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)

Neutron scattering. Lectures

International Nuclear Information System (INIS)

Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner

2010-01-01

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)

Scattering with polarized neutrons

International Nuclear Information System (INIS)

Schweizer, J.

2007-01-01

In the history of neutron scattering, it was shown very soon that the use of polarized neutron beams brings much more information than usual scattering with unpolarized neutrons. We shall develop here the different scattering methods that imply polarized neutrons: 1) polarized beams without polarization analysis, the flipping ratio method; 2) polarized beams with a uniaxial polarization analysis; 3) polarized beams with a spherical polarization analysis. For all these scattering methods, we shall give examples of the physical problems which can been solved by these methods, particularly in the field of magnetism: investigation of complex magnetic structures, investigation of spin or magnetization densities in metals, insulators and molecular compounds, separation of magnetic and nuclear scattering, investigation of magnetic properties of liquids and amorphous materials and even, for non magnetic material, separation between coherent and incoherent scattering. (author)

New generation of cryogen free advanced superconducting magnets for neutron scattering experiments

International Nuclear Information System (INIS)

Kirichek, O; Adroja, D T; Manuel, P; Bewley, R I; Brown, J; Kouzmenko, G; Wotherspoon, R

2012-01-01

Recent advances in superconducting technology and cryocooler refrigeration have resulted in a new generation of advanced superconducting magnets for neutron beam applications. These magnets have outstanding parameters such as high homogeneity and stability at highest magnetic fields possible, a reasonably small stray field, low neutron scattering background and larger exposure to neutron detectors. At the same time the pulse tube refrigeration technology provides a complete re-condensing regime which allows to minimise the requirements for cryogens without introducing additional noise and mechanical vibrations. The magnets can be used with dilution refrigerator insert which expands the temperature range from 20mK to 300K. Here we are going to present design, test results and the operational data of the 14T magnet for neutron diffraction and the 9T wide angle chopper magnet for neutron spectroscopy developed by Oxford Instruments in collaboration with ISIS neutron source. First scientific results obtained from the neutron scattering experiments with these magnets are also going to be discussed.

Neutron scattering investigation of magnetic excitations at high energy transfers

International Nuclear Information System (INIS)

Loong, C.K.

1984-01-01

With the advance of pulsed spallation neutron sources, neutron scattering investigation of elementary excitations in magnetic materials can now be extended to energies up to several hundreds of MeV. We have measured, using chopper spectrometers and time-of-flight techniques, the magnetic response functions of a series of d and f transition metals and compounds over a wide range of energy and momentum transfer. In PrO 2 , UO 2 , BaPrO 3 and CeB 6 we observed crystal-field transitions between the magnetic ground state and the excited levels in the energy range from 40 to 260 MeV. In materials exhibiting spin-fluctuation or mixed-valent character such as Ce 74 Th 26 , on the other hand, no sharp crystal-field lines but a broadened quasielastic magnetic peak was observed. The line width of the quasielastic component is thought to be connected to the spin-fluctuation energy of the 4f electrons. The significance of the neutron scattering results in relation to the ground state level structure of the magnetic ions and the spin-dynamics of the f electrons is discussed. Recently, in a study of the spin-wave excitations in itinerant magnetic systems, we have extended the spin-wave measurements in ferromagnetic iron up to about 160 MeV. Neutron scattering data at high energy transfers are of particular interest because they provide direct comparison with recent theories of itinerant magnetism. 26 references, 7 figures

Modern quantum magnetism by means of neutron scattering

International Nuclear Information System (INIS)

Grenier, B.; Ziman, T.

2007-01-01

We review a selection of recent applications of neutron scattering to the field of quantum magnetism. We focus on systems where, because of quantum fluctuations enhanced by frustration and low dimension, there is no long range magnetic order in the ground state. We select two examples that we treat in more depth to show how neutron studies, in conjunction with the results of other experimental techniques, can give new insights. The first is the case of the spin ladder NaV 2 O 5 , where the origin of the spin gap at low temperature is now understood in detail. Apparent contradictions between quantitative measures of the charge order from neutron inelastic scattering, resonant X-ray scattering and NMR have been resolved giving interesting insights into the correlations. The second case is that of spin dimer system Cs 3 Cr 2 X 9 (X = Br, Cl), undergoing transitions to field induced transverse magnetic order. The Br compound is attractive as the critical fields are sufficiently low that a complete study, in different field directions, is possible. In addition, it is noteworthy in that the magnon that softens and condenses is incommensurable with the lattice. The common description in terms of Bose-Einstein condensation must be extended to include a continuous degeneracy and single ion anisotropy, and conclusions can be drawn by comparison with the Cl compound. (authors)

Neutron scattering study of magnetic and crystalline electirc field interactions in RCrO3

International Nuclear Information System (INIS)

Shamir, N.

1978-05-01

Magnetic and crystalline electric field interactions in the compounds RCrO 3 (R-rare earth) , were studied by neutron scattering. Elastic neutron scattering was utilized in the study of the temperature dependence of the Cr 3+ and Ho 3+ magnetic reflections in Lu CrO 3 and HoCrO 3 , respectively. Analysis of this temperature dependence yielde constant canting angles for the Cr 3+ and Ho 3+ magnetic moments. Molecular magnetic field constants and crystalline electric field splitting were also calculated from the temperature dependence of the Ho 3+ magnetic reflection. These parameters were obtained directly by inelastic neutron scattering measurement. Inelastic neutron scattering measurements of crystlline electric field transitions of R 3+ (R=Pr, Nd, Tb, Ho, Er, Tm, Yb) in RCrO 3 , formed the basis for the calculation of the common crystalline electirc field parameters of the heavy R 3+ ions. (author)

Some neutron scattering studies on magnetic and molecular phase transitions

International Nuclear Information System (INIS)

Bevaart, L.

1978-01-01

In this thesis neutron-scattering investigations on two different systems are described. The first study is concerned with the magnetic ordering phenomena in pseudo two-dimensional (d = 2), two-component antiferromagnets K 2 Mnsub(1-x)Msub(x)F 4 (M = Fe, Co), as a function of the composition x and temperature T. For one of the samples in this series, K 2 Musub(0.978)Fesub(0.022)F 4 , the influence of an external magnetic field on the ordering characteristics was studied in addition. The second study deals with the rotational motions of the NH 4 + groups in NH 4 ZnF 3 in relation with the structural phase transition at Tsub(c) = 115.1 K. The experimental techniques were chosen according to the requirements of each of these two subjects. The former study was carried out by observing the elastic magnetic neutron scattering with a double-axis diffractometer, whereas for the latter study time-of-flight (TOF) techniques were applied to observe the inelastic and quasi-elastic incoherent neutron scattering by the protons of the rotating NH 4 + groups. (Auth.)

Polarized Neutron Scattering

OpenAIRE

Roessli, B.; Böni, P.

2000-01-01

The technique of polarized neutron scattering is reviewed with emphasis on applications. Many examples of the usefulness of the method in various fields of physics are given like the determination of spin density maps, measurement of complex magnetic structures with spherical neutron polarimetry, inelastic neutron scattering and separation of coherent and incoherent scattering with help of the generalized XYZ method.

Spin-resolved unpolarized neutron off-specular scattering for magnetic multilayer studies

CERN Document Server

Lauter, H J; Toperverg, B P; Romashev, L; Ustinov, V; Kravtsov, E; Vorobiev, A; Major, J; Nikonov, O A

2002-01-01

The capabilities of the method of using unpolarized neutron off-specular scattering for investigation of magnetic structures in exchange-coupled magnetic multilayers are thoroughly examined. It is demonstrated that strong anomalies in spin-flip selective scattering processes originating from magnetic fluctuations enables a straightforward determination of the coupling angle between the magnetization direction of successive Fe layers in Fe/Cr multilayers. A complete quantitative 2-dimensional data analysis of specular and off-specular scattering has been employed to provide detailed information on the lateral and transverse magnetization arrangement in the multilayer. (orig.)

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....

Neutron scattering study of the magnetism in a nanocrystalline/amorphous material

International Nuclear Information System (INIS)

Rosov, N.

1995-01-01

Recently developed nanocrystalline magnetic systems are of considerable interest fundamentally as well as technologically. One such material is Fe 73.5 B 9 Si 13.5 Cu 1 Nb 3 , which can be produced by heat treating the amorphous precursor. This forms a noncrystalline phase with typical dimension of 350 angstrom as determined by neutron diffraction. Small angle neutron scattering (SANS) has been employed to investigate the properties of the nanocrystallized material over the temperature range from 10 K to 725 K, a regime where no significant structural changes are expected to occur. In zero field and low temperature (10 K) the authors obtained an isotropic scattering pattern. The application of a relatively modest field to sweep out the domains changed the scattering to a butterfly wings pattern typical of patterns dominated by magnetic elastic intensity. Up to 450 K this pattern changed only modestly, while for substantially higher temperatures the ratio of inelastic to elastic scattering increased rapidly as the magnetic phase transition of the intergranular component (≅ 575 K) was approached. Triple axis inelastic measurements showed that the majority of the magnetic inelastic scattering was from the nanocrystalline phase

Neutron scattering study of the magnetism in a nanocrystalline/amorphous material

Energy Technology Data Exchange (ETDEWEB)

Rosov, N. [National Inst. of Standards and Technology, Gaithersburg, MD (United States). Reactor Radiation Div.; Lynn, J.W. [National Inst. of Standards and Technology, Gaithersburg, MD (United States). Reactor Radiation Div.]|[Univ. of Maryland, College Park, MD (United States). Dept. of Physics; Fish, G.E. [Allied Signal Inc., Morristown, NJ (United States)

1995-12-31

Recently developed nanocrystalline magnetic systems are of considerable interest fundamentally as well as technologically. One such material is Fe{sub 73.5}B{sub 9}Si{sub 13.5}Cu{sub 1}Nb{sub 3}, which can be produced by heat treating the amorphous precursor. This forms a noncrystalline phase with typical dimension of 350 {angstrom} as determined by neutron diffraction. Small angle neutron scattering (SANS) has been employed to investigate the properties of the nanocrystallized material over the temperature range from 10 K to 725 K, a regime where no significant structural changes are expected to occur. In zero field and low temperature (10 K) the authors obtained an isotropic scattering pattern. The application of a relatively modest field to sweep out the domains changed the scattering to a butterfly wings pattern typical of patterns dominated by magnetic elastic intensity. Up to 450 K this pattern changed only modestly, while for substantially higher temperatures the ratio of inelastic to elastic scattering increased rapidly as the magnetic phase transition of the intergranular component ({approx_equal} 575 K) was approached. Triple axis inelastic measurements showed that the majority of the magnetic inelastic scattering was from the nanocrystalline phase.

Zeeman splitting of surface-scattered neutrons

International Nuclear Information System (INIS)

Felcher, G.P.; Adenwalla, S.; De Haan, V.O.; Van Well, A.A.

1995-01-01

If a beam of slow neutrons impinges on a solid at grazing incidence, the neutrons reflected can be used to probe the composition and magnetization of the solid near its surface. In this process, the incident and reflected neutrons generally have identical kinetic energies. Here we report the results of an experiment in which subtle inelastic scattering processes are revealed as relatively large deviations in scattering angle. The neutrons are scattered from a ferromagnetic surface in the presence of a strong ambient magnetic field, and exhibit a small but significant variation in kinetic energy as a function of the reflection angle. This effect is attributable to the Zeeman splitting of the energies of the neutron spin states due to the ambient magnetic field: some neutrons flip their spins upon reflection from the magnetized surface, thereby exchanging kinetic energy for magnetic potential energy. The subtle effects of Zeeman splitting are amplified by the extreme sensitivity of grazing-angle neutron scattering, and might also provide a useful spectroscopic tool if significant practical obstacles (such as low interaction cross-sections) can be overcome. (author)

Introductory theory of neutron scattering

International Nuclear Information System (INIS)

Gunn, J.M.F.

1986-12-01

The paper comprises a set of six lecture notes which were delivered to the summer school on 'Neutron Scattering at a pulsed source', Rutherford Laboratory, United Kingdom, 1986. The lectures concern the physical principles of neutron scattering. The topics of the lectures include: diffraction, incoherent inelastic scattering, connection with the Schroedinger equation, magnetic scattering, coherent inelastic scattering, and surfaces and neutron optics. (UK)

Inelastic neutron scattering from superconducting rings

International Nuclear Information System (INIS)

Agafonov, A.I.

2010-01-01

For the first time the differential cross section for the inelastic magnetic neutron scattering by superconducting rings is derived taking account of the interaction of the neutron magnetic moment with the magnetic field generated by the superconducting current. Calculations of the scattering cross section are carried out for cold neutrons and thin film rings from type-II superconductors with the magnetic fields not exceeding the first critical field.

Neutron scattering investigations of frustated magnets

Science.gov (United States)

Fennell, Tom

This thesis describes the experimental investigation of frustrated magnetic systems based on the pyrochlore lattice of corner-sharing tetrahedra. Ho2Ti207 and Dy2Ti207 are examples of spin ices, in which the manifold of disordered magnetic groundstates maps onto that of the proton positions in ice. Using single crystal neutron scattering to measure Bragg and diffuse scattering, the effect of applying magnetic fields along different directions in the crystal was investigated. Different schemes of degeneracy removal were observed for different directions. Long and short range order, and the coexistence of both could be observed by this technique.The field and temperature dependence of magnetic ordering was studied in Ho2Ti207 and Dy2Ti207. Ho2Ti2()7 has been more extensively investigated. The field was applied on [00l], [hh0], [hhh] and [hh2h]. Dy2Ti207 was studied with the field applied on [00l] and [hho] but more detailed information about the evolution of the scattering pattern across a large area of reciprocal space was obtained.With the field applied on [00l] both materials showed complete degeneracy removal. A long range ordered structure was formed. Any magnetic diffuse scattering vanished and was entirely replaced by strong magnetic Bragg scattering. At T =0.05 K both materials show unusual magnetization curves, with a prominent step and hysteresis. This was attributed to the extremely slow dynamics of spin ice materials at this temperature.Both materials were studied in greatest detail with the field applied on [hh0]. The coexistence of long and short range order was observed when the field was raised at T = 0.05 K. The application of a field in this direction separated the spin system into two populations. One could be ordered by the field, and one remained disordered. However, via spin-spin interactions, the field restricted the degeneracy of the disordered spin population. The neutron scattering pattern of Dy2Ti207 shows that the spin system was separated

Studies of magnetism with inelastic scattering of cold neutrons

International Nuclear Information System (INIS)

Jacrot, B.

1964-01-01

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) [fr

Polarimetric neutron scattering

International Nuclear Information System (INIS)

Tasset, F.

2001-01-01

Polarimetric Neutron Scattering in introduced, both by, explaining methodological issues and the corresponding instrumental developments. After a short overview of neutron spin polarization and the neutron polarization 3d-vector a pictorial approach of the microscopic theory is used to show how a polarized beam interacts with lattice and magnetic Fourier components in a crystal. Examples are given of using Spherical Neutron Polarimetry (SNP) and the corresponding Cryopad polarimeter for the investigation of non-collinear magnetic structures. (R.P.)

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...... analyzed on the basis of a simple model with uniaxial anisotropy and the Neel-Brown theory for the relaxation....

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 on the neu......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...

Applications of neutron scattering to the study of magnetic materials

International Nuclear Information System (INIS)

Koehler, W.C.

1976-01-01

The types of interactions that neutrons undergo with condensed matter are reviewed and those properties of neutrons that make them an ideal probe for the study of magnetism on a microscopic scale are discussed. Following a very brief survey of experimental methods, a few illustrative examples of specific investigations are described in sufficient detail to illustrate the power of the techniques. Views as to the future directions that may be taken by neutron scattering are presented

Polarized neutron reflectivity and scattering studies of magnetic heterostructures

International Nuclear Information System (INIS)

Zabel, H; Theis-Broehl, K

2003-01-01

The current interest in the magnetism of ultrathin films and multilayers is driven by their manifold applications in the magneto-and spin-electronic areas, for instance as magnetic field sensors or as information storage devices. In this regard, there is a large interest in exploring spin structures and spin disorder at the interface of magnetic heterostructures, to investigate magnetic domains in thin films and superlattices, and to understand remagnetization processes of various laterally shaped magnetic nanostructures. Traditionally neutron scattering has played a dominant role in the determination of spin structures, phase transitions and magnetic excitations in bulk materials. Today, its potential for the investigation of thin magnetic films has to be redefined. Polarized neutron reflectivity (PNR) at small wavevectors can provide precise information on the magnetic field distribution parallel to the film plane and on layer resolved magnetization vectors. In addition, PNR is not only sensitive to structural interface roughness but also to the magnetic roughness. Furthermore, magnetic hysteresis measurements from polarized small angle Bragg reflections allows us to filter out correlation effects during magnetization reversals of magnetic stripes and islands. An overview is provided on most recent PNR investigations of magnetic heterostructures

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.

Neutron scattering studies of the heavy Fermion superconductors

International Nuclear Information System (INIS)

Goldman, A.I.

1985-01-01

Recent neutron scattering measurements of the heavy Fermion superconductors are described. Those materials offer an exciting opportunity for neutron scattering since the f-electrons, which couple directly to magnetic scattering measurements, seem to be the same electrons which form the superconducting state below T/sub c/. In addition, studies of the magnetic fluctuations in these, and other heavy Fermion systems, by inelastic magnetic neutron scattering can provide information about the nature of the low temperature Fermi liquid character of these novel compounds

Small angle neutron scattering measurements of magnetic cluster sizes in magnetic recorging disks

CERN Document Server

Toney, M

2003-01-01

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.

Magnetic photon scattering

International Nuclear Information System (INIS)

Lovesey, S.W.

1987-05-01

The report reviews, at an introductory level, the theory of photon scattering from condensed matter. Magnetic scattering, which arises from first-order relativistic corrections to the Thomson scattering amplitude, is treated in detail and related to the corresponding interaction in the magnetic neutron diffraction amplitude. (author)

Single Crystal Diffuse Neutron Scattering

Directory of Open Access Journals (Sweden)

Richard Welberry

2018-01-01

Full Text Available Diffuse neutron scattering has become a valuable tool for investigating local structure in materials ranging from organic molecular crystals containing only light atoms to piezo-ceramics that frequently contain heavy elements. Although neutron sources will never be able to compete with X-rays in terms of the available flux the special properties of neutrons, viz. the ability to explore inelastic scattering events, the fact that scattering lengths do not vary systematically with atomic number and their ability to scatter from magnetic moments, provides strong motivation for developing neutron diffuse scattering methods. In this paper, we compare three different instruments that have been used by us to collect neutron diffuse scattering data. Two of these are on a spallation source and one on a reactor source.

Ultra-High Field Magnets for X-Ray and Neutron Scattering using High Temperature Superconductors

Energy Technology Data Exchange (ETDEWEB)

Winn, Barry L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Broholm, C. [Johns Hopkins Univ., Baltimore, MD (United States); Bird, M. [Florida State Univ., Tallahassee, FL (United States). National High Magnetic Field Lab. (MagLab); Breneman, Bruce C. [General Atomics, San Diego, CA (United States); Coffey, Michael [Cryomagnetics, Oak Ridge, TN (United States); Cutler, Roy I. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Duckworth, Robert C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Erwin, R. [National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States); Hahn, Seungyong [Florida State Univ., Tallahassee, FL (United States). National High Magnetic Field Lab. (MagLab); Hernandez, Yamali [National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States); Herwig, Kenneth W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Holland, Leo D. [General Atomics, San Diego, CA (United States); Lonergan, Kevin M. [Oxford Instruments, Abingdon (United Kingdom); Melhem, Ziad [Oxford Instruments, Abingdon (United Kingdom); Minter, Stephen J. [Cryomagnetics, Oak Ridge, TN (United States); Nelson, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Paranthaman, M. Parans [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Pierce, Josh [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ruff, Jacob [Cornell Univ., Ithaca, NY (United States); Shen, Tengming [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sherline, Todd E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Smeibidl, Peter G. [Helmholtz-Zentrum Berlin (HZB), (Germany); Tennant, David [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); van der Laan, Danko [Advanced Conductor Technologies, LLC, Boulder, CO (United States); Wahle, Robert J. [Helmholtz-Zentrum Berlin (HZB), (Germany); Zhang, Yifei [SuperPower, Inc., Schenectady, NY (United States)

2017-01-01

X-ray and neutron scattering techniques are capable of acquiring information about the structure and dynamics of quantum matter. However, the high-field magnet systems currently available at x-ray and neutron scattering facilities in the United States are limited to fields of 16 tesla (T) at maximum, which precludes applications that require and/or study ultra-high field states of matter. This gap in capability—and the need to address it—is a central conclusion of the 2005 National Academy of Sciences report by the Committee on Opportunities in High Magnetic Field Science. To address this gap, we propose a magnet development program that would more than double the field range accessible to scattering experiments. With the development and use of new ultra-high field–magnets, the program would bring into view new worlds of quantum matter with profound impacts on our understanding of advanced electronic materials.

Structure of magnetic particles studied by small angle neutron scattering. [Magnetic colloid particles in stable liquid dispersion

Energy Technology Data Exchange (ETDEWEB)

Cebula, D J; Charles, S W; Popplewell, J

1981-03-01

The purpose of this note is to show how the use of small angle neutron scattering (SANS) can provide fundamental information on the structure of magnetic colloid particles in stable liquid dispersion. A more detailed account elaborating the use of the technique to provide fundamental information on interactions will appear later. This contribution contains some principal results on particle structure. The technique of SANS provides a very sensitive means of measuring particle size by measuring the scattered neutron intensity, I(Q), as a function of scattered wave vector, Q.

Small-angle neutron-scattering studies of the magnetic phase diagram of MnSi

DEFF Research Database (Denmark)

Harris, P.; Lebech, B.; Hae Seop Shim

1995-01-01

The antiferromagnetic order of MnSi has been studied as function of temperature and applied magnetic field using small-angle neutron scattering. The results were analyzed using the three-dimensional resolution function and the scattering cross-section to model the diffraction data. Physical...

Neutron scattering studies of a dilute magnetic semiconductor: Cd1-xMnxTe

DEFF Research Database (Denmark)

Steigenberger, Ursula; Lebech, Bente; Galazka, Robert R.

1986-01-01

The development of the magnetic ordering in the magnetic semiconductor Cd1-xMnxTe was investigated by elastic neutron scattering. A detailed study of the correlation length and the intensity as a function of temperature, direction in reciprocal space and concentration of the magnetic ions has been...

Neutron scattering equipments in JAERI. Current status

International Nuclear Information System (INIS)

Hamaguchi, Yoshikazu; Minakawa, Nobuaki

2003-01-01

24 neutron scattering instruments are installed in the JRR-3M research reactor. Among them JAERI has 12 neutron scattering instruments. Those instruments are HRPD for high-resolution structural analysis, TAS-1 and TAS-2 for elastic and inelastic scattering and for magnetic scattering measurements by the polarized neutron, LTAS for elastic and inelastic scattering measurement at a low energy region, and for neutron device development, PNO for topography and for very small angle scattering measurement in a small Q range, NRG for neutron radiography, RESA for internal strain measurements, SANS for the molecule and semi-macroscopic magnetic structural analysis, BIX-2 and BIX-3 for the biological structural analysis research, and PGA for the research of prompt gamma-ray analysis. The university groups have 12 neutron scattering instruments. Since those instruments were installed at the period when JRR-3M was completed, about 10 years have passed. In order to match the old control systems with the progress of recent computer technologies, and peripheral equipment, numbers of instruments are being renewed. In the neutron guide hall of JRR-3M, the Ni mirror guide tube was replaced by a super mirror guide tube to increase neutron flux. The intensity of 2A flux was increased by a factor of about two. (J.P.N.)

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

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

International Nuclear Information System (INIS)

Kreuzpaintner, Wolfgang

2010-01-01

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

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<=...

Ramsauer effect in triplet neutron-neutron scattering

International Nuclear Information System (INIS)

Pupyshev, V.V.; Solovtsova, O.P.

1995-01-01

As we show, due to interplay of pure nuclear and magnetic moment interactions, the total cross section of triplet neutron-neutron scattering should possess a non-zero limit at E cm = 0 and a local minimum at ∼ 20 keV. 17 refs., 1 fig

Neutron scattering investigation on low-dimensional, quantum and frustrated magnetism and utilization of neutron polarization analysis. My first encounter with neutron research

International Nuclear Information System (INIS)

Kakurai, Kazuhisa

2013-01-01

My first encounter with neutron scattering research on low-dimensional magnetism at the Hahn-Meitner Institut under the supervision of Prof. H. Dachs and Prof. M. Steiner, were it all began, is accounted for. The polarized neutron analysis research on low-dimensional magnetism at the Institut Laue Langevin under the supervision of Dr. R. Pynn is also reported. I would like to dedicate this article to late Prof. H. Dachs expressing may deepest gratitude for his warm guidance during the early period of my neutron science carrier. (author)

Magnetic diffuse scattering

International Nuclear Information System (INIS)

Cable, J.W.

1987-01-01

The diffuse scattering of neutrons from magnetic materials provides unique and important information regarding the spatial correlations of the atoms and the spins. Such measurements have been extensively applied to magnetically ordered systems, such as the ferromagnetic binary alloys, for which the observed correlations describe the magnetic moment fluctuations associated with local environment effects. With the advent of polarization analysis, these techniques are increasingly being applied to study disordered paramagnetic systems such as the spin-glasses and the diluted magnetic semiconductors. The spin-pair correlations obtained are essential in understanding the exchange interactions of such systems. In this paper, we describe recent neutron diffuse scattering results on the atom-pair and spin-pair correlations in some of these disordered magnetic systems. 56 refs

Thermal-neutron multiple scattering: critical double scattering

International Nuclear Information System (INIS)

Holm, W.A.

1976-01-01

A quantum mechanical formulation for multiple scattering of thermal-neutrons from macroscopic targets is presented and applied to single and double scattering. Critical nuclear scattering from liquids and critical magnetic scattering from ferromagnets are treated in detail in the quasielastic approximation for target systems slightly above their critical points. Numerical estimates are made of the double scattering contribution to the critical magnetic cross section using relevant parameters from actual experiments performed on various ferromagnets. The effect is to alter the usual Lorentzian line shape dependence on neutron wave vector transfer. Comparison with corresponding deviations in line shape resulting from the use of Fisher's modified form of the Ornstein-Zernike spin correlations within the framework of single scattering theory leads to values for the critical exponent eta of the modified correlations which reproduce the effect of double scattering. In addition, it is shown that by restricting the range of applicability of the multiple scattering theory from the outset to critical scattering, Glauber's high energy approximation can be used to provide a much simpler and more powerful description of multiple scattering effects. When sufficiently close to the critical point, it provides a closed form expression for the differential cross section which includes all orders of scattering and has the same form as the single scattering cross section with a modified exponent for the wave vector transfer

Neutron scattering observations on the magnetic phases of rareearth ternary superconductors

International Nuclear Information System (INIS)

Moncton, D.E.

1979-01-01

A number of ternary compounds become superconducting even though they contain a chemically ordered sublattice of magnetic rare-earth ions. Studies of the physical properties of these materials have revealed anomalies below T/sub c/ which have been attributed to magentic ordering transitions. Usng neutron spectrometers at the Brookhaven National Laboratory, a group of us has demonstrated that simple magnetic structures with long-range order do occur, and we have solved some of the magnetic structures of these superconductors. Specifically, we have found that in DyMo 6 S 8 and TbMo 6 S 8 an antiferromagnetic structure coexists with superconductivity. In two other compounds, ErRh 4 B 4 and HoMo 6 S 8 we have found that the development of ferromagnetism is responsible for the quenching of superconductivity. A study of the critical magnetic neutron scattering near the superconducting → ferromagnetic transitions shows the presence of fluctuations into a state with an oscillatory magnetization of wave length lambda = 100A

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

Larmor-precession based neutron scattering instrumentation

International Nuclear Information System (INIS)

Ioffe, Alexander

2009-01-01

The Larmor precession of the neutron spin in a magnetic field allows the attachment of a Larmor clock to every neutron. Such Larmor labelling opens the possibility for the development of unusual neutron scattering techniques, where the energy (momentum) resolution does not require the initial and final states to be well selected. This principally allows for achievement of very high energy (momentum) resolution that is not feasible at all with conventional neutron scattering techniques, because the required neutron beam monochromatization (collimation) will result in intolerable intensity losses. Such decoupling of resolution and collimation allows, for example, for a significant increase in the luminosity of small-angle scattering or high-resolution diffractometers; the fact that opens new perspectives for their implementation at middle flux neutron sources. Different kinds of Larmor clock-based instrumentation, particularly two alternative NSE techniques using rotating and time-gradient magnetic field arrangements, which can be considered as inexpensive and affordable alternatives to present day NSE techniques, will be discussed and results of simulations and first experiments will be presented. (author)

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)

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....

Studies of the dynamic properties of materials using neutron scattering

International Nuclear Information System (INIS)

Lovesey, S.W.; Windsor, C.G.

1985-09-01

The dynamic properties of materials using the neutron scattering technique is reviewed. The basic properties of both nuclear scattering and magnetic scattering are summarized. The experimental methods used in neutron scattering are described, along with access to neutron sources, and neutron inelastic instruments. Applied materials science using inelastic neutron scattering; rotational tunnelling of a methyl group; molecular diffusion from quasi-elastic scattering; and the diffusion of colloidal particles and poly-nuclear complexes; are also briefly discussed. (U.K.)

Neutron scattering—The key characterization tool for nanostructured magnetic materials

Energy Technology Data Exchange (ETDEWEB)

Fitzsimmons, M.R., E-mail: fitz@lanl.gov [Los Alamos National Laboratory (United States); Schuller, Ivan K. [University of California, San Diego (United States)

2014-01-15

The novel properties of materials produced using nanoscale manufacturing processes often arise from interactions across interfaces between dissimilar materials. Thus, to characterize the structure and magnetism of nanoscale materials demands tools with interface specificity. Neutron scattering has long been known to provide unique and quantitative information about nuclear and magnetic structures of bulk materials. Moreover, the specialty techniques of polarized neutron reflectometry and small angle neutron scattering (SANS) with polarized neutron beams and polarization analysis, are ideally and often uniquely suited to studies of nanostructured magnetic materials. Since neutron scattering is a weakly interacting probe, it gives quantifiable and easily-interpreted information on properties of statistically representative quantities of bulk, thin film and interfacial materials. In addition, neutron scattering can provide information to complement that obtained with bulk probes (magnetization, Kerr effect) or surface measurements obtained with scanning probe microscopy or resonant soft x-ray scattering. The straightforward interpretation and the simultaneous availability of structural information, make neutron scattering the technique of choice for the structural and physical characterization of many novel materials, especially those with buried interfaces, ones allowing for isotopic substitutions to decorate buried interfaces, or cases where the magnetic response to an external stimulus can be measured. We describe recent applications of neutron scattering to important thin film materials systems and future opportunities. Unquestionably, neutron scattering has played a decisive role in the development and study of new emergent phenomena. We argue with the advent of new techniques in neutron scattering and sample environment, neutron scattering's role in such studies will become even more dominant. In particular, neutron scattering will clarify and distinguish

The magnetic order of GdMn₂Ge₂ studied by neutron diffraction and x-ray resonant magnetic scattering.

Science.gov (United States)

Granovsky, S A; Kreyssig, A; Doerr, M; Ritter, C; Dudzik, E; Feyerherm, R; Canfield, P C; Loewenhaupt, M

2010-06-09

The magnetic structure of GdMn₂Ge₂ (tetragonal I4/mmm) has been studied by hot neutron powder diffraction and x-ray resonant magnetic scattering techniques. These measurements, along with the results of bulk experiments, confirm the collinear ferrimagnetic structure with moment direction parallel to the c-axis below T(C) = 96 K and the collinear antiferromagnetic phase in the temperature region T(C) < T < T(N) = 365 K. In the antiferromagnetic phase, x-ray resonant magnetic scattering has been detected at Mn K and Gd L₂ absorption edges. The Gd contribution is a result of an induced Gd 5d electron polarization caused by the antiferromagnetic order of Mn-moments.

Polarized neutron scattering research: the beginning

International Nuclear Information System (INIS)

Mezei, F.

2005-01-01

The visionary idea of using neutron scattering for the study of magnetic phenomena in condensed matter was proposed by Bloch in 1936, mere 4 years after the neutron was discovered. It was based on one of the surprises the neutron presented the scientific community with: it is neutral, yet it has a magnetic moment, which latter was then not yet directly observed though. Although the first results proved to be mathematically wrong, due to a non-trivial ambiguity of classical electromagnetism theory, which could only be settled by neutron beam experiments 15 years later, the recognition lead to the advent of a most productive area of modern research, which culminated in the development of the powerful and sophisticated techniques of polarized neutron scattering. This recollection traces the early milestones of the development of the field in strong interaction between theory and experiment

Shear- and magnetic-field-induced ordering in magnetic nanoparticle dispersion from small-angle neutron scattering

International Nuclear Information System (INIS)

Krishnamurthy, V.V.; Bhandar, A.S.; Piao, M.; Zoto, I.; Lane, A.M.; Nikles, D.E.; Wiest, J.M.; Mankey, G.J.; Porcar, L.; Glinka, C.J.

2003-01-01

Small-angle neutron scattering experiments have been performed to investigate orientational ordering of a dispersion of rod-shaped ferromagnetic nanoparticles under the influence of shear flow and static magnetic field. In this experiment, the flow and flow gradient directions are perpendicular to the direction of the applied magnetic field. The scattering intensity is isotropic in zero-shear-rate or zero-applied-field conditions, indicating that the particles are randomly oriented. Anisotropic scattering is observed both in a shear flow and in a static magnetic field, showing that both flow and field induce orientational order in the dispersion. The anisotropy increases with the increase of field and with the increase of shear rate. Three states of order have been observed with the application of both shear flow and magnetic field. At low shear rates, the particles are aligned in the field direction. When increasing shear rate is applied, the particles revert to random orientations at a characteristic shear rate that depends on the strength of the applied magnetic field. Above the characteristic shear rate, the particles align along the flow direction. The experimental results agree qualitatively with the predictions of a mean field model

Symposium on neutron scattering

International Nuclear Information System (INIS)

Lehmann, M.S.; Saenger, W.; Hildebrandt, G.; Dachs, H.

