An ultrastable low-noise current amplifier (ULCA) has been transferred between two laboratories, NPL and PTB, four times, with three of the transfers yielding a relative change in the trans-resistance gain of less than 2×10−7. This is a new bench-mark for inter-laboratory transfer of small current. We describe in detail the use of a cryogenic current comparator to calibrate the ULCA at NPL, and the use of the ULCA to measure 1 GΩ resistors with relative uncertainties at the 10−7 level.
Cite
@article{arxiv.1808.09741,
title = {Inter-laboratory nanoamp current comparison with sub-part-per-million uncertainty},
author = {Stephen Giblin and Dietmar Drung and Martin Goetz and Hansjoerg Scherer},
journal= {arXiv preprint arXiv:1808.09741},
year = {2019}
}