Review of the Experimental Results with a Cryogenic Current Comparator

A new type of beam transformer, using the principle of a Cryogenic Current Comparator, was built to measure ex-tracted ion beams from the SIS, the heavy ion synchroton at GSI. A current resolution of 0.1-0.3 nA/ p Hz, depend-ing on the frequency range, could be achieved which allows to measure ion beams with intensities greater than 109 par-ticles per second with high accuracy. Numerous investiga-tions were carried out to study the zero drift of the system which shows a strong exponential slope with two differ-ent time constants. Furthermore the microphonic sensis-tivity of the system was studied by taking noise spectra of the detector output signal. Additional measurements were made with a vibration sensor to separate the horizontal and vertical components of the mechanical influences from the disturbing electrical interferences. The recent results- in-cluding the first tests with ion beams- will be presented in this paper