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NIST Authors in Bold

Displaying 526 - 550 of 807

A 3He beam stop for minimizing gamma-ray and fast-neutron background

August 6, 2016
Author(s)
Danyal J. Turkoglu, Robert G. Downing, Wangchun Chen, Dagistan Sahin, Jeremy C. Cook
Prompt gamma-ray activation analysis facilities with high neutron currents (≥109 s-1) generate triton-induced fast neutrons from 6Li-loaded collimators and beam stops at rates that soon damage gamma-ray detectors. We develop an alternative beam stop design

Current status and future directions for in situ transmission electron microscopy

August 6, 2016
Author(s)
M. L. Taheri, Eric Stach, Ilke Arslan, Peter A. Crozier, Kabius Bernd, Thomas LaGrange, Andrew Minor, Seiji Takeda, Mihaela M. Tanase, Jakob B. Wagner, Renu Sharma
This review article discusses the current and future possibilities for the application of in situ transmission electron microscopy to reveal synthesis pathways and functional mechanisms in complex and nanoscale materials. The findings of a group of

Crystal Structures and Phase Equilibria in the Hafnium-Palladium System

August 1, 2016
Author(s)
Judith K. Stalick, Richard M. Waterstrat
Portions of the Hf-Pd phase diagram have been reinvestigated in an attempt to resolve contradictions that occur between two previous studies. Techniques employed include Rietveld refinement using x-ray and high-temperature neutron diffraction data to

Precision measurement of the radiative beta decay of the free neutron

June 14, 2016
Author(s)
Jeffrey S. Nico, Kevin J. Coakley, Maynard S. Dewey, Thomas R. Gentile, Hans P. Mumm, Alan Keith Thompson, M J. Bales, R. Alarcon, C. D. Bass, E J. Beise, H Breuer, Jim Byrne, R L. Cooper, B. O'Neill, F E. Wietfeldt, T E. Chupp
The theory of quantum electrodynamics predicts that a continuous spectrum of photons is emitted in the beta decay of the free neutron in addition to a proton, an electron, and an antineutrino. We report the first precision test of the shape of the photon

MPInterfaces: A Materials Project based Python Tool for a High Throughput Computational Screening of Interfacial Systems

May 31, 2016
Author(s)
Arunima Singh, Kiran Mathew, Joshua Grabriel, Kamal Choudhary, Susan B. Sinnott, Albert Davydov, Francesca M. Tavazza, Richard G. Hennig
A Materials Project based open-source python tool, MPInterfaces, has been developed to automate the high throughput computational screening and study of interfacial systems. The framework encompasses creation and manipulation of interface structures for

Applications of Neutron Imaging and Future Possibilities

May 15, 2016
Author(s)
Daniel S. Hussey, David L. Jacobson
Neutron imaging applications exploit the power of neutrons to penetrate through metals and measure small concentrations of hydrogen and lithium with high sensitivity. The recent advances made in digital imaging devices have enabled many novel neutron

Dynamic Onset of Feynman Relation in the Phonon Regime

May 9, 2016
Author(s)
Lu Deng, Edward W. Hagley, Yan Li, Chengjie Zhu
The Feynman relation 1, a much celebrated condensed matter physics gemstone for more than 70 years, predicts that the density excitation spectrum and structure factor of a condensed Bosonic system in the phonon regime drops linear and continuously to zero

Neutron Limit on the Strongly-Coupled Chameleon Field

March 11, 2016
Author(s)
Michael G. Huber, Muhammad D. Arif, David G. Cory, R. Haun, B. Heacock, Joachim Nsofini, Dimitry A. Pushin, P Saggu, C.B Shahi, William M. Snow, A.R. Young
The physical origin of the dark energy which causes the accelerated expansion rate of the universe is one of the major open questions of cosmology. One set of theories postulates the existence of a self-interacting scalar eld for dark energy coupling to

The JAR Extractor: a Soxhlet Modified Into a Large-Diameter Wafer Washer

October 20, 2015
Author(s)
Richard J. Sheridan, Aaron V. Kirchhoff
A closed-atmosphere, solvent-recirculating, large diameter wafer washer was fabricated for neutron reflectivity research at the National Institute of Standards and Technology. Manufacturing feasibility for the public sector was increased by simplicity in

Equilibrium Self-Assembly, Structure, and Dynamics of Clusters of Star-Like Micelles

