Recent Progress of the 2e/h Measurement at PTB

Kose, V.; Melchert, F.; Fack, H.; Hetzel, Walter

doi:10.1109/tim.1972.4314033

Cited by 6 publications

(3 citation statements)

References 3 publications

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“…The random uncertainty of the mean of these nine measurements was 2.3 parts in 108. This determination was related to the results of other workers [2,13,141 (2e/h),,= 483593.444 k 0.049 GHz/V7,,, (0.04 ppm) .…”

Section: Nbs Voltage Maintenance and Dissemination Prior To July 1972supporting

confidence: 88%

“…Since the first high precision measurements of 2e/h by Parker, Taylor and Langenberg [ I O ] , the potential significance of a precision voltage standard based on 2e/h has been recognized throughout the world [ I , 2,[11][12][13][14]. It was first demonstrated by Finnegan, Denenstein, and Langenberg (FDL) that standard cells could be maintained with a precision of io-' via a Josephson 2elh apparatus over extended periods of time emf based on a fundamental physical phenomenon such as the ac Josephson effect removes many of the inherent difficulties in using a large group of standard cells to maintain a unit of emf.…”

Section: Introductionmentioning

confidence: 99%

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Volt Maintenance at NBS via 2e/h: A New Definition of the NBS Volt

Field¹,

Finnegan²,

Toots³

1973

Metrologia

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This paper describes in detail the procedures, methods and measurements used to establish a new definition of the U.S. legal volt via the ac Josephson effect. This new definition has been made possible by the use of thin film tunnel junctions (capable of producing 10 mV outputs) and high accuracy voltage comparators. The Josephson junction is used as a precise frequency-to-voltage converter with a conversion factor equal to 2e/h. A series of measurements of 2e/h has been carried out at NBS referenced to the as-maintained unit of emf based on a large group of standard cells. Measurements made at regular intervals over a one year period (1971 to 1972) indicate that the mean emf of this group of standard cells has decreased about 4 parts in 107. Primarily to remove the effects of this drift, on July 1, 1972 a new as-maintained unit was defined by choosing a value of 2e/h consistent with the existing unit of emf. The adopted value of 2e/h is 483593.420 GHz/VNBS. The precision (one standard deviation) with which the new unit of emf can be maintained with the present techniques and apparatus is about 2 parts in 108. The accuracy of the present system is estimated to be 4 parts in 108. Comparisons of 2e/h systems at different national laboratories have been limited by uncertainties associated with the physical transfer of standard cells. In order to determine the relative agreement of the various 2e/h systems with precision better than 1 or 2 parts in 107, it appears desirable to compare 2e/h systems directly by transporting one of them.

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Section: Nbs Voltage Maintenance and Dissemination Prior To July 1972supporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Volt Maintenance at NBS via 2e/h: A New Definition of the NBS Volt

Field¹,

Finnegan²,

Toots³

1973

Metrologia

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“…IN RECENT years the use of Josephson junction (J-J) as a tool for maintaining the unit of voltage has played a very significant role in the various national laboratories of the world [1]- [6].…”

Section: Introductionmentioning

confidence: 99%

An Evaluation of Josephson-Effect Voltage Standard for the US Army: A Preliminary Report

Becker

1985

IEEE Trans. Instrum. Meas.

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The experimental procedure used and the results obtained on the evaluation of the Josephson-Effect Voltage (JEV) Standard at the US Army Primary Standards Laboratory (APSL) are reported. The inherent precision of measurement is 0.62 ppm (3c). The accuracy of the final result which is determined by various uncertainties is about 1 ppm. The Josephson junction (J-J) is used as a frequency-to-voltage converter with a conversion factor equal to 2e/h. The adopted value of 2e/h is 483593.420 GHz/V(NBS).

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Kritisch eingeschätzte und empfohlene Stoffdaten¹): Die Fundamentalkonstanten

1976

Zeitschrift fuer Chemie

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Recent Progress of the 2e/h Measurement at PTB

Cited by 6 publications

References 3 publications

Volt Maintenance at NBS via 2e/h: A New Definition of the NBS Volt

Volt Maintenance at NBS via 2e/h: A New Definition of the NBS Volt

An Evaluation of Josephson-Effect Voltage Standard for the US Army: A Preliminary Report

Kritisch eingeschätzte und empfohlene Stoffdaten¹): Die Fundamentalkonstanten

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Recent Progress of the 2e/h Measurement at PTB

Cited by 6 publications

References 3 publications

Volt Maintenance at NBS via 2e/h: A New Definition of the NBS Volt

Volt Maintenance at NBS via 2e/h: A New Definition of the NBS Volt

An Evaluation of Josephson-Effect Voltage Standard for the US Army: A Preliminary Report

Kritisch eingeschätzte und empfohlene Stoffdaten1): Die Fundamentalkonstanten

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Kritisch eingeschätzte und empfohlene Stoffdaten¹): Die Fundamentalkonstanten