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Search Publications

NIST Authors in Bold

Displaying 34151 - 34175 of 73697

An Octagonal Architecture for High Strength PIT Nb 3 Sn Conductors

June 6, 2006
Author(s)
L. R. Motowidlo, E Barzi, D. Turrioni, Najib Cheggour, Loren F. Goodrich
Powder-in-Tube (PIT) Nb 3Sn conductors have been fabricated utilizing a low-cost intermetallic Cu 5Sn 4 powder as the tin source. A novel octagonal PIT design that incorporates dispersion strengthened copper as well as a hexagonal PIT design were

Solution and Surface Composition Gradients via Microfluidic Confinement: Fabrication of a Statistical-Copolymer-Brush Composition Gradient

June 6, 2006
Author(s)
Chang Xu, Susan E. Barnes, Tao Wu, Daniel A. Fischer, Dean M. DeLongchamp, J Batteas, Kathryn L. Beers
A simple method to generate solution gradients through microfluidic confinement is described. The solution gradient inside a microchannel was formed by varying the relative infusion rates of two solutions that differed in compositions. The establishment

A Local Oscillator for Chip-Scale Atomic Clocks at NIST

June 5, 2006
Author(s)
Alan Brannon, J Breitbarth, Z Popovic, Vladislav Gerginov, V Shah, Svenja A. Knappe, Leo W. Hollberg, John E. Kitching
We report the first local oscillator (LO) demonstrating viability in terms of performance, size, and power, for chip-scale atomic clocks (CSAC) at the National Institute of Standards and Technology in Boulder, CO. This volgate-controlled oscillator (VCO)

Absolute Optical Frequency Measurements with a Fractional Uncertainty at 1 x 10 -15

June 5, 2006
Author(s)
Jason Stalnaker, Scott A. Diddams, Leo W. Hollberg, Kyoungsik Kim, Elizabeth A. Donley, Thomas P. Heavner, Steven R. Jefferts, Filippo Levi, Thomas E. Parker, James C. Bergquist, Wayne M. Itano, Marie J. Jensen, Luca Lorini, Windell Oskay, Tara M. Fortier, J Torgerson
We report the technical details specific to our recent measurements of the optical frequency of the mercury single-ion clock in terms of the SI second as realized by the NIST-F1 cesium fountain clock. In these measurements the total fractional uncertainty

Active light-shift stabilization in modulated CPT clocks

June 5, 2006
Author(s)
V Shah, P Schwindt, Vladislav Gerginov, Svenja A. Knappe, Leo W. Hollberg, John E. Kitching
We demonstrate a simple technique to significantly improve the long-term frequency stability in atomic clocks based on coherent population trapping (CPT). In this technique an additional servo is used to control the local oscillator power level to ensure

Comparison of AM noise in commercial amplifiers and oscillators at X-band

June 5, 2006
Author(s)
Archita Hati, David A. Howe, Craig Nelson
In this paper we discuss the importance of amplitude modulated (AM) noise. AM noise is often neglected and considered as a minor problem. However, AM noise can become very important in high performance systems that require ultra-low phase modulated (PM)

Kinetics Governing Phase Separation of Nanostructured Sn(x)Ge(1a 'x) Alloys.

June 5, 2006
Author(s)
Regina Regan, Harry A. Atwater, Jonathan E. Guyer, Erik Meserole, Mark S. Gorrsky
We have studied the dynamic phenomenon of SnxGe1a 'x/Ge phase separation during deposition by molecular beam epitaxy on Ge(001) substrates.Phase-separation leads to the formation of direct bandgap semiconductor nanowire arrays embedded in Ge oriented along

Low Phase Noise Amplifier and Oscillator using Feed-Forward Technique at 10 GHz

June 5, 2006
Author(s)
Archita Hati, Craig Nelson, David A. Howe
We discuss the performance of a feed-forward amplifier (FFA) at 10 GHz. The feed-forward method is primarily used to suppress intermodulation distortion in amplifiers to suppress up-converted near-DC noise. The main amplifier in this configuration is a low

