A5052669062- Nuclear Physics and Applications
- Atomic and Subatomic Physics Research
- Radiation Detection and Scintillator Technologies
- High-pressure geophysics and materials
- Quantum, superfluid, helium dynamics
- Crystallography and Radiation Phenomena
- Particle Detector Development and Performance
- Nuclear reactor physics and engineering
- Physics of Superconductivity and Magnetism
- Rare-earth and actinide compounds
- Electron and X-Ray Spectroscopy Techniques
- Particle accelerators and beam dynamics
- Magnetic properties of thin films
- X-ray Spectroscopy and Fluorescence Analysis
- Superconducting Materials and Applications
- Magnetic Properties and Applications
- Particle Accelerators and Free-Electron Lasers
- Nuclear Materials and Properties
- Theoretical and Computational Physics
- X-ray Diffraction in Crystallography
- Graphite, nuclear technology, radiation studies
- Enzyme Structure and Function
- Space Technology and Applications
- Radiation Therapy and Dosimetry
- Advanced NMR Techniques and Applications
Oak Ridge National Laboratory
2013-2024
Government of the United States of America
2022
University of Missouri
1986-2020
Indiana University Bloomington
2020
Spallation Neutron Source
2004-2015
Los Alamos National Laboratory
1999-2002
University of Rhode Island
1988-1998
The first high-resolution neutron protein structure of perdeuterated rubredoxin from Pyrococcus furiosus ( Pf Rd) determined using the new IMAGINE macromolecular crystallography instrument at Oak Ridge National Laboratory is reported. Neutron diffraction data extending to 1.65 Å resolution were collected a relatively small 0.7 mm 3 Rd crystal 2.5 d (60 h) beam time. refined contains 371 out 391, or 95%, D atoms and 58 solvent molecules. designed provide near atomic (1.5 Å) crystals with...
A scintillator-based Timepix3 (TPX3) detector was developed to resolve the high-frequency modulation of a neutron beam in both spatial and temporal domains, as required for spin-echo experiments. In this system, light from scintillator is manipulated with an optical lens intensified using image intensifier, making it detectable TPX3 chip. Two different scintillators, namely, 6LiF:ZnS(Ag) 6LiI:Eu, were investigated achieve high resolution needed modulated small-angle scattering (SEMSANS)...
We discuss the viscosity damping effect on capillary waves in a binary-liquid system, using linearized Navier-Stokes equation. The correction for dispersion relation depends wave vector k as well interfacial tension. calculated k-dependence of is characterized by critical capillary-wave-number value , which separates regions weak and strong damping. surface roughnesses binary liquid system with large depths are compared to experiments. Although analysis has been restricted classical,...
The magnetism of antiferromagnetic ${\mathrm{Fe}}_{x}{\mathrm{Pt}}_{1\ensuremath{-}x}$ thin films $(x=0.27$ and 0.30) epitaxially grown onto MgO (110) a-axis sapphire $(\ensuremath{\alpha}{\ensuremath{-}\mathrm{A}\mathrm{l}}_{2}{\mathrm{O}}_{3})$ substrates has been studied by elastic neutron x-ray scattering. Bulk chemically ordered ${\mathrm{FePt}}_{3}$ exhibits an spin structure with a wave vector ${Q}_{1}=2\ensuremath{\pi}/a(\frac{1}{2}\frac{1}{2}0)$ below...
Results of neutron transmission Bragg edge spectroscopic experiments performed at the SNAP beamline Spallation Neutron Source are presented. A high resolution counting detector with a sensitive microchannel plate and Timepix ASIC readout is capable energy resolved two dimensional mapping spatial accuracy ∼55 μm, limited by pixel size, duration initial pulse. map Fe 110 position was obtained for bent steel screw sample. Although pulse corresponded to ∼30 mÅ 15.3 m flight path, in our...
