Gert Rietveld

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—A high accuracy current source has been developed for the generation of very small currents (below 200 pA) based on applying a linear voltage ramp to a capacitor. Using software-controlled compensation for the nonlinearity of the voltage ramp, a stable current can be reached within a few seconds. A voltage ramp within typically 10 10 6 of any desired value(More)
—We have developed a 1:30000 winding ratio cryogenic current comparator (CCC) for measurement of small currents, e.g., generated by a single electron transport device. A dedicated low-noise SQUID is used for the readout, which allows reaching a sensitivity close to ideal, that is without loss of sensitivity in the flux transformer coupling the CCC and the(More)
—A new methodology for conductivity measurements, where square metallic samples are measured with the Van der Pauw technique, has been successfully implemented. The uncertainty obtained is 0.04% and a comparison between national metrology institutes gives an agreement of the measurement values within 0.035%. Major advantages of the new method are that(More)