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The international community started recently to look for a new way to define the Kelvin. Different experiments around the world have begun. This presentation will describe very briefly the four different techniques currently used for the redetermination of k, namely the measurement of the speed of sound in pure helium-4, the determination deduce of the Doppler profile of the linear absorption line,...
We have developed a Johnson noise thermometry system that is calibrated by precision waveforms synthesized with a quantized voltage noise source (QVNS). Significant improvements to the QVNS and the cross-correlation measurement electronics have dramatically reduced systematic errors and measurement uncertainty. We describe some of these improvements and discuss the potential for this system to contribute...
We have been developing a spectrometer to record an accurate absorption line profile of a rovibrational transition of acetylene in the 1.54 mum region using an extended cavity laser diode (ECLD) and a mode-locked fiber frequency comb. With the spectrometer, we have recorded the absorption line profiles for various pressures and have observed the collisional narrowing effect on the inhomogeneous Gaussian...
A simple setup for the accurate measurement of Johnson noise of a resistor is here presented. The setup is composed of a digital correlation spectrum analyzer, and of a calibration signal source traceable to ac voltage and frequency standards. If resistor temperature is measured, an estimate of the Boltzmann constant kB can be obtained. Presently, measured kB has a relative error below 1times10-3...
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