ1-42 in agreement with 3D NMR structures in similar solvents suggesting a solvent surface layer with 5% increased density. After initial dissolution in dHFIP Aβ aggregates sediment with a major component of pure monomers showing a hydrodynamic radius of 1.8±0.3 nm for Aβ1-40 and 3.2±0.4 nm for Aβ1-42 including a surface layer of dHFIP solvent molecules.