During the period of this report, the Electricity section carried out two on-site Josephson comparisons, three comparisons with Zener voltage transfer standards, three comparisons with resistance transfer standards and two comparisons with capacitance transfer standards. The resistance comparison with the NIST will allow us to link the results of the SIM.EM-K1 comparison, with six participants, to the ongoing BIPM key comparison BIPM.EM-K13.a. The capacitance comparison with the NIST had been initiated by the BIPM to verify our measurement uncertainties after the recent changes of staff and the modifications of the measurement systems.
The key comparison of the conventional Josephson arrays of the BIPM and the LNE was followed by a “scientific” comparison of our 10 V programmable SINIS array, offered by the PTB, with the conventional array of the LNE. Both arrays were found to be in excellent agreement within an exceptionally small uncertainty. This is only the second time that agreement between the voltages realized with the traditional arrays and the new type of programmable SINIS arrays has been demonstrated at the level of 10 V.
In the field of impedance metrology, new ac-dc transfer resistors with improved stability have been introduced in the work with the quadrature bridge. This reduces the main uncertainty component in the traceability chain from the quantum Hall resistance standard to capacitance. Statistical techniques, which were developed recently in the section to treat correlated time series, were applied to measurements made with our impedance bridges and led to a better understanding of their statistical uncertainties. A good agreement was obtained between the predictions of these techniques on the influence of a low pass filter, and experiment. These studies allow reliable determinations of Type A uncertainties of our bridge measurements in the presence of time correlations.
The preparations for the start of measurements with the calculable capacitor are now finished and we are waiting for the instrument to arrive. Work has started on the fabrication of a Josephson voltage standard for the watt balance experiment, based on an SNS array, offered by the NIST.
During the year 2007 the Electricity section has provided 49 calibrations certificates and three study notes for 15 NMIs of Member States. Calibrations are carried out for voltage (1.018 V and 10 V), resistance (1 
, 100 and 10 k) and capacitance (1 pF, 10 pF and 100 pF) and are offered mainly to smaller NMIs that do not yet possess their own primary standards.
Summary
