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The scientific community is presently engaged in a historic attempt to fix the value of the Planck constant h so that it might ultimately serve as a base constant in a revised system of units. To assist this effort, NIST is examining its existing watt balance experiment, NIST-3, and will measure h once again, aiming at a final rigorous test of reproducibility. The main objectives are to modify and...
A blind test was conducted with mass references of a 0.5 kg silicon and 1 kg each of steel and gold-plated copper, calibrated in vacuum at the NPL and measured with the watt balance at the National Institute of Standards and Technology (NIST). The results were analyzed against a 1 kg PtIr mass calibrated at NIST. The results showed good and consistent agreement between the Si, steel, and PtIr masses...
This paper describes a new method to damp out balance pan oscillations, even when the balance is operated in a vacuum. The key is to tune the wavelength of the damping liquid by adjusting the depth. The liquid is sealed in a vacuum-compatible container attached above the pan, and the time that the wave travels from one side of the container to the other can be adjusted for maximum damping at the natural...
Variable magnetic field Hall measurements were performed to investigate the electrical properties in In0.52Al0.48 As/In0.65Ga0.35As metamorphic high electron mobility transistors (MMHEMTs) on GaAs substrate at the temperature range from 4 to 100 K. The Shubnikov-de Hass (SdH) measurement shows the two-dimensional electronic behavior and two-subband electron occupation in MMHEMTs. The electron densities...
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