1984-01-01

Extended abstracts of the named symposium are presented. The first part of this report contains the abstracts of the lectures, the second those of the posters. Topics discussed on the symposium include neutron diffraction and neutron scattering studies in magnetism, solid state chemistry and physics, materials research. Some papers discussing instruments and methods are included too. (GSCH)

Polarized neutron inelastic scattering experiments on spin dynamics

International Nuclear Information System (INIS)

Kakurai, Kazuhisa

2016-01-01

The principles of polarized neutron scattering are introduced and examples of polarized neutron inelastic scattering experiments on spin dynamics investigation are presented. These examples should demonstrate the importance of the polarized neutron utilization for the investigation of non-trivial magnetic ground and excited states in frustrated and low dimensional quantum spin systems. (author)

Small angle neutron scattering investigations of spin disorder in nanocomposite soft magnets

International Nuclear Information System (INIS)

Vecchini, C.; Moze, O.; Suzuki, K.; Cadogan, J.M.; Pranzas, K.; Michels, A.; Weissmueller, J.

2006-01-01

The technique of SANS (small angle neutron scattering) furnishes unique information on the characteristic magnetic length scales and local magnetic anisotropies at the nanoscale in nanocomposite ferromagnets. Such information is not presently available using any other microscopic technique. The basic principles and results of the technique will be presented with regard to a unique and unexpected observation of a dipole field controlled spin disorder in a prototypical soft nanocomposite ferromagnet of the Nanoperm type

La nouvelle vague in polarized neutron scattering

International Nuclear Information System (INIS)

Mezei, F.

1986-01-01

Polarized neutron research, like many other subjects in neutron scattering developed in the footsteps of Cliff Shull. The classical polarized neutron technique he pioneered was generalized around 1970 to vectorial beam polarizations and this opened up the way to a ''nouvelle vague'' of neutron scattering experiments. In this paper I will first reexamine the old controversy on the question whether the nature of the neutron magnetic moment is that of a microscopic dipole or of an Amperian current loop. The problem is not only of historical interest, but also of relevance to modern applications. This will be followed by a review of the fundamentals on spin coherence effects in neutron beams and scattering, which are the basis of vectorial beam polarization work. As an example of practical importance, paramagnetic scattering will be discussed. The paper concludes with some examples of applications of the vector polarization techniques, such as study of ferromagnetic domains by neutron beam depolarization and Neutron Spin Echo high resolution inelastic spectroscopy. The sample results presented demonstrate the new opportunities this novel approach opened up in neutrons scattering research. (orig.)

Scattering of neutrons and critical phenomena in antiferromagnetic fermi liquid

International Nuclear Information System (INIS)

Akhiezer, I.A.; Barannik, E.A.

1980-01-01

The scattering of slow neutrons in an antiferromagnetic with collectivized magnetic electrons is considered and it is shown to significantly differ from the neutron scattering in an antiferromagnetic with localized magnetic electrons. The behaviour of scattering cross sections and fluctuation correlators near the Neel point is studied. These magnitudes are shown to increase with the critical index r=-1 [ru

Magnetic inelastic scattering: Present results and future trends

Energy Technology Data Exchange (ETDEWEB)

Osborn, R.

1996-04-01

Experience over the last 15 years has shsown that pulsed neutron spectrometers are able to contribute to the field of magnetic inelastic scattering. Such spectrometers have high resolution and wide dynamic range, both of which are necessary in order to characterize the magnetic response of the complex systems of current interest, ranging from rare earth-transition metal permanent magnets to quantum critical scatterers. Howevera, all these studies have been constrained by current flux limitations. The development of more powerful spallation neutron sources, such as the JHP, is likely to transform these interesting demonstrations of the potential of pulsed neutron scattering into routine tools for the study of magnetic correlations.

Neutron spin echo scattering angle measurement (SESAME)

International Nuclear Information System (INIS)

Pynn, R.; Fitzsimmons, M.R.; Fritzsche, H.; Gierlings, M.; Major, J.; Jason, A.

2005-01-01

We describe experiments in which the neutron spin echo technique is used to measure neutron scattering angles. We have implemented the technique, dubbed spin echo scattering angle measurement (SESAME), using thin films of Permalloy electrodeposited on silicon wafers as sources of the magnetic fields within which neutron spins precess. With 30-μm-thick films we resolve neutron scattering angles to about 0.02 deg. with neutrons of 4.66 A wavelength. This allows us to probe correlation lengths up to 200 nm in an application to small angle neutron scattering. We also demonstrate that SESAME can be used to separate specular and diffuse neutron reflection from surfaces at grazing incidence. In both of these cases, SESAME can make measurements at higher neutron intensity than is available with conventional methods because the angular resolution achieved is independent of the divergence of the neutron beam. Finally, we discuss the conditions under which SESAME might be used to probe in-plane structure in thin films and show that the method has advantages for incident neutron angles close to the critical angle because multiple scattering is automatically accounted for

Neutron scattering studies of magnetism in the high-Tc materials

International Nuclear Information System (INIS)

Sinha, S.K.

1990-01-01

In this paper, I shall attempt to review what has been learned about magnetism in the high-T c family of compounds using neutron scattering techniques. Whether or not it is true that magnetic effects are involved in an essential way in the mechanism for superconductivity in these materials (a point which has not yet been firmly established), they offer fascinating examples for the study of magnetism for its own sake, being realizations of spin 1/2 2D quantum antiferromagnets. Further, the rare earth spins in these materials also order at low temperatures reminiscent of the coexistence of antiferromagnetism and superconductivity in the earlier well-studied families of magnetic superconductors such as ErRh 4 B 4 and the Chevrel-phase compounds, with the difference that the ordering here is primarily 2D in character

Magnetic X-Ray Scattering with Synchrotron Radiation

DEFF Research Database (Denmark)

Moncton, D. E.; Gibbs, D.; Bohr, Jakob

1986-01-01

With the availability of high-brilliance synchrotron radiation from multiple wigglers, magnetic X-ray scattering has become a powerful new probe of magnetic structure and phase transitions. Similar to the well-established magnetic neutron scattering technique, magnetic X-ray scattering methods have...... many complementary advantages. A brief review is presented of the history of magnetic X-ray scattering as well as recent results obtained in studies of the rare-earth magnet holmium with emphasis on instrumentational aspects. In particular, the development of a simple polarization analyzer...... to distinguish charge and magnetic scattering is described....

Investigation of the chiral magnets NdFe3(11BO3)4 and MnSi by means of neutron scattering

International Nuclear Information System (INIS)

Janoschek, Marc

2008-01-01

We investigated two different magnetic compounds that display magnetic chirality within the framework of this thesis, namely the multiferroic compound NdFe 3 ( 11 BO 3 ) 4 and the itinerant helimagnet MnSi. We investigated the magnetic structure of NdFe 3 ( 11 BO 3 ) 4 by unpolarised and polarised neutron scattering. As a result of this investigation we identified that NdFe 3 ( 11 BO 3 ) 4 orders antiferromagnetically below T N =31 K. By combined magnetic symmetry analysis and Rietvield fits of the powder diffraction data we identified two magnetic models for the commensurate magnetic phase that fitted our data equally well. By the use of spherical neutron polarimetry we finally revealed that for the correct magnetic model the magnetic moments of both Fe 3+ and Nd 3+ are oriented parallel to the basal hexagonal plane and couple antiferromagnetically along the hexagonal c-axis. Additionally the polarised neutron data yields that in the incommensurate magnetic phase below T ICM the magnetic structure is transformed into a long-period antiferromagnetic spiral that propagates parallel to the c-direction with a pitch of approximately 1140 A. Hence, our investigation clearly showed for the first time that NdFe 3 ( 11 BO 3 ) 4 is also a chiral magnet. Furthermore, a high resolution neutron diffraction experiment showed the presence of third order harmonics of the propagation vector in the incommensurate magnetic phase and suggests the evolution of a magnetic soliton lattice below the commensurate to incommensurate phase transition without the application of external forces like magnetic fields or pressure. Further we report our work on the cubic itinerant helimagnet MnSi. We carried out extensive unpolarised and polarised elastic neutron scattering experiments in the temperature regime where the sphere of magnetic intensity is observed in order to clarify the issue of a possible intermediate phase. Our data suggests that the cubic anisotropy energy that locks the

Debye-Waller Factor in Neutron Scattering by Ferromagnetic Metals

Science.gov (United States)

Paradezhenko, G. V.; Melnikov, N. B.; Reser, B. I.

2018-04-01

We obtain an expression for the neutron scattering cross section in the case of an arbitrary interaction of the neutron with the crystal. We give a concise, simple derivation of the Debye-Waller factor as a function of the scattering vector and the temperature. For ferromagnetic metals above the Curie temperature, we estimate the Debye-Waller factor in the range of scattering vectors characteristic of polarized magnetic neutron scattering experiments. In the example of iron, we compare the results of harmonic and anharmonic approximations.

Introduction of sample environment equipment for neutron scattering experiments

International Nuclear Information System (INIS)

Shimojo, Yutaka; Ihata, Yoshiaki; Kaneko, Koji; Takeda, Masayasu

2013-02-01

Neutron scattering experiments have been frequently performed under variety of sample conditions, such as various temperatures, pressures, magnetic fields and stresses, and those complex conditions to fully utilize superior properties of neutron. To this aim, a number of sample environment equipment, refrigerators, furnaces, pressure cells, superconducting magnets are equipped in JRR-3 to be used for experiments. In this document, all available sample environment equipment in both JRR-3 reactor and guide halls are summarized. We hope this document would help neutron scattering users to perform effective and excellent experiments. (author)

Calculations of neutron spectra after neutron-neutron scattering

Energy Technology Data Exchange (ETDEWEB)

Crawford, B E [Gettysburg College, Box 405, Gettysburg, PA 17325 (United States); Stephenson, S L [Gettysburg College, Box 405, Gettysburg, PA 17325 (United States); Howell, C R [Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Mitchell, G E [North Carolina State University, Raleigh, NC 27695-8202 (United States); Tornow, W [Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Furman, W I [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Lychagin, E V [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Muzichka, A Yu [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Nekhaev, G V [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Strelkov, A V [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Sharapov, E I [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Shvetsov, V N [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation)

2004-09-01

A direct neutron-neutron scattering length, a{sub nn}, measurement with the goal of 3% accuracy (0.5 fm) is under preparation at the aperiodic pulsed reactor YAGUAR. A direct measurement of a{sub nn} will not only help resolve conflicting results of a{sub nn} by indirect means, but also in comparison to the proton-proton scattering length, a{sub pp}, shed light on the charge-symmetry of the nuclear force. We discuss in detail the analysis of the nn-scattering data in terms of a simple analytical expression. We also discuss calibration measurements using the time-of-flight spectra of neutrons scattered on He and Ar gases and the neutron activation technique. In particular, we calculate the neutron velocity and time-of-flight spectra after scattering neutrons on neutrons and after scattering neutrons on He and Ar atoms for the proposed experimental geometry, using a realistic neutron flux spectrum-Maxwellian plus epithermal tail. The shape of the neutron spectrum after scattering is appreciably different from the initial spectrum, due to collisions between thermal-thermal and thermal-epithermal neutrons. At the same time, the integral over the Maxwellian part of the realistic scattering spectrum differs by only about 6 per cent from that of a pure Maxwellian nn-scattering spectrum.

Inelastic magnetic scattering of polarized neutrons by a superconducting ring

International Nuclear Information System (INIS)

Agafonov, A. I.

2011-01-01

The inelastic scattering of cold neutrons by a ring leads to quantum jumps of a superconducting current which correspond to a decrease in the fluxoid quantum number by one or several units while the change in the ring energy is transferred to the kinetic energy of the scattered neutron. The scattering cross sections of transversely polarized neutrons have been calculated for a thin type-II superconductor ring, the thickness of which is smaller than the field penetration depth but larger than the electron mean free path.

Direct observation of electronic and nuclear ground state splitting in external magnetic field by inelastic neutron scattering on oxidized ferrocene and ferrocene containing polymers

Science.gov (United States)

Appel, Markus; Frick, Bernhard; Elbert, Johannes; Gallei, Markus; Stühn, Bernd

2015-01-01

The quantum mechanical splitting of states by interaction of a magnetic moment with an external magnetic field is well known, e.g., as Zeeman effect in optical transitions, and is also often seen in magnetic neutron scattering. We report excitations observed in inelastic neutron spectroscopy on the redox-responsive polymer poly(vinylferrocene). They are interpreted as splitting of the electronic ground state in the organometallic ferrocene units attached to the polymer chain where a magnetic moment is created by oxidation. In a second experiment using high resolution neutron backscattering spectroscopy we observe the hyperfine splitting, i.e., interaction of nuclear magnetic moments with external magnetic fields leading to sub-μeV excitations observable in incoherent neutron spin-flip scattering on hydrogen and vanadium nuclei.

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.

Neutron-scattering studies of magnetic superconductors

International Nuclear Information System (INIS)

Sinha, S.K.; Crabtree, G.W.; Hinks, D.G.; Mook, H.A.; Pringle, O.A.

1982-01-01

Results obtained in the last few years obtained by neutron diffraction on the nature of the magnetic ordering in magnetic superconductors are reviewed. Emphasis is given to studies of the complex intermediate phase in ferromagnetic superconductors where both superconductivity and ferromagnetism appear to coexist

Early history of neutron scattering at Oak Ridge

International Nuclear Information System (INIS)

Wilkinson, M.K.

1985-07-01

Most of the early development of neutron scattering techniques utilizing reactor neutrons occurred at the Oak Ridge National Laboratory during the years immediately following World War II. C.G. Shull, E.O. Wollan, and their associates systematically established neutron diffraction as a quantitative research tool and then applied this technique to important problems in nuclear physics, chemical crystallography, and magnetism. This article briefly summarizes the very important research at ORNL during this period, which laid the foundation for the establishment of neutron scattering programs throughout the world. 47 refs., 10 figs

Long-Lifetime Low-Scatter Neutron Polarization Target

International Nuclear Information System (INIS)

Richardson, Jonathan M.

2004-01-01

Polarized neutrons scattering is an important technology for characterizing magnetic and other materials. Polarized helium three (P-3He) is a novel technology for creating polarized beams and, perhaps more importantly, for the analysis of polarization in highly divergent scattered beams. Analysis of scattered beams requires specialized targets with complex geometries to ensure accurate results. Special materials and handling procedures are required to give the targets a long useful lifetime. In most cases, the targets must be shielded from stray magnetic fields from nearby equipment. SRL has developed and demonstrated hybrid targets made from glass and aluminum. We have also developed and calibrated a low-field NMR system for measuring polarization lifetimes. We have demonstrated that our low-field system is able to measure NMR signals in the presence of conducting (metallic) cell elements. We have also demonstrated a non-magnetic valve that can be used to seal the cells. We feel that these accomplishments in Phase I are sufficient to ensure a successful Phase II program. The commercial market for this technology is solid. There are over nine neutron scattering centers in the US and Canada and over 22 abroad. Currently, the US plans to build a new $1.4B scattering facility called the Spallation Neutron Source (SNS). The technology developed in this project will allow SRL to supply targets to both existing and future facilities. SRL is also involved with the application of P-3He to medical imaging

Small-Angle Neutron Scattering investigations of ferrofluids with different carrier liquids

International Nuclear Information System (INIS)

Balasoiu, M.; Avdeev, M. V.; Hasegan, D.; Ghenescu, V.; Ghenescu, M.; Bica, D.; Vekas, L.

2004-01-01

The aim of this paper is to present a method to investigate the properties of magnetic fluids by means of small angle neutron scattering (SANS). Ferrofluids are dispersions of small, single-domain magnetic particles suspended in a fluid carrier. The neutron scattering methods have been largely used the last two decades for the determination of structural properties of magnetic liquids at microscopic level. There can be investigated the structure of the particle, the aggregation phenomena, the magnetic liquid dynamics, particle-surfactant interaction, surfactant liquid-base interaction and structure and magnetic behavior of the samples. SANS is often used in structural studies of ferrofluids exploring two specific features of neutrons, the possibility of wide contrast variation using protonated/deuterated components and high magnetic scattering from ferromagnetics. This method can be effectively used for determination of the structural parameters of ferrofluids at the scale interval of 1-100 nm. In previous SANS experiments with ferrofluids of the same type it was shown that the nuclear scattering is described well by the spherical core-shell model (magnetite core plus surfactant shell) in a wide interval of momentum transfer (0.05 - 5 nm -1 ) and no significant effects of aggregation and interparticle interaction were observed in this interval for the magnetite concentration up to 5 vol. %. Experiments on small angle neutron scattering were carried out on SANS instrument YuMO in function at IBR-2 high pulsed reactor at the Frank Laboratory of Neutron Physics, Joint Institute of Nuclear Research, Dubna, Russia. (authors)

Inelastic neutron scattering for materials science and engineering

International Nuclear Information System (INIS)

Shapiro, S.M.

1995-01-01

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 γ-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

Cryogen free high magnetic field and low temperature sample environments for neutron scattering - latest developments

International Nuclear Information System (INIS)

Burgoyne, John

2016-01-01

Continuous progress has been made over many years now in the provision of low- and ultra-low temperature sample environments, together with new high-field superconducting magnets and increased convenience for both the user and the neutron research facility via new cooling technologies. Within Oxford Instrument's experience, this has been achieved in many cases through close collaboration with neutron scientists, and with the neutron facilities' sample environment leaders in particular. Superconducting magnet designs ranging from compact Small Angle (SANS) systems up to custom-engineered wide-angle scattering systems have been continuously developed. Recondensing, or 'zero boil-off' (ZBO), systems are well established for situations in which a high field magnet is not conducive to totally cryogen free cooling solutions, and offer a reliable route with the best trade-offs of maximum system capability versus running costs and user convenience. Fully cryogen free solutions for cryostats, dilution refrigerators, and medium-field magnets are readily available. Here we will present the latest technology developments in these options, describing the state-of-the art, the relative advantages of each, and the opportunities they offer to the neutron science community. (author)

Neutron Scattering Software

Science.gov (United States)

Home Page | Facilities | Reference | Software | Conferences | Announcements | Mailing Lists Neutron Scattering Banner Neutron Scattering Software A new portal for neutron scattering has just been established sets KUPLOT: data plotting and fitting software ILL/TAS: Matlab probrams for analyzing triple axis data

Strongly correlated electron systems and neutron scattering. Magnetism, superconductivity, structural phase transition

Energy Technology Data Exchange (ETDEWEB)

Katano, Susumu [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1998-03-01

Neutron scattering experiments in our group on strongly correlated electron systems are reviewed Metal-insulator transitions caused by structural phase transitions in (La{sub 1-x}Sr{sub x}) MnO{sub 3}, a novel magnetic transition in the CeP compound, correlations between antiferromagnetism and superconductivity in UPd{sub 2}Al{sub 3} and so forth are discussed. Here, in this note, the phase transition of Mn-oxides was mainly described. (author)

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.

Magnetic Order and Crystal Field Excitations in Er2Ru2O7: A Neutron Scattering Study

International Nuclear Information System (INIS)

Ehlers, Georg; Gardner, Jason

2009-01-01

The magnetic pyrochlore Er 2 Ru 2 O 7 has been studied with neutron scattering and susceptibility measurements down to a base temperature of 270 mK. For the low temperature phase in which the Er sublattice orders, new magnetic Bragg peaks are reported which can be indexed with integer (hkl) for a face centered cubic cell. Inelastic measurements reveal a wealth of crystal field levels of the Er ion and a copious amount of magnetic scattering below 15 meV. The three lowest groups of crystal field levels are at 6.7, 9.1 and 18.5 meV.

Neutron scattering at the high-flux isotope reactor

International Nuclear Information System (INIS)

Cable, J.W. Chakoumakos, B.C.; Dai, P.

1995-01-01

The title facilities offer the brightest source of neutrons in the national user program. Neutron scattering experiments probe the structure and dynamics of materials in unique and complementary ways as compared to x-ray scattering methods and provide fundamental data on materials of interest to solid state physicists, chemists, biologists, polymer scientists, colloid scientists, mineralogists, and metallurgists. Instrumentation at the High- Flux Isotope Reactor includes triple-axis spectrometers for inelastic scattering experiments, a single-crystal four diffractometer for crystal structural studies, a high-resolution powder diffractometer for nuclear and magnetic structure studies, a wide-angle diffractometer for dynamic powder studies and measurements of diffuse scattering in crystals, a small-angle neutron scattering (SANS) instrument used primarily to study structure-function relationships in polymers and biological macromolecules, a neutron reflectometer for studies of surface and thin-film structures, and residual stress instrumentation for determining macro- and micro-stresses in structural metals and ceramics. Research highlights of these areas will illustrate the current state of neutron science to study the physical properties of materials

Inelastic neutron scattering from cerium under pressure

International Nuclear Information System (INIS)

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

1976-01-01

Inelastic neutron scattering from Ce metal at 300K 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 paramagnetic scattering in the γ-phase increases with pressure. (Auth.)

Elastic and inelastic neutron scattering studies on 3d and 4f magnetic compounds

International Nuclear Information System (INIS)

Erkelens, W.A.C.

1987-01-01

First, some theoretical aspects of neutron scattering techniques are given, and the cyrogenic equipment and the neutron spectrometers employed are described. Experiments on a 3-d Ising system are described, performed at very low temperatures and in a magnetic field. Experimental proof has been obtained for the theoretical prediction that the critical behaviour of a d-dimensional Ising system in a transverse magnetic field near T=0 is identical to that of a d+1 dimensional Ising system as a function of temperature in zero field. Experiments are described on a Ni 2+ compound which represents a good example of a 1-d antiferromagnetic Heisenberg (HAF), spin s=1, system. The results give evidence for the so called 'Haldane conjecture', a theory which predicts that the ground state of HAF systems with integer spin is a nonmagnetic many-body singlet. The excited states are separated from the ground state by an energy gap. Contrastingly, half-integer spin systems are predicted to have no such gap. A short introduction is given to phenomena in rare earth, 4f compunds, like the Kondo effect and heavy fermion behaviour. Experimental results on the RE hexaborides are reported, among which CeB 6 , a typical Kondo system with complex magnetic orderings. Furthermore, inelastic neutron scattering experiments on NdB 6 and CeB 6 , performed in order to get insight in the various reaction mechanisms, are presented. Finally a report is given on magnetic correlations and excitations in two nonmagnetically ordered heavy fermion compounds, CeCu 6 and CeRu 2 Si 2 and their interpretation in the light of existing theories. 201 refs.; 61 figs.; 4 tabs

Magnetization reversal of a Nd-Cu-infiltrated Nd-Fe-B nanocrystalline magnet observed with small-angle neutron scattering

Energy Technology Data Exchange (ETDEWEB)

Saito, Kotaro, E-mail: kotaro.saito@kek.jp; Ono, Kanta [Institute of Materials Structure Science, High Energy Accelerator Research Organization, 1-1 Oho, 305-0803 Tsukuba (Japan); Ueno, Tetsuro [Elements Strategy Initiative Center for Magnetic Materials, National Institute for Materials Science, 1-2-1 Sengen, 305-0047 Tsukuba (Japan); Yano, Masao; Shoji, Tetsuya; Sakuma, Noritsugu; Manabe, Akira; Kato, Akira [Toyota Motor Corporation, Toyota, Aichi 471-8571 (Japan); Harada, Masashi [Toyota Central R and D Labs, Inc., Aichi 480-1192 (Japan); Keiderling, Uwe [Helmholtz-Zentrum Berlin für Materialien and Energie, 14109 Berlin (Germany)

2015-05-07

The magnetization reversal process of Nd-Fe-B nanocrystalline magnets infiltrated with Nd-Cu alloy was examined using small-angle neutron scattering (SANS). The magnetic-field dependence of SANS intensity revealed a qualitative difference between Nd-Cu-infiltrated samples and as-deformed samples. Insufficient magnetic isolation along the direction perpendicular to the nominal c-axis is expected from comparable SANS intensities for different ranges of q values along this direction. For small q values near the coercivity field, Nd-Cu-infiltrated samples show a noticeable reduction in SANS intensity along the nominal c-axis, which is parallel to the external magnetic field. This indicates less spatial fluctuation of magnetic moments in Nd-Cu-infiltrated samples, owing to magnetically isolated Nd{sub 2}Fe{sub 14}B grains.

Magnetization reversal of a Nd-Cu-infiltrated Nd-Fe-B nanocrystalline magnet observed with small-angle neutron scattering

International Nuclear Information System (INIS)

Saito, Kotaro; Ono, Kanta; Ueno, Tetsuro; Yano, Masao; Shoji, Tetsuya; Sakuma, Noritsugu; Manabe, Akira; Kato, Akira; Harada, Masashi; Keiderling, Uwe

2015-01-01

The magnetization reversal process of Nd-Fe-B nanocrystalline magnets infiltrated with Nd-Cu alloy was examined using small-angle neutron scattering (SANS). The magnetic-field dependence of SANS intensity revealed a qualitative difference between Nd-Cu-infiltrated samples and as-deformed samples. Insufficient magnetic isolation along the direction perpendicular to the nominal c-axis is expected from comparable SANS intensities for different ranges of q values along this direction. For small q values near the coercivity field, Nd-Cu-infiltrated samples show a noticeable reduction in SANS intensity along the nominal c-axis, which is parallel to the external magnetic field. This indicates less spatial fluctuation of magnetic moments in Nd-Cu-infiltrated samples, owing to magnetically isolated Nd 2 Fe 14 B grains

Spin excitations in 3D molecular magnets probed by neutron scattering

CERN Document Server

Bordallo, H N; Chapon, L C; Manson, J L; Cook, J C; Lee, S H; Copley, J R D; Yildirim, T; Kern, S

2002-01-01

The emerging field of molecular magnetism constitutes a new branch of materials science that deals with the magnetic properties of molecules, or assemblies of molecules, that contain magnetic centers. The growing interest in understanding the origin of the magnetic ordering in these materials is to obtain novel multiproperty molecular magnetic materials with high transition temperatures. Molecules based on the dicyanamide ion [N ident to C-N-C ident to N], abbreviated (dca), such as M(dca) sub 2 [M=Mn, Ni], have shown interesting bulk properties that prompted our inelastic neutron scattering (INS) studies. While the Mn sup 2 sup + ion is isotropic because of its L=0 configuration, the isostructural Ni analog has S=1 and demonstrates marked single-ion anisotropy. Mn(dca) sub 2 is a canted antiferromagnet below 16 K, while Ni(dca) sub 2 is a ferromagnet below 21 K. INS has been used to investigate the magnetic excitations in Mn(dca) sub 2 and Ni(dca) sub 2. For Mn(dca) sub 2 , a Heisenberg model gives good corr...

Inelastic neutron scattering from clusters

International Nuclear Information System (INIS)

Gudel, H.U.

1985-01-01

Magnetic excitations in clusters of paramagnetic ions have non-vanishing cross-sections for inelastic neutron scattering (INS). Exchange splittings can be determined, the temperature dependence of exchange can be studied, intra- and intercluster effects can be separated and magnetic form factors determined. INS provides a more direct access to the molecular properties than bulk techniques. Its application is restricted to complexes with no or few (< 10%) hydrogen atoms

Basis for calculating cross sections for nuclear magnetic resonance spin-modulated polarized neutron scattering.

Science.gov (United States)

Kotlarchyk, Michael; Thurston, George M

2016-12-28

In this work we study the potential for utilizing the scattering of polarized neutrons from nuclei whose spin has been modulated using nuclear magnetic resonance (NMR). From first principles, we present an in-depth development of the differential scattering cross sections that would arise in such measurements from a hypothetical target system containing nuclei with non-zero spins. In particular, we investigate the modulation of the polarized scattering cross sections following the application of radio frequency pulses that impart initial transverse rotations to selected sets of spin-1/2 nuclei. The long-term aim is to provide a foundational treatment of the scattering cross section associated with enhancing scattering signals from selected nuclei using NMR techniques, thus employing minimal chemical or isotopic alterations, so as to advance the knowledge of macromolecular or liquid structure.

X-ray magnetic circular dichroism and small angle neutron scattering studies of thiol capped gold nanoparticles

International Nuclear Information System (INIS)

de la Venta, J.; Bouzas, V.; Pucci, A.; Laguna-Marco, M.A.; Haskel, D.; te Velthuis, S.G.E; Hoffmann, A.; Lal, J.; Bleuel, M.; Ruggeri, G.; de Julian Fernandez, C.; Garcia, M.A.

2009-01-01

X-ray magnetic circular dichroism (XMCD) and Small Angle Neutron Scattering (SANS) measurements were performed on thiol capped Au nanoparticles (NPs) embedded into polyethylene. An XMCD signal of 0.8 · 10 -4 was found at the Au L 3 edge of thiol capped Au NPs embedded in a polyethylene matrix for which Superconducting Quantum Interference Device (SQUID) magnetometry yielded a saturation magnetization, M s , of 0.06 emu/g Au . SANS measurements showed that the 3.2 nm average-diameter nanoparticles are 28% polydispersed, but no detectable SANS magnetic signal was found with the resolution and sensitivity accessible with the neutron experiment. A comparison with previous experiments carried out on Au NPs and multilayers, yield to different values between XMCD signals and magnetization measured by SQUID magnetometer. We discuss the origin of those differences

Neutron scattering studies of Mn12-acetate

International Nuclear Information System (INIS)

Robinson, R.A.

2000-01-01

Full text: The S=10 magnetic molecule Mn 12 -acetate, which crystallises into a tetragonal crystal structure, has attracted substantial recent attention by virtue of its low temperature bulk magnetic properties, which give evidence for resonant quantum tunnelling of the magnetisation. We report a full neutron crystal structure including positions of all protons/deuterons, including the solvated water and acetic acid, a polarised-neutron study of the real space magnetisation, which confirms a simple magnetic-structure model for the molecule, albeit with reduced Mn moments, and inelastic neutron scattering data containing both the excitations within the 21-fold degenerate S=10 manifold, and those from S=10 to the S=9 manifolds. Both manifolds are split by uniaxial magnetic anisotropy, and we report coefficients for 2nd and 4th-order terms in the magnetic Hamiltonian

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

Scattering and depolarization of polarized neutrons in ferrofluids

International Nuclear Information System (INIS)

Balasoiu, M.; Dokukin, E.B.; Kozhevnikov, S.V.; Nikitenko, Y.V.

1999-01-01

On the SPN - 1 polarized neutron spectrometer at IBR -2 high - flux pulsed rector there were carried out preliminary measurements on transmission and polarization of a neutron beam passing through a magnetic colloidal system of Fe 3 O 4 particles in transformer oil and dodecane carriers. It was found that in the ferrofluids with magnetite particles exist, dependent on the particle volume concentration and the magnitude of the external magnetic field, effects of depolarization and nuclear - magnetic small angle scattering. (author)

Neutron scattering studies on the high Tc superconductor YBa2Cu306+x

International Nuclear Information System (INIS)

Jurgens, M.J.G.M.

1990-01-01

The aim of the work described in this thesis is to clarify some of the magnetic aspects of high T c superconductors across the phase diagram as a function of doping and temperature, for which YBa 2 Cu 3 o 6+x has been chosen. Mainly the neutron scattering technique has been employed, which supplies a very powerful tool for this kind of research, for it directly shows the microscopic phenomena of the magnetism involved. First an introduction to the neutron scattering technique is given and a description of the spectrometers employed (ch. 2). The determination of the crystal structure of YBa 2 Cu 3 o 6+x is described, and the single crystals which were used during all the experiments on the magnetic properties as described in this thesis, are characterized (ch. 3). Ch. 4 deals with the phase diagram of the insulating antiferromagnetic phase in YBa 2 Cu 3 o 6+x , as obtained with neutron scattering. The inelastic scattering experiments on the magnetic excitations in this system are presented in ch. 5. In ch. 6 the total susceptibility, measure with a AQUID, is discussed. The local magnetizations, as determined with a polarized neutron scattering technique are the subject of ch. 7. (author). 254 refs.; 77 figs.; 25 tabs

Nonlocal fluctuational electromagnetic response and neutron magnetic scattering near the superconducting transition temperature

International Nuclear Information System (INIS)

Barash, Yu.S.; Galaktionov, A.V.

1992-01-01

A general expression is found for superconducting fluctuation contribution to transverse permittivity c tr f (Ω, Q) of a standard massive isotopic metal near T c at Ω c and Qζ 0 0 is the coherence length at zero temperature, Q is the external electromagnetic field pulse), depending on frequency and wave vector. Differential cross section of magnetic scattering of neutrons near T c in the region of comparatively small angles is considered

X-ray magnetic circular dichroism and small angle neutron scattering studies of thiol capped gold nanoparticles.

Energy Technology Data Exchange (ETDEWEB)

de la Venta, J.; Bouzas, V.; Pucci, A.; Laguna-Marco, M. A.; Haskel, D.; te Velthuis, S. G. E; Hoffmann, A.; Lal, J.; Bleuel, M.; Ruggeri, G.; de Julian Fernandez, C.; Garcia, M. A.; Univ.Complutense de Madrid; Inst. de Magnetismo Aplicado; Univ. of Pisa; Lab. di Magnetismo Molecolare

2009-01-01

X-ray magnetic circular dichroism (XMCD) and Small Angle Neutron Scattering (SANS) measurements were performed on thiol capped Au nanoparticles (NPs) embedded into polyethylene. An XMCD signal of 0.8 {center_dot} 10{sup -4} was found at the Au L{sub 3} edge of thiol capped Au NPs embedded in a polyethylene matrix for which Superconducting Quantum Interference Device (SQUID) magnetometry yielded a saturation magnetization, M{sub s}, of 0.06 emu/g{sub Au}. SANS measurements showed that the 3.2 nm average-diameter nanoparticles are 28% polydispersed, but no detectable SANS magnetic signal was found with the resolution and sensitivity accessible with the neutron experiment. A comparison with previous experiments carried out on Au NPs and multilayers, yield to different values between XMCD signals and magnetization measured by SQUID magnetometer. We discuss the origin of those differences.