October 17, 2015
Author(s)
Vivek M. Prabhu, Shrinivas Venkataraman, Yi Yan Yang, James Hedrick
Small-angle neutron scattering and static and dynamic light scattering have characterized the hierar-chical structure and dynamics of clusters of self-assembled star-like micelles formed by oligocarbonate-fluorene func-tionalized polyethylene glycol

Hydration of Conduction Pores in KcsA Potassium Channel and M2 Proton Channel

September 14, 2015
Author(s)
J L. Blasic, David L. Worcester, Klaus Gawrisch, Philip A. Gurnev, Mihaela Mihailescu
Water-filled hydrophobic cavities of channel proteins serve as gateways for transfer of ions across membrane. However, functional implications of hydration-dehydration transitions remain elusive due to difficulties to detect and quantify water in channel

Macroscopic Subkelvin Refrigerator Employing Superconducting Tunnel Junctions

August 10, 2015
Author(s)
Xiaohang NMN Zhang, Peter J. Lowell, Brandon L. Wilson, Galen C. O'Neil, Joel N. Ullom
In this paper, we demonstrate a general-purpose macroscopic refrigerator based on the transport of hot electrons through superconducting tunnel junctions. Our refrigerator is intended to provide access to temperatures below those accessible using pumped

Development of an Ultra-Pure, Carrier-Free 209Po Solution Standard

July 23, 2015
Author(s)
Ronald Colle, Ryan P. Fitzgerald, Lizbeth Laureano-Perez
Ultra-pure, carrier-free 209Po solution standards have been prepared and standardized for their massic alpha-particle emission rate. The standards, which will be disseminated by the National Institute of Standards and Technology (NIST) as Standard

A New Cold Neutron Imaging Instrument at NIST

July 6, 2015
Author(s)
Daniel S. Hussey, Christoph W. Brocker, David L. Jacobson, Thomas R. Gentile, Wangchun Chen, Elias M. Baltic, DV Baxter, J. Doskow, Muhammad D. Arif
The NIST neutron imaging program will build a new imaging instrument in the NCNR guide hall at the end of the neutron guide NG-6, beginning operation in summer of 2014. The NG-6 guide has a spectrum that is strongly peaked at a neutron wavelength of 5 Å

Deuteration in Biological Neutron Reflectometry

June 30, 2015
Author(s)
Frank N. Heinrich
Neutron reflectometry is uniquely positioned in structural biology, because of its ability to characterize biomimetic interfacial architectures like lipid membranes and membrane-associated proteins non-destructively and in their native environment

Flexible metal-organic framework compounds: In situ studies for selective CO2 capture

June 19, 2015
Author(s)
Andrew J. Allen, Laura Espinal, Winnie K. Wong-Ng, Wendy Queen, Craig Brown, Steven R. Kline, Kristi L. Kauffman, Jeffrey T. Culp
Results from in situ experiments are presented to correlate carbon capture with dynamic structural changes in two flexible metal-organic framework (MOF) materials: porous coordination polymers (PCPs) exhibiting promising carbon dioxide adsorption

Elemental characterization of Single-Wall Carbon Nanotube (SWCNT-1) reference material by neutron and prompt gamma activation analysis

April 7, 2015
Author(s)
Rick L. Paul, Rabia Oflaz, Jan Kucera, J W Bennett, E. A. De Nadai Fernandes, M. Kubesova, M. A. Bacchi, A. J. Stopic, R. E. Sturgeon, P. Grinberg
Instrumental neutron activation analysis with both relative and k0 standardization was used in four experienced laboratories to determine element mass fractions in single-wall carbon nanotube certified reference material (CRM) SWCNT-1. Results obtained

NGD Cold Neutron Prompt Gamma-ray Activation Analysis Spectrometer at NIST

April 1, 2015
Author(s)
Rick L. Paul, Dagistan NMN Sahin, Jeremy C. Cook, Christoph W. Brocker, Richard M. Lindstrom, Donna J. O'Kelly
A new instrument for cold neutron prompt gamma-ray activation analysis (CNPGAA) has been designed and constructed as part of the recent expansion of the cold neutron guide hall at the NIST Center for Neutron Research (NCNR). Located on neutron guide NGD

Local Strain Exerted on Nb 3 Sn Filaments in an ITER Strand

March 13, 2015
Author(s)
Kozo Osamura, Shutaro Machiya, Stefanus Harjo, Tatsushi Nakamoto, Najib Cheggour, Arend Nijhuis
As part of an international project to benchmark facilities for measuring the strain dependence of critical current in ITER Nb 3Sn strands, direct measurement of local strain exerted on Nb 3Sn filaments was attempted at cryogenic temperature by means of
Displaying 526 - 550 of 807