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Publications

Search Publications by Jon R. Pratt

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Displaying 1 - 25 of 113

The Design of an Instrument to Realize Small Torque at NIST

August 22, 2020
Author(s)
Leon S. Chao, Rafael Marangoni, Frank C. Seifert, Darine El Haddad, Jon R. Pratt, David B. Newell, Stephan Schlamminger
After the recent redefinition of the International System of Units (SI), torque no longer needs to be traceable to a calibrated mass in a gravitational field suspended from a known lever arm and disseminated through a chain of torque transducers.An SI

Contributions of precision engineering to the revision of the SI

November 28, 2017
Author(s)
Stephan Schlamminger, Harald Bosse, Horst Kunzmann, Jon R. Pratt, Ian Robinson, Michael de Podesta, Paul Shore, Paul Morantz
All measurements performed in science and industry are based on the International System of Units, the SI. It has been proposed to revise the SI following an approach which had already been implemented for the redefinition of the unit of length, the metre

Measurement of the Planck constant at the National Institute of Standards and Technology from 2015 to 2017

July 28, 2017
Author(s)
Darine El Haddad, Frank C. Seifert, Leon S. Chao, Antonio M. Possolo, David B. Newell, Jon R. Pratt, Carl J. Williams, Stephan Schlamminger
Researchers at the National Institute of Standards and Technology(NIST) estimate the value of the Planck constant as h = 6.62606994(10) x 10^-34 Js, hence with relative standard uncertainty 15.3 x 10^-9. This measurement result is based on over 17,000

Bridging classical and quantum mechanics

September 28, 2016
Author(s)
Darine El Haddad, Frank C. Seifert, Leon S. Chao, Shisong Lee, David B. Newell, Jon R. Pratt, Carl J. Williams, Stephan Schlamminger
Using a watt balance and a frequency comb, a mass-energy equivalence is derived. The watt balance compares mechanical power measured in terms of the meter, the second, and the kilogram to electrical power measured in terms of the volt and the ohm. A direct

Milligram mass metrology using an electrostatic force balance

September 28, 2016
Author(s)
Gordon A. Shaw, Julian Stirling, John A. Kramar, Alexander D. Moses, Patrick J. Abbott, Richard L. Steiner, Andrew D. Koffman, Jon R. Pratt, Zeina J. Kubarych
Although mass is typically defined within the International System of Units (SI) at the Kilogram level, the pending redefinition of the SI provides an opportunity to realize mass at any scale using electrical metrology. We propose the use of an

Design of a Table-Top Watt Balance

July 26, 2016
Author(s)
Stephan Schlamminger, Jon R. Pratt, David B. Newell, Frank C. Seifert, Michael Liu, Leon S. Chao, Luis Manuel Pea Prez, Shisong Li, Darine El Haddad
Measurements of the Planck constant with watt balances using 1 kg masses have achieved relative standard uncertainties below 2 x 10-8. Having established a metrological link between the kilogram and this fundamental constant of nature, a redefinition of

First mass measurements with the NIST-4 watt balance

July 10, 2016
Author(s)
Darine El Haddad, Leon S. Chao, Frank C. Seifert, David B. Newell, Jon R. Pratt, Stephan Schlamminger
In the past four years, we have constructed a new watt balance at the National Institute of Standards and Technology (NIST), with the goal to realize the unit of mass after the redefinition of the International System of Units, expected to occur in 2018

A precise instrument to determine the Planck constant, and the future kilogram

June 21, 2016
Author(s)
Darine El Haddad, Frank C. Seifert, Leon S. Chao, David B. Newell, Jon R. Pratt, Carl J. Williams, Stephan Schlamminger, Shisong Li
A precise instrument, called a watt balance, compares mechanical power measured in terms of the meter, the second and the kilogram to electrical power measured in terms of the volt and the ohm. A direct link between mechanical action and the Planck

Coil motion effects in watt balances: a theoretical check

February 10, 2016
Author(s)
Stephan Schlamminger, Shisong Li, Darine El Haddad, Frank C. Seifert, Leon S. Chao, Jon R. Pratt
A watt balance is a precision apparatus for the measurement of the Planck constant that has been proposed as a primary method for realizing the unit of mass in a revised International System of Units. In contrast to an ampere balance, which was

A LEGO Watt Balance, An apparatus to demonstrate the definition of mass based on the new SI

October 20, 2015
Author(s)
Leon S. Chao, Stephan Schlamminger, David B. Newell, Jon R. Pratt, Georgio A. Sineriz, Frank C. Seifert, Darine El Haddad, Yusi A. Cao, Xiang Zhang
A redefinition of our system of units, the SI, is currently being discussed and its implementation is expected in 2018. With the redefinition, the current base units will no longer be required and all units henceforth will be based upon fixed values of

Optomechanical reference accelerometer

September 8, 2015
Author(s)
Oliver Gerberding, Felipe Guzman, John T. Melcher, Jon R. Pratt, Jacob M. Taylor
We present an opto-mechanical accelerometer device with high dynamic range, high bandwidth and readout noise levels exceeding 10 μg/√Hz . The straightforward assembly and small cost of our device make it a prime candidate to perform on-site calibrations