X-ray magnetic circular dichroism and small angle neutron scattering study of thiol capped gold nanoparticles.

Energy Technology Data Exchange (ETDEWEB)

de la Venta, J.; Bouzas, V.; Pucci, A.; Laguna-Marco, M. A.; Haskel, D.; Pinel, E. F.; te Velthuis, S. G. E.; Hoffmann, A.; Lal, J.; Bleuel, M.; Ruggeri, G.; de Julian, C.; Garcia, M. A.; Univ. Complutense de Madrid; Inst. de Magnetismo Aplicado UCM; Univ. Pisa; Univ. di Padova

2009-11-01

X-ray magnetic circular dichroism (XMCD) and Small Angle Neutron Scattering (SANS) measurements were performed on thiol capped Au nanoparticles (NPs) embedded into polyethylene. An XMCD signal of 0.8 {center_dot} 10{sup -4} was found at the Au L{sub 3} edge of thiol capped Au NPs embedded in a polyethylene matrix for which Superconducting Quantum Interference Device (SQUID) magnetometry yielded a saturation magnetization, M{sub s}, of 0.06 emu/g{sub Au}. SANS measurements showed that the 3.2 nm average-diameter nanoparticles are 28% polydispersed, but no detectable SANS magnetic signal was found with the resolution and sensitivity accessible with the neutron experiment. A comparison with previous experiments carried out on Au NPs and multilayers, yield to different values between XMCD signals and magnetization measured by SQUID magnetometer. We discuss the origin of those differences.

Summary of neutron scattering lengths

International Nuclear Information System (INIS)

Koester, L.

1981-12-01

All available neutron-nuclei scattering lengths are collected together with their error bars in a uniform way. Bound scattering lengths are given for the elements, the isotopes, and the various spin-states. They are discussed in the sense of their use as basic parameters for many investigations in the field of nuclear and solid state physics. The data bank is available on magnetic tape, too. Recommended values and a map of these data serve for an uncomplicated use of these quantities. (orig.)

The magnetic order of GdMn{sub 2}Ge{sub 2} studied by neutron diffraction and x-ray resonant magnetic scattering

Energy Technology Data Exchange (ETDEWEB)

Granovsky, S A [M V Lomonosov Moscow State University, 119991 GSP-1 Moscow (Russian Federation); Kreyssig, A; Canfield, P C [Ames Laboratory USDOE, Iowa State University, Ames, IA 50011 (United States); Doerr, M; Loewenhaupt, M [TU Dresden, Institut fuer Festkoerperphysik, D-01062, Dresden (Germany); Ritter, C [Institut Laue-Langevin, F-38042 Grenoble Cedex 9 (France); Dudzik, E; Feyerherm, R, E-mail: ser@plms.r [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, BESSY, D-12489, Berlin (Germany)

2010-06-09

The magnetic structure of GdMn{sub 2}Ge{sub 2} (tetragonal I4/mmm) has been studied by hot neutron powder diffraction and x-ray resonant magnetic scattering techniques. These measurements, along with the results of bulk experiments, confirm the collinear ferrimagnetic structure with moment direction parallel to the c-axis below T{sub C} = 96 K and the collinear antiferromagnetic phase in the temperature region T{sub C} < T < T{sub N} = 365 K. In the antiferromagnetic phase, x-ray resonant magnetic scattering has been detected at Mn K and Gd L{sub 2} absorption edges. The Gd contribution is a result of an induced Gd 5d electron polarization caused by the antiferromagnetic order of Mn-moments.

Development of neutron diffuse scattering analysis code by thin film and multilayer film

International Nuclear Information System (INIS)

Soyama, Kazuhiko

2004-01-01

To research surface structure of thin film and multilayer film by neutron, a neutron diffuse scattering analysis code using DWBA (Distorted-Wave Bron Approximation) principle was developed. Subjects using this code contain the surface and interface properties of solid/solid, solid/liquid, liquid/liquid and gas/liquid, and metal, magnetism and polymer thin film and biomembran. The roughness of surface and interface of substance shows fractal self-similarity and its analytical model is based on DWBA theory by Sinha. The surface and interface properties by diffuse scattering are investigated on the basis of the theoretical model. The calculation values are proved to be agreed with the experimental values. On neutron diffuse scattering by thin film, roughness of surface of thin film, correlation function, neutron propagation by thin film, diffuse scattering by DWBA theory, measurement model, SDIFFF (neutron diffuse scattering analysis program by thin film) and simulation results are explained. On neutron diffuse scattering by multilayer film, roughness of multilayer film, principle of diffuse scattering, measurement method and simulation examples by MDIFF (neutron diffuse scattering analysis program by multilayer film) are explained. (S.Y.)To research surface structure of thin film and multilayer film by neutron, a neutron diffuse scattering analysis code using DWBA (Distorted-Wave Bron Approximation) principle was developed. Subjects using this code contain the surface and interface properties of solid/solid, solid/liquid, liquid/liquid and gas/liquid, and metal, magnetism and polymer thin film and biomembran. The roughness of surface and interface of substance shows fractal self-similarity and its analytical model is based on DWBA theory by Sinha. The surface and interface properties by diffuse scattering are investigated on the basis of the theoretical model. The calculation values are proved to be agreed with the experimental values. On neutron diffuse scattering

Latest developments of neutron scattering instrumentation at the Juelich Centre for Neutron Science

International Nuclear Information System (INIS)

Ioffe, Alexander

2013-01-01

Jülich Centre for Neutron Science (JCNS) is operating a number of world-class neutron scattering instruments situated at the most powerful and advanced neutron sources (FRM II, ILL and SNS) and is continuously undertaking significant efforts in the development and upgrades to keep this instrumentation in line with the continuously changing scientific request. These developments are mostly based upon the latest progress in neutron optics and polarized neutron techniques. For example, the low-Q limit of the suite of small angle-scattering instruments has been extended to 4·10 -5 Å -1 by the successful use of focusing optics. A new generation of correction elements for the neutron spin-echo spectrometer has allowed for the use of the full field integral available, thus pushing further the instrument resolution. A significant progress has been achieved in the developments of 3 He neutron spin filters for purposes of the wide-angle polarization analysis for off-specular reflectometry and (grazing incidence) small-angle neutron scattering, e.g. the on-beam polarization of 3 He in large cells is allowing to achieve a high neutron beam polarization without any degradation in time. The wide Q-range polarization analysis using 3 He neutron spin filters has been implemented for small-angle neutron scattering that lead to the reduction up to 100 times of the intrinsic incoherent background from non-deuterated biological molecules. Also the work on wide-angle XYZ magnetic cavities (Magic PASTIS) will be presented. (author)

Diffuse scattering of neutrons

International Nuclear Information System (INIS)

Novion, C.H. de.

1981-02-01

The use of neutron scattering to study atomic disorder in metals and alloys is described. The diffuse elastic scattering of neutrons by a perfect crystal lattice leads to a diffraction spectrum with only Bragg spreads. the existence of disorder in the crystal results in intensity and position modifications to these spreads, and above all, to the appearance of a low intensity scatter between Bragg peaks. The elastic scattering of neutrons is treated in this text, i.e. by measuring the number of scattered neutrons having the same energy as the incident neutrons. Such measurements yield information on the static disorder in the crystal and time average fluctuations in composition and atomic displacements [fr

Neutron scattering in applied research: possibilities for medium-flux research reactors

International Nuclear Information System (INIS)

Reijonen, H.

1977-01-01

The possibilities for neutron scattering techniques in applied research are reviewed. The areas covered are magnetism, determination of hydrogen self-diffusion constants and ionic mobility in superionic conductors, liquid crystals, molecular solids, polymers, surface chemistry and catalysts, colloids biology, physical metallurgy and neutron diagnostics. Established applications and new proposals for research projects are presented in various degrees of detail. Small angle scattering techniques, physical metallurgy and biology were identified as having particular potential. Prospective users should be realistically informed of the possibilities of neutron scattering techniques. (author)

Anomalous neutron scattering in nuclear-polarized media

International Nuclear Information System (INIS)

Bashkin, E.P.

1989-01-01

A novel inelastic scattering exchange mechanism involving spin flip is considered for slow neutrons moving through a nuclear-polarized medium. The scattering is accompanied by the emission or absorption of thermal fluctuations of the transverse magnetization of the medium. The main role in the fluctuations is played by weakly decaying Larmor precession of the nuclear spins in an external magnetic field. Under 'giant opalescence' conditions the effect is enormous and the respective cross sections exceed significantly those for ordinary elastic scattering. Thus, for 29 Si and 3 He in typical experimental conditions the cross sections for the inelastic processes are of the order of 10 5 -10 6 barn

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...

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...... moment at the antiferromagnetic Bragg reflection. We have studied different weightings of the particle size distribution. The data and their temperature dependence can with good agreement be interpreted on the basis of the Neel-Brown theory for superparamagnetic relaxation and a model for the collective...

Structural and magnetic properties of transition metal substituted BaFe₂As₂ compounds studied by x-ray and neutron scattering

Energy Technology Data Exchange (ETDEWEB)

Kim, Min Gyu [Iowa State Univ., Ames, IA (United States)

2012-01-01

The purpose of my dissertation is to understand the structural and magnetic properties of the newly discovered FeAs-based superconductors and the interconnection between superconductivity, antiferromagnetism, and structure. X-ray and neutron scattering techniques are powerful tools to directly observe the structure and magnetism in this system. I used both x-ray and neutron scattering techniques on different transition substituted BaFe₂As₂ compounds in order to investigate the substitution dependence of structural and magnetic transitions and try to understand the connections between them.

Investigation of coercivity mechanism in hot deformed Nd-Fe-B permanent magnets by small-angle neutron scattering

International Nuclear Information System (INIS)

Yano, M.; Manabe, A.; Shoji, T.; Kato, A.; Ono, K.; Harada, M.; Kohlbrecher, J.

2014-01-01

The magnetic reversal behaviors of single domain sized Nd-Fe-B permanent magnets, with and without isolation between the Nd 2 Fe 14 B grains, was clarified using small-angle neutron scattering (SANS). The SANS patterns obtained arose from changes in the magnetic domains and were analyzed using the Teubner–Stray model, a phenomenological correlation length model, to quantify the periodicity and morphology of the magnetic domains. The results indicated that the magnetic reversal evolved with the magnetic domains that had similar sized grains. The grain isolation enabled us to realize the reversals of single domains

Investigation of the chiral magnets NdFe{sub 3}({sup 11}BO{sub 3}){sub 4} and MnSi by means of neutron scattering

Energy Technology Data Exchange (ETDEWEB)

Janoschek, Marc

2008-09-05

We investigated two different magnetic compounds that display magnetic chirality within the framework of this thesis, namely the multiferroic compound NdFe{sub 3}({sup 11}BO{sub 3}){sub 4} and the itinerant helimagnet MnSi. We investigated the magnetic structure of NdFe{sub 3}({sup 11}BO{sub 3}){sub 4} by unpolarised and polarised neutron scattering. As a result of this investigation we identified that NdFe{sub 3}({sup 11}BO{sub 3}){sub 4} orders antiferromagnetically below T{sub N}=31 K. By combined magnetic symmetry analysis and Rietvield fits of the powder diffraction data we identified two magnetic models for the commensurate magnetic phase that fitted our data equally well. By the use of spherical neutron polarimetry we finally revealed that for the correct magnetic model the magnetic moments of both Fe{sup 3+} and Nd{sup 3+} are oriented parallel to the basal hexagonal plane and couple antiferromagnetically along the hexagonal c-axis. Additionally the polarised neutron data yields that in the incommensurate magnetic phase below T{sub ICM} the magnetic structure is transformed into a long-period antiferromagnetic spiral that propagates parallel to the c-direction with a pitch of approximately 1140 A. Hence, our investigation clearly showed for the first time that NdFe{sub 3}({sup 11}BO{sub 3}){sub 4} is also a chiral magnet. Furthermore, a high resolution neutron diffraction experiment showed the presence of third order harmonics of the propagation vector in the incommensurate magnetic phase and suggests the evolution of a magnetic soliton lattice below the commensurate to incommensurate phase transition without the application of external forces like magnetic fields or pressure. Further we report our work on the cubic itinerant helimagnet MnSi. We carried out extensive unpolarised and polarised elastic neutron scattering experiments in the temperature regime where the sphere of magnetic intensity is observed in order to clarify the issue of a possible

The small-angle neutron scattering facility at the SAFARI-1 reactor

International Nuclear Information System (INIS)

Hofmeyr, C.; Mayer, R.M.; Tillwick, D.L.

1979-01-01

A long-wavelength neutron scattering facility at the SAFARI-1 reactor is described. Neutrons of wavelength between 5 and 15 A can be selected. Features of the facility are the use of microwave guides as neutron conductors, flexible guide-pipe configuration and automatic sequential sample changing. Examples are given of measurements on radiation-induced voids in copper, aluminium, Al-0.4%Si and Al-0.1%In after neutron irradiation and magnetic scattering in US and in 80US-10UC-10UC 2 . (Auth.)

Interesting results from neutron-scattering

International Nuclear Information System (INIS)

Woods, A.D.B.

Neutron scattering has been a useful tool in the determination of the lattice dynamics of metals, studies of the physics of magnetism in rare-earth systems, observing changes in the structure of DNA bases after ultraviolet irradiation, looking at plastic crystals, following structural phase changes in ferroelectric materials, and studying liquid He. Both low- and high-flux facilities are useful. (LL)

Magnetic phase diagram of MnSi near critical temperature studied by neutron small angle scattering

International Nuclear Information System (INIS)

Ishikawa, Yoshikazu; Arai, Masatoshi

1984-01-01

The magnetic phase diagram of MnSi near the critical temperature T sub(N)=29.5K has been studied by neutron small angle scattering at KENS. It has been found that the anomalous new phase predicted by various methods to exist around at 28 K and 2 kOe is the paramagnetic phase where the magnetic correlations exhibit the same characteristics as those found at 29.5 K and zero magnetic field. This phenomenon, together with the sharp decrease of the magnetic phase boundary at T sub(N) and the substantial increase of the satellite Q vector at this temperature, has been found not to be interpreted by the current theories. (author)

Neutron scattering studies of mixed-valence semiconductors

Energy Technology Data Exchange (ETDEWEB)

Mignot, J M [Laboratoire Leon Brillouin (LLB) - Centre d` Etudes de Saclay, 91 - Gif-sur-Yvette (France); Alekseev, P A [Kurchatov Institute, Moscow (Russian Federation)

1994-12-31

Neutron scattering experiments on the mixed-valence (MV) compounds SmB{sub 6} are reported. The inelastic magnetic response of SmB{sub 6} at T = 2 K, measured on a double-isotope single crystal,displays a strongly damped peak at 35 meV corresponding to the inter multiplet transition of Sm{sup 2+}. At lower energies ( h.{omega} {approx_equal} 14 meV), a narrow magnetic excitation is observed, with remarkable scattering-vector and temperature dependences of its intensity. This novel feature is discussed in terms of recent theoretical works describing the formation of an anisotropic local bound state in semiconducting MV materials. If the average samarium valence is decreased by substituting La for Sm, a peak is found to appear at high energies. The elastic magnetic form factor of SmB{sub 6} was determined using polarised neutrons and no significant difference is observed in its Q-dependence with respect to that of pure divalent samarium. This surprising behaviour is constant with previous measurements on the gold (high-pressure) phase of SmS. The above results are compared to those already reported for other MV materials. In particular existing information for TmSe is supplemented by recent inelastic scattering measurements carried out on a large stoichiometric single crystal. (author). 44 refs., 7 figs.

A new instrumental set-up for polarized neutron scattering experiments

International Nuclear Information System (INIS)

Schmidt, Wolfgang; Ohl, Michael

2005-01-01

Neutron scattering with polarization analysis is a powerful tool to determine magnetic structures and excitations. A common setup is to mount the sample at the center of a Helmholtz-type coil which can provide a magnetic field of any direction at the sample position and also a guide field along the neutron flight paths around the sample. Recent experiments showed quite a high demand for measurements at low momentum transfers. For the corresponding low scattering angles air scattering gives rise to a very large background. For this reason we have extended the standard setup to a combination of a large vacuum tank surrounded by electrical coils. The vacuum tank eliminates the air scattering and we can use the polarization analysis down to the lowest accessible momentum transfers. The coils themselves also show some new features: In contrary to the classic (symmetric) coil distribution we use an asymmetric setup which gives the advantage of a larger scattering window. Due to a more sophisticated current distribution this modified coil arrangement needs not to be rotated for different scattering conditions. The whole set-up will soon be available at IN12, a cold neutrons three-axis spectrometer operated by FZ Juelich in collaboration with CEA Grenoble as a CRG-B instrument at the Institut Laue Langevin in Grenoble

Fingerprints of orbital physics in magnetic resonant inelastic X-ray scattering

Science.gov (United States)

Marra, Pasquale

2012-09-01

Orbital degrees of freedom play a major role in the physics of many strongly correlated transition metal compounds. However, they are still very difficult to access experimentally, in particular by neutron scattering. We propose here how to reveal orbital occupancies of the system ground state by magnetic resonant inelastic x-ray scattering (RIXS). This is possible because, unlike in neutron scattering, the intensity of the magnetic excitations in RIXS depends essentially on the symmetry of the orbitals where the spins are in.

Spin dynamics above the Curie temperature studied by neutron scattering

International Nuclear Information System (INIS)

Steinsvoll, O.; Riste, T.

1986-01-01

Neutron scattering can in principle give information about magnetic fluctuations over the entire atomic space and time domain. The weakness of the neutron-matter interaction renders this information undistorted by the neutron probe, but at the same time puts intensity limitations on the method. A considerable number of studies on the magnetism of 3d metals have been performed at some of the larger reactor laboratories. In the regions of overlap the experimental results from the different laboratories are consistent, but the interpretations are along different lines. Among the controversial issues are itinerancy versus localization, the degree of order above T C . In our talk we shall give an introduction to the neutron scattering method, including some of the sophisticated polarized beam methods. In the rest of the talk we shall review recent experimental results and some of the theoretical models used in their interpretation. (orig.)

Inelastic scattering and neutron polarimetry. Application to a few low-dimensioned magnetic systems

International Nuclear Information System (INIS)

Boullier, C.

2005-10-01

This work introduces the spherical polarization analysis used in the case of the inelastic scattering of polarized neutrons. With this kind of analysis, we are able to access some non-trivial dynamical correlation functions. Those correlation functions are related to nuclear and magnetic degrees of freedom. To study these correlations in the case of inelastic scattering, we used an optimized version of the experimental set-up called CRYOPAD (Cryogenic Polarisation Analysis Device) for which we will introduce a new calibration process. To illustrate the importance of such analysis, we will use it on two low-dimensional systems: the first one is BaCo 2 (AsO 4 ) 2 with a planar spin system and the second one is Sr 14 Cu 24 O 41 showing both chain and ladder spin systems. The spherical polarization analysis of both elastic and inelastic signal on the compound BaCo 2 (AsO 4 ) 2 has allowed us to determine its low temperature magnetic structure and the nature of its magnetic excitations. With the compound Sr 14 Cu 24 O 41 we demonstrated the evidence of a big anisotropy between the out-of-plane and the in-plane magnetic dynamical correlation functions for both the chain and ladder subsystems. Finally, studying the inelastic signal of the chains under a magnetic field, we tried to better understand the 'dynamical chirality' associated with clockwise and anti-clockwise precessions of a magnetic triplet. (author)

Observation of spin-wave dispersion in Nd-Fe-B magnets using neutron Brillouin scattering

International Nuclear Information System (INIS)

Ono, K.; Inami, N.; Saito, K.; Takeichi, Y.; Kawana, D.; Yokoo, T.; Itoh, S.; Yano, M.; Shoji, T.; Manabe, A.; Kato, A.; Kaneko, Y.

2014-01-01

The low-energy spin-wave dispersion in polycrystalline Nd-Fe-B magnets was observed using neutron Brillouin scattering (NBS). Low-energy spin-wave excitations for the lowest acoustic spin-wave mode were clearly observed. From the spin-wave dispersion, we were able to determine the spin-wave stiffness constant D sw (100.0 ± 4.9 meV.Å 2 ) and the exchange stiffness constant A (6.6 ± 0.3 pJ/m)

Neutron scattering (progress report) January - December 1991

International Nuclear Information System (INIS)

Buehrer, W.; Fischer, P.; Furrer, A.

1992-02-01

Progress made by the Laboratory for Neutron Scattering of the Swiss Federal Institute of Technology during the year 1991 in the fields of high-T c superconductors, materials science, magnetism, structural research, lattice dynamics, phase transitions, instrumental and support activities is reported. figs., tabs., refs

Progress towards magnetic trapping of ultra-cold neutrons

CERN Document Server

Huffman, P R; Butterworth, J S; Coakley, K J; Dewey, M S; Dzhosyuk, S N; Gilliam, D M; Golub, R; Greene, G L; Habicht, K; Lamoreaux, S K; Mattoni, C E H; McKinsey, D N; Wietfeldt, F E; Doyle, J M

2000-01-01

We report progress towards magnetic trapping of ultra-cold neutrons (UCN) in preparation for a neutron lifetime measurement. UCN will be produced by inelastic scattering of cold (0.89 nm) neutrons in a reservoir of superfluid sup 4 He and confined in a three-dimensional magnetic trap. As the trapped neutrons decay, recoil electrons will generate scintillations in the liquid He, which should be detectable with nearly 100% efficiency. This direct measure of the number of UCN decays vs. time can be used to determine the neutron beta-decay lifetime.

Study of the in-plane magnetic structure of a layered system using polarized neutron scattering under grazing incidence geometry

Energy Technology Data Exchange (ETDEWEB)

Maruyama, R., E-mail: ryuji.maruyama@j-parc.jp [J-PARC Center, Japan Atomic Energy Agency, 2-4 Shirakata Shirane, Tokai, Ibaraki 319-1195 (Japan); Bigault, T.; Wildes, A.R.; Dewhurst, C.D. [Institut Laue Langevin, 71 avenue des Martyrs, 38042 Grenoble (France); Soyama, K. [J-PARC Center, Japan Atomic Energy Agency, 2-4 Shirakata Shirane, Tokai, Ibaraki 319-1195 (Japan); Courtois, P. [Institut Laue Langevin, 71 avenue des Martyrs, 38042 Grenoble (France)

2016-05-21

The in-plane magnetic structure of a layered system with a polycrystalline grain size less than the ferromagnetic exchange length was investigated using polarized neutron off-specular scattering and grazing incidence small angle scattering measurements to gain insight into the mechanism that controls the magnetic properties which are different from the bulk. These complementary measurements with different length scales and the data analysis based on the distorted wave Born approximation revealed the lateral correlation on a length scale of sub- μm due to the fluctuating orientation of the magnetization in the layer. The obtained in-plane magnetic structure is consistent with the random anisotropy model, i.e. competition between the exchange interactions between neighboring spins and the local magnetocrystalline anisotropy.

PREFACE: Structure and dynamics determined by neutron and x-ray scattering Structure and dynamics determined by neutron and x-ray scattering

Science.gov (United States)

Müller-Buschbaum, Peter

2011-06-01

Neutron and x-ray scattering have emerged as powerful methods for the determination of structure and dynamics. Driven by emerging new, powerful neutron and synchrotron radiation sources, the continuous development of new instrumentation and novel scattering techniques gives rise to exciting possibilities. For example, in situ observations become possible via a high neutron or x-ray flux at the sample and, as a consequence, morphological transitions with small time constants can be detected. This special issue covers a broad range of different materials from soft to hard condensed matter. Hence, different material classes such as colloids, polymers, alloys, oxides and metals are addressed. The issue is dedicated to the 60th birthday of Professor Winfried Petry, scientific director of the Research Neutron Source Heinz Maier-Leibnitz (FRM-II), Germany, advisor at the physics department for the Bayerische Elite-Akademie, chair person of the Arbeitsgemeinschaft Metall- und Materialphysik of the German Physical Society (DPG) and a member of the professional council of the German Science Foundation (Deutsche Forschungsgemeinschaft, DFG). We would like to acknowledge and thank all contributors for their submissions, which made this special issue possible in the first place. Moreover, we would like to thank the staff at IOP Publishing for helping us with the administrative aspects and for coordinating the refereeing process, and Valeria Lauter for the beautiful cover artwork. Finally, to the readers, we hope that you find this special issue a valuable resource that provides insights into the present possibilities of neutron and x-ray scattering as powerful tools for the investigation of structure and dynamics. Structure and dynamics determined by neutron and x-ray scattering contents In situ studies of mass transport in liquid alloys by means of neutron radiography F Kargl, M Engelhardt, F Yang, H Weis, P Schmakat, B Schillinger, A Griesche and A Meyer Magnetic spin

The electron-spin--nuclear-spin interaction studied by polarized neutron scattering.

Science.gov (United States)

Stuhrmann, Heinrich B

2007-11-01

Dynamic nuclear spin polarization (DNP) is mediated by the dipolar interaction of paramagnetic centres with nuclear spins. This process is most likely to occur near paramagnetic centres at an angle close to 45 degrees with respect to the direction of the external magnetic field. The resulting distribution of polarized nuclear spins leads to an anisotropy of the polarized neutron scattering pattern, even with randomly oriented radical molecules. The corresponding cross section of polarized coherent neutron scattering in terms of a multipole expansion is derived for radical molecules in solution. An application using data of time-resolved polarized neutron scattering from an organic chromium(V) molecule is tested.

Neutron scattering studies of low dimensional magnetic systems

DEFF Research Database (Denmark)

Hansen, Ursula Bengård

investigated at low temperaturesand in a longitudinal magnetic eld using neutron spectroscopy. Here we observe thehybridisation of the magnon bound states, inherent to the low dimensional nature ofCoCl2 · 2D2O.At higher temperature, signatures which can be attributed to Magnetic Bloch Oscillationsis observed...

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)

Development of new methods for studying nanostructures using neutron scattering

International Nuclear Information System (INIS)

Pynn, Roger

2016-01-01

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.

Inelastic neutron scattering on a mixed-valence dodecanuclear polyoxovanadate cluster

CERN Document Server

Basler, R; Andrés, H; Güdel, H U; Koegerler, P; Krickemeier, E; Bögge, H; Müller, A; Mutka, H

2002-01-01

The magnetic exchange interactions in the mixed-valence dodecanuclear polyoxovanadate cluster compound (NHEt sub 3) sub 4 [V sub 1 sub 2 As sub 8 O sub 4 sub 0 (H sub 2 O)] x H sub 2 O were investigated by a detailed inelastic neutron scattering study using cold neutrons. The data show clear evidence for the presence of a magnetic anisotropy within the cluster. Exchange parameters are accurately determined. (orig.)

Anomalous scattering of neutrons in spin-polarized media

International Nuclear Information System (INIS)

Bashkin, E.P.

1989-01-01

A new exchange mechanism of inelastic scattering with spin flip for slow neutrons propagating through a spin-polarized medium is studied. The scattering is accompanied by emission or absorption of thermal fluctuations of the transverse magnetization of the medium; the weakly damped Larmor precession of nuclear spins in the external magnetic field plays the main role in these fluctuations. Under the conditions of giant opalescence the effect is enormous and the corresponding cross sections are significantly greater than the standard elastic scattering cross sections. Thus in the case of 29 Si↑ and 3 He↑ under typical experimental conditions the cross sections of these inelastic processes are of the order of 10 5 -10 6 b

Neutron reflectivity of electrodeposited thin magnetic films

International Nuclear Information System (INIS)

Cooper, Joshaniel F.K.; Vyas, Kunal N.; Steinke, Nina-J.; Love, David M.; Kinane, Christian J.; Barnes, Crispin H.W.

2014-01-01

Highlights: • Electrodeposited magnetic bi-layers were measured by polarised neutron reflectivity. • When growing a CoNiCu alloy from a single bath a Cu rich region is initially formed. • This Cu rich region is formed in the first layer but not subsequent ones. • Ni deposition is inhibited in thin film growth and Co deposits anomalously. • Alloy magnetism and neutron scattering length give a self-consistent model. - Abstract: We present a polarised neutron reflectivity (PNR) study of magnetic/non-magnetic (CoNiCu/Cu) thin films grown by single bath electrodeposition. We find that the composition is neither homogeneous with time, nor consistent with bulk values. Instead an initial, non-magnetic copper rich layer is formed, around 2 nm thick. This layer is formed by the deposition of the dilute, but rapidly diffusing, Cu 2+ ions near the electrode surface at the start of growth, before the region is depleted and the deposition becomes mass transport limited. After the region has been depleted, by growth etc., this layer does not form and thus may be prevented by growing a copper buffer layer immediately preceding the magnetic layer growth. As has been previously found, cobalt deposits anomalously compared to nickel, and even inhibits Ni deposition in thin films. The layer magnetisation and average neutron scattering length are fitted independently but both depend upon the alloy composition. Thus these parameters can be used to check for model self-consistency, increasing confidence in the derived composition

Activity report on neutron scattering research. V. 1, 1994

International Nuclear Information System (INIS)

Fujii, Y.; Oohara, Y.

1994-09-01

In April, 1993, the Neutron Scattering Laboratory attached to the Institute for Solid State Physics, University of Tokyo, was newly established in Tokai, Ibaraki Prefecture, to promote nationwide users' programs for utilizing the university-owned neutron instruments installed at the JRR-3M reactor of Japan Atomic Energy Research Institute. This upgraded reactor (20 MW, the cold source is installed) has drastically expanded the number of users and research areas since 1990 when it became operational. Currently 8 and 3 out of 18 new spectrometers in total at the JRR-3M are owned by ISSP and Tohoku University, respectively, while the remaining 7 spectrometers belong to JAERI. In addition, 3 conventional spectrometers in the 30 years old JRR-2 reactor (10 MW) have also supported research activities. This is the first issue of 'Activity report on neutron scattering research', and it is to be published annually. In this report, the brief history of neutron scattering research, the users' programs, the committees, the neutron scattering instruments available at the JRR-3M and the JRR-2M, the activity reports on structures and excitation, magnetism, superconductors, liquid and glass, material science, polymers, biology and instrumentation, and publication list are reported. (K.I.)

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)

Neutron scattering. Experiment manuals

International Nuclear Information System (INIS)

Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner

2010-01-01

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)

Neutron scattering. Experiment manuals

International Nuclear Information System (INIS)

Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner

2014-01-01

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

Magnetic small-angle scattering of subthermal neutrons by internal stress fields in work-hardened nickel single crystals oriented for multiple glide

International Nuclear Information System (INIS)

Vorbrugg, W.; Schaerpf, O.

1975-01-01

The small-angle scattering of Ni single crystals with (111) and (100) axis orientation is measured by a photographic method in the work-hardened state after tensile deformation. Parameters are the external magnetic field H parallel to the axis (600 2 ]<=8,8), and the elastic stress tausub(el)(0<=tausub(el)<=tausub(pl)) applied to the deformed crystals during the experiments. The scattering is found to be anisotropic and characteristic for the chosen orientation. The quantitative photometric analysis shows that the parameters mentioned above only influence the intensity but not the distribution of the scattered neutrons. The scattering increases with the elastic stress and decreases with the magnetic field. In particular, in the unloaded state there is a linear relation between the scattered intensity and the plastic shear stress. (author)

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...

Deep inelastic neutron scattering

International Nuclear Information System (INIS)

Mayers, J.

1989-03-01

The report is based on an invited talk given at a conference on ''Neutron Scattering at ISIS: Recent Highlights in Condensed Matter Research'', which was held in Rome, 1988, and is intended as an introduction to the techniques of Deep Inelastic Neutron Scattering. The subject is discussed under the following topic headings:- the impulse approximation I.A., scaling behaviour, kinematical consequences of energy and momentum conservation, examples of measurements, derivation of the I.A., the I.A. in a harmonic system, and validity of the I.A. in neutron scattering. (U.K.)

Periodic magnetic field as a polarized and focusing thermal neutron spectrometer and monochromator

Energy Technology Data Exchange (ETDEWEB)

Cremer, J. T.; Williams, D. L.; Fuller, M. J.; Gary, C. K.; Piestrup, M. A. [Adelphi Technology, Inc., 2003 East Bayshore Rd., Redwood City, California 94063 (United States); Pantell, R. H.; Feinstein, J. [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Flocchini, R. G.; Boussoufi, M.; Egbert, H. P.; Kloh, M. D.; Walker, R. B. [Davis McClellan Nuclear Radiation Center, University of California, McClellan, California 95652 (United States)

2010-01-15

A novel periodic magnetic field (PMF) optic is shown to act as a prism, lens, and polarizer for neutrons and particles with a magnetic dipole moment. The PMF has a two-dimensional field in the axial direction of neutron propagation. The PMF alternating magnetic field polarity provides strong gradients that cause separation of neutrons by wavelength axially and by spin state transversely. The spin-up neutrons exit the PMF with their magnetic spins aligned parallel to the PMF magnetic field, and are deflected upward and line focus at a fixed vertical height, proportional to the PMF period, at a downstream focal distance that increases with neutron energy. The PMF has no attenuation by absorption or scatter, as with material prisms or crystal monochromators. Embodiments of the PMF include neutron spectrometer or monochromator, and applications include neutron small angle scattering, crystallography, residual stress analysis, cross section measurements, and reflectometry. Presented are theory, experimental results, computer simulation, applications of the PMF, and comparison of its performance to Stern-Gerlach gradient devices and compound material and magnetic refractive prisms.

