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Displaying 551 - 575 of 807

An approach for identification and determination of arsenic species in the extract of kelp

March 3, 2015
Author(s)
Lee L. Yu, Rolf L. Zeisler, Rabia Oflaz, Wei Chao, Junting Tong, Haixia Bao, Jun Wang
The National Institute of Standards and Technology is developing a kelp standard reference material (SRM) in support of dietary supplement measurements. Edible seaweeds such as kelp and laver consumed as diet or dietary supplement contain tens of mg/kg

Critical Examination of the Colloidal Particle Model of Globular Proteins

February 3, 2015
Author(s)
Prasad S. Sarangapani, Steven D Hudson, Ronald L. Jones, Jack F. Douglas, Jai A. Pathak
Recent studies of globular protein solutions have uniformly adopted a colloidal view of proteins as particles, a perspective that neglects the polymeric primary structure of these biological macromolecules, their intrinsic flexibility and their ability to

Beyond the International Year of Crystallography

February 1, 2015
Author(s)
Andrew J. Allen, Janos Hajdu, Anke R. Kaysser-Pyzalla
It is now one year since all International Union of Crystallography (IUCr) journals became online only, and this is just one of the developments during the International Year of Crystallography, IYCr 2014. Perhaps, most conspicuously, IUCr’s new flagship

Reevaluation of Neutron Flux Characterization Parameters for NIST RT-2 Facility

December 31, 2014
Author(s)
Dagistan Sahin, Vladimir Radulovic, Richard M. Lindstrom, Andrej Trkov
It has been difficult to characterize the thermal to epithermal neutron flux ratio (f) and the measure of the nonideal epithermal neutron flux distribution (α) for the RT-2 pneumatic rabbit facility at the NIST National Bureau of Standards Reactor (NBSR)

Physical Properties of LiMn 2-x MxO 4 (M = Ni, Fe) Sol-Gel Nanopowders

December 15, 2014
Author(s)
E. Talik, L. Lipinska, A. Guzik, Pawel Zajdel, M. Michalska, M. Szubka, M. Kadziolka-Gawel, Rick L. Paul
The Pechini sol-gel method was applied to obtain LiMn 2-xT xO 4 (T=Ni, Fe; x = 0.1 to 0.5) nanopowders. Crystal and electronic structures, chemical composition and magnetic properties of the materials were characterized by X-ray diffraction, XPS, SEM/EDX

Recent Work Leading Toward a New Evaluation of Neutron Standards

December 8, 2014
Author(s)
Allan D. Carlson, V G. Pronyaev, R. Capote, G M. Hale, F. J. Hambsch, T Kawano, S. Kunieda, W Mannhart, R O. Nelson, D. Neudecker, P Schillebeeckx, S Simakov, P Talou, X Tao, D. L. Smith, W Wang, A. Wallner
A number of national cross section libraries are planning new versions of their libraries including ENDF/B and JEFF. The first step in producing these new libraries is evaluating the neutron standards. A new evaluation of the standards is now underway

Toward a New Evaluation of the Neutron Standards

December 6, 2014
Author(s)
Allan D. Carlson, V G. Pronyaev, R. Capote, G M. Hale, F. J. Hambsch, T Kawano, S. Kunieda, R O. Nelson, D. Neudecker, P Schillebeeckx, S Simakov, D L. Smith, X Talou, A Wallner, W Wang
A new version of the ENDF/B library has been planned. The first step in producing this new library is evaluating the neutron standards. An evaluation is now underway with support from a Data Development Project of the IAEA. In addition to the neutron cross

Nonproportionality in the scintillation light yield of bismuth germanate

November 11, 2014
Author(s)
Thomas R. Gentile, M J. Bales, H Breuer, T E. Chupp, Kevin J. Coakley, R L. Cooper, Jeffrey S. Nico, B. O'Neill
We present measurements of nonproportionality in the scintillation light yield of bismuth germanate (BGO) for gamma-rays with energies between 6 keV and 662 keV. The scintillation light was read out by avalanche photodiodes (APDs) with both the BGO

Fast Neutron Detection with a Segmented Spectrometer

November 3, 2014
Author(s)
Jeffrey S. Nico, T J. Langford, Christopher D. Bass, H Breuer, Craig Heimbach, D. K. Erwin
A fast neutron spectrometer consisting of segmented plastic scintillator and He-3 proportional counters was constructed for the measurement of neutrons in the energy range 1 MeV to 200 MeV. We discuss its design, principles of operation, and the method of

