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Search Publications by: Darine El Haddad (Fed)

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Displaying 1 - 25 of 39

Flexures for Kibble balances: Minimizing the effects of anelastic relaxation

July 1, 2024
Author(s)
Lorenz Keck, Stephan Schlamminger, Rene Theska, Frank Seifert, Darine El Haddad
Modern weighing cells would not be possible without flexure technology. Flexures are thin metal strips that form pivots, and they can be engineered to bend in a prescribed fashion, producing a desired restoring torque. In contrast to other pivots, flexures

The Quantum Electro-Mechanical Metrology Suite

March 27, 2024
Author(s)
Frank Seifert, Lorenz Keck, David B. Newell, Darine El Haddad
The National Institute of Standards and Technology (NIST) is building a robust open-source hardware and software Quantum Electro-Mechanical Metrology Suite (QEMMS) that can provide quantum voltage, resistance, current, mass, and force dissemination

A Macroscopic Mass From Quantum Behavior In An Integrated Approach

December 10, 2022
Author(s)
Frank Seifert, Alireza Panna, Lorenz Keck, Leon Chao, Shamith Payagala, Dean G. Jarrett, Dipanjan Saha, Randolph Elmquist, Stephan Schlamminger, Albert Rigosi, David B. Newell, Darine El Haddad
The revision of the International System of Units (SI) on May 20th, 2019, has enabled new improved experiments to consolidate and simplify electrical and mechanical metrology currently underway. Historically within the SI, the definition of energy was only

Calculation of magnetic forces and torques on the Kibble coil

October 22, 2022
Author(s)
Stephan Schlamminger, Lorenz Keck, Frank Seifert, Leon Chao, Darine El Haddad, Shisong Li
Analytically the force and torques on a coil in a field of magnetic flux density can be calculated one of two ways. The line integral can be conducted along the coil's wire, summing up the differential force contribution. For each differential line segment

Resolution of the paradox of the diamagnetic force on the Kibble coil

January 13, 2021
Author(s)
Stephan Schlamminger, Shisong Li, Rafael Marangoni, Darine El Haddad, Qing Wang, Wei Zhao
Employing very simple electro-mechanical principles known from classical physics, the Kibble balance establishes a very precise and absolute link between quantum electrical standards and macroscopic mass or force measurements. The success of the Kibble

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

The Design and Development of a Tabletop Kibble Balance at NIST

May 23, 2019
Author(s)
Leon S. Chao, Frank C. Seifert, Darine El Haddad, Julian Stirling, David B. Newell, Stephan Schlamminger
On November 16, 2018, the 26th General Conference on Weights and Measures (CGPM) voted unanimously to revise the International System of Units (SI) from a system built on seven base units to one built on seven defining constants and will officially become

The Kibble balance and the kilogram

March 25, 2019
Author(s)
Stephan Schlamminger, Darine El Haddad
Dr. Bryan Kibble invented the watt balance in 1975 to improve the realization of the unit for electrical current, the ampere. With the discovery of the Quantum Hall e ect in 1980 by Dr. Klaus von Klitzing and in conjunction with the previously predicted

The Design and Development of a Tabletop Kibble Balance at NIST

March 20, 2019
Author(s)
Leon S. Chao, Frank C. Seifert, Darine El Haddad, Stephan Schlamminger
A global paradigm shift to redefine the International System of Units (SI) from a system based on seven fundamental units to seven fundamental constants is well under way. More specifically, the unit of mass, the kilogram, will be realized via a fixed

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 Seifert, Leon Chao, Antonio 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

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

Quantum Hall Resistance Traceability for the NIST-4 Watt Balance

July 10, 2016
Author(s)
Dean G. Jarrett, Randolph Elmquist, Marlin E. Kraft, George R. Jones Jr., Shamith Payagala, Frank Seifert, Stephan Schlamminger, Darine El Haddad
Scaling from the quantum Hall resistance to 100 Ω standard resistors used by the NIST-4 Watt Balance involves multiple resistance standards and bridges to provide the lowest possible uncertainty. Described here is the infrastructure and procedures

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

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

March 31, 2015
Author(s)
Darine El Haddad, Frank Seifert, Leon 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 summary of the Planck constant measurements using a watt balance with a superconducting solenoid at NIST

February 5, 2015
Author(s)
Stephan Schlamminger, Richard L. Steiner, Darine El Haddad, David B. Newell, Frank C. Seifert, Leon S. Chao, Ruimin Liu, Edwin R. Williams
Researchers at the National Institute of Standards and Technology have been using a watt balance, NIST-3, to measure the Planck constant h for over ten years. Two recently published values disagree by more than one standard deviation. The motivation for