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Search Publications by: Tom Parker (Assoc)

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Displaying 26 - 50 of 249

First Accuracy Evaluation of NIST-F2

May 1, 2014
Author(s)
Thomas P. Heavner, Steven R. Jefferts, Jon H. Shirley, Thomas E. Parker, Elizabeth A. Donley, Neil Ashby, Stephan E. Barlow, Filippo Levi, Giovanni Costanzo
We report the first accuracy evaluation of NIST-F2, a second generation laser-cooled Cesium fountain primary standard developed at NIST with a cryogenic (Liquid Nitrogen) microwave cavity and flight region. The 80 K atom interrogation environment reduces

High-accuracy measurement of the black-body radiation frequency shift of the ground-state hyperfine transition in 133 Cs

February 7, 2014
Author(s)
Steven R. Jefferts, Thomas P. Heavner, Thomas E. Parker, Jon H. Shirley, Elizabeth A. Donley, Neil Ashby
We report a high-accuracy direct measurement of the blackbody radiation shift (BBR) of 133Cs ground state hyperfine transition. This frequency shift is one of the largest systematic frequency biases encountered in realizing the current definition of the SI

Three-Corner Hat Analysis of the Stability of UTC and Various UTC(k)s

December 5, 2013
Author(s)
Thomas E. Parker
The stabilities of some local UTC time scales have recently improved dramatically with the increasing use of cesium or rubidium fountains as nearly always present frequency references. Along with time scales using maser ensembles, there are now a number of

A Study of the Diurnal in the Transatlantic TWSTFT Difference

September 7, 2013
Author(s)
Victor S. Zhang, Thomas E. Parker
The daily variation (diurnal) in the two-way satellite time and frequency transfer (TWSTFT) difference is one of the most significant instabilities of the TWSTFT technique. The diurnal comes from the daily delay change of the TWSTFT signal paths. In recent

Enabling accurate differential calibration of modern GPS receivers

November 26, 2012
Author(s)
Stefania Romisch, Victor S. Zhang, Thomas E. Parker, Steven R. Jefferts
The difference between the local time reference and a GNSS receiver's internal time base is an essential contributor to the calibration of that receiver when used as a timing device. In the past, in the absence of a PPS output signal provided by the

Measurement of the velocity of the neutrino with MINOS

November 26, 2012
Author(s)
Stefania Romisch, P Adamson, Neil Ashby, G. Barr, M. Bishal, A. Blake, G. J. Bock, D. Bogert, Russell Bumgarner, S. V. Cao, S. Childress, M. Christensen, J. Coelho, L. Corwin, D. Cronin-Hennessy, J. K. de Jong, N. E. Devenish, M. V. Diwan, C. O. Escobar, J. J. Evans, E. Falk, G. J. Feldman, C. Flores, Blair Fonville, M. V. Frohne, H. R. Gallager, A. Gavrilenko, R. A. Gomes, P. Gouffon, N. Graf, R. Gran, K. Grzelak, A. Habig, J. Hartnell, R. Hatcher, Jonathan Hirschauer, A. Holin, J. Hylen, G M. Irwin, Z. isvan, C. James, Steven R. Jefferts, D. Jensen, T. Kafka, S. M. Kasahara, G. Koizumi, M. Kordosky, A. Kreymer, K. Lang, J. Ling, P. J. Litchfield, P. Lucas, W. A. Mann, M. L. Marshak, M. Mathis, Demetrios Matsakis, N. Mayer, Angela Mckinley, M. M. Medeiros, R. Mehdiyev, J. R. Meier, B. Mercurio, M. D. Messier, W. H. Miller, S. R. Mishra, S. Moed Sher, C. D. Moore, L. Mualem, J. A. Musser, J. K. Nelson, H. Newman, R. J. Nichol, J. A. Nowak, J. C. O'Conner, W. P. Oliver, M. Orchanian, R. B. Pahlka, J. Paley, Thomas E. Parker, R. B. Patterson, G. Pawloski, S. PhanBudd, R. K. Plunkett, N. Poonthattatil, Ed Powers, X. Qiu, A. Radovic, B. Rebel, C. Rosenfeld, H. A. Rubin, M. C. Sanchez, J. Schneps, P Schireiner, A. Schreckenberger, R. Sharma, A, Sousa, N. Tagg, R, L. Talaga, J. Thomas, M. A. Thomson, X. Tian, S. C. Tognini, R. Toner, D. Torretta, G. Tzanakos, J. Urheim, P. Vahel, A. Webber, R. C. Webb, C. White, L. H. Whitehead, L. Whitehead, K. P. Wilson, S. G. Wojcicki, J. Wright, Victor S. Zhang, R. Zwaska
The MINOS experiment uses a beam of predominantly muon-type neutrinos generated using protons from the Main Injector at Fermilab in Batavia, IL and travelling 735 km through the Earth to a disused iron mine in Soudan, MN. The 10 us-long beam pulse contains

Recent Calibrations of UTC(NIST) and UTC(USNO)

November 26, 2012
Author(s)
Victor S. Zhang, Thomas E. Parker, Russell Bumgarner, Jonathan Hirschauer, Angela Mckinley, Stephen Mitchell, Ed Powers, Jim Skinner, Demetrios Matsakis
The National Institute of Standards and Technology (NIST) and the United States Naval Observatory (USNO) use GPS common-view, carrier-phase time transfer and Two Way Satellite Time and Frequency Transfer (TWSTFT, also known as TWSTT) techniques in our time

Synchronization between remote sites for the MINOS experiment

November 26, 2012
Author(s)
Stefania Romisch, Steven R. Jefferts, Victor S. Zhang, Thomas E. Parker, Neil Ashby, P Adamson, G. Barr, A. Habig, J Meier, C. James, R. Nicol, R. Plunkett, C. Rosenfeld, Russell Bumgarner, M. Christensen, Jonathan Hirschauer, Blair Fonville, Demetrios Matsakis, Ed Powers, J. Wright, Angela Mckinley
In the context of time-of-flight measurements, the timing at the departure and arrival locations is obviously critical to the outcome of the experiment. In the case of neutrino time-of-flight experiments, the locations are many hundreds of kilometers apart

A digital time scale at the National Institute of Standards and Technology

August 13, 2011
Author(s)
Stefania Romisch, Steven R. Jefferts, Thomas E. Parker
An integrated time scale has as primary data unit of duration (time interval) defined by atomic standards according to the definition of the SI second. The availability of more than one atomic standard allows for averaging, thereby improving the

Comparing Room Temperature and Cryogenic Cesium Fountains

July 31, 2011
Author(s)
Steven R. Jefferts, Thomas P. Heavner, Thomas E. Parker, Jon H. Shirley, Elizabeth A. Donley, Filippo Levi, Davide Calonico, C Calosso, Giovanni Costanzo, B. Mongino
We have compared the frequency of a room temperature cesium fountain primary frequency standard with that of a cryogenic (~80K) cesium fountain. This comparison yields a measurement of the blackbody frequency shift of the room temperature fountain.

Towards an all-digital time scale

July 31, 2011
Author(s)
Stefania Romisch, Steven R. Jefferts, Thomas E. Parker
The implementation of an all-digital time scale is under way at NIST, using a novel 8-channel, all-digital phase measurement system based on subsampling techniques. The phase measurement system is used to compare output signals from several commercial