Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 21: Superconductivity: Poster Session
TT 21.49: Poster
Montag, 16. März 2015, 15:00–18:00, Poster B
SQUIDs for the readout of metallic magnetic calorimeters — •Anna Ferring, Mathias Wegner, Andreas Fleischmann, Loredana Gastaldo, Sebastian Kempf, and Christian Enss — Kirchhoff-Institute for Physics, Heidelberg University, Germany.
Superconducting quantum interference devices (SQUIDs) are the devices of choice to read out metallic magnetic calorimeters (MMCs). Here, the temperature change of the detector upon the absorption of an energetic particle is measured as a magnetization change of a paramagnetic temperature sensor that is situated in a weak magnetic field. Driven by the need for devices that allow for the readout of large-scale detector arrays with hundreds or even thousands of individual detectors as well as of single channel detectors with sub-eV energy resolution, we have recently started the development of low-Tc current-sensing SQUIDs. In particular, we are developing cryogenic frequency-domain multiplexers based on non-hysteretic rf-SQUIDs for detector array readout as well as dc-SQUIDs for single channel detector readout. We discuss our SQUID designs and the performance of prototype SQUIDs. We particularly focus on the frequency and temperature dependence of the SQUID noise as well as the reliability of our SQUID fabrication process for Nb/Al-AlOx/Nb Josephson junctions. Additionally, we demonstrate experimentally that state-of-the-art MMCs can successfully be read out with our current devices. Finally, we discuss different strategies to improve the SQUID and detector performance aiming to reach sub-eV energy resolution for individual detectors as well as for detector arrays.