Long-term Study on Travelling Standards for Capacitance and Resistance

We have investigated the long-term properties of two 10 nF capacitance standards and two resistance standards of 10 kΩ and 12.9 kΩ over a period of almost four years. All four standards are integrated into the same two-stage thermostat. The observed daily drift is approximately -1 nF/F for both capacitance standards and less than -2 nΩ/Ω for the resistance standards. The temperature controller is equipped with back-up batteries to supply the thermostat during power failures (black out) and transport. Due to this feature, the standards took part in the first comparison between pulse-driven Josephson impedance bridges.