Optomechanical Motion Sensors

July 8, 2015
Author(s)
Felipe Guzman, Oliver Gerberding, John T. Melcher, Julian Stirling, Jon R. Pratt, Gordon A. Shaw, Jacob M. Taylor
Compact optical cavities can be combined with motion sensors to yield unprecedented resolution and SI-traceability in areas such as acceleration sensing and atomic force microscopy AFM, among others. We have incorporated Fabry-Perot fiber-optic micro

The Redefinition of the SI: Impact on Calibration Services at NIST

June 1, 2015
Author(s)
Neil M. Zimmerman, Jon R. Pratt, Michael R. Moldover, David B. Newell, Gregory F. Strouse
As most readers are probably at least vaguely aware, it is likely that the SI system of units will be redefied in 2018. This redefinition would fundamentally change the logical structure of the SI, with one result being a substantial change in how mass is

First measurements of the flux integral with the new NIST-4 watt balance

March 31, 2015
Author(s)
Darine El Haddad, Frank C. Seifert, Leon S. Chao, Yusi A. Cao, Georgio A. Sineriz, Jon R. Pratt, David B. Newell, Stephan Schlamminger
In early 2014, construction of a new watt balance, named NIST-4, has started at the National Institute of Standards and Technology (NIST). In a watt balance, similar to a mass comparator, the gravitational force of an unknown mass is compensated by an

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

A self-calibrating optomechanical force sensor with femtonewton resolution

December 10, 2014
Author(s)
John T. Melcher, Julian Stirling, Felipe Guzman, Jon R. Pratt, Gordon A. Shaw
We report the development of an ultrasensitive optomechanical sensor designed to improve the accuracy and precision of force measurements with atomic force microscopy. The sensors achieve quality factors of 4.3x10^6 (a 100-fold improvement over quartz

A constant from a mass, a mass from a constant

November 9, 2014
Author(s)
Jon R. Pratt, Stephan Schlamminger, David B. Newell, Leon S. Chao, Zeina J. Kubarych, Patrick J. Abbott, Yusi A. Cao, Frank C. Seifert, Darine El Haddad
NIST recently used a watt balance instrument known as NIST-3 to measure the Planck constant in terms of IPK with a relative uncertainty of approximately 45 parts in 10e9. Along the way to this new NIST value of h, the instrument was also employed to

THE CONSTRUCTION AND CHARACTERIZATION OF THE NIST-4 PERMANENT MAGNET SYSTEM

November 9, 2014
Author(s)
Leon S. Chao, Frank C. Seifert, Shisong Li, Darine El Haddad, Stephan Schlamminger, Jon R. Pratt
A watt balance is an electromagnetic force balancing instrument to realize the unit of mass at the kilogram level. The magnet system is one of the key components. Our group at the National Institute of Standards and Technology is currently building a next

Alignment and testing of the NIST Calculable Capacitor

August 24, 2014
Author(s)
Yicheng Wang, Felipe Guzman, Corey A. Stambaugh, Radek Smid, Hugo Zuniga Calvo, Andrew D. Koffman, Jon R. Pratt, John R. Lawall
This paper reports progress on the NIST effort to develop a new calculable capacitor, focusing on improvement of the guard electrode motion control as well as issues associated with the overall electrode alignment. Design of a multi-wavelength Fabry-Perot

Construction and Performance of the NIST-4 Magnet System

August 24, 2014
Author(s)
Frank C. Seifert, Alireza R. Panna, Leon S. Chao, Yusi A. Cao, Darine El Haddad, Shisong Li, Stephan Schlamminger, Jon R. Pratt, Heeju Choi, Lori Haley
A watt balance is a promising instrument to realize the unit of mass at the kilogram level. The magnet system is one of the key elements of such an instrument. For the new watt balance currently under construction at the National Institute of Standards and

Heterodyne interferometer with subnanometer accuracy

August 24, 2014
Author(s)
Darine El Haddad, Frank C. Seifert, Stephan Schlamminger, Leon S. Chao, David B. Newell, Jon R. Pratt
This paper gives a brief description of the laser interferometer system designed for the next generation watt balance experiment aimed to realize the unit of mass by direct link to Planck constant at the National Institute of Standards and Technology. The

The Design of the NEW NIST-4 Watt Balance

August 24, 2014
Author(s)
Leon S. Chao, Stephan Schlamminger, Frank C. Seifert, Yusi A. Cao, Darine El Haddad, David B. Newell, Jon R. Pratt
The design of the new permanent-magnet driven watt balance and novel mechanical features will demonstrate the high-precision capabilities of a large complex mass measurement system with expected overall uncertainties on the order of 3 parts in 10^8.

The Measurement of the Local Acceleration of Gravity for the NIST4 Watt Balance

August 24, 2014
Author(s)
David B. Newell, Jacques Liard, Leon S. Chao, Yusi A. Cao, Frank C. Seifert, Darine El Haddad, Jon R. Pratt, Stephan Schlamminger
A new watt balance is being constructed at NIST in preparation for the redefinition of the International System of Units and the realization of mass through an exact value of the Planck constant. We describe the procedures used and give results for the