(Color online) Schematic view of the CRESST II setup. The detectors are cooled by an Oxford Instruments dilution refrigerator. To shield them from particles and radiation caused by radioactive impurities in the materials the dilution refrigerator unit is made of, an internal lead shield is installed. For more details see the text.
Circuit for a single SQUID channel to read out a SPT of a CRESST II detector.
(Color online) Top: Schematic drawing of the connector for the readout circuit on the vacuum side of the flange between helium bath and vacuum chamber at a temperature of . Bottom: Pictures of the assembled PTFE plug block with connector pins (left) and the connected connector (right). The sum of parasitic resistances at this level must be less than .
Left: SQUID output as expected for different resistances in a shorted circuit. Right: SQUID output measured with a superconducting loop (bottom) and with the connector pin and shorted woven cable attached to a SQUID six pack (top). The superconducting loop does not show any indication of contact resistance, whereas the shorted connector pin woven cable circuit exhibits a decay time of the order of . This can be attributed to a finite resistance due to the CuNi matrix of the NbTi wire that has not been removed on the level of the circuit in order to allow for easier soldering.
(Color online) Left: Two SQUID six packs attached to the woven cable leading to the mixing chamber. For the resistance measurements the twisted pair cables were shorted at the circuit board. Right: The modular superconducting connectors installed on the vacuum side of the flange at the Gran Sasso cryostat.
Resistance values of six of the shorted CRESST SQUID circuits. The values are given for a total loop inductance of . The error given is purely statistical. Additionally, a systematic error of 20% should be added for the resistance values due to the uncertainty in the total inductance of the circuit.
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