A new quantum voltage calibrated Johnson noise thermometer (JNT) was developed at NIM to demonstrate the electrical approach that determines the Boltzmann constant k by comparing electrical and thermal noise power. A measurement with integration period of 10 hours and bandwidth of 640 kHz results in relative offset of 0.5106 from the current CODATA value of k, and type A relative standard uncertainty of 23106. The quadratic fitting parameters of the ratio spectrum show a flat frequency response with respect to the measurement bandwidth. This flat response is a dramatic improvement compared to the response produced by the NIST JNT system that dominated the relative combined uncertainty of previous measurements of k.
Proceedings Title: Conference on Precision Electromagnetic Measurements Conference Digest
Conference Dates: July 1-6, 2012
Conference Location: National Harbor, MD
Conference Title: Conference on Precision Electromagnetic Measurements
Pub Type: Conferences
Boltzmann equation, Correlation, Digital-analog conversion, Josephson arrays, Measurement units, Noise Measurement, Quantization, Signal synthesis, Standards, Temperature