Periodic magnetic field as a polarized and focusing thermal neutron spectrometer and monochromator.

Science.gov (United States)

Cremer, J T; Williams, D L; Fuller, M J; Gary, C K; Piestrup, M A; Pantell, R H; Feinstein, J; Flocchini, R G; Boussoufi, M; Egbert, H P; Kloh, M D; Walker, R B

2010-01-01

A novel periodic magnetic field (PMF) optic is shown to act as a prism, lens, and polarizer for neutrons and particles with a magnetic dipole moment. The PMF has a two-dimensional field in the axial direction of neutron propagation. The PMF alternating magnetic field polarity provides strong gradients that cause separation of neutrons by wavelength axially and by spin state transversely. The spin-up neutrons exit the PMF with their magnetic spins aligned parallel to the PMF magnetic field, and are deflected upward and line focus at a fixed vertical height, proportional to the PMF period, at a downstream focal distance that increases with neutron energy. The PMF has no attenuation by absorption or scatter, as with material prisms or crystal monochromators. Embodiments of the PMF include neutron spectrometer or monochromator, and applications include neutron small angle scattering, crystallography, residual stress analysis, cross section measurements, and reflectometry. Presented are theory, experimental results, computer simulation, applications of the PMF, and comparison of its performance to Stern-Gerlach gradient devices and compound material and magnetic refractive prisms.

Research within the coordinated programme on neutron scattering techniques in applied research

International Nuclear Information System (INIS)

Satya Murthy, N.S.

1982-02-01

This paper reviews developments of neutron scattering studies at Bhabha Atomic Research Centre (BARC) over the past two decades through utilisation of Apsara and Circus reactor facilities. Salient results in neutron crystallography, magnetic diffraction and inelastic neutron scattering will be presented highlighting progressive involvement in more and more complex studies. The growth of non-neutronic activities as a natural outcome of overall necessity and interest of investigators will be indicated. A description of facilities planned at R5 and the nature of studies that are likely to be taken up at R5 will be briefly discussed. (author)

Neutron scattering science in Australia

International Nuclear Information System (INIS)

Knott, Robert

1999-01-01

Neutron scattering science in Australia is making an impact on a number of fields in the scientific and industrial research communities. The unique properties of the neutron are being used to investigate problems in chemistry, materials science, physics, engineering and biology. The reactor HIFAR at the Australian Nuclear Science and Technology Organisation research laboratories is the only neutron source in Australia suitable for neutron scattering science. A suite of instruments provides a wide range of opportunities for the neutron scattering community that extends throughout universities, government and industrial research laboratories. Plans are in progress to replace the present research reactor with a modern multi-purpose research reactor to offer the most advanced neutron scattering facilities. The experimental and analysis equipment associated with a modern research reactor will permit the establishment of a national centre for world class neutron science research focussed on the structure and functioning of materials, industrial irradiations and analyses in support of Australian manufacturing, minerals, petrochemical, pharmaceuticals and information science industries. (author)

Neutron scattering science in Australia

Energy Technology Data Exchange (ETDEWEB)

Knott, Robert [Australian Nuclear Science and Technology Organisation, Menai, NSW (Australia)

1999-10-01

Neutron scattering science in Australia is making an impact on a number of fields in the scientific and industrial research communities. The unique properties of the neutron are being used to investigate problems in chemistry, materials science, physics, engineering and biology. The reactor HIFAR at the Australian Nuclear Science and Technology Organisation research laboratories is the only neutron source in Australia suitable for neutron scattering science. A suite of instruments provides a wide range of opportunities for the neutron scattering community that extends throughout universities, government and industrial research laboratories. Plans are in progress to replace the present research reactor with a modern multi-purpose research reactor to offer the most advanced neutron scattering facilities. The experimental and analysis equipment associated with a modern research reactor will permit the establishment of a national centre for world class neutron science research focussed on the structure and functioning of materials, industrial irradiations and analyses in support of Australian manufacturing, minerals, petrochemical, pharmaceuticals and information science industries. (author)

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.

Neutron scattering. Lectures of the JCNS laboratory course held at Forschungszentrum Juelich and the research reactor FRM II of TU Munich

International Nuclear Information System (INIS)

Brueckel, T.; Heger, G.; Richter, D.; Zorn, R.

2007-01-01

The following topics are dealt with: Fourier transform, basic assumptions of quantum mechanics and the Born approximation, symmtery in crystals, neutron sources, neutron elastic scattering and properties, polarized neutron scattering, correlation functions measured by scattering experiments, grazing incidence neutron scattering, neutron diffractometers, small-angle scattewring inelastic crystal spectrometers, time-of-flight spectrometers using NSE, structure determination, inelastic neutron scattering with phonon and magnon excitations, structure of complex fluids and macromolecules, polymer dynamics, magnetism. (HSI)

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.

Measurement and modeling of polarized specular neutron reflectivity in large magnetic fields.

Science.gov (United States)

Maranville, Brian B; Kirby, Brian J; Grutter, Alexander J; Kienzle, Paul A; Majkrzak, Charles F; Liu, Yaohua; Dennis, Cindi L

2016-08-01

The presence of a large applied magnetic field removes the degeneracy of the vacuum energy states for spin-up and spin-down neutrons. For polarized neutron reflectometry, this must be included in the reference potential energy of the Schrödinger equation that is used to calculate the expected scattering from a magnetic layered structure. For samples with magnetization that is purely parallel or antiparallel to the applied field which defines the quantization axis, there is no mixing of the spin states (no spin-flip scattering) and so this additional potential is constant throughout the scattering region. When there is non-collinear magnetization in the sample, however, there will be significant scattering from one spin state into the other, and the reference potentials will differ between the incoming and outgoing wavefunctions, changing the angle and intensities of the scattering. The theory of the scattering and recommended experimental practices for this type of measurement are presented, as well as an example measurement.

Detection of explosives by neutron scattering

International Nuclear Information System (INIS)

Brooks, F.D.; Buffler, A.; Allie, M.S.; Nchodu, M.R.; Bharuth-Ram, K.

1998-01-01

For non-intrusive detection of hidden explosives or other contraband such as narcotics a fast neutron scattering analysis (FNSA) technique is proposed. An experimental arrangement uses a collimated, pulsed beam of neutrons directed at the sample. Scattered neutrons are detected by liquid scintillation counters at different scattering angles. A scattering signature is derived from two-parameter data, counts vs pulse height and time-of-flight measured for each element (H, C, N or O) at each of two scattering angles and two neutron energies. The elemental signatures are very distinctive and constitute a good response matrix for unfolding elemental components from the scattering signatures measured for different compounds

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

The microstructure of neutron-irradiated Fe-Cr alloys: A small-angle neutron scattering study

International Nuclear Information System (INIS)

Heintze, C.; Bergner, F.; Ulbricht, A.; Eckerlebe, H.

2009-01-01

Ferritic-martensitic chromium steels are candidate materials for future applications in both Gen-IV fission and fusion technology. Experimental investigation of neutron-irradiated Fe-Cr model alloys is important in order to gain a better understanding of the interplay of chromium content and irradiation behaviour. Small-angle neutron scattering (SANS) is particularly well suited to unfold the size distribution of non-planar irradiation-induced nanoscale features such as defect-solute clusters, nanovoids and α'- particles. This size distribution represents a statistically reliable average over a macroscopic volume. Assumptions on the dominant type of features can be checked against the ratio of magnetic and nuclear scattering. The materials investigated in this work are commercial-purity Fe-Cr alloys of nominal compositions Fe-2.5Cr, Fe-5Cr, Fe- 9Cr and Fe-12.5Cr (at %). Neutron irradiation was performed in the reactor BR2 at Mol (Belgium) at a temperature of 300 deg. C and neutron flux of 9 x 10 13 cm -2 s -1 (E > 1 MeV) [Matijasevic, JNM 377 (2008) 147]. The neutron exposures expressed in units of displacements per atom correspond to 0.6 and 1.5 dpa. A wavelength of 0.58 nm and three detector-sample distances of 1, 4 and 16 m were used in the SANS experiments carried out at the SANS-2 facility of GKSS Geesthacht (Germany). The samples were placed in a saturation magnetic field in order to separate magnetic and nuclear contributions. The scattering curves obtained for the unirradiated conditions of the four Fe-Cr alloys were taken as reference. We have found that the volume fraction of scatterers slightly increases with neutron exposure (Fe-9Cr) or exhibits a saturation-like behaviour (Fe-2.5Cr, Fe-5Cr and Fe-12.5Cr) and that the volume fraction at 1.5 dpa is an increasing function of the chromium level with a slight increase up to 9 at%Cr and a steep increase between 9 and 12.5 at%Cr. The radii of irradiation-induced scatterers are essentially less than 8 nm and

Applications of thermal neutron scattering

International Nuclear Information System (INIS)

Kostorz, G.

1978-01-01

Although in the past neutrons have been used quite frequently in the study of condensed matter, a more recent development has lead to applications of thermal neutron scattering in the investigation of more practical rather than purely academic problems. Physicists, chemists, materials scientists, biologists, and others have recognized and demonstrated that neutron scattering techniques can yield supplementary information which, in many cases, could not be obtained with other methods. The paper illustrates the use of neutron scattering in these areas of applied research. No attempt is made to present all the aspects of neutron scattering which can be found in textbooks. From the vast amount of experimental data, only a few examples are presented for the study of structure and atomic arrangement, ''extended'' structure, and dynamic phenomena in substances of current interest in applied research. (author)

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 which...... does not have very high thermal-neutron capture cross section, so that inelastic neutron scattering experiments can give satisfactory information on magnon dispersion relations....

Spectrum of ferromagnetic transition metal magnetic excitations and neutron scattering

International Nuclear Information System (INIS)

Kuzemskij, A.L.

1979-01-01

Quantum statistical models of ferromagnetic transition metals as well as methods of their solutions are reviewed. The correspondence of results on solving these models and the data on scattering thermal neutrons in ferromagnetic is discussed

Diffuse neutron scattering study of metallic interstitial solid solutions

International Nuclear Information System (INIS)

Barberis, P.

1991-10-01

We studied two interstitial solid solutions (Ni-C(1at%) and Nb-O(2at%) and two stabilized zirconia (ZrO2-CaO(13.6mol%) and ZrO2-Y2O3(9.6mol%) by elastic diffuse neutron scattering. We used polarized neutron scattering in the case of the ferromagnetic Ni-based sample, in order to determine the magnetic perturbation induced by the C atoms. Measurements were made on single crystals in the Laboratoire Leon Brillouin (CEA-CNRS, Saclay, France). An original algorithm to deconvolve time-of-flight spectra improved the separation between elastically and inelastically scattered intensities. In the case of metallic solutions, we used a simple non-linear model, assuming that interstitials are isolated and located in octahedral sites. Results are: - in both compounds, nearest neighbours are widely displaced away from the interstitial, while next nearest neighbours come slightly closer. - the large magnetic perturbation induced by carbon in Nickel decreases with increasing distance on the three first neighbour shells and is in good agreement with the total magnetization variation. - no chemical order between solute atoms could be evidenced. Stabilized zirconia exhibit a strong correlation between chemical order and the large displacements around vacancies and dopants. (Author). 132 refs., 38 figs., 13 tabs

Application of hot neutron scattering to the problem of 3d metallic paramagnetism

International Nuclear Information System (INIS)

Brown, P.J.; Capellmann, H.; Deportes, J.; Givord, D.; Johnson, S.M.; Ziebeck, K.R.A.

1984-01-01

The authors report in this paper on experiments performed in Fe and Ni in their paramagnetic state. Scattering of polarized neutrons with polarization analysis has been used to separate out the magnetic scattering from other sources of scattering. Large quasi-elastic scattering is observed which characterizes ferromagnetic correlations over several inter-atomic distances. The large-Q component of the scattering is fairly small as expected for itinerant electrons in which the energy of magnetic excitations may be of the order of the bandwidth. These should help discriminate between the itinerant and localized models

Application of neutron scattering in polymers

International Nuclear Information System (INIS)

Han, C.C.

2003-01-01

Full text: Neutron scattering offers many opportunities in sciences and technology. This is particularly true in the field of polymer sciences and materials. It is mainly because that the scattering length scales (q -1 ) and scattering contrast (scattering cross-sections) makes neutron a perfect tool for polymer studies. Several examples will be used to illustrate the importance of the small angle neutron scattering and the neutron reflection studies in polymer physics. These include the determination of phase diagram, interaction parameter, and spinodal decomposition kinetics by SANS. In the dynamics area, examples will be given to illustrate the critical temperature shift and mixing of polymer blends under shear flow. Also, the confinement effect on the phase separated structure of polymer blend films will be used to demonstrate the importance of the neutron reflectivity measurement

Neutron scattering studies of the actinides

International Nuclear Information System (INIS)

Lander, G.H.

1979-01-01

The electronic structure of actinide materials presents a unique example of the interplay between localized and band electrons. Together with a variety of other techniques, especially magnetization and the Mossbauer effect, neutron studies have helped us to understand the systematics of many actinide compounds that order magnetically. A direct consequence of the localization of 5f electrons is the spin-orbit coupling and subsequent spin-lattice interaction that often leads to strongly anisotropic behavior. The unusual phase transition in UO 2 , for example, arises from interactions between quadrupole moments. On the other hand, in the monopnictides and monochalcogenides, the anisotropy is more difficult to understand, but probably involves an interaction between actinide and anion wave functions. A variety of neutron experiments, including form-factor studies, critical scattering and measurements of the elementary excitations have now been performed, and the conceptual picture emerging from these studies will be discussed

Influence of multiple small-angle neutron scattering on diffraction peak broadening in ferritic steel

Czech Academy of Sciences Publication Activity Database

Woo, W.; Em, V.; Shin, E.; Mikula, Pavol; Ryukhtin, Vasyl

2015-01-01

Roč. 48, APR (2015), s. 350-356 ISSN 0021-8898 R&D Projects: GA ČR GB14-36566G; GA MŠk(CZ) LM2011019 Institutional support: RVO:61389005 Keywords : peak broadening * small-angle neutron scattering * neutron diffraction * magnetic domain Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.720, year: 2014

Neutron scattering studies in the actinide region

International Nuclear Information System (INIS)

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

1993-09-01

This report discusses the following topics: Prompt fission neutron energy spectra for 235 U and 239 Pu; Two-parameter measurement of nuclear lifetimes; ''Black'' neutron detector; Data reduction techniques for neutron scattering experiments; Inelastic neutron scattering studies in 197 Au; Elastic and inelastic scattering studies in 239 Pu; and neutron induced defects in silicon dioxide MOS structures

A neutron scattering study on the antiferromagnet in an exchange biased systems

Energy Technology Data Exchange (ETDEWEB)

Solina, Danica; Lott, Dieter; Fenske, Jochen; Schreyer, Andreas [Institute of Materials Research, GKSS Research Centre, Geesthacht (Germany); Schmidt, Wolfgang [Institut-Laue-Langevin, Grenoble (France); Wu, Yu-Chang; Lai, Chih-Huang [Department of Materials Science and Engineering, National Tsing Hua University, HsinChu (China)

2008-07-01

The magnetic structure of single crystal antiferromagnetic PtMn that biases CoFe has been studied using neutron scattering. Polarized neutron reflection (PNR) was used to determine the switching behaviour of the ferromagnetic layer and polarized neutron diffraction (PND) to probe the magnetic configuration of the anti-ferromagnetic layer. PNR suggests a combination of rotation and domain formation. Changes were observed in the PND patterns taken at points around the hysteresis loop. The diffraction data has been simulated with a 'twisting' of part of the anti-ferromagnetic layer as the ferromagnetic layer changes.

Summary of coherent neutron scattering length

International Nuclear Information System (INIS)

Rauch, H.

1981-07-01

Experimental values of neutron-nuclei bound scattering lengths for some 354 isotopes and elements and the various spin-states are compiled in a uniform way together with their error bars as quoted in the original literature. Recommended values are also given. The definitions of the relevant quantities presented in the data tables and the basic principles of measurements are explained in the introductory chapters. The data is also available on a magnetic tape

Neutron-proton scattering

International Nuclear Information System (INIS)

Doll, P.

1990-02-01

Neutron-proton scattering as fundamental interaction process below and above hundred MeV is discussed. Quark model inspired interactions and phenomenological potential models are described. The seminar also indicates the experimental improvements for achieving new precise scattering data. Concluding remarks indicate the relevance of nucleon-nucleon scattering results to finite nuclei. (orig.) [de

Investigation of short range order in Fe-C melts by neutron scattering

International Nuclear Information System (INIS)

Weber, M.; Steeb, S.

1978-01-01

Neutron diffraction measurements were done with Fe-C-melts (5; 13; and 17 at % C) using the method of isotopic substitution. The neutron small angle scattering effect observed could be explained by magnetic scattering, caused by spin-fluctuations still existing in the molten state far away from the Curie temperature. Total structure factors were calculated from observed intensities taking into account the correction for magnetic scattering. For each carbon concentration two alloys were investigated, one using iron of natural isotopic abundance and the other using enriched 57 Fe. From a comparison of the q-region below the first maximum of the total structure factor as obtained using Fesup(nat) or 57 Fe, respectively, a tendency to the preference of unlike nearest neighbours is concluded, the distance between Fe-C-pairs being 2.2 A. (orig.) [de

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.

Neutron scattering in Australia

International Nuclear Information System (INIS)

Knott, R.B.

1994-01-01

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

3rd AINSE neutron scattering conference, Lucas Heights -AINSE Theatre

International Nuclear Information System (INIS)

1986-01-01

Abstracts of papers, the conference program and general information is included in the conference handbook. The program is divided into the following sessions: hydrogeneous and biological materials, industrial applications, phase transitions, magnetism, small angle neutron scattering and new developments

Neutron scattering

International Nuclear Information System (INIS)

1991-02-01

The annual report on hand gives an overview of the research work carried out in the Laboratory for Neutron Scattering (LNS) of the ETH Zuerich in 1990. Using the method of neutron scattering, it is possible to examine in detail the static and dynamic properties of the condensed material. In accordance with the multidisciplined character of the method, the LNS has for years maintained a system of intensive co-operation with numerous institutes in the areas of biology, chemistry, solid-state physics, crystallography and materials research. In 1990 over 100 scientists from more than 40 research groups both at home and abroad took part in the experiments. It was again a pleasure to see the number of graduate students present, who were studying for a doctorate and who could be introduced into the neutron scattering during their stay at the LNS and thus were in the position to touch on central ways of looking at a problem in their dissertation using this modern experimental method of solid-state research. In addition to the numerous and interesting ways of formulating the questions to explain the structure, nowadays the scientific programme increasingly includes particularly topical studies in connection with high temperature-supraconductors and materials research

Interpretation of the quasi-elastic neutron scattering on PAA by rotational diffusion models

International Nuclear Information System (INIS)

Bata, L.; Vizi, J.; Kugler, S.

1974-10-01

First the most important data determined by other methods for para azoxy anisolon (PAA) are collected. This molecule makes a rotational oscillational motion around the mean molecular direction. The details of this motion can be determined by inelastic neutron scattering. Quasielastic neutron scattering measurements were carried out without orienting magnetic field on a time-of-flight facility with neutron beam of 4.26 meV. For the interpretation of the results two models, the spherical rotation diffusion model and the circular random walk model are investigated. The comparison shows that the circular random walk model (with N=8 sites, d=4A diameter and K=10 10 s -1 rate constant) fits very well with the quasi-elastic neutron scattering, while the spherical rotational diffusion model seems to be incorrect. (Sz.N.Z.)

Dynamically Polarized Sample for Neutron Scattering At the Spallation Neutron Source

International Nuclear Information System (INIS)

Pierce, Josh; Zhao, J. K.; Crabb, Don

2009-01-01

The recently constructed Spallation Neutron Source at the Oak Ridge National Laboratory is quickly becoming the world's leader in neutron scattering sciences. In addition to the world's most intense pulsed neutron source, we are continuously constructing state of the art neutron scattering instruments as well as sample environments to address today and tomorrow's challenges in materials research. The Dynamically Polarized Sample project at the SNS is aimed at taking maximum advantage of polarized neutron scattering from polarized samples, especially biological samples that are abundant in hydrogen. Polarized neutron scattering will allow us drastically increase the signal to noise ratio in experiments such as neutron protein crystallography. The DPS project is near completion and all key components have been tested. Here we report the current status of the project.

Progress on the Magnetic Trapping of Ultra-cold Neutrons

Science.gov (United States)

Doyle, John M.

1998-04-01

Ultra-cold neutrons (UCN) have been instrumental in making improved measurements of the neutron beta-decay lifetime and in searches for a permanent electric dipole moment.(R. Golub, D. Richardson and S.K. Lamoreaux, Ultra-cold Neutrons), Adam Hilger, 1991 The most accurate experiments have taken place using in-core devices at ILL (Grenoble, France) and PNPI (St. Petersburg, Russia). Superthermal techniques offer the promise of high-density sources of UCN via scattering of cold neutrons. Cold neutron beams are available at many neutron facilities. We are currently working on the development of a superfluid helium UCN source using the Cold Neutron Research Facility at the NIST Research Reactor (Gaithersburg) . Our first experiment plans to use superthermal scattering of neutrons in superfluid helium to produce UCN within a magnetic trapping volume. A magnetic trap 30 cm long and 4 cm diameter will be filled with helium at about 100 mK. Cold neutrons (around 11 K) will be introduced into the trapping region where some of them scatter to low enough energies (around 1 mK) so that they are magnetically trapped. Once trapped the UCN travel undisturbed; they have a very small probability of upscattering. Detection will be accomplished as the UCN beta-decay. The resultant high-energy electron creates excited molecular helium dimers, a portion which decay in less than 10 ns and emit radiation in the XUV (50-100 nm). We have developed techniques to measure these scintillations. Analysis indicates that a high accuracy measurement of the neutron beta decay lifetime should be possible using our techniques. An apparatus has been constructed and initial runs are underway. An overview of the experiment, discussion of systematic errors and recent experimental progress will be presented. This work is done in collaboration with C. Brome, J. Butterworth, S. Dzhosyuk, P. Huffman, C. Mattoni, D. McKinsey, M. Cooper, G. Greene, S. Lamoreaux, R. Golub, K. Habicht, K. Coakley, S. Dewey, D

Huang diffuse scattering of neutrons

International Nuclear Information System (INIS)

Burkel, E.; Guerard, B. v.; Metzger, H.; Peisl, J.

1979-01-01

Huang diffuse neutron scattering was measured for the first time on niobium with interstitially dissolved deuterium as well as on MgO after neutron irradiation and Li 7 F after γ-irradiation. With Huang diffuse scattering the strength and symmetry of the distortion field around lattice defects can be determined. Our results clearly demonstrate that this method is feasible with neutrons. The present results are compared with X-ray experiments and the advantages of using neutrons is discussed in some detail. (orig.)

Absence of a long-range ordered magnetic ground state in Pr3Rh4Sn13 studied through specific heat and inelastic neutron scattering

Science.gov (United States)

Nair, Harikrishnan S.; Ogunbunmi, Michael O.; Ghosh, S. K.; Adroja, D. T.; Koza, M. M.; Guidi, T.; Strydom, A. M.

2018-04-01

Signatures of absence of a long-range ordered magnetic ground state down to 0.36 K are observed in magnetic susceptibility, specific heat, thermal/electrical transport and inelastic neutron scattering data of the quasi-skutterudite compound Pr3Rh4Sn13 which crystallizes in the Yb3Rh4Sn13-type structure with a cage-like network of Sn atoms. In this structure, Pr3+ occupies a lattice site with D 2d point symmetry having a ninefold degeneracy corresponding to J  =  4. The magnetic susceptibility of Pr3Rh4Sn13 shows only a weak temperature dependence below 10 K otherwise remaining paramagnetic-like in the range, 10 K-300 K. From the inelastic neutron scattering intensity of Pr3Rh4Sn13 recorded at different temperatures, we identify excitations at 4.5(7) K, 5.42(6) K, 10.77(5) K, 27.27(5) K, 192.28(4) K and 308.33(3) K through a careful peak analysis. However, no signatures of long-range magnetic order are observed in the neutron data down to 1.5 K, which is also confirmed by the specific heat data down to 0.36 K. A broad Schottky-like peak is recovered for the magnetic part of the specific heat, C 4f, which suggests the role of crystal electric fields of Pr3+ . A crystalline electric field model consisting of 7 levels was applied to C 4f which leads to the estimation of energy levels at 4.48(2) K, 6.94(4) K, 11.23(8) K, 27.01(5) K, 193.12(6) K and 367.30(2) K. The CEF energy levels estimated from the heat capacity analysis are in close agreement with the excitation energies seen in the neutron data. The Sommerfeld coefficient estimated from the analysis of magnetic specific heat is γ = 761(6) mJ K-2 mol-Pr which suggests the formation of heavy itinerant quasi-particles in Pr3Rh4Sn13. Combining inelastic neutron scattering results, analysis of the specific heat data down to 0.36 K, magnetic susceptibility and, electrical and thermal transport, we establish the absence of long-range ordered magnetic ground state in Pr3Rh4Sn13.

Theory of magnetic neutron small-angle scattering using the dynamical theory of diffraction instead of the Born approximation. I

International Nuclear Information System (INIS)

Schaerpf, O.

1978-01-01

Two ways are given for solving the problem of the dependence of the refraction on the direction of magnetization on both sides of the refractive boundary, one applying the Halpern magnetic scattering vector, the other applying the dynamical theory of diffraction. They lead to different results. Experimental investigation of refraction by magnetic boundaries shows no dependence of the angle of deflection on the relative angles of magnetization in adjacent domains. This behaviour is only described correctly by the dynamical theory, which far from Laue reflections leads to a treatment by the Schoedinger equation with a spin-dependent potential dependent on the average continuous homogenous magnetic induction, both for the law of refraction and for the precession of the spin. The results of this treatment are discussed as a consequence of the behaviour of the spin of the neutrons. This gives some insight about how and why, with refraction, the intensities of the direct and deflected beams depend on the magnetization directions in adjacent domains. The dynamical theory also shows that the Halpern magnetic scattering vector applies only with Laue or Bragg reflections and not with transmission far from those reflections. (Auth.)

The Green's function approach to the neutron-inelastic-scattering determination of magnon dispersion relations for isotropic disordered magnets

International Nuclear Information System (INIS)

Czachor, A.; Al-Wahsh, H.

1999-01-01

Complete text of publication follows. To determine the neutron inelastic coherent scattering (MS) cross section for disordered magnets a system of equations of motion for the Green functions (GF) related to the localized-spin correlation-functions, has been exploited. The higher-order Green functions are decoupled using a symmetric 'equal access' (EA) form of the RPA decoupling scheme. The quasi-crystal approximation (QCA) was applied to construct the space-time Fourier transformed GF Q (ω)> related to neutron scattering. On assuming isotropy of the magnetic structure and a short range coupling between the spins (on the sphere approximation, OSA) we have found an explicit analytic form of this function. Poles of the Q (ω)> determine the dispersion relation ω = ω Q for elementary excitations, such as they are seen in the MS experiment - the positions of the MS profile maxima in the ω-Q space. Single formula for the dispersion relations derived here covers a variety of isotropic spin structures: in particular disordered 'longitudinal' ferrornagnets (ω ∼Q z , Q→ 0), disordered 'transverse' spin structures (ω ∼Q, Q→0), and some intermediate cases. For the system of spins coupled identically - the magnetization and the magnetic susceptibility calculated within the present EA-RPA approach do agree with the results of exact calculations. It provides an interesting insight into the nature of the RPA approach do agree with the results of exact calculations. It provides an interesting insight into the nature of the RPA - treatment of the localized spin dynamics. (author)

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...

Neutron scattering study of two-magnon states in the quantum magnet copper nitrate

DEFF Research Database (Denmark)

Tennant, D.A.; Broholm, C.; Reich, D.H.

2003-01-01

We report measurements of the two-magnon states in a dimerized antiferromagnetic chain material, copper nitrate [Cu(NO3)(2).2.5D(2)O]. Using inelastic neutron scattering we have measured the one- and two-magnon excitation spectra in a large single crystal. The data are in excellent agreement...... with a perturbative expansion of the alternating Heisenberg Hamiltonian from the strongly dimerized limit. The expansion predicts a two-magnon bound state for qsimilar to(2n+1)pid which is consistent with the neutron scattering data....

Dynamics in γ-Fe₂O₃ nanoparticles studied by time-of-flight polarized neutron scattering

DEFF Research Database (Denmark)

Kuhn, L.T.; Lefmann, K.; Klausen, S.N.

2004-01-01

The inelastic neutron-scattering signal from magnetic nanoparticles contains information on magnetic dynamics like superparamagnetic relaxation and collective magnetic excitations. Often another, very broad quasi-elastic component is observed in addition. We have studied this quasi-elastic neutron...... signal from 4 nm ferrimagnetic maghemite (gamma-Fe(2)O(3)) particles, and by means of time-of-flight polarised neutron scattering we have identified the source of (most of) this signal to be water adsorbed at the surface of the nanoparticles. A minor part of the signal has its origin in dynamics...

Eighth International Conference on Neutron Scattering ICNS2005. Final Programme and Abstract Book

International Nuclear Information System (INIS)

2005-01-01

Full text: This conference encompassed a very wide range of neutron-related research. Topics addressed ranged from almost all applications of neutron scattering and diffraction like discovering magnetic ordering, magnetic properties and structural analysis, negative thermal expansion, spin states, proton dynamics, crystal structure, phase transitions and phase morphology, neutron spin echo to neutron powder diffraction studies and new generation neutron analysis methods as well as x-ray reflectivity versus neutron reflectivity, neutron resonance, cold and thermal neutron studies and spectrometers. Areas of research covered bacteria, DNA, drugs targeting, enzyme arrangement, structure of cholesterol, lung surfactant action, nanocapsules, disease, muscles, lipids, liquids, crystals, industrial gauges, metals, rare earths, shielding and geopolymers. Not all abstracts are included in this input; there exists an emphasis on Australian contributions and those from ANSTO

A mechanical rotator for neutron scattering measurements

International Nuclear Information System (INIS)

Thaler, A.; Northen, E.; Aczel, A. A.; MacDougall, G. J.

2016-01-01

We have designed and built a mechanical rotation system for use in single crystal neutron scattering experiments at low temperatures. The main motivation for this device is to facilitate the application of magnetic fields transverse to a primary training axis, using only a vertical cryomagnet. Development was done in the context of a triple-axis neutron spectrometer, but the design is such that it can be generalized to a number of different instruments or measurement techniques. Here, we discuss some of the experimental constraints motivating the design, followed by design specifics, preliminary experimental results, and a discussion of potential uses and future extension possibilities.

Neutron scattering lengths of 3He

International Nuclear Information System (INIS)

Alfimenkov, V.P.; Akopian, G.G.; Wierzbicki, J.; Govorov, A.M.; Pikelner, L.B.; Sharapov, E.I.

1976-01-01

The total neutron scattering cross-section of 3 He has been measured in the neutron energy range from 20 meV to 2 eV. Together with the known value of coherent scattering amplitude it leads to the two sts of n 3 He scattering lengths

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...

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...

Neutron scattering in Indonesia. Country report

Energy Technology Data Exchange (ETDEWEB)

Ikram, Abarrul [Neutron Scattering Laboratory, R and D Center for Materials Science and Technology, National Nuclear Energy Agency, Serpong (Indonesia)

2000-10-01

Neutron scattering in Indonesia is still alienated due to some reasons and conditions which are discussed. The reactor and its latest operation mode are also described. The neutron beam facilities which include one diffractometer for residual stress measurement, one diffractometer for single crystal structural determination and texture measurement, one high resolution powder diffractometer, one neutron radiography facility, one triple axis spectrometer, one small angle neutron scattering spectrometer and one high resolution small angle neutron scattering spectrometer were presented briefly together with improvements of neutron intensities at some spectrometers in connection with the setting of main beam shutter position. Special attention is given for four instruments mostly related to this workshop. Their performances and problems faced in the past 9 months are presented as well as the future plan for refurbishment and development. (author)

Neutron Scattering Differential Cross Sections for 12C

Science.gov (United States)

Byrd, Stephen T.; Hicks, S. F.; Nickel, M. T.; Block, S. G.; Peters, E. E.; Ramirez, A. P. D.; Mukhopadhyay, S.; McEllistrem, M. T.; Yates, S. W.; Vanhoy, J. R.

2016-09-01

Because of the prevalence of its use in the nuclear energy industry and for our overall understanding of the interactions of neutrons with matter, accurately determining the effects of fast neutrons scattering from 12C is important. Previously measured 12C inelastic neutron scattering differential cross sections found in the National Nuclear Data Center (NNDC) show significant discrepancies (>30%). Seeking to resolve these discrepancies, neutron inelastic and elastic scattering differential cross sections for 12C were measured at the University of Kentucky Acceleratory Laboratory for incident neutron energies of 5.58, 5.83, and 6.04 MeV. Quasi mono-energetic neutrons were scattered off an enriched 12C target (>99.99%) and detected by a C6D6 liquid scintillation detector. Time-of-flight (TOF) techniques were used to determine scattered neutron energies and allowed for elastic/inelastic scattering distinction. Relative detector efficiencies were determined through direct measurements of neutrons produced by the 2H(d,n) and 3H(p,n) source reactions, and absolute normalization factors were found by comparing 1H scattering measurements to accepted NNDC values. This experimental procedure has been successfully used for prior neutron scattering measurements and seems well-suited to our current objective. Significant challenges were encountered, however, with measuring the neutron detector efficiency over the broad incident neutron energy range required for these measurements. Funding for this research was provided by the National Nuclear Security Administration (NNSA).

