A5060035704- Nuclear Physics and Applications
- Atomic and Subatomic Physics Research
- High-pressure geophysics and materials
- Nuclear reactor physics and engineering
- Magnetic Properties and Applications
- Material Dynamics and Properties
- Magnetic properties of thin films
- Quantum, superfluid, helium dynamics
- X-ray Diffraction in Crystallography
- Radiation Detection and Scintillator Technologies
- Theoretical and Computational Physics
- Metallic Glasses and Amorphous Alloys
- Advanced materials and composites
- Hydrogen Storage and Materials
- Aerogels and thermal insulation
- Nuclear Materials and Properties
- Microstructure and mechanical properties
- Particle physics theoretical and experimental studies
- Magnetic and transport properties of perovskites and related materials
- Nanoporous metals and alloys
- Hydrocarbon exploration and reservoir analysis
- Powder Metallurgy Techniques and Materials
- nanoparticles nucleation surface interactions
- Inorganic Fluorides and Related Compounds
- Polymer Surface Interaction Studies
NIST Center for Neutron Research
2009-2024
National Institute of Standards and Technology
2013-2024
Australian Nuclear Science and Technology Organisation
2021
Karlsruhe Institute of Technology
2004-2005
United States Naval Research Laboratory
1995
Istituto Nazionale di Fisica Nucleare, Sezione di Pavia
1992
University of Pavia
1992
Two high-resolution, general-purpose, small-angle neutron scattering instruments have been constructed at the National Institute of Standards and Technology's Center for Neutron Research. The are 30 m long utilize mechanical velocity selectors, pinhole collimation high-data-rate two-dimensional position-sensitive detectors. incident wavelength, wavelength resolution effective length independently variable, under computer control, provide considerable flexibility in optimizing beam intensity...
An ultra-high-resolution small-angle neutron scattering (USANS) double-crystal diffractometer (DCD) is now in operation at the NIST Center for Neutron Research (NCNR). The instrument uses multiple reflections from large silicon (220) perfect single crystals, before and after sample, to produce both high beam intensity a low background suitable measurements. minimum detector ratio (noise-to-signal, N/S) q ≥ 5 × 10 −4 Å −1 4 −7 . 2.38 wavelength neutrons on dedicated thermal port, producing...
A description and the performance of very small angle neutron scattering diffractometer at National Institute Standards Technology are presented. The measurement range instrument extends over three decades momentum transfer
The focusing of a cold neutron beam by multiple biconcave lenses has recently been proposed as practical means extending the lower limit Q in conventional, long flight-path small-angle scattering (SANS) instruments. To test feasibility this approach, we have carried out extensive measurements on one 30 m SANS instruments at NIST characteristics set 28 MgF 2 lenses. focused profile measured over several orders magnitude using high resolution auto-radiography. lens configuration outperforms...
Small angle neutron scattering experiments were carried out on a charged stabilized dense colloidal suspension to observe changes in lattice structure as function of shear rate. It is shown that (1) the will evolve from crystalline state equilibrium polycrystalline if subjected very low shear; and (2) increased, partial order reestablished with apparent appearance sliding layer flow. The transitions are reversible. first transition occurs when dynamic yield stress exceeded; second...
A numerical calculation method for determining the resolution functions radially symmetric collimation and scattering is described. In present approach, total number of integrations reduced to four by use radial symmetry geometry. Furthermore, beam-stop shadowing effect included exactly. typical can be completed in minutes on current personal computers. An interactive computer program allows user enter experimental parameters such as aperture size wavelength spread, allowing smearing...
Four different poly(ethylene oxide) [PEO] molecules were compared as grafted polymer layers for biomaterials' substrates: two linear polymers and star polymers. Conditions maximizing surface coverage each molecule employed with the aim of inhibiting protein adsorption increasing density end groups. Neutron reflectivities immersed in deuterium oxide (heavy water) measured used to calculate volume fraction profiles a function distance from surface. These combined data on compare recent...
Thin film miscible blends of poly(methyl methacrylate) (PMMA) and a branched random copolymer methyl methacrylate methoxy poly(ethylene glycol) monomethacrylate, P(MMA-r-MnG), were investigated by neutron reflectivity. The copolymer, which has higher surface tension than PMMA, was nevertheless found to segregate completely cover both the silicon substrate following annealing in 2000 A thick films with ≥2 wt % P(MMA-r-MnG). This is contrast linear polyethylene oxide, depleted at interfaces...
