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Search Publications by: Weston L. Tew (Fed)

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Displaying 26 - 50 of 151

The NIST Johnson noise thermometry system for the determination of the Boltzmann constant

December 29, 2017
Author(s)
Nathan Flowers-Jacobs, Alessio Pollarolo, Kevin Coakley, Adam C. Weis, Anna Fox, Horst Rogalla, Weston L. Tew, Samuel Benz
In preparation for the redefinition of the International System of Units (SI), five different electronic measurements of the Boltzmann constant have been performed using different Johnson noise thermometry (JNT) systems over the past seven years. In this

A Boltzmann Constant Determination Based on Johnson Noise Thermometry

August 10, 2017
Author(s)
Nathan E. Flowers-Jacobs, Alessio Pollarolo, Kevin J. Coakley, Anna E. Fox, Horst Rogalla, Weston L. Tew, Samuel P. Benz
A value for the Boltzmann constant was measured electronically using an improved version of the Johnson Noise Thermometry (JNT) system at the National Institute of Standards and Technology (NIST), USA. This system is different from prior ones, including

An improved electronic measurement of the Boltzmann constant by Johnson noise thermometry

July 18, 2017
Author(s)
Jifeng Qu, Samuel Benz, Kevin Coakley, Horst Rogalla, Weston L. Tew, David R. White, Kunli Zhou, Zhenyu Zhou
Recent measurements using acoustic gas thermometry have determined the value of the Boltzmann constant, k, with a relative uncertainty less than 110-6. These results have been supported by a measurement with a relative uncertainty of 1.910-6 made with

Improved spectra aberration in the Johnson Noise Thermometry

July 9, 2016
Author(s)
Alessio Pollarolo, Horst Rogalla, Anna Fox, Kevin J. Coakley, Weston L. Tew, Samuel P. Benz
SPECTRAL ABERRATION HAS BEEN FOR A LONG TIME THE MAIN SOURCE OF UNCERTAINTY IN THE JOHNSON NOISE THERMOMETRY APPROACH TO MEASURING THE BOLTZMANN CONSTANT. RECENTLY, WITH NEWLY DEVELOPED HARDWARE AND THE INTRODUCTION OF A NOVEL FITTING ALGORITHM FOR

SRM 1967a: High-Purity Platinum Thermoelement

March 9, 2016
Author(s)
Karen M. Garrity, Weston L. Tew, Dean C. Ripple
Consisting of a 1 m long piece of 0.5 mm diameter platinum wire, SRM 1967a meets the requirements for a thermoelectric reference material for temperatures from 196 °C up to approximately 1700 °C. We have tested the thermoelectric emf of four SRM 1967a

Advances in Thermometry

January 1, 2016
Author(s)
Michael R. Moldover, Weston L. Tew, Howard W. Yoon
The last 25 years have seen tremendous progress in thermometry in the moderate temperature range (1 K to 1235 K). Various primary thermometers — based on different physics —have uncovered errors in the International Temperature Scale of 1990 and set the

Improved electronic measurement of the Boltzmann constant by Johnson noise Thermometry

August 19, 2015
Author(s)
Weston L. Tew, Samuel P. Benz, Horst Rogalla, Alessio Pollarolo, David R. White, Jifeng Qu, Kunli Zhou
The unit of thermodynamic temperature, the kelvin, will be redefined in 2018 by fixing the value of the Boltzmann constant, k. The present CODATA recommended value of k is determined predominantly by acoustic gas-thermometry results. To provide a value of

Calibration of thin-film platinum sensors for use in the JILA Sr II Clock

March 29, 2015
Author(s)
Weston L. Tew, Travis L. Nicholson, Ross B. Hutson
A set two pairs of thin-film platinum resistance thermometers (TFPRTs) have been calibrated on the International Temperature Scale of 1990 (ITS-90) for the purposes of determining temperatures inside the JILA Sr II Optical Lattice Clock vacuum chamber. The

Systematic Error Resolved in NIST Johnson Noise Thermometer

August 24, 2014
Author(s)
Alessio Pollarolo, Weston L. Tew, Horst Rogalla, Samuel P. Benz
In the Johnson Noise Thermometry approach, Boltzmann’s constant k is obtained as the ratio of the noise power measured across a sense resistor at the triple point of water and the noise power measured for a synthesized reference waveform. The reference