U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Search Publications

NIST Authors in Bold

Displaying 1476 - 1500 of 2503

A determination of the local acceleration of gravity for the NIST-4 watt balance

January 21, 2015
Author(s)
David B. Newell, Eric J. Leaman, Darine El Haddad, Frank C. Seifert, Leon S. Chao, Yusi A. Cao, Jon R. Pratt, Stephan Schlamminger
A new watt balance is being constructed at the National Institute of Standards and Technology in preparation for the redefinition of the International System of Units and the realization of mass through an exact value of the Planck constant. The total

NIST program of spectroscopic data for light elements of fusion interest

January 15, 2015
Author(s)
Joseph Reader, Alexander Kramida, Yuri Ralchenko, Wolfgang L. Wiese, Jeffrey R. Fuhr
This paper summarizes work at the National Institute of Standards and Technology (NIST) in support of the IAEA Coordinated Research Project on “Light Element Atom, Molecule and Radical Behaviour in the Divertor and Edge Plasma Regions.” It includes

Reversing hydride-ion formation in quantum-information experiments with Be+

January 12, 2015
Author(s)
Brian C. Sawyer, Justin G. Bohnet, Joseph W. Britton, John J. Bollinger
We demonstrate photodissociation of BeH + ions within a Coulomb crystal of thousands of 9Be + confined in a Penning trap. The BeH + molecular ions form via exothermic reactions between trapped, laser-cooled Be +($^2\text{P}_{3/2}$) and background H 2

Phase steps and resonator detuning measurements in microresonator frequency combs

January 7, 2015
Author(s)
Pascal P. Del'Haye, Aurelien C. Coillet, William Loh, Katja M. Beha, Scott B. Papp, Scott A. Diddams
Significant progress has been made in the last years towards a better understanding and theoretical modeling of Kerr-effect induced generation of optical frequency combs in microresonators. However, the simultaneous interaction of hundreds or thousands of

The meaning of the universal WLF parameters of glass-forming polymer liquids

January 7, 2015
Author(s)
Jack F. Douglas, Jacek Dudowicz, Karl Freed
Although the Williams-Landell-Ferry (WLF) equation for the segmental relaxation time tau of glass forming materials is one of most commonly encountered relations in polymer physics, the molecular basis for this equation is not well understood. The WLF

Optical Lattice Clocks

January 1, 2015
Author(s)
Andrew D. Ludlow, Christopher W. Oates
Here we introduce and give a basic description of optical lattice clocks. We also briefly describe recent advances in these atomic frequency standards, looking to future work and applications.

Atomic Clock with 1x10 -18 Room-Temperature Blackbody Stark Uncertainty

December 31, 2014
Author(s)
Kyle P. Beloy, Nathan M. Hinkley, Nate B. Phillips, Jeffrey A. Sherman, Marco Schioppo, John H. Lehman, Ari D. Feldman, Leonard M. Hanssen, Christopher W. Oates, Andrew D. Ludlow
The Stark shift due to blackbody radiation (BBR) is a key factor limiting the performance of many atomic frequency standards, with the BBR environment inside the clock apparatus being difficult to characterize at a high level of precision. Here we

Advances in the generalized entropy theory of glass-formation in polymer melts

December 21, 2014
Author(s)
Jack F. Douglas, J Dudowicz, Karl Freed
The generalized entropy theory (GET) of polymeric glass-forming liquids is reformulated in a simpler and more natural formalism than our previous version of this theory. This new theory is then applied to survey essential trends in the dependence of the

Improving Photoelectron Counting and Particle Identification in Scintillation Detectors with Bayesian Techniques

December 19, 2014
Author(s)
Kevin J. Coakley, M. Akashi-Ronquest, P.-A. Amaudruz, B. Beltran, M. Bodmer, M.G. Boulay, R. Bourque, B. Buck, A. Butcher, B. Cai, T. Caldwell, M. Chen, Y. Chen, B. Cleveland, F. A. Duncan, E. O'Dwyer, E. Flores, J. A. Formaggio, D. Gastler, F. Giuliani, M. Gold, V. V. Golovko, P. Gore, K. Graham, E. Grace, J. Griego, N. Guerrero, V. Guiseppe, A. L. Hallin, P. Harvey, R. Henning, A, Hime, J. Hofgartner, S. Jaditz, C. J. Jillings, C. Kachulis, E. Kearns, J. Kelsey, J. R. Klein, M. Ku'zniak, A. Latorre, L. Lawson, O. Li, J. J. Lidgard, P. Liimatainen, S. Linden, W. H. Lippincott, F. Lopez, K. McFarlane, R. Mathew, A. B. McDonald, D.-M Mei, J. Monroe, A. Muir, C. Nantais, J. A. Nikkel, J. Oertel, K. Olsen, G. D. Orebi Gann, C. Oullet, K. Palladino, P. Pasuthip, G. Perumpilly, T. Pollmann, W. Rau, F. Reti'ere, L. Rodriguez, R. Schnee, S. Seibert, P. Skensved, T. Sonley, E. V'azquez Ja' uregui, J. Walding, B. Wang
Many current and future dark matter and neutrino detectors are designed to record scintillation light with a large array of photomultiplier tubes (PMTs). The energy resolution and particle identification capabilities of these detectors depend in part on

