Speaker
Description
Cryogenic Current Comparators (CCC) are presently used at CERN-AD (100 mm beamline diameter) and in the FAIR project at CRYRING (150 mm beamline diameter) for non-destructive absolute measurement of beam currents in the range of below 10 μA (current resolution 10 nA). Both sensor versions (CERN-Nb-CCC and FAIR-Nb-CCC-XD) use niobium as superconductor for the DC-transformer and magnetically shielding. The integrated flux concentrators have an inductance of below 100 μH at
4.2 Kelvin. The new Sm-series (Smart & Small) is designed for a beamline diameter of 63 mm and is using lead as superconductor. The first sensor (IFK-Pb-DCCC-Sm-200) has two core-based pickup coils (2x 100 µH at 4.2 K) and two SQUID units, to eliminate Barkhausen current jumps as part of the low frequency 1/f2-noise. During the construction some basic experiments on noise behavior (fluctuation– dissipation theorem, white noise below 2 pA/sqrt(Hz)) and magnetic shielding (core- inductance/meander-shielding-capacity resonance, additional mu-metal shielding) were undertaken, the results of which are presented here. Finally, a current resolution of 500 pA could be achieved in the laboratory.
Presented @ IBIC’22, 11th - 15th Sept. 2022, Krakow. Supported by the BMBF, project number 05P21SJRB1.
