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The watt balance Mark II of the Federal Institute of Metrology METAS is ready to start the measurement of the Planck constant. After an intensive conception phase, the different modules of the experiment have been designed, realized and characterized in close collaboration with external partners. Beside an overview of the experimental setup and some results, the present paper shows also theoretical...
In the context of the future definition of the mass unit, a promising approach is to link the kilogram to the Planck constant using, for example a watt balance. The Federal Institute of Metrology METAS is pursuing this route and is currently setting up a second version of the experiment. This METAS watt balance Mark II experiment is now assembled and ready for the first experimental tests. The design...
In the frame of the future redefinition of the International System of Units (SI), the unit of mass represents probably the biggest challenge. After the publication of the results from Mark I experiment, the effort is now concentrated on the development of the Mark II system. In this paper, we review the design and present the first tests of the individual components.
The METAS watt balance project has been in operation for 10 years. After different improvements and modifications, the present setup allows a reproducibility for a two weeks measurement series of 0.05 × 10-6 W/W. The analysis of several measurement campaigns is underway to produce a value of the Planck's constant h in the near future.
This paper describes the analysis of a measurement comparison of resistance standards, using a method of constrained least squares. The approach is based on [1] which provides a general framework for the analysis of measurement comparisons independent of their complexity.
After several mechanical improvements, the METAS watt balance has been fully operational during the last 18 months. The reproducibility, alignment issues and the long term stability of the apparatus are discussed.
The discovery of the quantum Hall effect (QHE) in 1980 by Klaus von Klitzing has revolutionized the resistance metrology. Today, the quantized Hall resistance (QHR), observed in a two-dimensional electron gas exposed to a high magnetic flux at low temperatures, is used worldwide as an invariant reference for electrical calibrations. It has improved the reproducibility of calibration results by up...
The Large Hadron Collider (LHC) particle accelerator project will require unprecedented accuracy in the control of the current to the superconducting magnets. A calibration infrastructure has been developed at CERN to ensure current measurement traceability to national standards. The traceability of CERN current measurement chain from 10 mA to 5 A has been assured by periodic calibrations at METAS...
At the Swiss Federal Office of Metrology and Accreditation (METAS), the watt balance apparatus has undergone important changes in the magnetic circuit. A new magnet design has been carefully studied, experimentally tested and successfully integrated in the existing set-up. The details of this development as well as new alignment capabilities are described
Twenty National Metrology Institutes have participated in the European DC voltage ratio key comparison (EUROMET.EM-K8). The results for the voltage ratios 1000V/10V and 100V/10V are reported
Measurements have been made of radial currents in a two dimensional electron gas in the quantum Hall regime using a Corbino ring geometry. A small solenoid is used to modulate the flux linking a high mobility GaAs-Al x Ga 1-x As Corbino ring, thereby inducing an alternating radial current flow. Plateaus of current value are observed giving a clear indication that quantization...
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