Very High Energy Neutron Scattering from Hydrogen

International Nuclear Information System (INIS)

Cowley, R A; Stock, C; Bennington, S M; Taylor, J; Gidopoulos, N I

2010-01-01

The neutron scattering from hydrogen in polythene has been measured with the direct time-of flight spectrometer, MARI, at the ISIS facility of the Rutherford Appleton Laboratory with incident neutron energies between 0.5 eV and 600 eV. The results of experiments using the spectrometer, VESUVIO, have given intensities from hydrogen containing materials that were about 60% of the intensity expected from hydrogen. Since VESUVIO is the only instrument in the world that routinely operates with incident neutron energies in the eV range we have chosen to measure the scattering from hydrogen at high incident neutron energies with a different type of instrument. The MARI, direct time-of-flight, instrument was chosen for the experiment and we have studied the scattering for several different incident neutron energies. We have learnt how to subtract the gamma ray background, how to calibrate the incident energy and how to convert the spectra to an energy plot . The intensity of the hydrogen scattering was independent of the scattering angle for scattering angles from about 5 degrees up to 70 degrees for at least 3 different incident neutron energies between 20 eV and 100 eV. When the data was put on an absolute scale, by measuring the scattering from 5 metal foils with known thicknesses under the same conditions we found that the absolute intensity of the scattering from the hydrogen was in agreement with that expected to an accuracy of ± 5.0% over a wide range of wave-vector transfers between 1 and 250 A -1 . These measurements show that it is possible to measure the neutron scattering with incident neutron energies up to at least 100 eV with a direct geometry time-of-flight spectrometer and that the results are in agreement with conventional scattering theory.

An empirical formula for scattered neutron components in fast neutron radiography

International Nuclear Information System (INIS)

Dou Haifeng; Tang Bin

2011-01-01

Scattering neutrons are one of the key factors that may affect the images of fast neutron radiography. In this paper, a mathematical model for scattered neutrons is developed on a cylinder sample, and an empirical formula for scattered neutrons is obtained. According to the results given by Monte Carlo methods, the parameters in the empirical formula are obtained with curve fitting, which confirms the logicality of the empirical formula. The curve-fitted parameters of common materials such as 6 LiD are given. (authors)

Scattering of fast neutrons from elemental molybdenum

International Nuclear Information System (INIS)

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

1982-11-01

Differential broad-resolution neutron-scattering cross sections of elemental molybdenum were measured at 10 to 20 scattering angles distributed between 20 and 160 degrees and at incident-neutron energy intervals of approx. = 50 to 200 keV from 1.5 to 4.0 MeV. Elastically-scattered neutrons were fully resolved from inelastic events. Lumped-level inelastic-neutron-scattering cross sections were determined corresponding to observed excitation energies of; 789 +- 23, 195 +- 23, 1500 +- 34, 1617 +- 12, 1787, 1874, 1991, 2063 +- 24, 2296, 2569 and 2802 keV. An optical-statistical model was deduced from the measured elastic-scattering results. The experimental values were compared with the respective quantities given in ENDF/B-V

DISCUS, Neutron Single to Double Scattering Ratio in Inelastic Scattering Experiment by Monte-Carlo

International Nuclear Information System (INIS)

Johnson, M.W.

1993-01-01

1 - Description of problem or function: DISCUS calculates the ratio of once-scattered to twice-scattered neutrons detected in an inelastic neutron scattering experiment. DISCUS also calculates the flux of once-scattered neutrons that would have been observed if there were no absorption in the sample and if, once scattered, the neutron would emerge without further re-scattering or absorption. Three types of sample geometry are used: an infinite flat plate, a finite flat plate or a finite length cylinder. (The infinite flat plate is included for comparison with other multiple scattering programs.) The program may be used for any sample for which the scattering law is of the form S(/Q/, omega). 2 - Method of solution: Monte Carlo with importance sampling is used. Neutrons are 'forced' both into useful angular trajectories, and useful energy bins. Biasing of the collision point according to the point of entry of the neutron into the sample is also utilised. The first and second order scattered neutron fluxes are calculated in independent histories. For twice-scattered neutron histories a square distribution in Q-omega space is used to sample the neutron coming from the first scattering event, whilst biasing is used for the second scattering event. (A square distribution is used so as to obtain reasonable inelastic-inelastic statistics.) 3 - Restrictions on the complexity of the problem: Unlimited number of detectors. Max. size of (Q, omega) matrix is 39*149. Max. number of points in momentum space for the scattering cross section is 199

Neutron diffraction studies of magnetic materials

International Nuclear Information System (INIS)

James, W.J.

1987-01-01

The ability of neutron diffraction in determining the nature and extent of magnetic ordering is illustrated for the intermetallic compounds, Y/sub 6/(Fe,Mn)/sub 23/ and ErFe/sub 3/. Substitution with other 3d transition metals influences the Fe-Fe exchange forces such as to alter, sometimes considerably, the magnetic properties, e.g., local site magnetic anisotropies in Er)Fe,Ni)/sub 3/ and thermal expansion anomalies in the R/sub 2/)Fe,Co)/sub 14/B compounds. When the 3d atoms are near neighbors in the periodic chart, their nuclear scattering lengths for neutrons are sufficiently different to permit the detection of preferential occupation of the several nonequivalent crystallographic 3d metal sites, i.e., atomic ordering, present in the R/sub 6/M/sub 23/, and R/sub 2/Fe/sub 14/B structures

Inelastic neutron scattering in the spin wave energy gap of the polydomain γ-Mn(12%Ge) alloy

International Nuclear Information System (INIS)

Jankowska-Kisielinska, J.; Mikke, K.

1999-01-01

The subject of the present experiment was the investigation of the inelastic neutron scattering (INS) for energy transfers lower than and close to the energy gap of the spin wave spectrum for long wavelengths. The aim was a search for the excitations at the magnetic Brillouin zone (MBZ) boundary in polydomain Mn(12%Ge) alloy. The present measurements were performed by a 3-axis spectrometer at Maria Reactor at IEA in Swierk. We observed the INS in the polydomain Mn(12%Ge) alloy for energies smaller than and close to the energy gap value of the spin wave spectrum at room temperature. The observed intensity can be treated as a sum of intensity of neutrons scattered on spin waves around magnetic Brillouin zone centre and that of neutrons scattered on fluctuations at the zone boundary. The intensity of both components for energies 2-6 MeV was found to be of the same order. For higher energies spin waves around magnetic zone centre dominate. (author)

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).

Magnetic neutron diffraction of MnO thin films

International Nuclear Information System (INIS)

Neubeck, W.; Vettier, C.; Mannix, D.; Bernhoeft, N.; Hiess, A.; Ranno, L.; Givord, D.

1999-01-01

We report on magnetic neutron diffraction carried out on various epitaxial MnO(III) thin films grown on sapphire and MgO substrates. In all samples, of masses between 5 and 50 μg, magnetic Bragg peaks have been observed. The films exhibit what appears to be continuous phase-transitions in contrast to the strongly discontinuous transition exhibited by bulk samples. In addition, the Neel temperature of films prepared on sapphire substrates is strongly enhanced above that of the bulk whilst that of the film grown on MgO is depressed. The possibility to measure magnetic excitations in such thin film systems is discussed in the light of promising test results obtained from an inelastic magnetic neutron scattering experiment on the IN8 spectrometer. (authors)

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.

German neutron scattering conference. Programme and abstracts

International Nuclear Information System (INIS)

Brueckel, Thomas

2012-01-01

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.

Investigation into magnetic correlations in cuprates by means of neutron scattering experiments

International Nuclear Information System (INIS)

Henggeler, W.

1996-01-01

This thesis shows the results of our investigation on cuprate materials containing rare earth ions. The main experimental tools were inelastic and elastic neutron scattering techniques. In some cases we also performed μSR, susceptibility and specific heat measurements. One aim was to learn more about the crystalline environment of the rare earth ions in these substances via the crystalline electric field (CEF) interaction. Furthermore, we investigated the correlations of the magnetic moments of these ions by a determination of the dispersion of the CEF excitations. The theory that is essential for the understanding of this work is outlined. The instruments on which the experiments have been performed are presented in the third chapter. In the fourth chapter we show the measurements of the CEF excitations of Ho 3+ in Y 0.99 Ho 0.01 Ba 2 Cu 3 O 6+x . The Ho ions represent ideal local probes to examine changes of the charge distribution in the copper oxide planes upon doping with oxygen. To prevent any influence of the Ho-Ho exchange interaction on the CEF excitations we performed the experiments on substances containing only one percent of Ho. Our results show that for all the intermediately doped compounds the charge distribution is very inhomogeneous. For all the highly doped samples we observe a line asymmetry for which several possible origins are discussed. In the fifth chapter we examine the Pr 3+ CEF excitations in the Pr 2-x Ce x CuO 4(-δ) (0≤x≤0.2)-substances. Our results show a coexistence of different environments of the Pr ions in all the doped compounds. We try to describe these inhomogeneities with the help of a model. We used the μSR-technique on some of these samples in order to learn more about the oxygen reduction process. Finally, we performed inelastic neutron scattering experiments on Pr 1.86 Ce 0.14 CuO 4 single crystal, which allowed a direct determination of the coupling constants between the magnetic moments of the Pr ions. (author

Evaluation of room-scattered neutrons at the JNC Tokai neutron reference field

Energy Technology Data Exchange (ETDEWEB)

Yoshida, Tadayoshi; Tsujimura, Norio [Japan Nuclear Cycle Development Inst., Tokai, Ibaraki (Japan). Tokai Works; Oyanagi, Katsumi [Japan Radiation Engineering Co., Ltd., Hitachi, Ibaraki (Japan)

2002-09-01

Neutron reference fields for calibrating neutron-measuring devices in JNC Tokai Works are produced by using radionuclide neutron sources, {sup 241}Am-Be and {sup 252}Cf sources. The reference field for calibration includes scattered neutrons from the material surrounding sources, wall, floor and ceiling of the irradiation room. It is, therefore, necessary to evaluate the scattered neutrons contribution and their energy spectra at reference points. Spectral measurements were performed with a set of Bonner multi-sphere spectrometers and the reference fields were characterized in terms of spectral composition and the fractions of room-scattered neutrons. In addition, two techniques stated in ISO 10647, the shadow-cone method and the polynomial fit method, for correcting the contributions from the room-scattered neutrons to the readings of neutron survey instruments were compared. It was found that the two methods gave an equivalent result within a deviation of 3.3% at a source-to-detector distance from 50cm to 500cm. (author)

Evaluation of room-scattered neutrons at the JNC Tokai neutron reference field

International Nuclear Information System (INIS)

Yoshida, Tadayoshi; Tsujimura, Norio

2002-01-01

Neutron reference fields for calibrating neutron-measuring devices in JNC Tokai Works are produced by using radionuclide neutron sources, 241 Am-Be and 252 Cf sources. The reference field for calibration includes scattered neutrons from the material surrounding sources, wall, floor and ceiling of the irradiation room. It is, therefore, necessary to evaluate the scattered neutrons contribution and their energy spectra at reference points. Spectral measurements were performed with a set of Bonner multi-sphere spectrometers and the reference fields were characterized in terms of spectral composition and the fractions of room-scattered neutrons. In addition, two techniques stated in ISO 10647, the shadow-cone method and the polynomial fit method, for correcting the contributions from the room-scattered neutrons to the readings of neutron survey instruments were compared. It was found that the two methods gave an equivalent result within a deviation of 3.3% at a source-to-detector distance from 50cm to 500cm. (author)

Neutron scattering on molten transition metals and on Fe-C melts

International Nuclear Information System (INIS)

Weber, M.

1978-01-01

In order to find out whether short-range order phenomena can be detected in iron-carbon melts, neutron scattering experiments were carried out in molten iron-carbon alloys. The method of isotope substitution, where the natural alloying iron was substituted by a 57 Fe-enriched isotope mixture, helped to increase the ratio between the scattering length of the carbon atoms and that of the iron atoms. The mean coherent scattering length for the isotope mixture which is required for further evaluation of the measurements, was determined in an experiment by measuring the limiting angle for total reflection of neutrons on evaporated films. From this determination of the scattering length, a value for the so far unknown scattering length of the 58 Fe isotope was obtained. The small angle scattering in corrected intensity curves of molten Fe-C alloys was investigated in detail. Scattering experiments in unalloyed Fe, Co, and Ni in the range of small scattering vectors proved that this small-angle scattering effect, which was observed here for the first time, is of magnetic origin. It is caused by short-range spin correlations fluctuating with space and time. [de

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

Neutron scattering studies of solid electrolytes

International Nuclear Information System (INIS)

Shapiro, S.M.

1976-01-01

The role which neutron scattering can play in determining the nature of the disorder and the conducting mechanism in the solid electrolytes is discussed. First, some of the general formalism for elastic and inelastic neutron scattering is reviewed, and the quantities which can be measured are pointed out. Then the application of neutron scattering to the studies of three different problems is examined; the anion disorder in the fluorite system, the dynamical behavior in beta-alumina, and the cation diffusion in αAgI are discussed. 8 figures

Magnetic Interactions in Tb and Tb-10% Ho from Inelastic Neutron Scattering

DEFF Research Database (Denmark)

Bjerrum Møller, Hans; Houmann, Jens Christian Gylden; Mackintosh, A.R.

1968-01-01

The magnon dispersion relations and lifetimes have been measured in Tb and a Tb‐10% Ho alloy by inelastic neutron scattering, in regions of both ferromagnetic and spiral ordering. In the ferromagnetic phase, the magnon energy is generally finite at zero wavevector and rises quadratically at low q....... The magnon energies scale approximately with the magnetization. In the spiral phase the magnon energy rises linearly from zero at low q. The Fourier‐transformed exchange parameter J(q) has pronounced peaks in the c direction, which are ascribed to transitions between states close to the Fermi surface....... These peaks are less pronounced in the ferromagnetic phase. The primary mechanism limiting the magnon lifetimes appears to be interaction with the conduction electrons. In the alloy, the lifetime for magnons propagating in the c direction in the ferromagnetic phase falls abruptly at about q  =  0.35 Å−1...

Material classification by fast neutron scattering

Energy Technology Data Exchange (ETDEWEB)

Buffler, A. E-mail: abuffler@physci.uct.ac.za; Brooks, F.D. E-mail: brooks@physci.uct.ac.za; Allie, M.S.; Bharuth-Ram, K.; Nchodu, M.R

2001-02-01

The scattering of a beam of fast monoenergetic neutrons is used to determine elemental compositions of bulk samples (0.2-0.8 kg) of materials composed from one or more of the elements H, C, N, O, Al, S, Fe and Pb. Scattered neutrons are detected by liquid scintillators placed at forward and at backward angles. Different elements are identified by their characteristic scattering signatures derived either from a combination of time-of-flight and pulse height measurements, or from pulse height measurements alone. Scattering signatures measured for multi-element samples are analysed to determine atom fractions for H, C, N, O and other elements in the sample. Atom fractions determined from scattering signatures are insensitive to neutron interactions in material surrounding the scattering sample, provided the amount of material is not excessive. The atom fraction data are used to classify scattering material into categories including 'explosives', 'illicit drugs' and 'other materials' for the purpose of contraband detection.

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.

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.

BUILDING A NETWORK FOR NEUTRON SCATTERING EDUCATION

International Nuclear Information System (INIS)

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

2008-01-01

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 scattering education. A

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

Possible magnetism in vortex cores of superconducting TmNi{sub 2}B{sub 2}C studied by small angle neutron scattering

Energy Technology Data Exchange (ETDEWEB)

Abrahamsen, Asger Bech

2003-11-01

The compound TmNi{sub 2}B{sub 2}C has previously been studied by Small Angle Neutron Scattering(SANS) with the applied field along the crystalline c-axis and a very rich phase diagram in terms of flux line lattices(FLL) with different symmetries have been observed. One of the FLL transitions is coincident with a magnetic phase transition between two spin density waves. In this thesis additional SANS studies of the FLL phases in TmNi{sub 2}B{sub 2}C are reported and an interpretation of the phase diagram in the paramagnetic region is presented. It is suggested that the square FLL observed is stable in between two transition lines determined by two different length scales. The lower transition field is reached when the distance between the flux lines becomes comparable to the non-locality radius resulting from non-local electrodynamics, whereas the upper transition field is determined from the crossover from intermediate to high flux line density where the vortex cores start to overlap and the superconducting order parameter is suppressed in between the flux lines. A detailed examination of the intensity of the neutron diffraction spots caused by scattering on the flux line lattice in TmNi{sub 2}B{sub 2}C is presented and analyzed on the basis of the form factor of an isolated flux line. This analysis can not provide a good explanation for the observed scattering and it is suggested that the scattering from the Tm ions must be considered. One can argue that the moments of the Tm ions are modulated by the flux line lattice, because the Ruderman-Kittel- Kasuya-Yosida(RKKY) interaction between the Tm ions might be different inside the vortex cores than outside in the superconducting phase. A calculation of the neutron scattering cross section of such a magnetic flux line lattice has been performed and compared to the SANS data. This offers a qualitative explanation of some of the observations, but future work is needed to perform a more quantitative comparison. (au)

Toward a new polyethylene scattering law determined using inelastic neutron scattering

International Nuclear Information System (INIS)

Lavelle, C.M.; Liu, C.-Y.; Stone, M.B.

2013-01-01

Monte Carlo neutron transport codes such as MCNP rely on accurate data for nuclear physics cross-sections to produce accurate results. At low energy, this takes the form of scattering laws based on the dynamic structure factor, S(Q,E). High density polyethylene (HDPE) is frequently employed as a neutron moderator at both high and low temperatures, however the only cross-sections available are for ambient temperatures (∼300K), and the evaluation has not been updated in quite some time. In this paper we describe inelastic neutron scattering measurements on HDPE at 5 and 294 K which are used to improve the scattering law for HDPE. We review some of the past HDPE scattering laws, describe the experimental methods, and compare computations using these models to the measured S(Q,E). The total cross-section is compared to available data, and the treatment of the carbon secondary scatterer as a free gas is assessed. We also discuss the use of the measurement itself as a scattering law via the one phonon approximation. We show that a scattering law computed using a more detailed model for the Generalized Density of States (GDOS) compares more favorably to this experiment, suggesting that inelastic neutron scattering can play an important role in both the development and validation of new scattering laws for Monte Carlo work. -- Highlights: ► Polyethylene at 5 K and 300 K is measured using inelastic neutron scattering (INS). ► Measurements conducted at the Wide Angular-Range Chopper Spectrometer at SNS. ► Several models for Polyethylene are compared to measurements. ► Improvements to existing models for the polyethylene scattering law are suggested. ► INS is shown to be highly valuable tool for scattering law development

Report on inelastic neutron scattering for the Australian Replacement Research Reactor

International Nuclear Information System (INIS)

Cussen, L.

2001-01-01

The Replacement Reactor Project includes a sub project, the Neutron Beam Instrument project, to construct a suite of eight leading edge neutron scattering instruments to be ready at reactor start up in 2005. Amongst these will be an inelastic scattering instrument and this workshop explored the options that would best serve the future needs of the Australian neutron scattering community.Considering the dynamic range of each of these instruments and the ability to address the needs of the widest group of problems, the workshop endorsed the recommendation of the Beam Facilities Consultative Group to build a thermal neutron three-axis spectrometer, which offers the project the best opportunity and flexibility in terms of the available wave-vector and energy range. It was also recommend that priority consideration be given to developing cold neutron three-axis and time-of-flight spectrometers, perhaps in collaboration with outside organisations, after completion of the initial project. thermal neutron three axis spectrometer. The workshop recommended that such an instrument should be built at the reactor face on a thermal beam, using a double-focussing monochromator and analyser. Polarisation analysis should be available as an option and that the instrument perform at or close to world's best level. Recommendations were received on sample environment requirements and low temperature, high temperature and strong magnetic fields are seen as necessary

Reports of the study group for neutron scattering

International Nuclear Information System (INIS)

1982-01-01

This report covers the activities from July 1980 to December 1981. Within this period, the project for reactor extension (including a thermal neutron source and a hall for the neutron guide), was worked out in detail. Like the Fritz-Haber Institute, the Institute for Crystallography of Tuebingen University decided to send a number of guest-scientists for studies at the Hahn-Meitner Institute on a permanent basis. The HMI also organized the 5th International Conference on Small-Angle Scattering, held in Berlin in October 1980. The scientific research work was mainly concerned with magnetic systems, molecular crystals, and the determination of electron densities. (orig.)

Superconducting magnetic Wollaston prism for neutron spin encoding

Energy Technology Data Exchange (ETDEWEB)

Li, F., E-mail: fankli@indiana.edu; Parnell, S. R.; Wang, T.; Baxter, D. V. [Center for Exploration of Energy and Matter, Indiana University, Bloomington, Indiana 47408 (United States); Hamilton, W. A. [Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830 (United States); Maranville, B. B. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Semerad, R. [Ceraco Ceramic Coating GmbH, Ismaning 85737 (Germany); Cremer, J. T. [Adelphi Technology Inc., Redwood City, California 94063 (United States); Pynn, R. [Center for Exploration of Energy and Matter, Indiana University, Bloomington, Indiana 47408 (United States); Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830 (United States)

2014-05-15

A magnetic Wollaston prism can spatially split a polarized neutron beam into two beams with different neutron spin states, in a manner analogous to an optical Wollaston prism. Such a Wollaston prism can be used to encode the trajectory of neutrons into the Larmor phase associated with their spin degree of freedom. This encoding can be used for neutron phase-contrast radiography and in spin echo scattering angle measurement (SESAME). In this paper, we show that magnetic Wollaston prisms with highly uniform magnetic fields and low Larmor phase aberration can be constructed to preserve neutron polarization using high temperature superconducting (HTS) materials. The Meissner effect of HTS films is used to confine magnetic fields produced electromagnetically by current-carrying HTS tape wound on suitably shaped soft iron pole pieces. The device is cooled to ∼30 K by a closed cycle refrigerator, eliminating the need to replenish liquid cryogens and greatly simplifying operation and maintenance. A HTS film ensures that the magnetic field transition within the prism is sharp, well-defined, and planar due to the Meissner effect. The spin transport efficiency across the device was measured to be ∼98.5% independent of neutron wavelength and energizing current. The position-dependent Larmor phase of neutron spins was measured at the NIST Center for Neutron Research facility and found to agree well with detailed simulations. The phase varies linearly with horizontal position, as required, and the neutron beam shows little depolarization. Consequently, the device has advantages over existing devices with similar functionality and provides the capability for a large neutron beam (20 mm × 30 mm) and an increase in length scales accessible to SESAME to beyond 10 μm. With further improvements of the external coupling guide field in the prototype device, a larger neutron beam could be employed.

Superconducting magnetic Wollaston prism for neutron spin encoding

Science.gov (United States)

Li, F.; Parnell, S. R.; Hamilton, W. A.; Maranville, B. B.; Wang, T.; Semerad, R.; Baxter, D. V.; Cremer, J. T.; Pynn, R.

2014-05-01

A magnetic Wollaston prism can spatially split a polarized neutron beam into two beams with different neutron spin states, in a manner analogous to an optical Wollaston prism. Such a Wollaston prism can be used to encode the trajectory of neutrons into the Larmor phase associated with their spin degree of freedom. This encoding can be used for neutron phase-contrast radiography and in spin echo scattering angle measurement (SESAME). In this paper, we show that magnetic Wollaston prisms with highly uniform magnetic fields and low Larmor phase aberration can be constructed to preserve neutron polarization using high temperature superconducting (HTS) materials. The Meissner effect of HTS films is used to confine magnetic fields produced electromagnetically by current-carrying HTS tape wound on suitably shaped soft iron pole pieces. The device is cooled to ˜30 K by a closed cycle refrigerator, eliminating the need to replenish liquid cryogens and greatly simplifying operation and maintenance. A HTS film ensures that the magnetic field transition within the prism is sharp, well-defined, and planar due to the Meissner effect. The spin transport efficiency across the device was measured to be ˜98.5% independent of neutron wavelength and energizing current. The position-dependent Larmor phase of neutron spins was measured at the NIST Center for Neutron Research facility and found to agree well with detailed simulations. The phase varies linearly with horizontal position, as required, and the neutron beam shows little depolarization. Consequently, the device has advantages over existing devices with similar functionality and provides the capability for a large neutron beam (20 mm × 30 mm) and an increase in length scales accessible to SESAME to beyond 10 μm. With further improvements of the external coupling guide field in the prototype device, a larger neutron beam could be employed.

Phase transitions and neutron scattering

International Nuclear Information System (INIS)

Shirane, G.

1993-01-01

A review is given of recent advances in neutron scattering studies of solid state physics. I have selected the study of a structural phase transition as the best example to demonstrate the power of neutron scattering techniques. Since energy analysis is relatively easy, the dynamical aspects of a transition can be elucidated by the neutron probe. I shall discuss in some detail current experiments on the 100 K transition in SrTiO 3 , the crystal which has been the paradigm of neutron studies of phase transitions for many years. This new experiment attempts to clarify the relation between the neutron central peak, observed in energy scans, and the two length scales observed in recent x-ray diffraction studies where only scans in momentum space are possible. (author)

Commercial applications of neutron scattering

International Nuclear Information System (INIS)

Hutchings, M.T.

1993-01-01

The fact that industry is now willing to pay the full commercial cost for certain neutron scattering experiments aimed at solving its urgent materials - related problems is a true testimony to the usefulness of neutrons as microscopic probes. This paper gives examples of such use of three techniques drawn mainly from our experience at AEA Technology Harwell Laboratory. These are diffraction to measure residual stress, small angle neutron scattering to examine hardening precipitates in ferritic steels brought about by irradiation, and reflectivity to study amorphous diamond layers deposited on silicon. In most cases it is the penetrative power of the neutron which proves to be its best asset for commercial industrial applicaitons. (author)

Neutron scattering studies in the actinide region

International Nuclear Information System (INIS)

Beghian, L.E.; Kegel, G.H.R.

1991-08-01

During the report period we have investigated the following areas: Neutron elastic and inelastic scattering measurements on 14 N, 181 Ta, 232 Th, 238 U and 239 Pu; Prompt fission spectra for 232 Th, 235 U, 238 U and 239 Pu; Theoretical studies of neutron scattering; Neutron filters; New detector systems; and Upgrading of neutron target assembly, data acquisition system, and accelerator/beam-line apparatus

Developments of the neutron scattering analysis method for the determination of magnetic structures

Energy Technology Data Exchange (ETDEWEB)

Park, Je-Geun; Chung, Jae Gwan; Park, Jung Hwan; Kong, Ung Girl [Inha Univ., Incheon (Korea); So, Ji Yong [Seoul National University, Seoul(Korea)

2001-04-01

Neutron diffraction is up to now almost the only and very important experimental method of determining the magnetic structure of materials. Unlike the studies of crystallographic structure, however to use neutron diffraction for magnetic structure determination is not easily accessible to non-experts because of the complexity of magnetic group theory: which is very important in the magnetic structure analysis. With the recent development of computer code for magnetic group, it is now time to rethink of these difficulties. In this work, we have used the computer code of the magnetic group (Mody-2) and Fullprof refinement program in order to study the magnetic structure of YMnO{sub 3} and other interesting materials. YMnO{sub 3} forms in the hexagonal structure and show both ferroelectric and antiferromagnetic phase transitions. Since it was recently found that YMnO{sub 3} can be used as a nonvolatile memory device, there has been many numbers of applied research on this material. We used neutron diffraction to determine the magnetic structure, and, in particular, to investigate the correlation between the order parameters of the ferroelectric and antiferromagnetic phase transitions. From this study, we have demonstrated that with a proper use of the computer code of the magnetic group one can overcome most of difficulties arising from the magnetic group theory. 4 refs., 8 figs., 5 tabs. (Author)

Instruments and accessories for neutron scattering research

International Nuclear Information System (INIS)

Ishii, Yoshinobu; Morii, Yukio

2000-04-01

This report describes neutron scattering instruments and accessories installed by four neutron scattering research groups at the ASRC (Advanced Science Research Center) of the JAERI and the recent topics of neutron scattering research using these instruments. The specifications of nine instruments (HRPD, BIX-I, TAS-1 and PNO in the reactor hall, RESA, BIX-II, TAS-2, LTAS and SANS-J in the guide hall of the JRR-3M) are summarized in this booklet. (author)

Neutrons scattering studies in the actinide region

International Nuclear Information System (INIS)

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

1992-09-01

During the report period were investigated the following areas: prompt fission neutron energy spectra measurements; neutron elastic and inelastic scattering from 239 Pu; neutron scattering in 181 Ta and 197 Au; response of a 235 U 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

Quasi-free Compton scattering and the polarizabilities of the neutron

International Nuclear Information System (INIS)

Kossert, K.; Camen, M.; Wissmann, F.; Schumacher, M.; Seitz, B.; Ahrens, J.; Arends, H.J.; Beck, R.; Caselotti, G.; Jahn, O.; Jennewein, P.; Olmos de Leon, V.; Annand, J.R.M.; McGeorge, J.C.; Rosner, G.; Grabmayr, P.; Natter, A.; Levchuk, M.I.; L'vov, A.I.; Petrun'kin, V.A.; Smend, F.; Thomas, A.; Weihofen, W.; Zapadtka, F.

2003-01-01

Differential cross-sections for quasi-free Compton scattering from the proton and neutron bound in the deuteron have been measured using the Glasgow/Mainz photon tagging spectrometer at the Mainz MAMI accelerator together with the Mainz 48cm diameter x 64cm NaI(Tl) photon detector and the Goettingen SENECA recoil detector. The data cover photon energies ranging from 200MeV to 400MeV at θ LAB γ =136.2 . Liquid deuterium and hydrogen targets allowed direct comparison of free and quasi-free scattering from the proton. The neutron detection efficiency of the SENECA detector was measured via the reaction p(γ,π + n). The ''free'' proton Compton scattering cross-sections extracted from the bound proton data are in reasonable agreement with those for the free proton which gives confidence in the method to extract the differential cross-section for free scattering from quasi-free data. Differential cross-sections on the free neutron have been extracted and the difference of the electromagnetic polarizabilities of the neutron has been determined to be α n -β n =9.8±3.6(stat) +2.1 -1.1 (syst)±2.2(model) in units of 10 -4 fm 3 . In combination with the polarizability sum α n +β n =15.2±0.5 deduced from photoabsorption data, the neutron electric and magnetic polarizabilities, α n =12.5±1.8(stat) + 1 .1 -0.6 (syst)±1.1(model) and β n =2.7±1.8(stat) +0.6 -1.1 (syst)±1.1(model) are obtained. The backward spin polarizability of the neutron was determined to be γ (n) π =(58.6±4.0) x 10 -4 fm 4 . (orig.)

Next generation neutron scattering at Neutron Science Center project in JAERI

International Nuclear Information System (INIS)

Yamada, Yasusada; Watanabe, Noboru; Niimura, Nobuo; Morii, Yukio; Katano, Susumu; Aizawa, Kazuya; Suzuki, Jun-ichi; Koizumi, Satoshi; Osakabe, Toyotaka.

1997-01-01

Japan Atomic Energy Research Institute (JAERI) has promoted neutron scattering researches by means of research reactors in Tokai Research Establishment, and proposes 'Neutron Science Research Center' to develop the future prospect of the Tokai Research Establishment. The scientific fields which will be expected to progress by the neutron scattering experiments carried out at the proposed facility in the Center are surveyed. (author)

Magnetic field strength of a neutron-star-powered ultraluminous X-ray source

Science.gov (United States)

Brightman, M.; Harrison, F. A.; Fürst, F.; Middleton, M. J.; Walton, D. J.; Stern, D.; Fabian, A. C.; Heida, M.; Barret, D.; Bachetti, M.

2018-04-01

Ultraluminous X-ray sources (ULXs) are bright X-ray sources in nearby galaxies not associated with the central supermassive black hole. Their luminosities imply they are powered by either an extreme accretion rate onto a compact stellar remnant, or an intermediate mass ( 100-105M⊙) black hole1. Recently detected coherent pulsations coming from three bright ULXs2-5 demonstrate that some of these sources are powered by accretion onto a neutron star, implying accretion rates significantly in excess of the Eddington limit, a high degree of geometric beaming, or both. The physical challenges associated with the high implied accretion rates can be mitigated if the neutron star surface field is very high (1014 G)6, since this suppresses the electron scattering cross-section, reducing the radiation pressure that chokes off accretion for high luminosities. Surface magnetic field strengths can be determined through cyclotron resonance scattering features7,8 produced by the transition of charged particles between quantized Landau levels. Here, we present the detection at a significance of 3.8σ of an absorption line at 4.5 keV in the Chandra spectrum of a ULX in M51. This feature is likely to be a cyclotron resonance scattering feature produced by the strong magnetic field of a neutron star. Assuming scattering off electrons, the magnetic field strength is implied to be 1011 G, while protons would imply a magnetic field of B 1015 G.

Neutron scattering studies on magnetic excitations in complex ordered manganites

International Nuclear Information System (INIS)

Senff, D.

