Accurate Measurement of the Planck Constant

The determination of the Fermi coupling constant, G F , is examined in the light of recently calculated 2-loop QED corrections and planned experiments to measure the muon lifetime to a level below 1 ppm. The methods used in the calculation of the QED corrections are described in detail. Sources of the dominant theoretical and experimental uncertainties are identified. Finally the incorporation of G F into analyses using the full electroweak Standard Model is discussed.

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“…A new measurement of Planck's constant, h, [46] means that this can now be converted to units of MeV without introducing additional errors.…”

Section: Experimental Uncertaintiesmentioning

confidence: 99%

On the precise determination of the Fermi coupling constant from the muon lifetime

2000

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“…The test masses of 1 kg are made of Au and Pt-Ir. The first result from this apparatus was published in 1998 with a relative uncertainty of 8.7 parts in 10 8 [23,24]. The experiment was then largely rebuilt to eliminate many of the previous error sources, but the base concept stayed the same.…”

Section: The Existing Watt Balance Experimentsmentioning

confidence: 99%

“…An interesting question in this respect is in how far the NIST 1998 result [23] can be seen as independent from the later results, because the apparatus had been considerably modified. However, its uncertainty of 8.7 parts in 10 8 is too large to fulfil the first condition.…”

Section: Status Of the Redefinition Of The Kilogrammentioning

confidence: 99%

The watt balance: determination of the Planck constant and redefinition of the kilogram

Stöck

2011

Phil. Trans. R. Soc. A.

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Since 1889, the international prototype of the kilogram has served as the definition of the unit of mass in the International System of Units (SI). It is the last material artefact to define a base unit of the SI, and it influences several other base units. This situation is no longer acceptable in a time of ever-increasing measurement precision. It is therefore planned to redefine the unit of mass by fixing the numerical value of the Planck constant. At the same time three other base units, the ampere, the kelvin and the mole, will be redefined. As a first step, the kilogram redefinition requires a highly accurate determination of the Planck constant in the present SI system, with a relative uncertainty of the order of 1 part in 10 8 . The most promising experiment for this purpose, and for the future realization of the kilogram, is the watt balance. It compares mechanical and electrical power and makes use of two macroscopic quantum effects, thus creating a relationship between a macroscopic mass and the Planck constant. In this paper, the operating principle of watt balance experiments is explained and the existing experiments are reviewed. An overview is given of all available experimental determinations of the Planck constant, and it is shown that further investigation is needed before the redefinition of the kilogram can take place. Independent of this requirement, a consensus has been reached on the form that future definitions of the SI base units will take.

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“…The combination of the quantum Hall effect with the Josephson effect (which allows an representation of the electrical voltage in units of h/e) leads to the possibility, to compare electrical power (which depends on the Planck constant h) with mechanical power (which depends on the mass m). The best value for the Planck constant is obtained using such a Watt balance [26]. Alternatively, one may fix the Planck constant (like the fixed value for the velocity of light for the definition of the unit of length) in order to have a new realization of the unit of mass.…”

Section: Quantum Hall Effect and Metrologymentioning

confidence: 99%

25 Years of Quantum Hall Effect (QHE) A Personal View on the Discovery, Physics and Applications of this Quantum Effect

Klitzing

2005

The Quantum Hall Effect

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Accurate Measurement of the Planck Constant

Cited by 152 publications

References 12 publications

On the precise determination of the Fermi coupling constant from the muon lifetime

On the precise determination of the Fermi coupling constant from the muon lifetime

The watt balance: determination of the Planck constant and redefinition of the kilogram

25 Years of Quantum Hall Effect (QHE) A Personal View on the Discovery, Physics and Applications of this Quantum Effect

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