International Key Comparison of Neutron Fluence Measurements in Monoenergetic Neutron Fields – CCRI(III)-K11

November 3, 2014
Author(s)
Maynard S. Dewey, V. Gressier, A. C. Bonaldi, David M. Gilliam, H. Harano, A. Masuda, T Matsumoto, N. Moiseev, Jeffrey S. Nico, R. Notle, S. Oberstedt, N. J. Roberts, S. Rottger, D. J. Thomas
To ensure the validity of their national standards, National Metrology Institutes, NMIs, participate regularly in international comparisons. In the area of neutron metrology, Section III of the Consultative Committee for Ionizing Radiation is in charge of

Quantum correlations in a noisy neutron interferometer

September 15, 2014
Author(s)
Michael G. Huber, Muhammad D. Arif, Christopher Wood, D G. Cory, M. O. Abutaleb, Dimitry A. Pushin
We investigate quantum coherences in the presence of noise by entangling the spin and path degrees of freedom of the output neutron beam from a noisy three-blade perfect crystal neutron interferometer. We nd that in the presence of dephasing noise on the

On the limits of spin-exchange optical pumping of 3He

July 2, 2014
Author(s)
Thomas R. Gentile, T G. Walker, E Babcock, Qiang NMN Ye, Wangchun Chen
Using diode bar lasers spectrally narrowed with chirped volume holographic gratings (VHGs), we have obtained an improvement in the 3He polarization achievable by spin-exchange optical pumping (SEOP). As compared to our past results with lasers narrowed

Incoherent Quasielastic Neutron Scattering Study of the Relaxation Dynamics in Molybdenum-Oxide Based Keplerate Type Nanocages

June 19, 2014
Author(s)
Antonio Faraone, Emiliano Fratini, Somenath Garai, Achim Muller, Madhu Sudan Tyagi, Timothy Jenkins, Eugene Mamontov, Rick L. Paul, John R. Copley, Piero Baglioni
The single particle relaxation dynamics of hydrogen atoms in different oxomolybdate Keplerate type nanocages characterized by a (metal) 30 icosidodecahedron and a size of {approximately equal}25 A were studied using Incoherent Quasielastic Neutron

Noble Gas Excimer Scintillation Following Neutron Capture in Boron Thin Films

April 11, 2014
Author(s)
Alan K. Thompson, Jacob McComb, Charles W. Clark, Michael A. Coplan, Mohamad Al-Sheikhly, Robert E. Vest
Far-ultraviolet (FUV) scintillation signals have been measured in heavy noble gases (argon, krypton, xenon) following boron-neutron capture (10B(n,α)7Li) in 10B thin films. The observed scintillation yields are comparable to the yields from some liquid and

Are Bragg Peaks Gaussian?

March 12, 2014
Author(s)
Boualem Hammouda
It is common practice to assume that Bragg scattering peaks have Gaussian shape. The Gaussian shape function is used to perform instrumental smearing corrections. Using Monte Carlo ray tracing simulation, the resolution of a realistic small-angle neutron

Certification of Total Arsenic in Blood and Urine Standard Reference Materials by Radiochemical Neutron Activation Analysis and Inductively Coupled Plasma Mass Spectrometry

March 1, 2014
Author(s)
Rick L. Paul, William C. Davis, Karen E. Murphy, Colleen E. Bryan Sallee, Lee L. Yu, William F. Guthrie, Dennis D. Leber, Thomas W. Vetter
A newly developed procedure for determination of arsenic by radiochemical neutron activation analysis was used to measure arsenic in SRM 955c Toxic Elements in Caprine Blood and SRM 2668 Toxic Elements in Frozen Human Urine for the purpose of providing

Polarized 3HE Spin Filters for Neutron Science

February 12, 2014
Author(s)
Thomas R. Gentile, Wei-Chen N. Chen
The large spin dependence of the absorption cross section for neutrons by 3He gas provides a method to polarize neutron beams. For certain applications, such polarized 3He-based neutron "spin filters" have advantages over conventional neutron optical
Displaying 551 - 575 of 807