A determination of Planck's constant using the NRC watt balance

Sánchez, C.; Wood, B.M.; Green, R G; Liard, J.; Inglis, D.

doi:10.1088/0026-1394/51/2/s5

Cited by 92 publications

(100 citation statements)

References 22 publications

(40 reference statements)

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“…22 The National Research Council (NRC) of Canada purchased the NPL apparatus in 2011 and made improvements that lowered the overall uncertainty. 23 The National Institute of Metrology (NIM) of China proposed a Joule balance, in which the derivative of the flux with respect to z is calibrated using a mutual inductance method instead of moving the coil in the magnetic flux. 24 The principle of the watt balance experiment is presented in the simplified scheme of Fig.…”

Section: Background On Watt Balances and The Link To Hmentioning

confidence: 99%

Invited Article: A precise instrument to determine the Planck constant, and the future kilogram

Haddad

Seifert

Chao

et al. 2016

Review of Scientific Instruments

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A precise instrument, called a watt balance, compares mechanical power measured in terms of the meter, the second, and the kilogram to electrical power measured in terms of the volt and the ohm. A direct link between mechanical action and the Planck constant is established by the practical realization of the electrical units derived from the Josephson and the quantum Hall effects. We describe in this paper the fourth-generation watt balance at the National Institute of Standards and Technology (NIST), and report our initial determination of the Planck constant obtained from data taken in late 2015 and the beginning of 2016. A comprehensive analysis of the data and the associated uncertainties led to the SI value of the Planck constant, h = 6.626 069 83(22) × 10−34 J s. The relative standard uncertainty associated with this result is 34 × 10−9.

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Section: Background On Watt Balances and The Link To Hmentioning

confidence: 99%

Invited Article: A precise instrument to determine the Planck constant, and the future kilogram

Haddad

Seifert

Chao

et al. 2016

Review of Scientific Instruments

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“…Several scientific publications from 2007 to 2017 [18][19][20][21][22][23][24][25][26][27] were analysed from the position of the relative and comparative uncertainty values reached. The data are summarized in Table 1.…”

Section: Applications Of µ Si For Plank Constant Measurementmentioning

confidence: 99%

Plank’s Constant: Evaluation of Measurement Uncertainty

Menin¹,

Expert²

2018

NHMP

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Abstract. In this article, we present a new metric called the comparative uncertainty, according to which the least achievable relative uncertainty is calculated when measuring the Planck constant. To calculate the comparative uncertainty, information theory is used. The optimizing criterion is the number of quantities considered in the model. Its calculation is possible due to the fact that any model contains a certain amount of information about the object under study. Comparative uncertainty can be verified by field trials or computer simulations within a specified range of changes of the Planck constant. The concept of introduced uncertainty is universal and can be recommended for estimating the accuracy of measurements in the study of physical phenomena and technological processes. Examples of application of the proposed approach are discussed.

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“…Note that there are some other realizations of watt balance magnets, e.g., [11,24]. Although the model and analysis presented in this paper is based on the magnet shown in figure 1, they can be also applied in other magnet structures.…”

Section: Magnet Structurementioning

confidence: 99%

“…As a result, N + 1 unknown parameters, i.e., β i (i = 1, 2, ..., N) and α, can be solved by N + 1 equations in (11). Substituting the solved parameters back into equation (10), the B z (r, z) function on the whole air gap is obtained.…”

Section: Algorithmmentioning

confidence: 99%

“…As a result, the Planck constant h can be related to the test mass m by comparing the electrical power to the mechanical power in conjunction with the quantum Hall effect [3] and the Josephson effect [4]. Since the proposal in 1975, the watt balance has been widely spread and persuaded at many national metrology institutes (NMIs) [5][6][7][8][9][10][11][12][13]. The detailed principle and recent progress of watt balance experiments at NMIs can be found in several review papers, e.g., [14][15][16].…”

Section: Introductionmentioning

confidence: 99%

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Field representation of a watt balance magnet by partial profile measurements

Yuan

Zhao

et al. 2015

Metrologia

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Abstract. Permanent magnets with high-permeability yokes have been widely used in watt balances for supplying a robust and strong magnetic field at the coil position. Subjected to the mechanical realization, only several B r (z) (radial magnetic field along the vertical direction) profiles can be measured by coils for field characterization. In this article, we present an algorithm that can construct the global magnetic field of the air gap based on N (N ≥ 1) additional measurements of B r (z) profiles. The proposed algorithm is realized by polynomially estimating the B z (r) function with analysis of basic relations between two magnetic components in air gap, i.e., B r (r, z) and B z (r, z), following the Maxwell's equations. The algorithm, verified by FEM simulations, can characterize the three-dimensional contribution of the magnetic field for a watt balance magnet with acceptable accuracy, which would supply basic field parameters for alignment and misalignment corrections.

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A determination of Planck's constant using the NRC watt balance

Cited by 92 publications

References 22 publications

Invited Article: A precise instrument to determine the Planck constant, and the future kilogram

Invited Article: A precise instrument to determine the Planck constant, and the future kilogram

Plank’s Constant: Evaluation of Measurement Uncertainty

Field representation of a watt balance magnet by partial profile measurements

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