2007-09-01

This thesis deals with magnetic excitations in three different Manganese oxides, single-layered LaSrMnO 4 , charge- and orbital-ordered La 1/2 Sr 3/2 MnO 4 , and multiferroic TbMnO 3 , which are studied by means of inelastic neutron scattering. The properties of the first system, LaSrMnO 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 4 suggests a heterogenous ground state with ferromagnetic orbital polarons embedded in an antiferromagnetic background. The doped system La 1/2 Sr 3/2 MnO 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 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 allows to identify all relevant modes of the

Early Years of Neutron Scattering and Its Manpower Development in Indonesia

International Nuclear Information System (INIS)

Marsongkohadi

2008-01-01

In this paper I shall give a short history of the development of neutron scattering at the Research Centre for Nuclear Techniques (PPTN), in Bandung, and the early development of a more advanced facilities at the Neutron Scattering Laboratory (NSL BATAN), Centre of Technology for Nuclear Industrial Materials, in Serpong. The first research reactor in Indonesia was the TRIGA MARK II in Bandung, which became operational in 1965, with a power of 250 KW, upgraded to 1 MW in 1971, and to 2 MW in 2000. The neutron scattering activities was started in 1967, with the design and construction of the first powder diffractometer, and put in operation in 1970. It was followed by the second instrument, the filter detector spectrometer built in 1975 in collaboration with the Bhabha Atomic Research Centre (BARC), India. A powder diffractometer for magnetic studies was built in 1980, and finally, a modification of the filter detector spectrometer to measure textures was made in 1986. A brief description of the design and construction of the instruments, and a highlight of some research topics will be presented. Early developments of neutron scattering activities at the 30 MW, RSG-GAS reactor in Serpong in choosing suitable research program, which will be mainly centred around materials testing/characterization, and materials/condensed matter researches has been agreed. Instrument planning and layout which were appropriate to carry out the program had been decided. Manpower development for the neutron scattering laboratory is a severe problem. The efforts to overcome this problem has been solved. International Cooperation through workshops and on the job trainings also support the supply of qualified manpower

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.

American Conference on Neutron Scattering 2014

International Nuclear Information System (INIS)

Dillen, J. Ardie

2014-01-01

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.

Neutron scattering from (CD3ND3)2MnCl4

International Nuclear Information System (INIS)

Lehner, N.

1978-12-01

For the perovskite-type crystal (CD 3 ND 3 ) 2 MnCl 4 neutron scattering experiments were performed concerning the magnetic behaviour, critical phenomena and lattice dynamics. The crystal is built up from layers, resulting in a quasi two-dimensional antiferromagnetic order, whereas the lattice dynamics shows a more three-dimensional behaviour; this can be explained by long-range Coulomb forces. Only the correlation lengths, which were determined by critical scattering, show a pronounced anisotropy. (orig.) [de

Applications of polarized neutrons

International Nuclear Information System (INIS)

Mezei, F.

1993-01-01

The additional spin degree of freedom of the neutron can be made use of in neutron scattering work in two fundamental ways: (a) directly for the identification of magnetic scattering effects and (b) indirectly as a spectroscopic tool for modulating and analysing beams. Although strong magnetic scattering contributions can often be studied by unpolarized neutrons, a fully unambiguous separation of nuclear and magnetic phenomena can only be achieved by the additional information provided by polarized neutrons, especially if one of the two kinds of contributions is weak compared to the other. In the most general case a sample with both magnetic and nuclear features can be characterized by as many as 16 independent dynamic correlation functions instead of the single well known S(q, ω) for non-magnetic nuclear scattering only. Polarization analysis in principle allows one to determine all these 16 functions. The indirect applications of polarized neutrons are also steadily gaining importance. The most widely used method of this kind, the application of Larmor precessions for high resolution energy analysis in Neutron Spin Echo spectroscopy opened up a whole new domain in inelastic neutron scattering which was not accessible to any other spectroscopic method with or without neutrons before. (author)

Neutron scattering instruments for the Spallation Neutron Source (SNS)

International Nuclear Information System (INIS)

Crawford, R.K.; Fornek, T.; Herwig, K.W.

1998-01-01

The Spallation Neutron Source (SNS) is a 1 MW pulsed spallation source for neutron scattering planned for construction at Oak Ridge National Laboratory. This facility is being designed as a 5-laboratory collaboration project. This paper addresses the proposed facility layout, the process for selection and construction of neutron scattering instruments at the SNS, the initial planning done on the basis of a reference set of ten instruments, and the plans for research and development (R and D) to support construction of the first ten instruments and to establish the infrastructure to support later development and construction of additional instruments

Non-destructive diagnostics of irradiated materials using neutron scattering from pulsed neutron sources

Energy Technology Data Exchange (ETDEWEB)

Korenev, Sergey E-mail: sergey_korenev@steris.com; Sikolenko, Vadim

2004-10-01

The advantage of neutron-scattering studies as compared to the standard X-ray technique is the high penetration of neutrons that allow us to study volume effects. The high resolution of instrumentation on the basis neutron scattering allows measurement of the parameters of lattice structure with high precision. We suggest the use of neutron scattering from pulsed neutron sources for analysis of materials irradiated with pulsed high current electron and ion beams. The results of preliminary tests using this method for Ni foils that have been studied by neutron diffraction at the IBR-2 (Pulsed Fast Reactor at Joint Institute for Nuclear Research) are presented.

Non-destructive diagnostics of irradiated materials using neutron scattering from pulsed neutron sources

Science.gov (United States)

Korenev, Sergey; Sikolenko, Vadim

2004-09-01

The advantage of neutron-scattering studies as compared to the standard X-ray technique is the high penetration of neutrons that allow us to study volume effects. The high resolution of instrumentation on the basis neutron scattering allows measurement of the parameters of lattice structure with high precision. We suggest the use of neutron scattering from pulsed neutron sources for analysis of materials irradiated with pulsed high current electron and ion beams. The results of preliminary tests using this method for Ni foils that have been studied by neutron diffraction at the IBR-2 (Pulsed Fast Reactor at Joint Institute for Nuclear Research) are presented.

Set of thermal neutron-scattering experiments for the Weapons Neutron Research Facility

International Nuclear Information System (INIS)

Brugger, R.M.

1975-12-01

Six classes of experiments form the base of a program of thermal neutron scattering at the Weapons Neutron Research (WNR) Facility. Three classes are to determine the average microscopic positions of atoms in materials and three are to determine the microscopic vibrations of these atoms. The first three classes concern (a) powder sample neutron diffraction, (b) small angle scattering, and (c) single crystal Laue diffraction. The second three concern (d) small kappa inelastic scattering, (e) scattering surface phonon measurements, and (f) line widths. An instrument to couple with the WNR pulsed source is briefly outlined for each experiment

Introduction to neutron scattering. Lecture notes of the introductory course

International Nuclear Information System (INIS)

Furrer, A.

1996-01-01

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

New Techniques in Neutron Scattering

DEFF Research Database (Denmark)

Birk, Jonas Okkels

potential performance than any existing facility, however in order to use this pulse structure optimally many existing neutron scattering instruments will need to be redesigned. This defense will concentrate on the design and optimization of the inverse time-of-flight cold neutron spectrometer CAMEA......, simulations and prototyping to optimize the instrument and ensure that it will deliver the predicted performance when constructed. During the design a new prismatic analyser concept that can be of interest to many other neutron spectrometers was developed. The design work was compiled into an instrument......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...

ELECTRON SCATTERING EXPERIMENTS ON THE NEUTRON AND PROTON

Energy Technology Data Exchange (ETDEWEB)

Berkelman, Karl

1963-06-15

The electric and magnetic helicity form factors of the proton are measured at 4-momentum transfers (squared) of 25 to 45 f/sup -2/, by means of electron scattering by protons at high energies. The results are combined with other e/sup -/--p and e/sup -/--d experimental findings in order to show the proton form fuctors from 0 to 45 f/sup -2/ and the neutron form factors from 0 to 25 f/sup -2/. (T.F.H.)

The analysis and correction of neutron scattering effects in neutron imaging

International Nuclear Information System (INIS)

Raine, D.A.; Brenizer, J.S.

1997-01-01

A method of correcting for the scattering effects present in neutron radiographic and computed tomographic imaging has been developed. Prior work has shown that beam, object, and imaging system geometry factors, such as the L/D ratio and angular divergence, are the primary sources contributing to the degradation of neutron images. With objects smaller than 20--40 mm in width, a parallel beam approximation can be made where the effects from geometry are negligible. Factors which remain important in the image formation process are the pixel size of the imaging system, neutron scattering, the size of the object, the conversion material, and the beam energy spectrum. The Monte Carlo N-Particle transport code, version 4A (MCNP4A), was used to separate and evaluate the effect that each of these parameters has on neutron image data. The simulations were used to develop a correction algorithm which is easy to implement and requires no a priori knowledge of the object. The correction algorithm is based on the determination of the object scatter function (OSF) using available data outside the object to estimate the shape and magnitude of the OSF based on a Gaussian functional form. For objects smaller than 1 mm (0.04 in.) in width, the correction function can be well approximated by a constant function. Errors in the determination and correction of the MCNP simulated neutron scattering component were under 5% and larger errors were only noted in objects which were at the extreme high end of the range of object sizes simulated. The Monte Carlo data also indicated that scattering does not play a significant role in the blurring of neutron radiographic and tomographic images. The effect of neutron scattering on computed tomography is shown to be minimal at best, with the most serious effect resulting when the basic backprojection method is used

Applications of thermal neutron scattering in biology, biochemistry and biophysics

International Nuclear Information System (INIS)

Worcester, D.L.

1977-01-01

Biological applications of thermal neutron scattering have increased rapidly in recent years. The following categories of biological research with thermal neutron scattering are presently identified: crystallography of biological molecules; neutron small-angle scattering of biological molecules in solution (these studies have already included numerous measurements of proteins, lippoproteins, viruses, ribosomal subunits and chromatin subunit particles); neutron small-angle diffraction and scattering from biological membranes and membrane components; and neutron quasielastic and inelastic scattering studies of the dynamic properties of biological molecules and materials. (author)

In-depth magnetic characterization of a [2 × 2] Mn(III) square grid using SQUID magnetometry, inelastic neutron scattering, and high-field electron paramagnetic resonance spectroscopy

DEFF Research Database (Denmark)

Konstantatos, Andreas; Bewley, Robert; Barra, Anne Laure

2016-01-01

. Combined inelastic neutron scattering (INS) and electron paramagnetic resonance (EPR) experiments provided the necessary information in order to successfully model the magnetic properties of Mn4. The resulting model takes into account both the magnitude and the relative orientations of the single...

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.)

Fast-neutron scattering from elemental cadmium

International Nuclear Information System (INIS)

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

1982-07-01

Neutron differential-elastic-scattering cross sections of elemental cadmium are measured from approx. = 1.5 to 4.0 MeV at incident-neutron energy intervals of 50 to 200 keV and at 10 to 20 scattering angles distributed between approx. = 20 and 160 degrees. Concurrently, lumped-level neutron inelastic-excitation cross sections are measured. The experimental results are used to deduce parameters of an optical-statistical model that is descriptive of the observables and are compared with corresponding quantities given in ENDF/B-V

Point defects and magnetic properties of neutron irradiated MgO single crystal

Directory of Open Access Journals (Sweden)

Mengxiong Cao

2017-05-01

Full Text Available (100-oriented MgO single crystals were irradiated to introduce point defects with different neutron doses ranging from 1.0×1016 to 1.0×1020 cm-2. The point defect configurations were studied with X-ray diffuse scattering and UV-Vis absorption spectra. The isointensity profiles of X-ray diffuse scattering caused by the cubic and double-force point defects in MgO were theoretically calculated based on the Huang scattering theory. The magnetic properties at different temperature were measured with superconducting quantum interference device (SQUID. The reciprocal space mappings (RSMs of irradiated MgO revealed notable diffuse scattering. The UV-Vis spectra indicated the presence of O Frenkel defects in irradiated MgO. Neutron-irradiated MgO was diamagnetic at room temperature and became ferromagnetic at low temperature due to O Frenkel defects induced by neutron-irradiation.

Slow neutron scattering experiments

International Nuclear Information System (INIS)

Moon, R.M.

1985-01-01

Neutron scattering is a versatile technique that has been successfully applied to condensed-matter physics, biology, polymer science, chemistry, and materials science. The United States lost its leadership role in this field to Western Europe about 10 years ago. Recently, a modest investment in the United States in new facilities and a positive attitude on the part of the national laboratories toward outside users have resulted in a dramatic increase in the number of US scientists involved in neutron scattering research. Plans are being made for investments in new and improved facilities that could return the leadership role to the United States. 23 references, 4 figures, 3 tables

Current status of neutron scattering in Thailand

International Nuclear Information System (INIS)

Ampornrat, Pantip

1999-01-01

Thailand's neutron spectrometer has been installed soon after the startup of the reactor. The neutron scattering experiments have been done continuously, although there were some problems involving the neutron intensity and instruments. Development program has been planned for better experimental result. This paper reports the past and present status of neutron scattering equipment and experiments in Thailand. In addition, installation of a HRPD (High Resolution Powder Diffraction) system is included within the scope of the Ongkharak Nuclear Research Center project. (author)

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)

Estimation of Amount of Scattered Neutrons at Devices PFZ and GIT-12 by MCNP Simulations

Directory of Open Access Journals (Sweden)

Ondrej Šíla

2013-01-01

Full Text Available Our work is dedicated to pinch effect occurring during current discharge in deuterium plasma, and our results are connected with two devices – plasma focus PFZ, situated in the Faculty of Electrical Engineering, CTU, Prague, and Z-pinch GIT-12, which is situated in the Institute of High Current Electronics, Tomsk. During fusion reactions that proceed in plasma during discharge, neutrons are produced. We use neutrons as instrument for plasma diagnostics. Despite of the advantage that neutrons do not interact with electric and magnetic fields inside device, they are inevitably scattered by materials that are placed between their source and probe, and information about plasma from which they come from is distorted. For estimation of rate of neutron scattering we use MCNP code.

Magnetic compound refractive lens for focusing and polarizing cold neutron beams

International Nuclear Information System (INIS)

Littrell, K. C.; Velthuis, S. G. E. te; Felcher, G. P.; Park, S.; Kirby, B. J.; Fitzsimmons, M. R.

2007-01-01

Biconcave cylindrical lenses are used to focus beams of x rays or neutrons using the refractive properties of matter. In the case of neutrons, the refractive properties of magnetic induction can similarly focus and simultaneously polarize the neutron beam without the concomitant attenuation of matter. This concept of a magnetic refractive lens was tested using a compound lens consisting of 99 pairs of cylindrical permanent magnets. The assembly successfully focused the intensity of a white beam of cold neutrons of one spin state at the detector, while defocusing the other. This experiment confirmed that a lens of this nature may boost the intensity locally by almost an order of magnitude and create a polarized beam. An estimate of the performance of a more practically dimensioned device suitable for incorporation in reflectometers and slit-geometry small angle scattering instruments is given

Magnetic compound refractive lens for focusing and polarizing cold neutron beams.

Science.gov (United States)

Littrell, K C; te Velthuis, S G E; Felcher, G P; Park, S; Kirby, B J; Fitzsimmons, M R

2007-03-01

Biconcave cylindrical lenses are used to focus beams of x rays or neutrons using the refractive properties of matter. In the case of neutrons, the refractive properties of magnetic induction can similarly focus and simultaneously polarize the neutron beam without the concomitant attenuation of matter. This concept of a magnetic refractive lens was tested using a compound lens consisting of 99 pairs of cylindrical permanent magnets. The assembly successfully focused the intensity of a white beam of cold neutrons of one spin state at the detector, while defocusing the other. This experiment confirmed that a lens of this nature may boost the intensity locally by almost an order of magnitude and create a polarized beam. An estimate of the performance of a more practically dimensioned device suitable for incorporation in reflectometers and slit-geometry small angle scattering instruments is given.

Inelastic Neutron Scattering Study of Mn

Energy Technology Data Exchange (ETDEWEB)

Zhong, Y.; Sarachik, M.P.; Friedman, J.R.; Robinson, R.A.; Kelley, T.M.; Nakotte, H.; Christianson, A.C.; Trouw, F.; Aubin, S.M.J.; Hendrickson, D.N.

1998-11-09

The authors report zero-field inelastic neutron scattering experiments on a 14-gram deuterated sample of Mn{sub 12}-Acetate consisting of a large number of identical spin-10 magnetic clusters. Their resolution enables them to see a series of peaks corresponding to transitions between the anisotropy levels within the spin-10 manifold. A fit to the spin Hamiltonian H = {minus}DS{sub z}{sup 2} + {mu}{sub B}B{center_dot}g{center_dot}S-BS{sub z}{sup 4} + C(S{sub +}{sup 4} + S{sub {minus}}{sup 4}) yields an anisotropy constant D = (0.54 {+-} 0.02) K and a fourth-order diagonal anisotropy coefficient B = (1.2 {+-} 0.1) x 10{sup {minus}3}K. Unlike EPR measurements, their experiments do not require a magnetic field and yield parameters that do not require knowledge of the g-value.

Neutron scattering study of the magnetic phases of USb_0.8Te_0.2

DEFF Research Database (Denmark)

Langridge, S.; Stirling, W.G.; Nuttall, W.J.

1995-01-01

The magnetic phases of USb0.8Te0.2 have been studied by neutron diffraction. Above the ordering temperature a detailed study has been made of the critical scattering and of the anisotropy between correlations parallel and perpendicular to the ordering wave vector....

Background determination for the neutron-neutron scattering experiment at the reactor YAGUAR

Energy Technology Data Exchange (ETDEWEB)

Muzichka, A.Yu. [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Furman, W.I. [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Lychagin, E.V. [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Krylov, A.R. [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Nekhaev, G.V. [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Sharapov, E.I. [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Shvetsov, V.N. [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Strelkov, A.V. [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Levakov, B.G. [Russian Federal Nuclear Center-All-Russian Research Institute of Technical Physics, PO Box 245, 456770 Snezhinsk (Russian Federation); Lyzhin, A.E. [Russian Federal Nuclear Center-All-Russian Research Institute of Technical Physics, PO Box 245, 456770 Snezhinsk (Russian Federation); Chernukhin, Yu.I. [Russian Federal Nuclear Center-All-Russian Research Institute of Technical Physics, PO Box 245, 456770 Snezhinsk (Russian Federation); Kandiev, Ya.Z. [Russian Federal Nuclear Center-All-Russian Research Institute of Technical Physics, PO Box 245, 456770 Snezhinsk (Russian Federation); Howell, C.R. [Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Mitchell, G.E. [North Carolina State University, Raleigh, NC 27695-8202 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Crawford, B.E. [Gettysburg College, Box 405, Gettysburg, PA 17325 (United States); Stephenson, S.L. [Gettysburg College, Box 405, Gettysburg, PA 17325 (United States)]. E-mail: sstephen@gettysburg.edu; Tornow, W. [Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States)

2007-06-01

The motivation and design is outlined for the experiment to measure the neutron-neutron singlet scattering length directly with thermal neutrons at the pulsed reactor YAGUAR. A statistical accuracy of 3% can be reached, though achieving the goal of an overall accuracy of 3-5% for the nn-scattering length depends on the background level. Possible sources of background are discussed in depth and the results of extensive modeling of the background are presented. Measurements performed at YAGUAR to test these background calculations are described. The experimental results indicate an anticipated background level up to 30% relative to the expected nn effect at the maximal energy burst of the reactor. The conclusion is made that the nn experiment at YAGUAR is feasible to produce the first directly measured value for the neutron-neutron scattering length.

On the neutron charge radius and the new experiments proposed for the precise (n,e) - scattering length measurement

International Nuclear Information System (INIS)

Enik, T.L.; Mitsyna, L.V.; Nikolenko, V.G.; Oprea, I.A.; Parzhitsky, S.S.; Popov, A.B.; Samosvat, G.S.; Vtiuryn, V.A.

1999-01-01

Relationship between the n,e scattering length, b ne , the neutron mean square charge radius n 2 > and anomalous magnetic moment μ n , the quantities which characterize the internal structure of the neutron, was investigated. The performed analysis showed that in the framework of the modern cloudy bag model (CBM) of the nucleon the values of b ne is determined by the value of n 2 > without the so-called Foldy term being taken into account, while in the framework of the phenomenological Foldy approach the experimental values of ne > obtained up to date can be described only by this Foldy term within an accuracy of about 10%, i.e. by the anomalous magnetic moment of the neutron, μ n . Then a necessity is obvious to obtain b ne with higher accuracy than in previous experiments. To remove the contradictions in the experimental b ne estimates, new experiments to measure the energy dependence of the slow neutron scattering cross section by 86 Kr and scattering anisotropy on Xe isotopes, have been proposed. The investigation has been performed at Frank Laboratory of Neutron Physics, JINR. (authors)

Study of scattering in bi-dimensional neutron radiographic images

International Nuclear Information System (INIS)

Oliveira, K.A.M. de; Crispim, V.R.; Silva, F.C.

2009-01-01

The effect of neutron scattering frequently causes distortions in neutron radiographic images and, thus, reduces the quality. In this project, a type of filter, comprised of cadmium (a neutron absorber), was used in the form of a grid to correct this effect. This device generated image data in the discrete shadow bands of the absorber, components relative to neutron scattering on the test object and surroundings. Scattering image data processing, together with the original neutron radiographic image, resulted in a corrected image with improved edge delineation and, thus, greater definition in the neutron radiographic image of the test object. The objective of this study is to propose a theoretical/experimental methodology that is capable of eliminating the components relative to neutron scattering in neutron radiographic images, coming from the material that composes the test object and the materials that compose the surrounding area. (author)

Demonstration of Focusing Wolter Mirrors for Neutron Phase and Magnetic Imaging

Directory of Open Access Journals (Sweden)

Daniel S. Hussey

2018-03-01

Full Text Available Image-forming focusing mirrors were employed to demonstrate their applicability to two different modalities of neutron imaging, phase imaging with a far-field interferometer, and magnetic-field imaging through the manipulation of the neutron beam polarization. For the magnetic imaging, the rotation of the neutron polarization in the magnetic field was measured by placing a solenoid at the focus of the mirrors. The beam was polarized upstream of the solenoid, while the spin analyzer was situated between the solenoid and the mirrors. Such a polarized neutron microscope provides a path toward considerably improved spatial resolution in neutron imaging of magnetic materials. For the phase imaging, we show that the focusing mirrors preserve the beam coherence and the path-length differences that give rise to the far-field moiré pattern. We demonstrated that the visibility of the moiré pattern is modified by small angle scattering from a highly porous foam. This experiment demonstrates the feasibility of using Wolter optics to significantly improve the spatial resolution of the far-field interferometer.

Local-field refinement of neutron scattering lengths

International Nuclear Information System (INIS)

Sears, V.F.

1985-01-01

We examine the way in which local field effects in the neutron refractive index affect the values of coherent scattering lengths determined by various kinds of neutron optical measurements. We find that under typical experimental conditions these effects are negligible for interferometry measurements but that they are significant for gravity refractometry measurements, producing changes in the effective scattering length of as much as two or three standard deviations in some cases. Refined values of the scattering length are obtained for the thirteen elements for which data are presently available. The special role of local field effects in neutron transmission is also discussed. (orig.)

Local-field refinement of neutron scattering lengths

Energy Technology Data Exchange (ETDEWEB)

Sears, V F

1985-06-01

We examine the way in which local field effects in the neutron refractive index affect the values of coherent scattering lengths determined by various kinds of neutron optical measurements. We find that under typical experimental conditions these effects are negligible for interferometry measurements but that they are significant for gravity refractometry measurements, producing changes in the effective scattering length of as much as two or three standard deviations in some cases. Refined values of the scattering length are obtained for the thirteen elements for which data are presently available. The special role of local field effects in neutron transmission is also discussed.

Compact turnkey focussing neutron guide system for inelastic scattering investigations

Energy Technology Data Exchange (ETDEWEB)

Brandl, G., E-mail: g.brandl@fz-juelich.de [Heinz Maier-Leibnitz Zentrum (MLZ) and Physik Department E21, Technische Universität München, 85748 Garching, Germany and Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum - MLZ, Forschungszentrum Jülich GmbH, 85748 Garching (Germany); Georgii, R. [Heinz Maier-Leibnitz Zentrum (MLZ) and Physik Department E21, Technische Universität München, 85748 Garching (Germany); Dunsiger, S. R. [Physik Department E21, Technische Universität München, 85748 Garching, Germany and Center for Emergent Materials, Ohio State University, Columbus, Ohio 43210-1117 (United States); Tsurkan, V. [Experimental Physics V, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, 86159 Augsburg, Germany and Institute of Applied Physics, Academy of Sciences of Moldova, MD 2028 Chisinau, Republic of Moldova (Germany); Loidl, A. [Experimental Physics V, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, 86159 Augsburg (Germany); Adams, T.; Pfleiderer, C.; Böni, P. [Physik Department E21, Technische Universität München, 85748 Garching (Germany)

2015-12-21

We demonstrate the performance of a compact neutron guide module which boosts the intensity in inelastic neutron scattering experiments by approximately a factor of 40. The module consists of two housings containing truly curved elliptic focussing guide elements, positioned before and after the sample. The advantage of the module lies in the ease with which it may be reproducibly mounted on a spectrometer within a few hours, on the same timescale as conventional sample environments. It is particularly well suited for samples with a volume of a few mm{sup 3}, thus enabling the investigation of materials which to date would have been considered prohibitively small or samples exposed to extreme environments, where there are space constraints. We benchmark the excellent performance of the module by measurements of the structural and magnetic excitations in single crystals of model systems. In particular, we report the phonon dispersion in the simple element lead. We also determine the magnon dispersion in the spinel ZnCr{sub 2}Se{sub 4} (V = 12.5 mm{sup 3}), where strong magnetic diffuse scattering at low temperatures evolves into distinct helical order.

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

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.

Current status of neutron scattering in Thailand

International Nuclear Information System (INIS)

Kornduangkaeo, Areeratt; Pongkasem, Somchai; Putchar, Suriya; Ampornrat, Pantip; Kajornrith, Varavuth; Sangariyavanich, Archara

2003-01-01

The current neutron powder diffractometer at the Thai Research Reactor-1/M1 (TRR-1/M1) has been modified from the obsolete neutron diffractometer which had been used during 1968-1975. The upgraded diffractometer has medium resolution and is appropriate for studying samples with small unit cell dimensions and training university students in the field of neutron scattering. This paper describes the current activities of neutron scattering research in Thailand as well as a new research reactor for enlarging the perspectives of its utilization in the future. (author)

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.

Studies on biological macromolecules by neutron inelastic scattering

International Nuclear Information System (INIS)

Fujiwara, Satoru; Nakagawa, Hiroshi

2013-01-01

Neutron inelastic scattering techniques, including quasielastic and elastic incoherent neutron scattering, provide unique tools to directly measure the protein dynamics at a picosecond time scale. Since the protein dynamics at this time scale is indispensable to the protein functions, elucidation of the protein dynamics is indispensable for ultimate understanding of the protein functions. There are two complementary directions of the protein dynamics studies: one is to explore the physical basis of the protein dynamics using 'model' proteins, and the other is more biology-oriented. Examples of the studies on the protein dynamics with neutron inelastic scattering are described. The examples of the studies in the former direction include the studies on the dynamical transitions of the proteins, the relationship between the protein dynamics and the hydration water dynamics, and combined analysis of the protein dynamics with molecular dynamics simulation. The examples of the studies in the latter direction include the elastic incoherent and quasielastic neutrons scattering studies of actin. Future prospects of the studies on the protein dynamics with neutron scattering are briefly described. (author)

Studies performed on neutron-irradiated copper-doped iron specimens by means of neutron small-angle scattering

International Nuclear Information System (INIS)

Naraghi, M.

1978-01-01

By means of neutron small-angle scattering precipitation arising from heat-treatment and reactor irradiation in copper-alloyed iron specimens were studied. Copper content varried between 0 and 1.5%, irradiation temperature between 310 and 563K. The specimens had been cooled from the melt partly fast, partly slowely. By taking account of magnetic scattering and by investigating the azimuthal dependence of the total scattering it became possible to distinguish between copper precipitations and vacancy agglomerates. The most obvious effect in the slowly cooled specimens after irradiation with 2-10 19 fast neutrons per cm 2 at a temperature of 563 K is the existence of copper agglomerates with diameters of the order of magnitude of 5nm. Precipitation already occurs to a much lesser extent by the influence of temperature alone. Fast cooling from the melt or low irradiation temperature reduce precipitation during reactor irradiation. Moreover, there are indications on the formation of vacancy accumulations and dislocation rings, the latter especially in the fast cooled specimens. (orig.) [de

Fluence-compensated down-scattered neutron imaging using the neutron imaging system at the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Casey, D. T., E-mail: casey21@llnl.gov; Munro, D. H.; Grim, G. P.; Landen, O. L.; Spears, B. K.; Fittinghoff, D. N.; Field, J. E.; Smalyuk, V. A. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Volegov, P. L.; Merrill, F. E. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2016-11-15

The Neutron Imaging System at the National Ignition Facility is used to observe the primary ∼14 MeV neutrons from the hotspot and down-scattered neutrons (6-12 MeV) from the assembled shell. Due to the strong spatial dependence of the primary neutron fluence through the dense shell, the down-scattered image is convolved with the primary-neutron fluence much like a backlighter profile. Using a characteristic scattering angle assumption, we estimate the primary neutron fluence and compensate the down-scattered image, which reveals information about asymmetry that is otherwise difficult to extract without invoking complicated models.

Lectures on neutron scattering techniques: 1

International Nuclear Information System (INIS)

Carlile, C.J.

1988-08-01

The lecture on the production of neutrons was presented at a Summer School on neutron scattering, Rome, 1986. A description is given of the production of neutrons by natural radioactive sources, fission, and particle accelerator sources. Modern neutron sources with high intensities are discussed including the ISIS pulsed neutron source at the Rutherford Appleton Laboratory and the High Flux Reactor at the Institut Laue Langevin. (U.K.)

Monte Carlo simulations of neutron scattering instruments

International Nuclear Information System (INIS)

Aestrand, Per-Olof; Copenhagen Univ.; Lefmann, K.; Nielsen, K.

2001-01-01

A Monte Carlo simulation is an important computational tool used in many areas of science and engineering. The use of Monte Carlo techniques for simulating neutron scattering instruments is discussed. The basic ideas, techniques and approximations are presented. Since the construction of a neutron scattering instrument is very expensive, Monte Carlo software used for design of instruments have to be validated and tested extensively. The McStas software was designed with these aspects in mind and some of the basic principles of the McStas software will be discussed. Finally, some future prospects are discussed for using Monte Carlo simulations in optimizing neutron scattering experiments. (R.P.)

A diffuse neutron scattering study of clustering in copper-nickel alloys

International Nuclear Information System (INIS)

Vrijen, J.

1977-01-01

The amount of clustering in Cu-Ni alloys in thermal equilibrium at several temperatures between 400degC and 700degC and ranging in composition between 20 and 80 atomic percent Ni has been determined by means of diffuse neutron scattering. A rough calculation of the excess elastic energy due to alloying Cu with Ni shows that the contribution of size effects to the configurational energy is asymmetric in the composition with its maximum located between 60 and 70 atomic percent Ni. This asymmetry is caused by different elastic constants for Cu and Ni and it might explain part of the asymmetry of clustering in Cu-Ni and its temperature dependence. With the help of the measured cluster parameters, the magnetic diffuse neutron scattering cross-sections of several differently clustered compositions in Cu-Ni could be interpreted, both well inside the ferromagnetic phase and in the transition region between ferromagnetism and superparamagnetism. Giants moments have been observed. Non-equilibrium distributions and their changes during relaxing towards equilibrium have been investigated by measuring the time-evolution of the diffuse scattering. The relaxation of the null matrix (composition without Bragg reflections for neutron scattering) has been measured at five temperatures between 320degC and 450degC. The results of these relaxations were compared with a few available kinetic models

Some thoughts on the future of neutron scattering

International Nuclear Information System (INIS)

Egelstaff, P.A.

1991-01-01

Attendance of ICANS meetings believe that neutron scattering has a bright future, but critics of neutron scattering argue that its practitioners are an aging group, that they use a few, very expensive neutron sources and that the interesting science may be done by other techniques. The ICANS committee asked me to comment on the future of neutron scattering in the light of this contrast. Some comments will be made on the age distribution, on the proper distribution of sources, on the convenient availability of neutron instruments and methods, on the expansion into new areas of science, on applications to industry and on the probable impact of synchrotron sources. It is hoped that these comments will lead to an outward looking discussion on the future. (author)

Spectral distortion due to scattered cold neutrons in beryllium filter

International Nuclear Information System (INIS)

Sakamoto, Yukio; Inoue, Kazuhiko

1980-01-01

Polycrystalline beryllium filters are used to discriminate the cold neutrons from the thermal neutrons with energies above Bragg cut-off energy. The cold neutron scattering cross section is very small, but the remaining cross section is not zero. Then the neutrons scattered once from the filter in the cold neutron energy region have chance of impinging on the outlet of filter. Those neutrons are almost upscattered and develop into thermal neutrons; thus the discriminated cold neutrons include a small spectral distortion due to the thermal neutrons. In the present work we have evaluated the effect on the cold neutron spectrum due to the repeatedly scattered and transmitted neutrons by using a Monte Carlo calculation method. (author)

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

VI European Conference on Neutron Scattering (ECNS2015)

International Nuclear Information System (INIS)

2016-01-01

It was a great pleasure for the Materials Science Institute of Aragón (CSIC- University of Zaragoza) to host the VI European Conference on Neutron Scattering (ECNS) from the 30th of August until the 4th of September 2015. The meeting was held in Zaragoza, Spain, a prosperous and well communicated city founded by the Emperor Octavio Augustus over 2000 years ago. Zaragoza, a city where different cultures, Muslims, Jewish, and Christians have left their mark is famous for its landmarks such as the Basilica del Pilar, La Seo Cathedral and the Aljaferfa Palace as well as the local cuisine. The conference is organized every four years as a forum for the European neutron scattering community to discuss recent developments and advances in all branches of science in which neutron scattering is, or eventually could be used. In 2015 the conference gathered more than 650 participants from 31 different countries from around the globe including Japan, United States of America, Taiwan, Republic of Korea, India, Argentina, China and Australia. This volume assembles the proceedings of the ECNS 2015. The main topics in the conference were; Neutron Sources and Facilities, Neutron Instrumentation (Optics, Sample Environment, Detectors and Software), Fundamental Science, Chemistry of Materials, Magnetism, Superconductivity, Functional Materials, Glasses and Liquids, Thin Films and Interfaces, Soft Condensed Matter, Health and Life Sciences, Engineering applications, Cultural Heritage and Archaeometry. Jean-Marie Tarascon, J. Manuel Perez-Mato, Roberto Caciuffo, Paul Schofield, Peter Fierlinger, Helmut Schober and Frank Gabel presented plenary talks. In addition, 33 keynote talks and 222 oral presentations were given during the four parallel sessions as well as 325 poster presentations. The poster sessions, which were held during the lunch and coffee breaks, were well attended and participants had time to visit not only the posters but also the exhibition. The VI European Conference on

The contribution of neutron scattering to molecular biology

International Nuclear Information System (INIS)

Stuhrmann, H.B.

