SQUID BASED CRYOGENIC CURRENT COMPARATOR FOR MEASUREMENTS OF THE DARK CURRENT OF SUPERCONDUCTING CAVITIES

A newly high performance SQUID based measurement system for detecting dark currents, generated by superconducting cavities for the upcoming X-FEL project at DESY Hamburg, is proposed. It makes use of the Cryogenic Current Comparator principle and senses dark currents in the pA range with a measurement bandwidth of up to 70 kHz.