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You searched on: Author: weston tew

Displaying records 11 to 20 of 55 records.
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11. An electronic measurement of the Boltzmann constant
Published: 3/30/2011
Authors: Samuel Paul Benz, Alessio Pollarolo, Jifeng Qu, Horst Rogalla, Chiharu Urano, Weston Leo Tew, Paul David Dresselhaus, D. R White
Abstract: The Boltzmann constant was measured by comparing the Johnson noise of a resistor at the triple point of water with a quantum-based voltage reference signal generated with a superconducting Josephson-junction waveform synthesizer. The measured value ...

Published: 3/18/2011
Authors: Weston Leo Tew, Samuel Paul Benz
Abstract: The recent advances in ac waveform synthesis using quantized voltage pulses have enabled new methods for the measurement of absolute temperature. At the same time, the increased linearity and sampling rates of digital electronics have established fre ...

13. Improved Estimates of the Isotopic Correction Constants for the Triple Point of Water
Published: 9/14/2010
Authors: Weston Leo Tew, D. R White
Abstract: In 2006, the CIPM clarified the definition of the kelvin by specifying the isotopic composition of the water to be used in the realisation of the triple point. At the same time, the Consultative Committee on Thermometry gave recommended values for th ...

14. Recent Progress in Noise Thermometry at 505 K and 693 K Using Quantized Voltage Noise Ratio Spectra
Published: 9/6/2010
Authors: Weston Leo Tew, Paul David Dresselhaus, Kevin J Coakley, H Rogalla, D. R White, J Labenski
Abstract: We report on technical advances and new results in noise thermometry at temperatures near the tin freezing point and the zinc freezing point using a Quantized Voltage Noise Source (QVNS). The temperatures are derived in a series of separate measureme ...

15. Electronic Measurement of the Boltzmann Constant with a Quantum-Voltage-Calibrated Johnson-Noise Thermometer
Published: 11/22/2009
Authors: Samuel Paul Benz, D. R White, Jifeng Qu, Horst Rogalla, Weston Leo Tew
Abstract: Currently, the CODATA value of the Boltzmann constant is dominated by a single gas-based-thermometry measurement with a relative uncertainty of 1.8 ձ0^-6. This paper describes an electronic approach to measuring the Boltzmann constant that comp ...

16. Improvements in the NIST Johnson Noise Thermometry System
Published: 4/1/2009
Authors: Samuel Paul Benz, Jifeng Qu, Horst Rogalla, D. R White, Paul David Dresselhaus, Weston Leo Tew, Sae Woo Nam
Abstract: We have developed a Johnson noise thermometry (JNT) system that is calibrated by precision waveforms synthesized with a quantized voltage noise source (QVNS). Significant improvements to the QVNS and the cross-correlation measurement electronics have ...

17. Measurement Time and Statistics for a Noise Thermometer With a Synthetic-Noise Reference
Published: 8/1/2008
Authors: D. R White, Samuel Paul Benz, J Labenski, Sae Woo Nam, Jifeng Qu, H Rogalla, Weston Leo Tew
Abstract: This paper describes methods for reducing the statistical uncertainty in measurements made by noise thermometers using digital cross correlators, and in particular, for thermometers using pseudorandom noise for the reference signal. First, a discrete ...

18. Adjustments to the NIST Realization of the ITS-90 from 5 K to 24.5561 K
Published: 5/1/2008
Authors: Weston Leo Tew, Christopher W Meyer
Abstract: Recent clarifications issued by the Consultative Committee on Thermometry (CCT) for the definitions of the equilibrium hydrogen (e-H2) triple points (TPs) and vapor-pressure points (VPs) have resulted in adjustments to the NIST-disseminated ITS-90 (T ...

19. Estimating the Triple Point Isotope Effect and the Corresponding Uncertainties for Cryogenic Fixed Points
Published: 2/1/2008
Author: Weston Leo Tew
Abstract: The estimation of sensitivities of melting temperatures due to isotopic variations in monatomic and diatomic atmospheric gases is developed from both theoretical and semi-empirical standpoints. The state of what is currently known regarding vapor pre ...

20. A Determination of the Ratio of the Zinc Freezing Point to the Tin Freezing Point by Noise Thermometry
Published: 9/12/2007
Authors: Weston Leo Tew, John Labenski, Samuel Paul Benz, Sae Woo Nam, Paul David Dresselhaus
Abstract: We have used a Johnson-Noise Thermometer (JNT) with a Quantized Voltage Noise Source (QVNS) as a calculable reference to determine the ratio of temperatures near the Zn freezing point to those near the Sn freezing point. The temperatures are derived ...

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