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Displaying 776 - 800 of 925

Vertically Graded Anisotropy in Co/Pd Multilayers

March 8, 2010
Author(s)
Brian J. Kirby, Joseph E. Davies, Kai Liu, Shannon Watson, G. T. Zimanyi, Robert D. Shull, Paul A. Kienzle, Julie A. Borchers
It has been theoretically predicted that depth-grading the magnetic anisotropy in perpendicular magnetic media should reduce the field required to write data, without affecting the thermal stability. To study this prediction, we have produced a series of

Coexisting Magnetic Order and Cooperative Paramagnetism in the Stuffed Pyrochlore Tb 2+x Ti 2-2x Nb x O 7

February 18, 2010
Author(s)
Benjamin Ueland, Jason S. Gardner, A. J. Williams, M. L. Dahlberg, J.G. Kim, Yiming Qiu, John R. Copley, P. Schiffer, R J. Cava
Neutron scattering and magnetization measurements have been performed on the stuffed pyrochlore system Tb 2+xTi 2-2xNb xO 7. We find that despite the introduction of chemical disorder and increasingly antiferromagnetic interactions, cooperative

Electrically-stimulated gradients in water and counterion concentrations within electroactive polymer actuators

February 1, 2010
Author(s)
Jong Keun Park, Paul J. Jones, Chris Sahagun, Kirt A. Page, Daniel S. Hussey, David L. Jacobson, Sarah E. Morgan, Robert B. Moore
While ionic polymer metal composites (IPMCs) have been studied for more than 10 years, the specific actuation mechanism is still unclear. In this work, neutron imaging, applied potential (AP) and current sensing (CS) atomic force microscopy (AFM) methods

Solvent Retention In Thin Spin-Coated Polystyrene And Poly(Methyl Methacrylate) Homopolymer Films Studied By Neutron Reflectometry

January 19, 2010
Author(s)
Xiaohua Zhang, Kevin G. Yager, Shuhui Kang, Nathaniel J. Fredin, Bulent Akgun, Sushil K. Satija, Jack F. Douglas, Alamgir Karim, Ronald L. Jones
We utilize neutron reflectometry (NR) to probe the amount of residual solvent inside thin polystyrene (PS) and poly(methyl methacrylate) (PMMA) films spin-coated from deuterated toluene polymer solutions onto silicon substrates . The effect of thermal

Image-Based Feedback Control for Real-Time Sorting of Microspheres in a Microfluidic Device

January 1, 2010
Author(s)
Matt S. Munson, James Spotts, Antti Niemisto, Jyrki Selinummi, Jason G. Kralj, Marc L. Salit, Adrian Ozinsky
We have developed a fully automated control system to distribute user-defined numbers of antibody-functionalized fluorescent beads (scalable from tens to hundreds) to addressable assay chambers within a microfluidic PDMS device. We report an automated bead

Effects of High Flux Neutron Beams on He-3 cells Polarized In-situ with Spin-exchange Optical Pumping

December 30, 2009
Author(s)
E Babcock, Stephen Boag, Maria Becker, W.C. Chen, T E. Chupp, Thomas R. Gentile, G L. Jones, A K. Petukhov, Torsten Soldner, T G. Walker
Polarized 3He produced by spin-exchange optical pumping (SEOP) has potential as a neutron spin filter for polarization and polarization analysis in many neutron scattering and neutron particle physics applications. The advantage of the SEOP method is its

Determination of Elements in SRM Soil 2709a by Neutron Activation Analysis

December 1, 2009
Author(s)
Rick L. Paul, Elizabeth A. Mackey, Rolf L. Zeisler, Rabia Oflaz, Bryan E. Tomlin
A combination of instrumental neutron activation analysis (INAA) and prompt gamma-ray activation analysis (PGAA) was used to value assign 35 elements in SRM soil 2709a (San Joaquin Soil). INAA with counting of short-lived radioisotopes was used for

An experiment for the precision measurement of the radiative decay mode of the neutron

October 5, 2009
Author(s)
R Cooper, Christopher D. Bass, E Beise, H Breuer, Jim Byrne, T E. Chupp, Kevin Coakley, Maynard S. Dewey, B Fisher, Changbo Fu, Thomas R. Gentile, M. McGonagle, Hans Pieter Mumm, Jeffrey S. Nico, Alan Keith Thompson, F E. Wietfeldt
The neutron typically beta decays into a proton, electron, and antineutrino. In some decays, it can be accompanied by a high energy photon. We recently performed the rst observation of the radiative beta decay branch for the free neutron with photons of

Effects of high intensity neutron flux on in-situ spin-exchange optical pumping of He-3

September 17, 2009
Author(s)
Thomas R. Gentile, E Babcock, Stephen Boag, C. Becham, T E. Chupp, Gordon L. Jones, A K. Petukhov, T G. Walker
Prior studies revealed neutron beam-induced alkali-metal spin relaxation in 3He cells polarized in-situ by spin-exchange optical pumping. These effects are minor for neutron beams of low to moderate intensity, but become important at the highest neutron

