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Search Publications by: David B. Newell (Fed)

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Displaying 76 - 100 of 150

Edge-state Transport in Graphene p-n Junctions in the Quantum Hall Regime

December 7, 2015
Author(s)
Nikolai Klimov, Son T. Le, Jun Yan, Pratik Agnihotri, Everett Comfort, Ji Ung Lee, David B. Newell, Curt A. Richter
We experimentally investigate charge carrier transport in a graphene p-n junction device by using independent p-type and n-type electrostatic gating which allow full characterization of the junction interface in the quantum Hall regime covering a wide

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

CORRELATIONS AMONG ACOUSTIC MEASUREMENTS OF THE BOLTZMANN CONSTANT

September 9, 2015
Author(s)
Michael R. Moldover, Roberto M. Gavioso, David B. Newell
We review correlated uncertainties among the accurate determinations of the Boltzmann constant kB that used the techniques of primary acoustic gas thermometry (AGT). We consider uncertainty contributions from four sources: (1) resonator-dependent

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 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

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 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

Pseudomagnetic Fields in a Locally Strained Graphene Drumhead

August 25, 2014
Author(s)
Shuze Zhu, Yinjun Huang, Nikolai Klimov, David B. Newell, Nikolai Zhitenev, Joseph A. Stroscio, Santiago D. Solares Rivera, Teng Li
Recent experiments reveal that a scanning tunneling microscopy (STM) probe tip can generate a highly localized strain field in a graphene drumhead, which in turn leads to pseudomagnetic fields in the graphene that can spatially confine graphene charge

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

Development of Low Carrier Density Graphene Devices

August 1, 2014
Author(s)
Yanfei Yang, Lung-I Huang, David B. Newell, Yasuhiro Fukuyama, Mariano A. Real, Randolph Elmquist
Epitaxial graphene on SiC(0001) is used to fabricate Hall bar structures for metrological applications with a fabrication process that has been developed to eliminate organic chemical contamination of the graphene. Before any lithographic patterning a

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

Low carrier density epitaxial graphene devices on SiC

June 1, 2014
Author(s)
Yanfei Yang, Lung-I Huang, Yasuhiro Fukuyama, Fan-Hung Liu, Mariano Real, Paola Barbara, Chi-Te Liang, David B. Newell, Randolph Elmquist
Monolayer epitaxial graphene grown on a hexagonal silicon carbide (SiC) substrate is typically found to be heavily n-doped (10e13 cm-2) and in most devices made with the as-grown epitaxial graphene the quantized Hall resistance plateau with Landau level

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

Graphene Epitaxial Growth on SiC(0001) for Resistance Standards

June 3, 2013
Author(s)
Mariano A. Real, Eric Lass, Fan-Hung H. Liu, Tian T. Shen, George R. Jones Jr., Johannes A. Soons, David B. Newell, Albert Davydov, Randolph Elmquist
A well-controlled technique for high-temperature epitaxial growth on 6H-SiC(0001) substrates is shown to allow development of monolayer graphene that exhibits promise for precise metrological applications. Face-to-face (FTF) and face-to-graphite (FTG)

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

Electro-Mechanical Properties of Graphene Drumheads

June 22, 2012
Author(s)
Nikolai N. Klimov, Suyong S. Jung, Shuze Zhu, Teng Li, C. Alan Wright, Santiago Solares, David B. Newell, Nikolai B. Zhitenev, Joseph A. Stroscio
The electro-mechanical properties of a suspended graphene layer are determined by scanning tunneling microscopy (STM) and spectroscopy (STS) measurements and computational simulations of the graphene membrane mechanics and morphology. The graphene membrane

Characteristics of Graphene for Quantized Hall Effect Measurements

June 1, 2012
Author(s)
Randolph E. Elmquist, Mariano A. Real, Irene G. Calizo, Brian G. Bush, Tian T. Shen, Nikolai N. Klimov, David B. Newell, Angela R. Hight Walker, Randall M. Feenstra
This paper describes concepts and measurement techniques necessary for characterization of graphene in the development of graphene-based quantized Hall effect (QHE) devices and resistance standards. We briefly contrast the properties of graphene produced

CODATA Recommended Values of the Fundamental Physical Constants: 2010

March 1, 2012
Author(s)
Peter J. Mohr, Barry N. Taylor, David B. Newell
This paper give the 2010 self-consistent set of values of the basic constants and conversion factors of physics and chemistry recommended by the Committee on Data for Science and Technology (CODATA) for international use. The 2010 adjustment takes into

Graphene: Plane and Simple Electrical Metrology?

December 7, 2011
Author(s)
Randolph E. Elmquist, Felipe Hernandez-Marquez, Mariano Real, Tian T. Shen, David B. Newell, Colin J. Jacob, George R. Jones
The development of large-area graphene has direct application to electrical standards including the quantized Hall resistance because of unique characteristics not found in conventional devices. These include symmetrical conduction by electrons and holes