1983-01-01

About half of the atoms of living cells are hydrogens, and nearly all biological applications of neutron scattering rely on the well-known difference in the scattering lengths of the proton and the deuteron. This introduces us to a wide variety of biological problems, which are related with hydrogen in water, proteins, nucleic acids and lipids. Neutron scattering gives an answer to both structural and dynamical aspects of the system in question. With deuterium labelled samples unambiguous information about molecular structure and motion becomes accessible. The architecture of viruses, cell membranes and gene expressing molecules has become a lot clearer with neutron scattering. (author)

Investigation of the paramagnetic phase of bcc iron using polarized neutron scattering

International Nuclear Information System (INIS)

Wicksted, J.P.; Shirane, G.; Steinsvoll, O.

1983-01-01

Recent neutron scattering experiments on Ni and Fe (4%-Si) above T/sub c/ have demonstrated that a simple paramagnetic scattering function S(Qω) proportional to 1/(kappa 1 2 + q 2 ).GAMMA/(GAMMA 2 + ω 2 ) can explain the persistent spin wave ridges previously reported by Lynn and Mook. We present our new polarized beam results on pure Fe and describe in some detail the special problems associated with the unpolarized beam studies of magnetic cross sections at high temperatures

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...

New techniques in neutron scattering

International Nuclear Information System (INIS)

Hayter, J.B.

1993-01-01

New neutron sources being planned, such as the Advanced Neutron Source (ANS) or the European Spallation Source (ESS), will provide an order of magnitude flux increase over what is available today, but neutron scattering will still remain a signal-limited technique. At the same time, the development of new materials, such as polymer and ceramic composites or a variety of complex fluids, will increasingly require neutron-based research. This paper will discuss some of the new techniques which will allow us to make better use of the available neutrons, either through improved instrumentation or through sample manipulation. Discussion will center primarily on unpolarized neutron techniques since polarized neutrons will be the subject of the next paper. (author)

Neutron total scattering cross sections of elemental antimony

Energy Technology Data Exchange (ETDEWEB)

Smith, A.B.; Guenther, P.T.; Whalen, J.F.

1982-11-01

Neutron total cross sections are measured from 0.8 to 4.5 MeV with broad resolutions. Differential-neutron-elastic-scattering cross sections are measured from 1.5 to 4.0 MeV at intervals of 50 to 200 keV and at scattering angles distributed between 20 and 160 degrees. Lumped-level neutron-inelastic-scattering cross sections are measured over the same angular and energy range. The exPerimental results are discussed in terms of an optical-statistical model and are compared with respective values given in ENDF/B-V.

Neutron total scattering cross sections of elemental antimony

International Nuclear Information System (INIS)

Smith, A.B.; Guenther, P.T.; Whalen, J.F.

1982-11-01

Neutron total cross sections are measured from 0.8 to 4.5 MeV with broad resolutions. Differential-neutron-elastic-scattering cross sections are measured from 1.5 to 4.0 MeV at intervals of 50 to 200 keV and at scattering angles distributed between 20 and 160 degrees. Lumped-level neutron-inelastic-scattering cross sections are measured over the same angular and energy range. The exPerimental results are discussed in terms of an optical-statistical model and are compared with respective values given in ENDF/B-V

Spin waves in full-polarized state of Dzyaloshinskii-Moriya helimagnets: Small-angle neutron scattering study

Science.gov (United States)

Grigoriev, S. V.; Sukhanov, A. S.; Altynbaev, E. V.; Siegfried, S.-A.; Heinemann, A.; Kizhe, P.; Maleyev, S. V.

2015-12-01

We develop the technique to study the spin-wave dynamics of the full-polarized state of the Dzyaloshinskii-Moriya helimagnets by polarized small-angle neutron scattering. We have experimentally proven that the spin-waves dispersion in this state has the anisotropic form. We show that the neutron scattering image displays a circle with a certain radius which is centered at the momentum transfer corresponding to the helix wave vector in helimagnetic phase ks, which is oriented along the applied magnetic field H . The radius of this circle is directly related to the spin-wave stiffness of this system. This scattering depends on the neutron polarization showing the one-handed nature of the spin waves in Dzyaloshinskii-Moriya helimagnets in the full-polarized phase. We show that the spin-wave stiffness A for MnSi helimagnet decreased twice as the temperature increases from zero to the critical temperature Tc.

Vortex lattices in superconducting niobium and skyrmion lattices in chiral MnSi. An investigation by neutron scattering

International Nuclear Information System (INIS)

Muehlbauer, Sebastian C.

2009-01-01

In this thesis, we present a comprehensive small angle neutron scattering study of the vortex lattice (VL) in an ultra-pure Nb single crystal sample, characterized by a residual resistivity ratio of ∝ 10 4 . We systematically investigate the morphology of vortex structures with the magnetic field applied along a four-fold left angle 100 right angle axis. We succeed to deconvolute the general morphology of the VL and its orientation to three dominant mechanisms: First, non-local contributions, second, the transition between open and closed Fermi surface sheets and, third, the intermediate mixed state (IMS) between the Meissner and the Shubnikov phase. We present first time microscopic measurements of the intrinsic bulk VL tilt modulus c 44 by means of time resolved stroboscopic small angle neutron scattering in combination with a tailored magnetic field setup. In our study we find that the VL in Nb responds to an external force - in the form of a changed magnetic field - with an exponential relaxation. As expected, the relaxation process shows increasing VL stiffness with increasing magnetic field and reduced damping with increasing temperature. Besides this general trend, we observe a dramatic changeover of the relaxation process associated with the non-trivial VL morphology in the IMS and the crossover from attractive to repulsive vortex-vortex interaction. Furthermore we use small angle neutron scattering to establish the existence of a skyrmion lattice in the A-phase of MnSi. Due to a parallel alignment of the magnetic field with respect to the neutron beam, we are able to resolve the complete magnetic structure of the A-phase: The structure in the A-phase, reminiscent of a vortex lattice, consists of topological knots of the magnetization with particle-like properties, arranged in a regular six-fold lattice. The orientation of this lattice is strictly driven by the orientation of the applied magnetic field, regardless of the underlying crystal symmetry. The

Vortex lattices in superconducting niobium and skyrmion lattices in chiral MnSi. An investigation by neutron scattering

Energy Technology Data Exchange (ETDEWEB)

Muehlbauer, Sebastian C

2009-12-10

In this thesis, we present a comprehensive small angle neutron scattering study of the vortex lattice (VL) in an ultra-pure Nb single crystal sample, characterized by a residual resistivity ratio of {proportional_to} 10{sup 4}. We systematically investigate the morphology of vortex structures with the magnetic field applied along a four-fold left angle 100 right angle axis. We succeed to deconvolute the general morphology of the VL and its orientation to three dominant mechanisms: First, non-local contributions, second, the transition between open and closed Fermi surface sheets and, third, the intermediate mixed state (IMS) between the Meissner and the Shubnikov phase. We present first time microscopic measurements of the intrinsic bulk VL tilt modulus c{sub 44} by means of time resolved stroboscopic small angle neutron scattering in combination with a tailored magnetic field setup. In our study we find that the VL in Nb responds to an external force - in the form of a changed magnetic field - with an exponential relaxation. As expected, the relaxation process shows increasing VL stiffness with increasing magnetic field and reduced damping with increasing temperature. Besides this general trend, we observe a dramatic changeover of the relaxation process associated with the non-trivial VL morphology in the IMS and the crossover from attractive to repulsive vortex-vortex interaction. Furthermore we use small angle neutron scattering to establish the existence of a skyrmion lattice in the A-phase of MnSi. Due to a parallel alignment of the magnetic field with respect to the neutron beam, we are able to resolve the complete magnetic structure of the A-phase: The structure in the A-phase, reminiscent of a vortex lattice, consists of topological knots of the magnetization with particle-like properties, arranged in a regular six-fold lattice. The orientation of this lattice is strictly driven by the orientation of the applied magnetic field, regardless of the underlying

Inelastic scattering of 275 keV neutrons by silver

International Nuclear Information System (INIS)

Litvinsky, L.L.; Zhigalov, Ya.A.; Krivenko, V.G.; Purtov, O.A.; Sabbagh, S.

1997-01-01

Neutron total, elastic and inelastic scattering cross-scattering of Ag at the E n = 275 KeV neutron energy were measured by using the filtered neutron beam of the WWR-M reactor in Kiev. The d-neutron strength function S n2 of Ag was determined from the analysis of all available data in the E n ≤ keV energy region on neutron inelastic scattering cross-sections with excitation of the first isomeric levels I π m = 7/2 + , E m ∼ 90 keV of 107,109 Ag: S n2 = (1.03 ± 0.19) · 10 -4 . (author). 10 refs, 3 figs

Development of temperature related thermal neutron scattering database for MCNP

International Nuclear Information System (INIS)

Mei Longwei; Cai Xiangzhou; Jiang Dazhen; Chen Jingen; Guo Wei

2013-01-01

Based on ENDF/B-Ⅶ neutron library, the thermal neutron scattering library S(α, β) for molten salt reactor moderators was developed. The temperatures of this library were chose as the characteristic temperature of the molten salt reactor. The cross section of the thermal neutron scattering of ACE format was investigated, and this library was also validated by the benchmarks of ICSBEP. The uncertainties shown in the validation were in reasonable range when compared with the thermal neutron scattering library tmccs which included in the MCNP data library. It was proved that the thermal neutron scattering library processed in this study could be used in the molten salt reactor design. (authors)

Interface detection by neutron scattering

International Nuclear Information System (INIS)

De Monchy, A.R.; Kok, C.A.; Dorrepaal, J.

1979-01-01

A method and apparatus for detecting an interface of materials having different hydrogen content present in a metal vessel or pipe eg. made of steel, are described. Steel walls of columns, reactors, pipelines etc can be monitored. It is very suitable for detection of liquid water or hydrocarbons present in gas pipelines and also for the detection of a liquid hydrocarbon in a vessel or column. A series of measurements of the hydrogen density of the contents of a vessel or pipe are made using at least one californium-252 neutron source located near the outer side of the pipe. Neutrons are emitted and are scattered by the contents of the pipe. At least one neutron detector is located near the outer side of the metal wall. The detectors have a higher sensitivity for scattered neutrons (from the light hydrogen nuclei present in water or hydrocarbons). A source of 0.1 - 1 micrograms produces enough neutrons for most technical applications so the handling is relatively safe although shielding is advocated. The detectors contain helium-3 at a pressure of about 10 bar. Current pulses from the detector are counted. (U.K.)

Bose condensation in 4He and neutron scattering

International Nuclear Information System (INIS)

Silver, R.N.

1997-01-01

The discovery of superfluidity in liquid 4 He below T λ = 2.17 K, and its phenomenological characterization since then, has been one of the great success stories of condensed matter physics. The relation of superfluidity to the behavior of atoms was conjectured by F. London in 1938. Superfluidity is a manifestation of the Bose condensation of helium atoms, the extensive occupation of the zero momentum state. Ever since 4 He has been the paradigm in the search for Bose condensates in other systems. At the Pune meeting scientists have heard exciting new evidence for Bose condensates of laser cooled alkali atoms in magnetic traps, of excitons in Cu 2 O, and possibly pre-formed Cooper pairs of electrons in the high T c perovskite superconductors. There remains the holy-grail of forming a Bose condensate in spin-polarized hydrogen. In the current excitement for new types of Bose condensates, and new phenomena such as atom lasers, it may be useful to recall the older story of the experimental verification of a relation between superfluidity and Bose condensation in 4 He. This topic has been investigated over many years by neutron scattering experiments and quantum many-body theory. The authors goal is to illustrate the difficulties of establishing the existence of a Bose condensate in a strongly interacting system, even though its macroscopic effects are manifest. The author assumes readers have access to a review by Silver and Sokol which emphasizes the neutron scattering theory through 1990 and a review by Snow and Sokol of the deep inelastic neutron scattering (DINS) experiments through 1995

Polarized neutron reflectometry on thin magnetic films

International Nuclear Information System (INIS)

Van Der Graaf, A.

1997-01-01

In order to be sensitive to magnetic scattering with X-rays very high intensities have to be used. This makes it necessary to use large installations like synchroton radiation sources providing high X-ray intensities. Polarized neutron experiments can be performed even at small reactors like the 2 MW reactor of IRI. In general polarized neutron reflectometry (PNR) is used to determine magnetization depth profiles, whereas X-ray reflectometry is used to study magnetic surfaces. Chapters 2 through 4 of this thesis are general chapters. The theory of neutron reflectometry is described in chapter 2, followed by a description of the ROG instrument (a time-of-flight reflectometer) in chapter 3, and chapter 4 deals with the data analysis. In the subsequent chapters PNR-experiments on different kinds of samples are discussed. First, experiments on a Co-Cr layer, a candidate to be used as perpendicular recording medium, are described in chapter 5. In chapter 6 it is shown that PNR can give information on metal evaporated videotapes, as presently available in every ordinary shop selling videotapes, and also on the writing process in these tapes. Chapter 7 deals with experiments on Fe/Si multilayers. The initial interest in such multilayers was to obtain information on magnetic coupling through a semiconductor. In chapter 8 PNR-experiments on spin-valve systems, that probably will be used as magnetic read head material, are described. Finally, chapter 9 gives some conclusions and recommendations for the future. 78 refs

Diffuse neutron scattering signatures of rough films

International Nuclear Information System (INIS)

Pynn, R.; Lujan, M. Jr.

1992-01-01

Patterns of diffuse neutron scattering from thin films are calculated from a perturbation expansion based on the distorted-wave Born approximation. Diffuse fringes can be categorised into three types: those that occur at constant values of the incident or scattered neutron wavevectors, and those for which the neutron wavevector transfer perpendicular to the film is constant. The variation of intensity along these fringes can be used to deduce the spectrum of surface roughness for the film and the degree of correlation between the film's rough surfaces

Elements of slow-neutron scattering basics, techniques, and applications

CERN Document Server

Carpenter, J M

2015-01-01

Providing a comprehensive and up-to-date introduction to the theory and applications of slow-neutron scattering, this detailed book equips readers with the fundamental principles of neutron studies, including the background and evolving development of neutron sources, facility design, neutron scattering instrumentation and techniques, and applications in materials phenomena. Drawing on the authors' extensive experience in this field, this text explores the implications of slow-neutron research in greater depth and breadth than ever before in an accessible yet rigorous manner suitable for both students and researchers in the fields of physics, biology, and materials engineering. Through pedagogical examples and in-depth discussion, readers will be able to grasp the full scope of the field of neutron scattering, from theoretical background through to practical, scientific applications.

Current status of neutron scattering in Thailand

International Nuclear Information System (INIS)

Kornduangkaeo, Areeratt; Pongkasem, Somchai; Putchar, Suriya; Ampornrat, Pantip; Kajornrith, Varavuth; Chamchang, Jipawat

2006-01-01

The current neutron powder diffractometer at the Thai Research Reactor-1/Modification 1 (TRR-1/M1) has been modified from the obsolete neutron diffractometer which had been used during 1968-1975. The upgraded diffractometer has medium resolution and is appropriate for studying samples with small unit cell dimensions and training university students in the field of neutron scattering. This paper describes the current activities of neutron scattering research in Thailand, the current status of a new research reactor project at Ongkarak for enlarging the perspectives of its utilization in the future as well as the organizational reformation of the Office of Atomic Energy for Peace (OAEP). (author)

Inelastic neutron scattering and lattice dynamics of minerals

Indian Academy of Sciences (India)

We review current research on minerals using inelastic neutron scattering and lattice dynamics calculations. Inelastic neutron scattering studies in combination with first principles and atomistic calculations provide a detailed understanding of the phonon dispersion relations, density of states and their manifestations in ...

Inelastic neutron scattering and lattice dynamics of minerals

Indian Academy of Sciences (India)

Abstract. We review current research on minerals using inelastic neutron scattering and lattice dynamics calculations. Inelastic neutron scattering studies in combination with first principles and atomistic calculations provide a detailed understanding of the phonon dispersion relations, density of states and their ...

Advances in neutron scattering spectroscopy

International Nuclear Information System (INIS)

White, J.W.

1977-01-01

Some aspects of the application of neutron scattering to problems in polymer science, surface chemistry, and adsorption phenomena, as well as molecular biology, are reviewed. In all these areas, very significant work has been carried out using the medium flux reactors at Harwell, Juelich and Risoe, even without the use of advanced multidetector techniques or of a neutron cold source. A general tendency can also be distinguished in that, for each of these new fields, a distinct preference for colder neutrons rather than thermal neutron beams can be seen. (author)

Neutron-neutron quasifree scattering in nd breakup at 10 MeV

Science.gov (United States)

Malone, R. C.; Crowe, B.; Crowell, A. S.; Cumberbatch, L. C.; Esterline, J. H.; Fallin, B. A.; Friesen, F. Q. L.; Han, Z.; Howell, C. R.; Markoff, D.; Ticehurst, D.; Tornow, W.; Witała, H.

2016-03-01

The neutron-deuteron (nd) breakup reaction provides a rich environment for testing theoretical models of the neutron-neutron (nn) interaction. Current theoretical predictions based on rigorous ab-initio calculations agree well with most experimental data for this system, but there remain a few notable discrepancies. The cross section for nn quasifree (QFS) scattering is one such anomaly. Two recent experiments reported cross sections for this particular nd breakup configuration that exceed theoretical calculations by almost 20% at incident neutron energies of 26 and 25 MeV [1, 2]. The theoretical values can be brought into agreement with these results by increasing the strength of the 1S0 nn potential matrix element by roughly 10%. However, this modification of the nn effective range parameter and/or the 1S0 scattering length causes substantial charge-symmetry breaking in the nucleon-nucleon force and suggests the possibility of a weakly bound di-neutron state [3]. We are conducting new measurements of the cross section for nn QFS in nd breakup. The measurements are performed at incident neutron beam energies below 20 MeV. The neutron beam is produced via the 2H(d, n)3He reaction. The target is a deuterated plastic cylinder. Our measurements utilize time-of-flight techniques with a pulsed neutron beam and detection of the two emitted neutrons in coincidence. A description of our initial measurements at 10 MeV for a single scattering angle will be presented along with preliminary results. Also, plans for measurements at other energies with broad angular coverage will be discussed.

Quasielastic neutron scattering in biology: Theory and applications.

Science.gov (United States)

Vural, Derya; Hu, Xiaohu; Lindner, Benjamin; Jain, Nitin; Miao, Yinglong; Cheng, Xiaolin; Liu, Zhuo; Hong, Liang; Smith, Jeremy C

2017-01-01

Neutrons scatter quasielastically from stochastic, diffusive processes, such as overdamped vibrations, localized diffusion and transitions between energy minima. In biological systems, such as proteins and membranes, these relaxation processes are of considerable physical interest. We review here recent methodological advances and applications of quasielastic neutron scattering (QENS) in biology, concentrating on the role of molecular dynamics simulation in generating data with which neutron profiles can be unambiguously interpreted. We examine the use of massively-parallel computers in calculating scattering functions, and the application of Markov state modeling. The decomposition of MD-derived neutron dynamic susceptibilities is described, and the use of this in combination with NMR spectroscopy. We discuss dynamics at very long times, including approximations to the infinite time mean-square displacement and nonequilibrium aspects of single-protein dynamics. Finally, we examine how neutron scattering and MD can be combined to provide information on lipid nanodomains. This article is part of a Special Issue entitled "Science for Life" Guest Editor: Dr. Austen Angell, Dr. Salvatore Magazù and Dr. Federica Migliardo. Copyright © 2016 Elsevier B.V. All rights reserved.

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 ...

Proposal for the design of a small-angle neutron scattering facility at a pulsed neutron source

International Nuclear Information System (INIS)

Kley, W.

1980-01-01

The intensity-resolution-background considerations of an optimized small angle neutron scattering facility are reviewed for the special case of a pulsed neutron source. In the present proposal we conclude that for 'true elastic scattering experiments' filters can be used instead of expensive neutron guide tubes since low background conditions can be achieved by a combined action of filters as well as a proper time gating of the twodimensional detector. The impinging neutron beam is monochromatized by phasing a disk chopper to the neutron source pulses and in the scattered beam a second disk chopper is used to eliminate the inelastically scattered neutrons. Therefore, no time of fligh analysis is necessary for the scattered neutron intensity and true-elastic conditions are obtained by simply gating the two-dimensional detector. Considering a 4 m thick shield for the pulsed neutron source and choosing for optimum conditions a detector area element of (2.5 cm) 2 and a sample area of (1.25 cm) 2 , than for a minimum sample-detector-distance of 1.5 m, a maximum neutron source diameter of 6.67 cm is required in order to maintain always the optimum intensity- and resolution requirements

Neutron multimonochromator-bipolarizer based on magnetic multilayer Fe/Co and new scheme for the total neutron polarization analysis

International Nuclear Information System (INIS)

Syromyatnikov, V.G.; Zaw Lin, Kyaw

2017-01-01

In this paper, we present a new neutron-optical element, Neutron Multimonochromator-Bipolarizer (NMB). It consists of a multimultilayer structure made of 12 periodic multilayer Fe/Co magnetic nanostructures whose period increases with distance from the substrate. Results are presented of calculations of the reflection coefficients from the NMB. We propose a new scheme of the total neutron polarization analysis for the time-of-flight method in the reflectometry. In this scheme, double NMB is used as a polarizer and there is no spin-flipper before the sample. NMB can be used in polarized neutron reflectometry, in SESANS, and for research of low-angle and inelastic scattering of polarized neutrons. (paper)

New statistical model of inelastic fast neutron scattering

International Nuclear Information System (INIS)

Stancicj, V.

1975-07-01

A new statistical model for treating the fast neutron inelastic scattering has been proposed by using the general expressions of the double differential cross section in impuls approximation. The use of the Fermi-Dirac distribution of nucleons makes it possible to derive an analytical expression of the fast neutron inelastic scattering kernel including the angular momenta coupling. The obtained values of the inelastic fast neutron cross section calculated from the derived expression of the scattering kernel are in a good agreement with the experiments. A main advantage of the derived expressions is in their simplicity for the practical calculations

Status of thermal neutron scattering data for graphite

International Nuclear Information System (INIS)

Mattes, M.; Keinert, J.

2005-07-01

At thermal neutron energies, the binding of the scattering nucleus in a solid, liquid, or gas affects the cross sections and the angular and energy distributions of the scattered neutrons. These effects are described in the thermal sub-library of evaluated files in File 7 of the ENDF-6 format. A re-evaluation of thermal neutron scattering data for carbon bound in graphite has been performed to investigate the impact of models (e.g., generalised frequency distributions) based on different experimental and theoretical data for the generation of scattering law data files S(α,β,T) and coherent elastic scattering data. Two phonon frequency distributions of graphite published in 2002 and 2004 were considered and the results compared with those based on the phonon spectra from Koppel et al. (published in 1968), on which the evaluations of ENDF/B-VI and JEFF-3.1 are based. The new frequency distributions were partly derived from ab initio simulations. Detailed comparisons with measurements of differential and integral neutron cross sections and other relevant data are reported. In addition, thermal MCNP data sets for use in the continuous Monte Carlo codes MCNP and MCNPX were generated from these evaluations for different temperatures. Calculated neutron spectra were found to be in good agreement with the measurements. (author)

Neutron scattering and models: Silver

International Nuclear Information System (INIS)

Smith, A.B.

1996-07-01

Differential neutron elastic-scattering cross sections of elemental silver were measured from 1.5 → 10 MeV at ∼ 100 keV intervals up to 3 MeV, at ∼ 200 keV intervals from 3 → 4 MeV, and at ∼ 500 keV intervals above 4 MeV. At ≤ 4 MeV the angular range of the measurements was ∼ 20 0 → 160 0 with 10 measured values below 3 MeV and 20 from 3 → 4 MeV at each incident energy. Above 4 MeV ≥ 40 scattering angles were used distributed between ∼ 17 0 and 16 0 All of the measured elastic distributions included some contributions due to inelastic scattering. Below 4 MeV the measurements determined cross sections for ten inelastically-scattered neutron groups corresponding to observed excitations of 328 ± 13, 419 ± 50, 748 ± 25, 908 ± 26, 115 ± 38, 1286 ± 25, 1507 ± 20, 1632 ± 30, 1835 ± 20 and 1944 ± 26 keV. All of these inelastic groups probably were composites of contributions from the two isotopes 107 Ag and 109 Ag. The experimental results were interpreted in terms of the spherical optical model and of rotational and vibrational coupled-channels models, and physical implications are discussed. In particular, the neutron-scattering results are consistent with a ground-state rotational band with a quadrupole deformation Β 2 = 0.20 ± ∼ 10% for both of the naturally-occurring silver isotopes

A Monte Carlo evaluation of analytical multiple scattering corrections for unpolarised neutron scattering and polarisation analysis data

International Nuclear Information System (INIS)

Mayers, J.; Cywinski, R.

1985-03-01

Some of the approximations commonly used for the analytical estimation of multiple scattering corrections to thermal neutron elastic scattering data from cylindrical and plane slab samples have been tested using a Monte Carlo program. It is shown that the approximations are accurate for a wide range of sample geometries and scattering cross-sections. Neutron polarisation analysis provides the most stringent test of multiple scattering calculations as multiply scattered neutrons may be redistributed not only geometrically but also between the spin flip and non spin flip scattering channels. A very simple analytical technique for correcting for multiple scattering in neutron polarisation analysis has been tested using the Monte Carlo program and has been shown to work remarkably well in most circumstances. (author)

Proceedings of a workshop on methods for neutron scattering instrumentation design

International Nuclear Information System (INIS)

Hjelm, R.P.

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

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.

Resonance effects in neutron scattering lengths

Energy Technology Data Exchange (ETDEWEB)

Lynn, J.E.

1989-06-01

The nature of neutron scattering lengths is described and the nuclear effects giving rise to their variation is discussed. Some examples of the shortcomings of the available nuclear data base, particularly for heavy nuclei, are given. Methods are presented for improving this data base, in particular for obtaining the energy variation of the complex coherent scattering length from long to sub-/angstrom/ wave lengths from the available sources of slow neutron cross section data. Examples of this information are given for several of the rare earth nuclides. Some examples of the effect of resonances in neutron reflection and diffraction are discussed. This report documents a seminar given at Argonne National Laboratory in March 1989. 18 refs., 18 figs.

Resonance effects in neutron scattering lengths

International Nuclear Information System (INIS)

Lynn, J.E.

1989-01-01

The nature of neutron scattering lengths is described and the nuclear effects giving rise to their variation is discussed. Some examples of the shortcomings of the available nuclear data base, particularly for heavy nuclei, are given. Methods are presented for improving this data base, in particular for obtaining the energy variation of the complex coherent scattering length from long to sub-angstrom wave lengths from the available sources of slow neutron cross section data. Examples of this information are given for several of the rare earth nuclides. Some examples of the effect of resonances in neutron reflection and diffraction are discussed. This report documents a seminar given at Argonne National Laboratory in March 1989. 18 refs., 18 figs

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

Neutron magnetic scattering experiments performed by VIKRA group at the RA reactor in Vinca; Eksperimenti grupe VIKRA na reaktoru RA u Vinci sa rasejanjem neutrona na magnetnim materijalima

Energy Technology Data Exchange (ETDEWEB)

Kranicki, S; Rzany, H; Wanic, A [Institute of Nuclear Physics, Krakov (Poland); Szytula, A [Jagiellonian University, Krakov (Poland); Todorovic, J; Dimitrijevic, Z; Radenkovic, S [Institute of Nuclear Sciences Boris Kidric, Vinca, Beograd (Yugoslavia)

1978-05-15

A short communication about investigations of magnetic materials by means of the neutron magnetic scattering performed by Polish-Yugoslav group VIKRA (Vinca-Krakov) at the RA reactor in Vinca in the period 1962-1977 will be presented. In the field of neutron inelastic scattering information about magnetic interactions (exchange integrals) and their temperature behaviour in such substances as Fe{sub 7}S{sub 8}, {alpha}-Fe{sub 2}O{sub 3}, CR{sub 2}O{sub 3}, {alpha}-Co, Cu{sub 2}MnAl and Mn{sub 1.88}Cr{sub 0.12}Sb was obtained by measuring magnon dispersion relations. In the field of neutron elastic scattering valuable results concerning crystallographic and magnetic structures of oxyhydroxides, several Heusler alloys and intermetallic compounds of 3d metals (for instance of NiMnGe, CoMnSi) were obtained. A short description of the KSN spectrometer used in all experiments will also be given. (author) Dato je kratko saopstenje o istrazivanjima magnetnih materijala magnetnim neutronskim rasejanjem izvrsenim od strane poljsko-jugoslovenske grupe VIKRA (Vinca-Krakov) na reaktoru RA u Vinci u periodu od 1962-1977. U oblasti neelasticnog rasejanja neutrona, obavestenja o magnetnim uzajamnim dejstvima (integralima izmene) i njihovim temperaturskim ponasanjima su dobijeni merenjem disperzione relacije magnona u takvim materijalima kao sto su Fe{sub 7}S{sub 8}, {alpha}-Fe{sub 2}O{sub 3}, CR{sub 2}O{sub 3}, {alpha}-Co, Cu{sub 2}MnAl and Mn{sub 1.88}Cr{sub 0.12}Sb. U oblasti neutronskog elasticnog rasejanja dobijeni su korisni rezultati o kristalografskim i magnetnim strukturama oksihidroksida gvozdja, niza Heuslerovih legura i intermetalnih jedinjenja 3d metala (napr. NiMnGe, Co,MnSi). Dat je kratak opis KSN spektrometra upotrebljenog u svim ovim eksperimentima. (author)

Neutron scattering research at JAERI reactors - past, present and future -

International Nuclear Information System (INIS)

Funahashi, Satoru; Morii, Yukio; Minakawa, Nobuaki

1992-01-01

It was in 1961 that the first neutron scattering experiment was performed in Japan at JRR-2. The start of JRR-3 in 1964 accelerated the neutron scattering activities in Japan. The research in this field in Japan grew up by using these two research reactors. Among them JRR-2 has played an important role because its neutron flux was about seven times higher than that of the old JRR-3. The completion of the new JRR-3M in 1990 made an epoch to the neutron scattering activities in Japan. The long-waited JRR-3M came up to the expectations of the scientists of Japan. It is a realization of the ideal reactor with tangential beam holes, cold source and neutron guides in a large guide hall. The flux at the neutron scattering instruments is about five times higher than that of JRR-2. Utilization of JRR-3M has just started. Twelve neutron scattering machines are running there. The number will increase up to close twenty in a couple of years. (author)

Neutron detection efficiency determinations for the TUNL neutron-neutron and neutron-proton scattering-length measurements

International Nuclear Information System (INIS)

Trotter, D.E. Gonzalez; Meneses, F. Salinas; Tornow, W.; Crowell, A.S.; Howell, C.R.; Schmidt, D.; Walter, R.L.

2009-01-01

The methods employed and the results obtained from measurements and calculations of the detection efficiency for the neutron detectors used at Triangle Universities Nuclear Laboratory (TUNL) in the simultaneous determination of the 1 S 0 neutron-neutron and neutron-proton scattering lengths a nn and a np , respectively, are described. Typical values for the detector efficiency were 0.3. Very good agreement between the different experimental methods and between data and calculation has been obtained in the neutron energy range below E n =13MeV.

Neutron spectral modulation as a new thermal neutron scattering technique. Pt. 1

International Nuclear Information System (INIS)

Ito, Y.; Nishi, M.; Motoya, K.

1982-01-01

A thermal neutron scattering technique is presented based on a new idea of labelling each neutron in its spectral position as well as in time through the scattering process. The method makes possible the simultaneous determination of both the accurate dispersion relation and its broadening by utilizing the resolution cancellation property of zero-crossing points in the cross-correlated time spectrum together with the Fourier transform scheme of the neutron spin echo without resorting to the echoing. The channel Fourier transform applied to the present method also makes possible the determination of the accurate direct energy scan profile of the scattering function with a rather broad incident neutron wavelength distribution. Therefore the intensity sacrifice for attaining high accurarcy is minimized. The technique is used with either a polarized or unpolarized beam at the sample position with no precautions against beam depolarization at the sample for the latter case. Relative time accurarcy of the order of 10 -3 to 10 -4 may be obtained for the general dispersion relation and for the quasi-elastic energy transfers using correspondingly the relative incident neutron wavelength spread of 10 to 1% around an incident neutron energy of a few meV. (orig.)

Effect of covalent bonding on magnetism and the missing neutron intensity in copper oxide compounds

NARCIS (Netherlands)

Walters, A.C.; Perring, T.G.; Caux, J.S.; Savici, A.T.; Gu, G.D.; Lee, C.C.; Ku, W.; Zaliznyak, I.A.

2009-01-01

Theories involving highly energetic spin fluctuations are among the leading contenders for explaining high-temperature superconductivity in the cuprates(1). These theories could be tested by inelastic neutron scattering ( INS), as a change in the magnetic scattering intensity that marks the entry

Small angle neutron scattering

International Nuclear Information System (INIS)

Bernardini, G.; Cherubini, G.; Fioravanti, A.; Olivi, A.

