Improvements in resistance scaling at NIST using cryogenic current comparators

Cryogenic current comparators (CCCs) are being used at NIST to verify Hamon-type resistance scaling techniques from 1 to 100 Omega , 1 k Omega , 6453.20 Omega , and 10 k Omega . Measurements comparing the 10/1, 64.532/1, and 100/1 ratios of CCCs to that of Hamon transfer ratios agree to approximately=0.01 ppm, the practical limit of accuracy using Hamon transfer standards with conventional resistance bridges. The higher ration accuracies and sensitivities of CCC bridges will make it possible to lower the uncertainties associated with resistance scaling at NIST significantly.<
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