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Search Publications by: John Barker (Fed)

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Displaying 26 - 46 of 46

Comparison of Pinhole Collimation and Focusing Optics for SANS

September 21, 2015
Author(s)
Charles J. Glinka, John G. Barker, David F. Mildner
We examine quantitatively the instrumental factors that affect the theoretical performance and practical application of conventional pinhole collimation and focusing optics for Small-Angle Neutron Scattering (SANS) measurements. We calculate the relative

Experimental Characterization of the Advanced Liquid Hydrogen Cold Neutron Source Spectrum of the NBSR Reactor at the NIST Center for Neutron Research

August 1, 2015
Author(s)
Jeremy C. Cook, John G. Barker, J. Michael Rowe, Robert E. Williams, Cedric V. Gagnon, Richard M. Lindstrom, Richard Michael Ibberson, Dan A. Neumann
The recent expansion of the NIST Center for Neutron Research facility has offered a rare opportunity to perform an accurate measurement of the cold neutron spectrum at the exit of a newly-installed neutron guide. Using a combination of a neutron time-of

The Effect of Gravity on the Resolution of Small-Angle Neutron Diffraction Peaks

October 1, 2011
Author(s)
David F. Mildner, John G. Barker, Steven R. Kline
The resolution ellipses for neutron diffraction peaks at small vectors lie along lines that point to a position vertically above the beam center. This gravity effect is only noticeable for neutron beams at long wavelenghts and with large wavelength spreads

Neutron Transmission of Single-Crystal Magnesium Fluoride

November 27, 2008
Author(s)
John Barker, David F. Mildner, Jose Rodriguez Rivera, P. Thiyagarajan
The neutron attenuation through single-crystal magnesium fluoride has been measured as a function of wavelength at both room temperature and 77 K. These data confirm a total cross section that is lower than MgO for wavelengths greater than 0.2 nm. MgF 2

Optical and Structural Study of GaN Nanowires Grown by Catalyst-Free MBE: (II) Defect-Related Luminescence and Electron-Beam Irradiation Effects

June 1, 2007
Author(s)
Lawrence H. Robins, Kristine A. Bertness, John G. Barker, Norman A. Sanford, John B. Schlager
GaN nanowires grown by catalyst free molecular beam epitaxy were characterized by photoluminescence (PL) and cathodoluminescence (CL) spectroscopy at temperatures from 3 K to 295 K. Both as grown samples, which contained approximately vertically oriented

Abstracts for the MSEL Assessment Panel, March 2001

January 26, 2001
Author(s)
Leslie E. Smith, Alamgir Karim, Leonid A. Bendersky, C Lu, J J. Scott, Ichiro Takeuchi, Kathleen M. Flynn, Vinod K. Tewary, Davor Balzar, G A. Alers, Stephen E. Russek, Charles C. Han, Haonan Wang, William E. Wallace, Daniel A. Fischer, K Efimenko, Wen-Li Wu, Jan Genzer, Joseph C. Woicik, Thomas H. Gnaeupel-Herold, Henry J. Prask, Charles F. Majkrzak, Norman F. Berk, John G. Barker, Charles J. Glinka, Eric K. Lin, Ward L. Johnson, Paul R. Heyliger, David T. Read, R R. Keller, J Blendell, Grady S. White, Lin-Sien H. Lum, Eric J. Cockayne, Igor Levin, C E. Johnson, Maureen E. Williams, Gery R. Stafford, William J. Boettinger, Kil-Won Moon, Daniel Josell, Daniel Wheeler, Thomas P. Moffat, W H. Huber, Lee J. Richter, Clayton S. Yang, Robert D. Shull, R A. Fry, Robert D. McMichael, William F. Egelhoff Jr., Ursula R. Kattner, James A. Warren, Jonathan E. Guyer, Steven P. Mates, Stephen D. Ridder, Frank S. Biancaniello, D Basak, Jon C. Geist, Kalman D. Migler
Abstracts relating to research and development in the NIST Materials Science and Engineering Laboratory (MSEL) are presented for a poster session to be presented to the 2001 MSEL Assessment Panel.