In ferromagnets with a nonuniform magnetocrystalline and/or magnetoelastic anisotropy, such as nanocrystalline (nc-) or cold-worked (cw-) polycrystalline materials, the static magnetic microstructure gives rise to strong elastic small-angle neutron scattering (SANS). The paper explores method for analyzing field-dependent SANS data from materials in terms of model based on theory micromagnetics. Samples cw Ni and electrodeposited nc Co were characterized by x-ray magnetometry, investigated...
We have obtained the magnetic field dependence of static ferromagnetic correlations in nanocrystalline electrodeposited Co and Ni by means correlation function spin misalignment, determined from small-angle neutron scattering data. The approach yields a length ${l}_{C}$, which is measure for spatial extent inhomogeneities magnetization distribution. depends strongly on applied with values ranging 94 nm at low fields to about 15 saturation. results ${l}_{C}$ indicate that main source...
We present static light scattering results for Laponite suspensions. Analyzing our data using the Zimm technique, we measure a second virial coefficient of 6.0 × 10-23 m3 at an ionic strength 10-4 M. Both agree well with recent theories and computations thermodynamics hard disks. Our support conclusion that classical Onsager result underestimates repulsive contribution in discotic systems. also neutron very low q which conclusively confirm existence large-scale structure gels above...
Measurements and calculations of beam attenuation background scattering for common materials placed in a neutron are presented over the temperature range 300-700 K. Time-of-flight (TOF) measurements have also been made, to determine fraction that is either inelastic or quasi-elastic as measured with 3He detector. Other sources considered include double Bragg diffraction from windows samples, gases, phonon solids. Background residual air detector vacuum vessels dome presented. The thickness...
The surface adsorption behavior and solution aggregate microstructure of the dichain cationic surfactant dihexadecyl dimethylammonium bromide (DHDAB) have been studied using small angle neutron scattering (SANS), light scattering, reflectivity (NR), tension (ST). Using a combination reflectivity, DHDAB equilibrium excess at saturation has measured as 2.60 ± 0.05 × 10−10 mol·cm−2. values obtained by both methods are in good agreement consistent with reported for other dialkyl chain...
In small-angle scattering theory and data modeling, it is generally assumed that each scattered ray - photon or neutron only once on its path through the sample. This assumption greatly simplifies interpretation of valid in many cases. However, breaks down under conditions high power, increasing with sample concentration, contrast, length wavelength. For samples a significant disregarding multiple effects can lead to erroneous conclusions structure investigated this paper, impact different...
A neutron spin filter based on transmission through nuclear-spin-polarized 3 He gas has been applied to polarization analysis of small angle scattering (SANS). Such filters, which are the large dependence absorption neutrons by He, make SANS possible because their angular acceptance. In present experiment, a He-based analyzer was employed separate nuclear into its coherent and spin-incoherent components. Polarized analyzers were prepared two different optical pumping methods installed NG3...
This paper provides a comparison of the capabilities two techniques for extending range conventional small-angle neutron scattering (SANS) towards micrometre length scale, namely double-crystal diffraction ultra-small-angle (DCD USANS) technique, which uses perfect silicon crystals in Bragg reflection, and spin-echo SANS (SESANS), method that spin precessions polarized beam. Both methods encode angle to very high precision. Based on round-robin test measurements, strengths weaknesses are...
Small angle neutron scattering (SANS) is used to compare nanostructured Sn–Co–C alloys produced by vertical axis mechanical attriting those magnetron sputter deposition. The attrited materials have grain sizes that vary with composition and are on the order of in size. deposited either amorphous or a size approximately , depending composition. SANS results further understand electrochemistry these when as negative electrodes for lithium-ion batteries why mechanically alloyed far from...
In ferromagnets with a non-uniform magnetocrystalline and/or magnetoelastic anisotropy, such as nanocrystalline or cold-worked polycrystalline materials, the static magnetic microstructure gives rise to elastic small-angle neutron scattering (SANS). The paper explores method for determining exchange-stiffness constant A by analysis of dependence SANS cross-section on applied field. Experimental results and spin-wave stiffness D in Ni Co are found agree literature data obtained inelastic...
We present a new method for determining the exchange-stiffness constant A of ferromagnetic bulk material by field-dependent elastic small-angle neutron scattering (SANS). In limit high applied magnetic field H, which volume is single domain and magnetization nearly aligned with direction field, combination micromagnetics theory formalism suggests closed-form expressions differential cross section as function vector H. Based on these results it suggested that can be extracted from...
A small-angle neutron scattering study of the kinetics growth semiconductor crystallites in a glass matrix is presented. The scattered intensity I(k) exhibits peak at nonzero vector and decreases to zero as k goes zero. patterns measured different annealing temperatures present scaling behavior consistent with ripening approximation. We show that good agreement predictions simple phenomenological model, based on local mass conservation, which describes dilute gas surrounded by depletion zones.