The Cryogenic Current Comparator (CCC) is a superconducting device in use at metrological institutes to compare electric currents with highest precision. At CRYRING@ESR it is used as a non-interceptive beam diagnostic device to monitor deviations of the DC beam current with a resolution of nano-ampere. This is particularly useful at small ion currents below 1 μA where a calibrated absolute beam intensity is difficult to obtain across different ion species and beam conditions.
In this talk the CCC prototype for FAIR – including the dedicated beamline cryostat – is discussed together with the results of the recent beam time at CRYRING.