Stable cryogenic vacuum capacitor for single-electron charging experiments

For use in our single-electron charging experiment, a novel cryogenic vacuu m capacitor has been developed which is superior to the previous parallel-p late design. Due to its coaxial design consisting of a long cylindrical cen ter electrode and a shorter cylindrical ring electrode, it is inherently st able against mechanical vibrations and thermal cycling. Electrical insulati on is achieved by the exclusive use of sapphire, which promises extremely l ow leakage currents.