A SQUID-BASED BEAM CURRENT MONITOR FOR FAIR

A Cryogenic Current Comparator (CCC) was developed for the upcoming FAIR-Project, providing a non-destructive online monitoring of the beam current in the nA-range. The CCC was optimized for a lowest possible noise-limited current resolution together with a high system bandwidth. Therefore, the low temperature properties of ferromagnetic core materials used in the pick-up coil were investigated and different SQUID-systems were tested. In this contribution we present results of the completed Cryogenic Current Comparator for FAIR working in a laboratory environment, regarding the improvements in resolution and bandwidth due to the use of suitable ferromagnetic core materials and optimized SQUID-system components.