Uncertainty Improvements of the NIST Electronic Kilogram

Steiner, Reto; Williams, Edwin R.; Liu, Ruimin; Newell, David B.

doi:10.1109/tim.2007.890590

Cited by 137 publications

(117 citation statements)

References 13 publications

(13 reference statements)

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“…However, the current relative uncertainty on the experimental determinations of N A [71] or h [72] is of the order of a few parts of 10 8 . This is three orders of magnitude larger than the 'possible' shift of the Rydberg constant that may be disclosed by the new value of the proton size radius from muonic hydrogen.…”

Section: The Proton and The Redefinition Of The International System mentioning

confidence: 99%

Is the proton radius a player in the redefinition of the International System of Units?

Nez

Antognini

Amaro

et al. 2011

Phil. Trans. R. Soc. A.

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International audienceIt is now recognized that the International System of Units (SI units) will be redefined in terms of fundamental constants, even if the date when this will occur is still under debate. Actually, the best estimate of fundamental constant values is given by a least-squares adjustment, carried out under the auspices of the Committee on Data for Science and Technology (CODATA) Task Group on Fundamental Constants. This adjustment provides a significant measure of the correctness and overall consistency of the basic theories and experimental methods of physics using the values of the constants obtained from widely differing experiments. The physical theories that underlie this adjustment are assumed to be valid, such as quantum electrodynamics (QED). Testing QED, one of the most precise theories is the aim of many accurate experiments. The calculations and the corresponding experiments can be carried out either on a boundless system, such as the electron magnetic moment anomaly, or on a bound system, such as atomic hydrogen. The value of fundamental constants can be deduced from the comparison of theory and experiment. For example, using QED calculations, the value of the fine structure constant given by the CODATA is mainly inferred from the measurement of the electron magnetic moment anomaly carried out by Gabrielse's group. (Hanneke et al. 2008 Phys. Rev. Lett. 100, 120801) The value of the Rydberg constant is known from two-photon spectroscopy of hydrogen combined with accurate theoretical quantities. The Rydberg constant, determined by the comparison of theory and experiment using atomic hydrogen, is known with a relative uncertainty of 6.6 x 10(-12). It is one of the most accurate fundamental constants to date. A careful analysis shows that knowledge of the electrical size of the proton is nowadays a limitation in this comparison. The aim of muonic hydrogen spectroscopy was to obtain an accurate value of the proton charge radius. However, the value deduced from this experiment contradicts other less accurate determinations. This problem is known as the proton radius puzzle. This new determination of the proton radius may affect the value of the Rydberg constant R-infinity. This constant is related to many fundamental constants; in particular, R-infinity links the two possible ways proposed for the redefinition of the kilogram, the Avogadro constant N-A and the Planck constant h. However, the current relative uncertainty on the experimental determinations of N-A or h is three orders of magnitude larger than the 'possible' shift of the Rydberg constant, which may be shown by the new value of the size of the proton radius determined from muonic hydrogen. The proton radius puzzle will not interfere in the redefinition of the kilogram. After a short introduction to the properties of the proton, we will describe the muonic hydrogen experiment. There is intense theoretical activity as a result of our observation. A brief summary of possible theoretical explanations at the date of writing of the pap...

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Section: The Proton and The Redefinition Of The International System mentioning

confidence: 99%

Is the proton radius a player in the redefinition of the International System of Units?

Nez

Antognini

Amaro

et al. 2011

Phil. Trans. R. Soc. A.

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“…For watt balances, the permanent magnet [8]- [15] or a superconducting solenoid [3] is employed, and hence the magnetic field generated is relative strong, e.g., 0.5 T~1 T. The profiles of these watt balances are conventionally changing several parts in 10 4 in a typical measurement interval of several centimeters. In our design, since coils are applied as the excitation of the field, the magnitude of the magnetic field in the air gap is weaker than that of a watt balance, but a rather larger measurement interval can be obtained.…”

Section: Adopting the Magnetic Flux Linkage Directlymentioning

confidence: 99%

“…The linear part can be removed from a current reversal [3,8]. However, the quadratic parts cannot be eliminated and would generate a bias error during the measurement.…”

Section: Adopting the Magnetic Flux Linkage Directlymentioning

confidence: 99%

“…The key point of this method is to avoid the dynamic measurement during the coil movement for the watt balance method [2], [3], to try giving another method for the kg redefinition because comparison of results from different methods could get more information. The joule balance requires a rather large current in the exciting coil to provide the necessary magnetic field for the weighing phase.…”

Section: Introductionmentioning

confidence: 99%

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Coils and the Electromagnet Used in the Joule Balance at the NIM

Zhang

Han

et al. 2015

IEEE Trans. Instrum. Meas.

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Abstract-In the joule balance developed at National Institute of Metrology (NIM), the dynamic phase of a watt balance is replaced by the mutual inductance measurement in an attempt to provide an alternative method for the kg redefinition. But for this method a rather large current in the exciting coil, is needed to offer the necessary magnetic field in the force weighing phase, and the coil heating becomes an important uncertainty source. To reduce coil heating, a new coil system, in which a ferromagnetic material is used to increase the magnetic field was designed recently. But adopting the ferromagnetic material brings the difficulty from the nonlinear characteristic of material. This problem can be removed by measuring the magnetic flux linkage difference of the suspended coil at two vertical positions directly to replace the mutual inductance parameter. Some systematic effects of this magnet are discussed.

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“…Owing to the extreme accuracy of the Planck constant measurements, to gain confidence in the uncertainty of the no-effect statement, an equivalently accurate analysis is necessary. We have also been motivated by the spreadthe order of magnitude of which is 100 nW W −1 , to be compared with a targeted uncertainty of 10 nW W −1 -of the Planck constant values reported by the International Avogadro Coordination (IAC) [7,8], the National Institute of Standards and Technology (NIST-USA) [9,10], the Swiss Federal Office of Metrology (METAS-Switzerland) [11], the National Physical Laboratory (NPL-UK) [12] and the National Research Council (NRC-Canada) [13]. Our study demonstrates that an accurate calculation of these minute forces is possible and that their effect is actually irrelevant, thus confirming the no-effect assumption.…”

Section: Introductionmentioning

confidence: 99%