Optical and microwave frequency synthesis with an integrated fiber frequency comb

June 5, 2006
Author(s)
Ingmar Hartl, Martin E. Fermann, William C. Swann, John J. McFerran, Ian R. Coddington, Qudsia Quraishi, Scott Diddams, Nathan R. Newbury, Carston Langrock, Martin M. Fejer, Paul S. Westbrook, Jeffrey W. Nicholson, K Feder
We demonstrate optical coherence over a broad spectral range of two independent fiber frequency combs. Additionally, we demonstrate microwave stability of better than 2x10 -14 in 1 second for an optically integrated fiber frequency comb.

Relativity and Timing in X-ray Pulsar Navigation

June 5, 2006
Author(s)
Neil Ashby, David A. Howe
XNAV is a technology demonstration that will use photons from X-ray pulsars for navigation and spacecraft attitude determination. This paper summarizes relativistic effects in the context of XNAV. It also characterizes the primary task in the time domain

Stability measurements of the Ca and Yb Optical Frequency Standards

June 5, 2006
Author(s)
Christopher W. Oates, C Hoyt, Yann Le Coq, Zeb Barber, Tara M. Fortier, Jason Stalnaker, Scott A. Diddams, Leo W. Hollberg
In this paper we describe two types of optical atomic clocks. The first is based on freely expanding calcium atoms and is optimized for experimental simplicity and high stability. The second is based on Yb atoms confined to an optical lattice that is

TheoH Bias-removal Method

June 5, 2006
Author(s)
David A. Howe, Jennifer A. Taylor, Tiffany Tassett
A version of Theo1 variance, called TheoBR variance (BR for ''bias-removed'' relative to the Allan variance), is constructed. This relative bias correction is applied over a range of the longest-recommended Allan tau values for a given data run. The oH

Chip-Scale Atomic Devices

June 4, 2006
Author(s)
John E. Kitching, Svenja A. Knappe, P Schwindt, Ying-ju Wang, Hugh Robinson, Leo W. Hollberg, Li-Anne Liew, John Moreland, Alan Brannon, J Breitbarth, Brad Lindseth, Z Popovic, V Shah, Vladislav Gerginov, Matt Eardley
We present an overview of recent work to develop chip-scale atomic devices such as frequency references and magnetometers. These devices take advantage of advances over the last ten years in the fields of micro electro mechanical systems (MEMS), precision

100 mV AC-DC Transfer Standard Measurements Using An AC Josephson Voltage Standard

June 1, 2006
Author(s)
Charles J. Burroughs, Samuel Benz, Paul Dresselhaus
NIST is implementing the Josephson arbitrary waveform synthesizer as an ac Josephson Voltage Standard (ACJVS). Over the past few years we have demonstrated precision measurements of synthesized sine waves at rms voltage amplitudes up to 170 mV. The system

A Web Service-Based Reconfigurable Testbed for Business-to-Business (B2B) Integration

June 1, 2006
Author(s)
B Jeong, Jungyub Woo, Hyunbo Cho, Boonserm Kulvatunyou, James Lee
Several types of standards and corresponding software solutions have been created to enable business-to-business (B2B) integration. Testing for conformance and interoperability among these solutions are inter-dependent. This signifies the needs to make

Comparison of AM Noise in Commercial Amplifiers and Oscillators at X-Band

June 1, 2006
Author(s)
Archita Hati, David A. Howe, Craig W. Nelson
In this paper we discuss the importance of amplitude-modulated (AM) noise. AM noise is often neglected and considered a s a minor problem. However, AM noise can become very important in high performance systems that require ultra-low phase-modultaed (PM)

Critical Nucleus Phase Diagram for the Cu(100) Surface

June 1, 2006
Author(s)
Joshua M. Pomeroy, Joel D. Brock
An experimental exploration of island nucleation dynamics during epitaxial film growth on the Cu(100) surface is presented that connects previous results from other groups at low temperatures with the room temperature regime. The steady-state balance of
Displaying 34151 - 34175 of 73697
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