Transportability of the NML 1 Ω resistor

A group of three 1 Omega resistors designed and fabricated at the National Measurement Institute, Australia (NMIA), were transported by air freight between NMIA and the U.S. National Institute of Standards and Technology (NIST) to quantify travel-induced changes in resistance value. The resistors were exchanged between the two laboratories in two successive cycles in 2007-2008. The average travel-induced change was less than 0.02 muOmega/Omega and the maximum change was 0.04 muOmega/Omega. The long-term drift rate of the three resistors, measured over 12 years, was less than 0.01 muOmega/Omega per year.