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Search Publications by: Darine El Haddad (Fed)

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Displaying 26 - 38 of 38

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

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

Construction of a watt balance with the aim to realize the kilogram at the National Institute of Standards and Technology

August 1, 2014
Author(s)
Darine El Haddad, Leon Chao, Frank Seifert, David B. Newell, Jon R. Pratt, Stephan Schlamminger
A redefinition of the International System of Units, the SI, is impending and could occur as early as 2017. After redefinition a means to realize the unit of mass is required. A watt balance is a promising device to realize the unit of mass at the kilogram

Determination of the Planck constant at the National Institute of Standards and Technology

July 1, 2014
Author(s)
Stephan Schlamminger, Darine El Haddad, Frank C. Seifert, Leon S. Chao, David B. Newell, Ruimin Liu, Richard L. Steiner, Jon R. Pratt
In 2013, a new measurement of the Planck constant h was performed using a watt balance at the National Institute of Standards and Technology (NIST). The value is h=6.626 069 79(30) x 10^{-34} J s. The relative standard uncertainty of this determination is

Construction, Measurement, Shimming, and Performance of the NIST-4 Magnet System

June 6, 2014
Author(s)
Frank Seifert, Alireza Panna, Leon Chao, Bing Han, Shisong Li, Yusi A. Cao, Darine El Haddad, Stephan Schlamminger, Heeju Choi, Lori Haley
The magnet system is one of the key elements of a watt balance. For the new watt balance currently under construction at the National Institute of Standards and Technology a permanent magnet system was chosen. We describe the detailed construction of the

Determination of the Planck constant using a watt balance with a superconducting magnet system at the National Institute of Standards and Technology

March 31, 2014
Author(s)
Stephan Schlamminger, Darine El Haddad, Frank C. Seifert, Leon S. Chao, David B. Newell, Richard L. Steiner, Jon R. Pratt
In the past two years measurements were performed with a watt balance at the National Institute of Standards and Technology (NIST) to determine the Planck constant. A detailed analysis of these measurements and their uncertainties led to a value of h=6.626

The Planck constant, watt and vacuum balances, and an evolving Mise en pratique for the kilogram in North America

July 1, 2012
Author(s)
Jon R. Pratt, David B. Newell, Zeina J. Kubarych, Stephan Schlamminger, Darine El Haddad, Ruimin Liu, Edwin R. Williams, Dave Inglis, Barry M. Wood, Carlos Sanchez, Richard Green
We report preparations underway at the National Institute of Standards and Technology (NIST) in the United States and at the National Research Council (NRC) in Canada to support the redefinition of the international system of units (SI) and the development

Balance Pan Damping Using Rings Of Tuned Sloshing Liquids

April 1, 2009
Author(s)
Edwin R. Williams, Darine El Haddad, V Generalova, Pierre Gournay, C. Hauch, F. Villar, Richard L. Steiner, Ruimin Liu
This paper describes a new method to damp out balance pan oscillations even when the balance is operated in vacuum. The key is to tune the wavelength of the damping liquid, which resides in a sealed container attached above the pan, to the natural