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Search Publications by: John Barker (Fed)

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Displaying 1 - 25 of 29

Facile Polymerization in a Bicellar Template to Produce Polymer Nano-Rings

January 15, 2023
Author(s)
Chung-Hao Liu, Catherine Cheu, John Barker, Lin Yang, Mu-Ping Nieh
Hypothesis: A well-defined discoidal bicelle composed of three lipids, specifically zwitterionic long-chain 1,2-dipalmitoyl phosphocholine (DPPC) and short-chain 1,2-dihexanoyl phosphocholine (DHPC) doped with anionic 1,2-dipalmitoyl phosphoglycerol (DPPG)

The Very Small-Angle Neutron Scattering Instrument at the National Institute of Standards and Technology

February 27, 2022
Author(s)
John Barker, James Moyer, Steven Kline, G. Jensen, Jeremy Cook, Cedric V. Gagnon, Elizabeth Kelley, Jean Philippe Chabot, Nicholas C. Maliszewskyj, Chirag B. Parikh, Wangchun Chen, C. Glinka
A description and the performance of the Very Small-Angle Neutron Scattering (VSANS) Diffractometer at the National Institute of Standards and Technology are presented. The measurement range of the instrument extends over three decades of momentum transfer

Spin-Analyzed SANS for Soft Matter Applications

June 20, 2017
Author(s)
WangChun Chen, John Barker, Ronald L. Jones, Kathryn Krycka, Shannon Watson, Cedric Victor Lucien Gagnon, T. Perevozchivoka, Paul Butler, Thomas R. Gentile
The small angle neutron scattering (SANS) of nearly Q-independent nuclear spin-incoherent scattering from hydrogen present in most soft matter and biology samples may raise an issue in structure determination in certain soft matter applications. This is

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