1976-09-01

A method for the analysis of the data derived from neutron small angle scattering measurements has been accomplished in the case of homogeneous particles, starting from the basic theory without making any assumption on the form of particle size distribution function. The experimental scattering curves are interpreted with the aid the computer by means of a proper routine. The parameters obtained are compared with the corresponding ones derived from observations at the transmission electron microscope

Neutron scattering on equilibrium and nonequilibrium phonons, excitons and polaritons

International Nuclear Information System (INIS)

Broude, V.L.; Sheka, E.F.

1978-01-01

A number of problems of solid-state physics representing interest for neutron spectroscopy of future is considered. The development of the neutron inelastic scattering spectroscopy (neutron spectroscopy of equilibrium phonons) is discussed with application to nuclear dynamics of crystals in the thermodynamic equilibrium. The results of high-flux neutron source experiments on molecular crystals are presented. The advantages of neutron inelastic scattering over optical spectroscopy are discussed. The spectroscopy of quasi-equilibrium and non-equilibrium quasi-particles is discussed. In particular, the neutron scattering on polaritons, excitons in thermal equilibrium and production of light-excitons are considered. The problem of the possibility of such experiments is elucidated

The basic physics of neutron scattering experiments

International Nuclear Information System (INIS)

Mezei, F.

1999-01-01

The basic physical principles behind the well-established but also developing practice of neutron scattering experiments are presented. A few examples are given either to illustrate the physical principles or to give an idea of the variety, importance or magnitude of various phenomena. The evolution of neutron scattering experimental techniques is investigated from a special aspect: the increasing capability of taking into account more and more important and sometimes decisive finer details by using more and more realistic mathematical models of the evolution of the neutrons from birth do death, eventually passing by the sample and being scattered more than one times. Working with such numerical 'virtual instruments' one will have to go far beyond notions like resolution function, convolution etc, and actually eliminate a large number of approximations currently in use. (K.A.)

Neutron detection efficiency determinations for the TUNL neutron-neutron and neutron-proton scattering-length measurements

Energy Technology Data Exchange (ETDEWEB)

Trotter, D.E. Gonzalez [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States)], E-mail: crowell@tunl.duke.edu; Meneses, F. Salinas [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Tornow, W. [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States)], E-mail: tornow@tunl.duke.edu; Crowell, A.S.; Howell, C.R. [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Schmidt, D. [Physikalisch-Technische Bundesanstalt, D-38116, Braunschweig (Germany); Walter, R.L. [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States)

2009-02-11

The methods employed and the results obtained from measurements and calculations of the detection efficiency for the neutron detectors used at Triangle Universities Nuclear Laboratory (TUNL) in the simultaneous determination of the {sup 1}S{sub 0} neutron-neutron and neutron-proton scattering lengths a{sub nn} and a{sub np}, respectively, are described. Typical values for the detector efficiency were 0.3. Very good agreement between the different experimental methods and between data and calculation has been obtained in the neutron energy range below E{sub n}=13MeV.

Photon detectors for epithermal neutron scattering at high-ω and low-q

International Nuclear Information System (INIS)

Pietropaolo, A.; Senesi, R.; Tardocchi, M.; Andreani, C.; Gorini, G.

2004-01-01

Inelastic epithermal neutron scattering at high energy (ℎω≥1 eV) and low wave vector (q≤10 A -1 ) transfers is the unique technique for the investigation of high-energy excitations in a variety of systems, ranging from magnetic materials to semiconductors. The key issue in order to make these measurements feasible on inverse geometry spectrometers, is to develop suitable detection systems for neutrons in the energy range 1-100 eV. The Resonance Detector Spectrometer configuration has to be considered as the most promising approach for electron Volt neutron spectroscopy. This configuration will be employed in the new low angle detector bank, VLAD, planned for VESUVIO spectrometer operating at ISIS source

Quantum correlations and Bell’s inequality violation in a Heisenberg spin dimer via neutron scattering

Science.gov (United States)

Cruz, C.

The characterization of quantum information quantifiers has attracted a considerable attention of the scientific community, since they are a useful tool to verify the presence of quantum correlations in a quantum system. In this context, in the present work we show a theoretical study of some quantifiers, such as entanglement witness, entanglement of formation, Bell’s inequality violation and geometric quantum discord as a function of the diffractive properties of neutron scattering. We provide one path toward identifying the presence of quantum correlations and quantum nonlocality in a molecular magnet as a Heisenberg spin-1/2 dimer, by diffractive properties typically obtained via neutron scattering experiments.

Methods of contrast variation by nuclear polarisation in small-angle neutron scattering: Observation of domains of nuclear polarisation by neutron scattering

International Nuclear Information System (INIS)

Leymarie, E.

2002-11-01

In this thesis we study the theoretical and experimental aspects of Contrast Variation by Nuclear Polarization (CVNP) applied to small-angle neutron scattering. The basics of neutron scattering theory is developed by highlighting the origin of the CVNP method: the strong spin dependence of thermal neutron scattering, especially on protons. We also present the principles of NMR with a special attention on the method of dynamic nuclear polarization by the solid effect which makes it possible to control the proton polarization and therefore the contrast for neutron scattering. We present a theoretical study of the CVNP method called static which supposes that the nuclear polarization is homogeneous in the sample and constant during the experiment. We show that it allows one to obtain partial structure functions of systems with multiple components, by carrying out several acquisitions with different polarizations on a single sample. For this purpose, we tested a simple device to stabilize the nuclear polarization. We describe finally a new application of the CVNP method called dynamic. In a solution of deuterated glycerol-water containing a small concentration of paramagnetic centres, we showed the existence of domains of polarized protons at the onset of dynamic polarization. This reinforces considerably the coherent scattering of paramagnetic centres. We describe the theoretical reasons explaining the appearance of these domains of polarization, as well as the various techniques used to observe them by neutron scattering. (author)

Current status and future development of neutron scattering in CIAE

International Nuclear Information System (INIS)

Chen, D.F.; Gou, C.; Ye, C.T.; Guo, L.P.; Sun, K.

2003-01-01

Currently, the 15 MW Heavy Water Research Reactor (HWRR) at China Institute of Atomic Energy (CIAE) in Beijing is the only neutron source available for neutron scattering experiments in China. A 60 MW tank-in-pool inverse neutron trap-type research reactor, China Advanced Research Reactor (CARR), now is being built at CIAE to meet the increasing demand of neutron scattering research in China. According to design, the maximum unperturbed thermal neutron flux would be expected to be 8x10 14 n/cm 2 .s in the reflector region. Seven out of nine tangential horizontal beam tubes will be dedicated for neutron scattering experiments. A cold source, a hot source and a 30x60 m 2 guide tube hall will also be constructed. In this paper, a brief introduction of HWRR, the existing neutron scattering facilities and research activities at HWRR, CARR, and the facilities to be built at CARR are presented. (author)

Advantages of neutron scattering for biological structure analysis

International Nuclear Information System (INIS)

Schoenborn, B.P.

1975-01-01

The advantages and disadvantages of neutron scattering for protein crystallography, scattering from oriented systems, and solution scattering are summarized. Techniques for minimizing the disadvantages are indicated

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.

X-ray scattering study of the interplay between magnetism and structure in CeSb

DEFF Research Database (Denmark)

McMorrow, Desmond Francis; Lussier, J.-G.; Lebech, Bente

1997-01-01

appeared with commensurate wave vectors q. From their polarization and wave-vector dependence, the peaks are deduced to arise mainly from a periodic lattice distortion. In the resonant regime, when the x-ray energy was tuned to the L absorption edges of Ce, weak, resonantly enhanced magnetic scattering...... was observed at the L(II) edge (E = 6.164 keV), with no scattering found at either L(I) or L(III) Of the six possible zero-field commensurate magnetic structures reported in earlier neutron experiments, we found the phases with q(m) = 2/3 and 4/7 only, with the domain that has moments perpendicular...... to the surface absent. Neutron scattering experiments on the same single crystal confirm that the absence of the other phases is a bulk property of that particular crystal, but the absence of the domain is a feature of the near-surface region. These results are discussed in terms of the currently accepted model...

Neutron scattering studies of eco-friendly functional materials

International Nuclear Information System (INIS)

Mishra, S.K.; Gupta, M.K.; Mittal, R.; Krishna, P.S.R.; Chaplot, S.L.

2016-01-01

Niobate based materials are environment friendly and appropriate for wide piezoelectric applications due to their piezo-response that is comparable to Pb(Zr Ti)O_3 beyond the technological application, NaNbO_3 has been a rich model system for understanding of mechanisms of structural phase transitions when subject to changes in thermodynamical conditions like: temperature, pressure, and/or composition, particle size and external stimuli like electric/magnetic field etc. In the present work, we report systematic investigation of structural phase transitions with variations in temperature, external pressure and chemical pressure (via compositional modification) using the neutron scattering technique. (author)

Neutron scattering study of Ce3Au3Sb4

International Nuclear Information System (INIS)

Kasaya, Mitsuo; Katoh, Kenichi; Kohgi, Masahumi; Osakabe, Toyotaka

1993-01-01

Rare-earth compounds with an Y 3 Au 3 Sb 4 -type crystal structure are semiconductors or semi-metals. Among them, Ce 3 Au 3 Sb 4 is a semiconductor with an activation energy of about 640 K and shows no magnetic order down to 1.5 K. The magnetic part of the specific heat for Ce 3 Au 3 Sb 4 obtained by subtracting the value for La 3 Au 3 Sb 4 from the total specific heat of Ce 3 Au 3 Sb 4 shows a broad peak at around 10 K, the origin of which is well explained by the crystalline-field splitting determined by neutron scattering. (author)

High pressure apparatus for neutron scattering at low temperature

International Nuclear Information System (INIS)

Munakata, Koji; Uwatoko, Yoshiya; Aso, Naofumi

2010-01-01

Effects of pressure on the physical properties are very important for understanding highly correlated electron systems, in which pressure-induced attractive phenomena such as superconductivity and magnetically ordered non-Fermi liquid have been observed. Up to now, many scientists have developed a lot of high pressure apparatus for each purpose. The characteristic features of various materials and pressure transmitting media for use of high pressure apparatus are reported. Then, two kinds of clamp type high-pressure cell designed for low-temperature neutron diffraction measurements are shown; one is a piston cylinder type high-pressure cell which can be attached to the dilution refrigerator, and the other one is a newly-developed cubic anvil type high-pressure cell which can generate pressure above 7GPa. We also introduce the results of magnetic neutron scattering under pressure on a pressure-induced superconducting ferromagnet UGe 2 in use of the piston cylinder type clamp cell, and those on an iron arsenide superconductor SrFe 2 As 2 in use of the cubic anvil type clamp cell. (author)

Charged-particle magnetic-quadrupole spectrometer for neutron induced reactions

International Nuclear Information System (INIS)

Haight, R.C.; Grimes, S.M.; Tuckey, B.J.; Anderson, J.D.

1975-01-01

A spectrometer has been developed for measuring the charged particle production cross sections and spectra in neutron-induced reactions. The spectrometer consists of a magnetic quadrupole doublet which focuses the charged particles onto a silicon surface barrier detector telescope which is 2 meters or more from the irradiated sample. Collimators, shielding, and the large source-to-detector distance reduce the background enough to use the spectrometer with a 14-MeV neutron source producing 4 . 10 12 n/s. The spectrometer has been used in investigations of proton, deuteron, and alpha particle production by 14-MeV neutrons incident on various materials. Protons with energies as low as 1.1 MeV have been measured. The good resolution of the detectors has also made possible an improved measurement of the neutron- neutron scattering length from the 0 0 proton spectrum from deuteron breakup by 14-MeV neutrons

Neutron scattering investigation of Ce based heavy fermion systems. From magnetism to unconventional phenomena

Energy Technology Data Exchange (ETDEWEB)

Geselbracht, Philipp

2016-12-05

In Ce based heavy fermion systems the hybridization of the 4f orbital of the Ce ion and the conduction band lead to unconventional phenomena such as quantum critical points or superconductivity. The aim of this thesis is to investigate and compare the magnetism on a microscopic scale within the heavy fermion families CeT{sub 2}X{sub 2} (X=Si,Ge) and CeTIn{sub 5}. To do so neutron scattering was used as the experimental method. For CeCu{sub 2}Ge{sub 2}, the antiferromagnetic order AF1 (vector τ=(0.285 0.285 0.544)) is well described as a spin density wave with reduced ordered moments in [1 anti 10] direction. The phase diagram with magnetic field applied along [1 anti 10] direction was investigated. Two new phases were observed: the elliptical helix phase AF2 with modified propagation vector vector τ=(0.34 0.27 0.55) and the C-phase with a yet unknown magnetic order. Above T{sub N}, in zero field, short range order was observed, hinting competition of AF1 and AF2. It is assumed that both structures are due to different nesting properties of the Fermi surface. The RKKY character of the electronic system leads to effective Lande factors in the AF1 (g{sup eff}=0.36) and AF2 (g{sup eff}=0.525) phases. From the zero field dispersion the strength of the next nearest neighbor RKKY interactions was extracted, yielding 2SJ{sub 1}=(-0.042±0.007) meV (basal plane) and 2SJ{sub 2}=(-0.18±0.01) meV (body diagonal). Comparing the RKKY interaction to CeCu{sub 2}Si{sub 2} and CeNi{sub 2}Ge{sub 2} reveals a strong enhancement of the interaction in the basal plane going from antiferromagnetism (CeCu{sub 2}Ge{sub 2}) to superconductivity (CeCu{sub 2}Si{sub 2}) and finally paramagnetism (CeNi{sub 2}Ge{sub 2}). This new finding appears to be an important puzzle piece for the understanding of the CeT{sub 2}X{sub 2} family as it suggests a dependence of the anisotropy of the RKKY interaction from the hybridization strength of the 4f orbital and the conduction band. The obtained phase

Low energy neutron scattering for energy dependent cross sections. General considerations

Energy Technology Data Exchange (ETDEWEB)

Rothenstein, W; Dagan, R [Technion-Israel Inst. of Tech., Haifa (Israel). Dept. of Mechanical Engineering

1996-12-01

We consider in this paper some aspects related to neutron scattering at low energies by nuclei which are subject to thermal agitation. The scattering is determined by a temperature dependent joint scattering kernel, or the corresponding joint probability density, which is a function of two variables, the neutron energy after scattering, and the cosine of the angle of scattering, for a specified energy and direction of motion of the neutron, before the interaction takes place. This joint probability density is easy to calculate, when the nucleus which causes the scattering of the neutron is at rest. It can be expressed by a delta function, since there is a one to one correspondence between the neutron energy change, and the cosine of the scattering angle. If the thermal motion of the target nucleus is taken into account, the calculation is rather more complicated. The delta function relation between the cosine of the angle of scattering and the neutron energy change is now averaged over the spectrum of velocities of the target nucleus, and becomes a joint kernel depending on both these variables. This function has a simple form, if the target nucleus behaves as an ideal gas, which has a scattering cross section independent of energy. An energy dependent scattering cross section complicates the treatment further. An analytic expression is no longer obtained for the ideal gas temperature dependent joint scattering kernel as a function of the neutron energy after the interaction and the cosine of the scattering angle. Instead the kernel is expressed by an inverse Fourier Transform of a complex integrand, which is averaged over the velocity spectrum of the target nucleus. (Abstract Truncated)

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 ...

Fragility of complexity biophysical systems by neutron scattering

Energy Technology Data Exchange (ETDEWEB)

Magazu, Salvatore [Dipartimento di Fisica, Universita di Messina, P.O. Box 55, I-98166 Messina (Italy)]. E-mail: smagazu@unime.it; Migliardo, Federica [Dipartimento di Fisica, Universita di Messina, P.O. Box 55, I-98166 Messina (Italy); Bellocco, Ersilia [Dipartimento di Chimica Organica e Biologica, Universita di Messina, I-98166 Messina (Italy); Lagana, Giuseppina [Dipartimento di Chimica Organica e Biologica, Universita di Messina, I-98166 Messina (Italy); Mondelli, Claudia [CNR-INFM OGG and CRS-SOFT, c/o ILL, 6 Jules Horowitz, BP 156, 38042 Grenoble Cedex 9 (France)

2006-11-15

Neutron scattering is an exceptional tool to investigate structural and dynamical properties of systems of biophysical interest, such as proteins, enzymes, lipids and sugars. Moreover, elastic neutron scattering enhances the investigation of atomic motions in hydrated proteins in a wide temperature range and on the picosecond timescale. Homologous disaccharides, such as trehalose, maltose and sucrose, are cryptobiotic substances, since they allow to many organisms to undergo in a 'suspended life' state, known as cryptobiosis in extreme environmental conditions. The present paper is aimed to discuss the fragility degree of disaccharides, as evaluated of the temperature dependence of the mean square displacement by elastic neutron scattering, in order to link this feature with their bioprotective functions.

Neutron scattering from 12C in the few-MeV region

International Nuclear Information System (INIS)

Smith, A.; Holt, R.; Whalen, J.

1978-09-01

Neutron total cross sections of natural carbon are deduced from the observed transmission of approximately monoenergetic neutrons through carbon samples of varying thickness. The measurements extend from approximately equal to 0.1 to 4.5 MeV with resolutions of approximately equal to 2 to 100 keV. Neutron differential-elastic-scattering cross sections of natural carbon are measured from 1.5 to 4.0 MeV at incident-neutron energy intervals of approximately less than 100 keV, over an angular range of approximately equal to 20 to 160 0 and with energy resolutions of 20 to 50 keV. The experimental results are interpreted in terms of a multilevel R-function analysis. Results are compared with the large body of measured and evaluated neutron total and scattering cross sections and scattered neutron polarizations reported in the literature. It is suggested that the observed neutron total and scattering cross sections of carbon are physically consistent and suitable for use as a reference standard in experimental studies of neutron processes. The R-function description should provide a convenient description of neutron total and scattering cross sections of carbon as a function of both angle and energy. 88 references

A New Measurement of the 1S0 Neutron-Neutron Scattering Length using the Neutron-Proton Scattering Length as a Standard

OpenAIRE

Trotter, D. E. Gonzalez; Salinas, F.; Chen, Q.; Crowell, A. S.; Gloeckle, W.; Howell, C. R.; Roper, C. D.; Schmidt, D.; Slaus, I.; Tang, H.; Tornow, W.; Walter, R. L.; Witala, H.; Zhou, Z.

1999-01-01

The present paper reports high-accuracy cross-section data for the 2H(n,nnp) reaction in the neutron-proton (np) and neutron-neutron (nn) final-state-interaction (FSI) regions at an incident mean neutron energy of 13.0 MeV. These data were analyzed with rigorous three-nucleon calculations to determine the 1S0 np and nn scattering lengths, a_np and a_nn. Our results are a_nn = -18.7 +/- 0.6 fm and a_np = -23.5 +/- 0.8 fm. Since our value for a_np obtained from neutron-deuteron (nd) breakup agr...

The application of inelastic neutron scattering to explore the significance of a magnetic transition in an iron based Fischer-Tropsch catalyst that is active for the hydrogenation of CO

International Nuclear Information System (INIS)

Warringham, Robbie; McFarlane, Andrew R.; Lennon, David; MacLaren, Donald A.; Webb, Paul B.; Tooze, Robert P.; Taylor, Jon; Ewings, Russell A.; Parker, Stewart F.

2015-01-01

An iron based Fischer-Tropsch synthesis catalyst is evaluated using CO hydrogenation at ambient pressure as a test reaction and is characterised by a combination of inelastic neutron scattering (INS), powder X-ray diffraction, temperature-programmed oxidation, Raman scattering, and transmission electron microscopy. The INS spectrum of the as-prepared bulk iron oxide pre-catalyst (hematite, α-Fe 2 O 3 ) is distinguished by a relatively intense band at 810 cm −1 , which has previously been tentatively assigned as a magnon (spinon) feature. An analysis of the neutron scattering intensity of this band as a function of momentum transfer unambiguously confirms this assignment. Post-reaction, the spinon feature disappears and the INS spectrum is characterised by the presence of a hydrocarbonaceous overlayer. A role for the application of INS in magnetic characterisation of iron based FTS catalysts is briefly considered

Magnetic field effects on the soft mode in a singlet ground-state dimer system: a neutron scattering study of Cs3Cr2Br9

DEFF Research Database (Denmark)

Leuenberger, Bruno; Gudel, Hans U.; Feile, Rudolf

1985-01-01

Neutron scattering experiments in a magnetic field have been performed on the singlet ground-state dimer system Cs3Cr2Br9. At low fields the Zeeman splitting of the soft mode evolves in agreement with the isotropic random-phase approximation (RPA) model, with the notable absence of a quasielastic...... peak. At a temperature of 1.7K the expected long-range magnetic order is not found at the predicted field of 2.8 T, indicating the shortcomings of the isotropic RPA model in the critical region. Magnetic intensity on the weak nuclear Bragg peak (1¯1¯4) indicates a probable ordering with a ferromagnetic...

Experimental studies of the critical scattering of neutrons for large scattering vectors

International Nuclear Information System (INIS)

Ciszewski, R.

1972-01-01

The most recent results concerned with the critical scattering of neutrons are reviewed. The emphasis is on the so-called thermal shift, that is the shift of the main maximum in the intensity of critically scattered neutrons with temperature changes. Four theories of this phenomenon are described and their shortcomings are shown. It has been concluded that the situation is involved at present and needs further theoretical and experimental study. (S.B.)

Monte Carlo simulation of fast neutron scattering experiments including DD-breakup neutrons

Energy Technology Data Exchange (ETDEWEB)

Schmidt, D.; Siebert, B.R.L.

1993-06-01

The computational simulation of the deuteron breakup in a scattering experiment has been investigated. Experimental breakup spectra measured at 16 deuteron energies and at 7 angles for each energy served as the data base. Analysis of these input data and of the conditions of the scattering experiment made it possible to reduce the input data. The use of one weighted breakup spectrum is sufficient to simulate the scattering spectra at one incident neutron energy. A number of tests were carried out to prove the validity of this result. The simulation of neutron scattering on carbon, including the breakup, was compared with measured spectra. Differences between calculated and measured spectra were for the most part within the experimental uncertainties. Certain significant deviations can be attributed to erroneous scattering cross sections taken from an evaluation and used in the simulation. Scattering on higher-lying states in [sup 12]C can be analyzed by subtracting the simulated breakup-scattering from the experimental spectra. (orig.)

Monte Carlo simulation of fast neutron scattering experiments including DD-breakup neutrons

International Nuclear Information System (INIS)

Schmidt, D.; Siebert, B.R.L.

1993-06-01

The computational simulation of the deuteron breakup in a scattering experiment has been investigated. Experimental breakup spectra measured at 16 deuteron energies and at 7 angles for each energy served as the data base. Analysis of these input data and of the conditions of the scattering experiment made it possible to reduce the input data. The use of one weighted breakup spectrum is sufficient to simulate the scattering spectra at one incident neutron energy. A number of tests were carried out to prove the validity of this result. The simulation of neutron scattering on carbon, including the breakup, was compared with measured spectra. Differences between calculated and measured spectra were for the most part within the experimental uncertainties. Certain significant deviations can be attributed to erroneous scattering cross sections taken from an evaluation and used in the simulation. Scattering on higher-lying states in 12 C can be analyzed by subtracting the simulated breakup-scattering from the experimental spectra. (orig.)

Diffuse scattering of neutrons and X-rays

International Nuclear Information System (INIS)

Novion, C.H. de

1978-01-01

Diffuse scattering is used to study defect concentrations of about 10 -4 in the case of X-rays and 10 -3 in the case of neutrons. The foundations of diffuse scattering formalism are given, some experimental devices described and a few applications discussed: study by diffraction on powders of defects in CeOsub(2-x); short-range order study by X-rays on Cusub(0.75) Ausub(0.25); short-range order study by neutrons on Cusub(0.435)Nisub(0.565); short-range order study by electrons TiOx; study of irradiation-induced self-interstitials in Al; study of holes created by neutrons in Al [fr

SMALL-ANGLE NEUTRON SCATTERING CONTRIBUTION TO DEVELOPMENT OF SOME NOVEL MATERIALS

Czech Academy of Sciences Publication Activity Database

Strunz, Pavel; Mukherji, D.; Petrenec, Martin; Gilles, R.; Schumacher, G.; Pigozzi, G.; Keiderling, U.; Geue, T.; Gasser, U.; Šaroun, Jan; Rösler, J.

2013-01-01

Roč. 20, č. 2 (2013), s. 67-69 ISSN 1211-5894. [Struktura 2013 - Kolokvium Krystalografické společnosti. Češkovice (Blansko), 09.09.2013-13.09.2013] R&D Projects: GA ČR(CZ) GAP204/11/1453; GA MŠk(XE) LM2011019 Institutional support: RVO:68081723 ; RVO:61389005 Keywords : neutron scattering * superalloy * temperature dependence Subject RIV: BM - Solid Matter Physics ; Magnetism; JL - Materials Fatigue, Friction Mechanics (UFM-A)

Neutron reflectometry as a tool to study magnetism

International Nuclear Information System (INIS)

Felcher, G. P.

1999-01-01

Polarized-neutron specular reflectometry (PNR) was developed in the 1980's as a means of measuring magnetic depth profiles in flat films. Starting from simple profiles, and gradually solving structures of greater complexity, PNR has been used to observe or clarify a variety of magnetic phenomena. It has been used to measure the absolute magnetization of films of thickness not exceeding a few atomic planes, the penetration of magnetic fields in micron-thick superconductors, and the detailed magnetic coupling across non-magnetic spacers in multilayers and superlattices. Although PNR is considered a probe of depth dependent magnetic structure, laterally averaged in the plane of the film, the development of new scattering techniques promises to enable the characterization of lateral magnetic structures. Retaining the depth-sensitivity of specular reflectivity, off-specular reflectivity may be brought to resolve in-plane structures over nanometer to micron length scales

Neutron scattering facilities at China Institute of Atomic Energy. Present and future situations

International Nuclear Information System (INIS)

Ye, C.T.; Gou, C.; Yang, T.H.

2001-01-01

The 15 MW Heavy Water Research Reactor (HWRR) at CIAE in Beijing is the only neutron source available for neutron scattering experiments in China at present. So far totally 5 neutron scattering spectrometers are installed at 4 beam tubes. A 60 MW new research reactor, China Advanced Research Reactor (CARR), now is being built at CIAE to meet the increasing demand of neutron scattering research in China. A brief description of HWRR, the presently existing neutron scattering equipments at HWRP, CARR, and the neutron scattering facilities to be installed at CARR are presented. (J.P.N.)

Inelastic scattering of neutrons by laser photons and excitons in crystals

International Nuclear Information System (INIS)

Agranovich, V.M.; Lalov, I.J.

1975-01-01

The cross section for the neutron scattering by photons sharply increases in crystals. In view of the fact that a propagating photon in a crystal (polariton), being the superposition of transverse photons and Coulomb excitations (optical phonons, excitons, etc.), involves in the motion also a nucleus subsystem, the cross section for the neutron scattering on the photon turns out to be proportional to the cross section for neutron scattering on nuclei and to the strength function of phonons at the polariton frequency. Numerical estimates for the cross section of the noncoherent photon absorption by a neutron in the case of a LiH crystal in the presence of an intense, electromagnetic radiation point to the possibility of an action of neutron fluxes by laser radiation. A similar effect of involvement (superposition) also takes place for excitons. This fact can be used for calculations of the cross section for neutron inelastic scattering by excitons, which is proportional to the scattering of neutron on nuclei cross section. The paper also discussed the effect of laser radiation of neutron-induced nuclear reaction (radiative capture and threshold reactions)

Neutron scattering study of La1-xCaxMnO3 with x=0.15

International Nuclear Information System (INIS)

Begum, Shahnaz; Ono, Yasuhiro; Miyazaki, Yuzuru; Kajitani, Tsuyoshi; Tomioka, Yasuhide; Tokura, Yoshinori

2001-01-01

Elastic and inelastic neutron scattering measurements have been made on a perovskite hole doped manganite La 1-x Ca x MnO 3 with x=0.15 for both powder and single crystal samples to understand the magnetic properties of this compound. Strong diffuse scattering observed in the paramagnetic phase, originates from the ferromagnetic spin fluctuations. New peaks have been observed at 001, 100 and 1/2 0 1/2 from 15 K to the ambient temperature indicating the long-range and/or short-range charge and magnetic spin ordering. An anomalous temperature dependent inelastic scattering intensities were observed by the TOF neutron spectrometer AGNES at 2θ=57-64deg (close to 101 Bragg peak) at temperatures from 17 to 220 K for powder sample. The peak at about 1.0 meV was only observed at 17 and 98 K in the ferromagnetic region and smeared in the paramagnetic region which is possibly the indication of spin gap formation in the ferromagnetic region. The peak at about 1.0 meV at lower temperatures were also observed for single crystal sample close to 1/2 0 1/2 reciprocal point. (author)

A microstructural comparison of two nuclear-grade martensitic steels using small-angle neutron scattering

Science.gov (United States)

Coppola, R.; Fiori, F.; Little, E. A.; Magnani, M.

1997-06-01

Results are presented of a small-angle neutron scattering (SANS) study on two 10-13% Cr martensitic stainless steels of interest for nuclear applications, viz. DIN 1.4914 (MANET specification, for fusion reactors) and AISI 410. The investigation has focussed principally on microstructural effects associated with the differences in chromium content between the two alloys. The size distribution functions determined from nuclear and magnetic SANS components for the two steels given identical heat treatments are in accord with an interpretation based on the presence of ˜ 1 nm size CCr aggregates in the microstructure. Much larger (˜ 10 nm) scattering inhomogeneities with different magnetic contrast are also present and tentatively identified as carbides.

Magnetic model for Mn{sub 2}La{sub 2} developed from spectroscopic studies with inelastic neutron scattering and frequency-domain Fourier-transform THz EPR

Energy Technology Data Exchange (ETDEWEB)

Milazzo, R.; Nehrkorn, J.; Stuiber, S.; Waldmann, O. [Physikalisches Institut, Universitaet Freiburg (Germany); Akhtar, M.N.; Lan, Y.; Powell, A.K. [Institut fuer Anorganische Chemie, Universitaet Karlsruhe, KIT (Germany); Mutka, H. [Institut Laue Langevin, Grenoble (France); Dreiser, J. [Swiss Light Source, Paul Scherrer Institut (Switzerland); Schnegg, A. [Helmholtz-Zentrum Berlin, Institut fuer Silizium-Photovoltaik (Germany); Holldack, K. [Helmholtz-Zentrum Berlin, Institut fuer Synchrotonstrahlung (Germany)

2011-07-01

Molecular nanomagnets which contain several magnetic centers with a large single-ion magnetic anisotropy are of general interest, because they could lead to interesting phenomena such as single-molecule magnet (SMM) behavior. We performed spectroscopic experiments on Mn{sub 2}La{sub 2} using inelastic neutron scattering at the direct time-of-flight disc chopper spectrometer IN5 at ILL and the newly developed frequency-domain Fourier-transform THz EPR at BESSY. Based on the experimental results a magnetic model has been developed. It is discussed why no SMM behavior was observed, even though Mn{sub 2}La{sub 2} exhibits a remarkably high energy barrier of about 37 K for spin relaxation. Furthermore our results can be applied to analogous clusters, with the diamagnetic La{sup I}II ions replaced by magnetic rare earth ions.

Neutron scatter studies of chromatin structures related to functions

International Nuclear Information System (INIS)

Bradbury, E.M.

1992-01-01

Despite of setbacks in the lack of neutrons for the proposed We have made considerable progress in chromatin reconstitution with the VLR histone H1/H5 and in understanding the dynamics of nucleosomes. A ferromagnetic fluid was developed to align biological molecules for structural studies using small-angle-neutron-scattering. We have also identified and characterized an intrinsically bent DNA region flanking the RNA polymerase I binding site of the ribosomal RNA gene in Physarum Polycephalum. Finally projects in progress are in the areas of studying the interatctions of histone H4 amino-terminus peptide 1-23 and acetylated 1-23 peptide with DNA using thermal denaturation; study of GGAAT repeats found in human centromeres using high resolution Nuclear magnetic Resonance and nuclease sentivity assay; and the role of histones and other sperm specific proteins with sperm chromatin

LANSCE '90: the Manuel Lujan Jr. Neutron Scattering Center

International Nuclear Information System (INIS)

Pynn, Roger

1991-01-01

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 U.S. 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. (author)

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

International Nuclear Information System (INIS)

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

Steel research using neutron beam techniques. In-situ neutron diffraction, small-angle neutron scattering and residual stress analysis

International Nuclear Information System (INIS)

Sueyoshi, Hitoshi; Ishikawa, Nobuyuki; Yamada, Katsumi; Sato, Kaoru; Nakagaito, Tatsuya; Matsuda, Hiroshi; Arakaki, Yu; Tomota, Yo

2014-01-01

Recently, the neutron beam techniques have been applied for steel researches and industrial applications. In particular, the neutron diffraction is a powerful non-destructive method that can analyze phase transformation and residual stress inside the steel. The small-angle neutron scattering is also an effective method for the quantitative evaluation of microstructures inside the steel. In this study, in-situ neutron diffraction measurements during tensile test and heat treatment were conducted in order to investigate the deformation and transformation behaviors of TRIP steels. The small-angle neutron scattering measurements of TRIP steels were also conducted. Then, the neutron diffraction analysis was conducted on the high strength steel weld joint in order to investigate the effect of the residual stress distribution on the weld cracking. (author)

On the theory of ultracold neutrons scattering by Davydov solitons

International Nuclear Information System (INIS)

Brizhik, L.S.

1984-01-01

Elastic coherent scattering of ultracold neutrons by Davydov solitons in one-dimensional periodic molecular chains without account of thermal oscillations of chain atoms is studied. It is shown that the expression for the differential cross section of the elastic neutron scattering by Davydov soliton breaks down into two components. One of them corresponds to scattering by a resting soliton, the other is proportional to the soliton velocity and has a sharp maximum in the direction of mirror reflection of neutrons from the chain