Reassessment of the Uncertainties of the NRC Cryogenic Current Comparator and Quantum Hall Resistance Standard

This paper describes the main sources of error in the NRC Cryogenic Current Comparator (CCC) and Quantum Hall Resistance Standard (QHR) systems and reports their estimated uncertainty. The CCC type B uncertainty is evaluated to be 0.26 parts in 10(9), with the largest contribution being the effect of a noise-induced offset in the Superconducting Quantum Interference Device (SQUID). The relative uncertainty of the QHR system is estimated at 0.28 x 10(-9), with comparable contributions from leakage resistances between the leads and finite dissipation on the QHR sample.