Stable cryogenic vacuum capacitor for single-electron chargingexperiments

For use in our single-electron charging experiment, a novel cryogenic vacuum capacitor has been developed which is superior to the previous parallel-plate design. Due to its coaxial design consisting of a long cylindrical center electrode and a shorter cylindrical ring electrode, it is inherently stable against mechanical vibrations and thermal cycling. Electrical insulation is achieved by the exclusive use of sapphire, which promises extremely low leakage currents