PM Noise Measurement at W-Band

December 12, 2014
Author(s)
Archita Hati, Craig W. Nelson, David A. Howe
We present improved performance for a 92 - 96 GHz cross-spectrum phase modulated (PM) noise measurement system previously reported. The system is principally designed to measure amplifiers in pulsed mode with a duty cycle of 10% to 100% (CW) at a given

Experimental Bounds on Classical Random Field Theories

December 10, 2014
Author(s)
Joffrey K. Peters, Sergey V. Polyakov, Jingyun Fan, Alan L. Migdall
Alternative theories to quantum mechanics motivate important fundamental tests of our understanding and description of the smallest physical systems. Here we place experimental limits on those classical field theories which result in power-dependent

GPS Measurements Anomaly and Continuous GPS Carrier-Phase Time Transfer

December 4, 2014
Author(s)
Jian Yao, Judah Levine
The wide application of GPS carrier-phase (CP) time transfer is limited by the problem of boundary discontinuity (BD). The discontinuity has two categories. One is "day boundary discontinuity", which has been studied a lot and can be solved by a few

International Comparisons of Network Time Protocol Servers

December 4, 2014
Author(s)
Michael A. Lombardi, Judah Levine, Jose M. Lopez, Francisco Jimenez, John Bernard, Marina Gertsvolf, Harold Sanchez, Oscar G. Fallas, Liz C. Hernandez Ferero, Ricardo de Carvalho, Mario Fittipaldi, Raul Solis, Franklin Espejo
This paper describes a recently designed system that measures the time transmitted by network time protocol (NTP) servers located in North, Central, and South America. Direct measurements of the time transmitted by each server are obtained by comparing the

Measured Ionosphere Delay Correction for Code-Based GPS Time Transfer

December 4, 2014
Author(s)
Victor S. Zhang, Zhiqi Li
Nowadays, more and more dual-frequency, multichannel receivers are used in GPS time and frequency transfer applications. Instead of using the modeled ionosphere delay correction or using the IGS ionospheric map, we can obtain the ionosphere delay

Electron and Hole Photoemission Detection for Band Offset Determination of Tunnel Field-Effect Transistor Heterojunctions

November 24, 2014
Author(s)
Wei Li, Qin Zhang, R. Bijesh, Oleg A. Kirillov, Yiran Liang, Igor Levin, Lianmao Peng, Xuelei Liang, S. Datta, David J. Gundlach, Nhan V. Nguyen
The electrical performance of a tunnel field-effect transistor depends critically on the band offset at their semiconductor heterojunction interface. Historically, it has been difficult to experimentally determine how the electronic bands align at the

Quantum engineering of atomic phase shifts in optical clocks

November 24, 2014
Author(s)
Andrew D. Ludlow, T Zanon-willette, S. Almonacil, E. de Clercq, Ennio Arimondo
Quantum engineering of time-separated Raman laser pulses in three-level systems is presented to produce an ultra-narrow, optical-clock transition free from light shifts and with a significantly reduced sensitivity to laser parameter fluctuations. Based on

IR-enhanced Si reference detectors for 1-step scale transfers from 300 nm to 1000 nm

November 20, 2014
Author(s)
George P. Eppeldauer, Thomas C. Larason, Jeanne M. Houston, Robert E. Vest, Uwe Arp, Howard W. Yoon
IR-enhanced Si photodiodes have improved radiometric and electronic characteristics as compared to other widely used Si photodiodes and can be used as responsivity standards in the wavelength range from 300 nm to 1000 nm. Their low predicted uncertainty

Broadband Noise Limit in the Photodetection of Ultralow Jitter Optical Pulses

November 14, 2014
Author(s)
Franklyn J. Quinlan, W. Sun, Tara M. Fortier, Jean-Daniel Deschenes, Yang Fu, Scott A. Diddams, Joe Campbell
Applications with optical atomic clocks and precision timing often require the transfer of optical frequency references to the electrical domain with extremely high fidelity. Here we examine the impact of photocarrier scattering and distributed absorption

Measurement and Calculation of Absolute Single and Double Charge Exchange Cross Sections for O6+ Ions at 1.17 keV/u and 2.33 keV/u Impacting He and H2

November 10, 2014
Author(s)
J. R. Machacek, D. P. Mahapatra, D. R. Schultz, Yuri Ralchenko, A. Chutjian, J. Simcic, S. M. Madzunkov, R. J. Mawhorter
Absolute single and double charge-exchange (CE) cross sections for the astrophysically-prominent O6+ ion with the atomic and molecular targets He and H2 are reported. These collisions give rise to X-ray emissions in the interplanetary medium, planetary
Displaying 1476 - 1500 of 2503
Was this page helpful?