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TT: Fachverband Tiefe Temperaturen

TT 16: Poster Session Superconductivity, Cryogenic Particle Detectors, Cryotechnique

TT 16.26: Poster

Montag, 16. März 2020, 15:00–19:00, P2/EG

Reducing the influence of SQUID Joule heating in dc- SQUIDs on the performance of cryogenic detectors — •Felix Herrmann, Matthäus Krantz, Anna Ferring-Siebert, Christian Enss, and Sebastian Kempf — Kirchhoff-Institute for Physics, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany

Metallic magnetic calorimeters (MMCs) are energy dispersive single particle detectors that are usually operated at temperatures below 50 mK. By making use of a paramagnetic temperature sensor absorbed energy is converted into a magnetic flux change which is measured by a dc-SQUID using a superconducting flux transformer.
In order to reduce parasitic inductances within the flux transformer, detector and SQUID should be placed in close vicinity. However, the Joule heat dissipated by the SQUID might negatively effect the detector temperature, thereby degrading the energy resolution. The energy dissipation of the SQUID is even more important in MMCs with direct sensor readout, a highly promising readout scheme to push the energy resolution in the sub-eV range. There, the paramagnetic sensor is placed directly on top of the SQUID loop, maximizing signal coupling while minimizing stray inductances.
In this contribution we discuss our recent efforts to reduce the influence of SQUID Joule heating on the performance of MMCs. In particular, we present a setup allowing to operate large detector arrays read out by conventional dc-SQUIDs, several means to reduce SQUID Joule heating e.g. by changing the shunt resistor geometry, as well as advanced heat sinking techniques using on-chip membranes.