With one of the highest intrinsic magnetic moments $(10.6\phantom{\rule{0.16em}{0ex}}{\ensuremath{\mu}}_{B}/\mathrm{atom})$ among heavy rare-earth elements, dysprosium exhibits a rich phase diagram, including several modulated phases. Aided by Ruderman-Kittel-Kasuya-Yosida interaction, modulations propagate coherently over long range. Neutron diffraction experiments were performed to determine microscopic origin field induced phases in bulk Dy as function temperature, covering regions...
We report on the in situ polarized (3)He neutron polarization analyzer developed for time-of-flight Magnetism Reflectometer at Spallation Neutron Source Oak Ridge National Laboratory. Using spin exchange optical pumping method, we achieved a of 76% ± 1% and maintained it entire three-day duration test experiment. Based transmission measurements with unpolarized neutrons, show that average analyzing efficiency system is 98% wavelength band 2-5 Å. highly incident beam produced by supermirror...
The unique advantages of using polarized 3He as neutron spin filters, such broadband and wide angular acceptance beams, have made it widely used in most facilities. Over the last several years, we developed a program to meet increasing needs based filters at Oak Ridge National Laboratory's (ORNL) High Flux Isotope Reactor (HFIR) Spallation Neutron Source (SNS). At ORNL, is produced Spin Exchange Optical Pumping (SEOP). We constructed cell fabrication station produce cells different pressures...
We report a simple analytic form for the convolution integral in transmission M\"ossbauer spectroscopy allowing accurate representation of line shape even very thick absorbers (t=10), and permitting easy fitting to true line-shape function. This permits determination all M\"ossbauer-effect (ME) parameters, including position, width, cross section, interference. method can be applied deconvolute accurately information contained either source or absorber, an explicit emission absorption...
Abstract The neutron Larmor diffraction technique has been implemented using superconducting magnetic Wollaston prisms in both single-arm and double-arm configurations. Successful measurements of the coefficient thermal expansion a single-crystal copper sample demonstrates that method works as expected. experiment involves new tuning by varying field configurations device results agree well with previous measurements. difference between investigated experimentally. We conclude this...
Despite the challenges, neutron resonance spin echo still holds promise to improve upon for measurement of slow dynamics in materials. We present a bootstrap, radio frequency flipper using high temperature superconducting technology capable flipping with either nonadiabatic or adiabatic modes. A 2 MHz has been achieved, which would achieve an effective field integral 0.35 T m meter separation spectrometer at current device specifications. In bootstrap mode, self-cancellation Larmor phase...
We have developed a wavelength-Shifting-fiber Scintillator Detector (SSD) with 0.3 m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> area per module. Each module has 154 × 7 pixels and 5 mm 50 pixel size. Our goal is to design large neutron detector offering higher detection efficiency count-rate capability for Time-Of-Flight (TOF) diffraction in the Spallation Neutron Source (SNS). A ZnS/...
The phonon density-of-states (DOS) of elemental vanadium was measured at elevated temperatures by inelastic neutron scattering. softening predicted thermal expansion against the bulk modulus is much larger than shifts in energies. We conclude that anharmonicities associated with are largely canceled effects from phonon-phonon Prior measurements heat capacity and calculations electronic entropy assessed, consistency requires an explicit temperature dependence DOS. Using data literature,...
The analysis of neutron diffraction experiments often assumes that neutrons are elastically scattered from the sample. However, there is growing evidence a significant fraction detected in fact inelastically scattered, especially soft materials and aqueous samples. Ignoring these inelastic contributions gives rise to inaccurate experimental results. To date, has been no simple method with broad applicability for signal separation experiments. Here, we present robust believe could be suited...
This article reviews some current trends that can be observed in the development of neutron scattering instrument technologies. While number facilities worldwide and beam days they offer are largely stable, their scientific impact is increasing through improving instrumental capabilities, new more versatile instruments, efficient data collection protocols. Neutron beams becoming smaller but intense, instruments being designed to utilize ‘useful’ neutrons unit time. picks discusses a few...