Glassy Carbon as an Absolute Intensity Calibration Standard for Small Angle Scattering

August 19, 2009
Author(s)
Andrew J. Allen, Jan Ilavsky, Fan Zhang, Gabrielle G. Long, Pete R. Jemian
Absolute calibration of small-angle scattering (SAS) intensity data (in units of differential cross-section per unit sample volume per unit solid angle) is essential for many important aspects of quantitative SAS analysis, such as obtaining the number

Application of Thermal Gradients to Achieve Orientational Order in Block Copolymer Thin Films

August 18, 2009
Author(s)
Nathaniel J. Fredin, Brian Berry, Kevin G. Yager, Alamgir Karim, Sushil K. Satija, Deanna Pickel, Ronald L. Jones
The development of methods that permit control over the long-range order and orientation of microdomains in block copolymer (BCP) thin films for bottom-up approaches to nanoscale surface patterning is of great interest for many applications, including

Coupled magnetic and ferroelectric hysteresis in multiferroic Ni ^ d3 ^ V ^ d2 ^ O ^ d8 ^

August 18, 2009
Author(s)
I. Cabrera, M. Kenzelmann, Wangchun Chen, Ross Erwin, Thomas R. Gentile, Juscelino Leao, Jeffrey W. Lynn, N. Rogado, R. J. Cava, C. Broholm, G. Lawes, Ying Chen
Electric control of spin chirality in a magnetically frustrated multiferroic is demonstrated through polarized magnetic neutron diffraction. Cooling to the cycloidal multiferroic phase of Ni ^ d3 ^ V ^ d2 ^ O ^ d8 ^ in an electric field causes the

Anomalous thermal behavior in microcalorimeter gamma-ray detectors

July 20, 2009
Author(s)
Robert D. Horansky, James A. Beall, Kent D. Irwin, Joel N. Ullom
Improving the resolution of gamma-ray detectors is important for many fields, including determinations of the Lamb shift in atoms with high atomic numbers , nuclear treaty verification , and environmental monitoring. High-purity germanium detectors are

Combinatorial Study of Thin Film Metal Hydride by Prompt Gamma Activation Analysis

June 19, 2009
Author(s)
Raymond Cao, Jason Hattrick-Simpers, Richard Bindel, Bryan E. Tomlin, Rolf L. Zeisler, Rick L. Paul, Leonid A. Bendersky, Robert G. Downing
Cold neutron prompt gamma activation analysis (PGAA) was used to determine the amount of hydrogen in thin film Mg hydrides with varying hydrogenation times. The results suggest that the hydrogenation in the Mg thin films remains unsaturated even after 48

Phonon softening and anomalous mode near the x c = 0.5 quantum critical point inCa 2-x Sr x RuO 4

May 4, 2009
Author(s)
R. G. Moore, M. D. Lumsden, M. B. Stone, Jiandi Zhang, Ying Chen, Jeffrey Lynn, R. Jin, D Mandrus, E. W. Plummer
Inelastic neutron scattering is used to measure the temperature-dependent phonon dispersion in Ca2−xSrxRuO4(x=0.4,0.6). The in-plane Σ4 octahedral tilt mode softens significantly at the zone boundary of the high-temperature tetragonal (HTT) I41/acd

Itinerant spin excitations near the hidden order transition in URu2Si2

April 22, 2009
Author(s)
J. A. Janik, H. D. Zhou, Y.-J. Jo, L. Balicas, G. J. MacDougall, G. M. Luke, J. D. Garrett, K. J. McClellan, E. D. Bauer, J. L. Sarrao, Yiming Qiu, John R. Copley, Z. Yamani, W. J. Buyers, C. R. Wiebe
By means of neutron scattering we show that the high-temperature precursor to the hidden order state of the heavy fermion superconductor URu 2Si 2 exhibits heavily damped incommensurate paramagnons whose strong energy dispersion is very similar to that of

Measuring 6LI(N,T) and 10B(N,A) Cross Sections Using the NIST Alpha-Gamma Device

April 15, 2009
Author(s)
Maynard S. Dewey, David M. Gilliam, Jeffrey S. Nico, G.L. Green, A. Laptev, A. Yue
The 6LI(N,T) and 10B(N,A) cross sections are important neutron cross section standards. Precise knowledge of these cross sections is essential because they are often used as reference standards for obtaining the neutron fluence in investigations of the

A New Evaluation of the Half-life of 241Pu

April 14, 2009
Author(s)
Roger Wellum, Andre Verbruggen, Ruediger Kessel
A new evaluation of the half-life of 241Pu has been made by developing earlier methods and techniques and employing further measurements of the isotopic ratio of an initially enriched 241Pu material. A correction to the previous value has had to be made
Displaying 776 - 800 of 925
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