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Search Publications by: Tom Heavner (Fed)

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Displaying 51 - 75 of 89

NIST F1: Recent improvements and a resulting accuracy of df/f=0.53x10 -15

September 13, 2005
Author(s)
Thomas P. Heavner, Steven R. Jefferts, Elizabeth Donley, Jon H. Shirley, Tom Parker
In the last several years we have made many improvements to NIST-F1 (a laser-cooled Cs fountain primary frequency standard) resulting in over a factor of 2 reduction in the uncertainty in the realization of the SI second. The two most recent accuracy

Operation of the NIST-F1 Cesium Fountain Primary Frequency Standard with a Maser Ensemble

September 13, 2005
Author(s)
Thomas E. Parker, Steven R. Jefferts, Thomas P. Heavner, Elizabeth A. Donley
The operation of a caesium fountain primary frequency standard is greatly influenced by the characteristics of two other important capabilities. The first is a stable frequency reference and the second is the frequency-transfer system. A stable frequency

A New Microwave Synthesis Chain for the Primary Frequency Standard NIST-F1

August 29, 2005
Author(s)
Thomas P. Heavner, Steven R. Jefferts, Elizabeth A. Donley, F Levi, Thomas E. Parker
We present the design and measurements of the microwave synthesis chain presently used in NIST-F1, the laser-cooled cesium fountain primary frequency standard in operation at NIST, Boulder, CO. This system has been used in two accuracy evaluations of NIST

Laser cooling and launching performance in a (1,1,1) -geometry atomic fountain

August 29, 2005
Author(s)
Elizabeth A. Donley, Thomas P. Heavner, John O'Brien, Steven R. Jefferts, F Levi
We have successfully cooled and launched cesium atoms in the (1,1,1) atomic fountain geometry at temperatures as low as 0.8 mK. This corresponds to a mean thermal velocity of 0.7 cm/s, which is two times the photon recoil velocity of 0.35 cm/s. Factors

On the Power Dependence of Extraneous Microwave Fields in Atomic Frequency Standards

August 29, 2005
Author(s)
Steven R. Jefferts, Jon H. Shirley, Neil Ashby, Thomas P. Heavner, Elizabeth A. Donley, F Levi
We show that the frequency bias caused by distributed cavity phase has a strong dependence on microwave power. We also show that frequency biases associated with microwave leakage have distinct signatures in their dependence on microwave power and the

Progress Toward the Second-Generation Atomic Fountain Clock at NIST

August 23, 2005
Author(s)
Elizabeth Donley, M O. Tataw, F Levi, Steven R. Jefferts, Thomas P. Heavner
We present results on the performance of two important subsystems for NIST -F2 -the second-generation atomic fountain clock at NIST. Firstly, we demonstrate the efficient capture of cesium atoms from a low-velocity intense source (LVIS) of atoms into an

A compact double-pass acousto-optic modulator system

June 1, 2005
Author(s)
Elizabeth A. Donley, Thomas P. Heavner, F Levi, M O. Tataw, Steven R. Jefferts
A problem that arises when using acousto-optic modulators (AOMs) to scan the laser frequency is the dependence of the beam diffraction angle on the modulation frequency. Alignment problems with AOM-modulated laser beams can be effectively eliminated by

Frequency Biases Associated with Distributed Cavity Phase and Microwave Leakage in the Atomic Fountian Primary Frequency Standards IEN-CSF1 and NIST-F1

March 21, 2005
Author(s)
Steven R. Jefferts, Jon H. Shirley, Neil Ashby, Thomas P. Heavner, Elizabeth A. Donley, F Levi, Eric A. Burt, G J. Dick
The subject of frequency shifts in atomic frequency standards caused either by distributed cavity phase or microwave leakage goes back to the earliest days of the thermal beam standards [1,2], and has been the subject of continuing theoretical and

Improvements in NIST-F1 and a Resulting Accuracy of df/f = 0.61 * 10 -15

August 23, 2004
Author(s)
Thomas P. Heavner, Steven R. Jefferts, Elizabeth A. Donley, Jon H. Shirley, Thomas E. Parker
Over the last several years we have made many improvements to NIST-F1 (a laser-cooled cesium fountain primary frequency standard) resulting in a reduction in the uncertainty by nearly a factor of 2 in the realization of the SI second at NIST. We recently

A U.S. Laser-Cooled Atomic-Clock System for Space

January 1, 2001
Author(s)
Donald Sullivan, Thomas P. Heavner, Leo W. Hollberg, D Meekhof, Thomas E. Parker, William D. Phillips, S L. Rolston, Hugh Robinson, Jon H. Shirley, F L. Walls, Neil Ashby, W Kepstein, L Maleki, D Seidel, R Q. Thompson, S Wu, L Young, R Vessot, E Mattison, A Demarchi