Optimization of the Cryogenic Current Comparator (CCC) for Beam Intensity Measurement

Triggered by the need for current measurement in the nA range for slow extracted beams and for the beams in the storage rings at FAIR and CERN, the idea of the CCC as a current transformer has been revitalized during the last ten years. Compared to the first prototype, developed at GSI in the 90s, the second generation of CCCs is based on the possibility of detailed simulation of superconducting magnetic shielding properties, new nano-crystalline materials for the magnetic ring-cores, and on superior commercially available SQUID systems. In 2014, nA resolution measurements at 2 kHz bandwidth demonstrated the possibility of spill analysis at slow extracted beams from GSI SIS18. In the following year, the first stand-alone CCC system, including a cryostat with separate He liquefier, started operation in the CERN AD. Although the existing systems show an outstanding current resolution, their cost efficiency and robustness, as well as noise and vibration sensitivity can still be improved, which is subject of ongoing research. In this contribution recent results of our CCC tests are shown and future developments are discussed.