Regensburg 2019 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 67: Cryogenic Particle Detectors and Other Superconducting Electronics

TT 67.6: Talk

Friday, April 5, 2019, 10:45–11:00, H4

Microwave SQUID Multiplexing of Metallic Magnetic Calorimeters — •Mathias Wegner, Daniel Richter, Felix Ahrens, Christian Enss, and Sebastian Kempf — Kirchhoff-Institute for Physics, Heidelberg University, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany.

To our present knowledge the most suitable device for reading out large-scale detector arrays consisting of hundreds or thousands of metallic magnetic calorimeters (MMCs) is a microwave SQUID multiplexer (µMUX). Each channel of a µMUX consists of a non-hysteretic rf-SQUID which is used for detector readout and which is inductively coupled to a superconducting microwave λ/4 resonator with unique resonance frequency. Due to the magnetic flux dependence of the SQUID inductance as well as the mutual interaction between the SQUID and the associated resonator, the signal of the MMC is transduced into a resonance frequency shift of the related resonator.

While the basic multiplexer model developed in the context of transition edge sensors was sufficient for developing our first prototype µMUX devices, it does not include important aspects which need to be considered for an optimized MMC readout. In particular, the model does not describe the readout power dependence as well as the impact of the parasitic shunts of the Josephson junction and the influence of the MMCs on the µMUX characteristics.

In this contribution we present a refined version of the µMUX model which includes these aspects. Besides, we show that we gain a very good agreement between measured data and our refined multiplexer model.