Beam Intensity Monitoring with nA Resolution - the Cryogenic Current Comparator (CCC)

The storage of low current beams as well as the long extraction times from the synchrotrons at FAIR require non-destructive beam intensity monitoring with a current resolution of nanoampere. To fulfill this requirement, the concept of the Cryogenic Current Comparator (CCC), based on the low temperature SQUID, is used to obtain an extremely sensitive beam current transformer. During the last years, CCCs have been installed to do measurements of the spill structure in the extraction line of GSI SIS18 and for current monitoring in the CERN Antiproton Decelerator. From these experiences lessons can be learned to facilitate further developments. The goal of the ongoing research is to improve the robustness of the CCC towards external influences, such as vibrations, stray fields and He-pressure variations, as well as to develop a cost-efficient concept for the superconducting shield and the cryostat.