Berlin 2015 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 6: Superconductivity: Cryodetectors

TT 6.1: Talk

Monday, March 16, 2015, 09:30–09:45, H 2053

Solid State Physics and Engineering to Push the Resolving Power of Magnetic Calorimeters Beyond 10 000 — •D. Hengstler, J. Geist, M. Keller, M. Krantz, C. Schötz, S. Kempf, L. Gastaldo, A. Fleischmann, and C. Enss — Kirchoff-Institute for Physics, Heidelberg University

Metallic magnetic calorimeters are energy dispersive particle detectors operated at temperatures below 100 mK. They make use of a paramagnetic temperature sensor to convert the energy that is deposited by an absorbed particle into a magnetic flux change in a SQUID, which can be read-out as a voltage signal with low noise and large bandwidth.

During the last decade we have been optimizing the signal size of MMCs by numerical optimizations and by the consequent use of micro-fabrication techniques, while lowering the readout noise close to quantum limit. The combination of both rewarded us recently with an instrumental linewidth of 1.6 eV (FWHM) for 6 keV x-rays, which is a world record. Operating this detector with optimal parameters the signal-to-noise-ratio is actually equivalent to an energy resolution below 1.0 eV (FWHM). At energies in the keV-range however, this resolution could not be achieved. Such discrepancies can arise from a-thermal phonon loss or position dependencies.

In this talk we summerize the physics of MMCs focusing on solid state effects and show recent results of these detectors in various applications. This includes the use of Ag:Er as a paramagnetic sensor material instead of Au:Er to increase the energy resolution at temperatures below 50 mK.