Berlin 2018 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 29: Poster Session: Cryogenic Particle Detectors and Cyotechnique
TT 29.4: Poster
Montag, 12. März 2018, 15:00–19:00, Poster B
Superconducting GHz Resonators for Microwave SQUID Multiplexing of MMCs — •Felix Ahrens, Mathias Wegner, Andreas Fleischmann, Sebastian Kempf, and Christian Enss — Kirchhoff Institute for Physics, Heidelberg University, Germany
Microwave SQUID multiplexing is the most promising way to read out large metallic magnetic calorimeter (MMC) detector arrays. A key element of cryogenic multiplexing is superconducting GHz resonators, which provide the required frequency encoding. To maintain the very fast signal rise time of MMCs we design our resonators to have a bandwidth of ∼1 MHz. This value directly sets the required frequency spacing between two neighbouring channels to ∼10 MHz taking into account our present fabrication accuracy and the required crosstalk level below 10−4. Using capacitively coupled CPW transmission line resonators, the resonance frequency fr and the loaded quality factor Ql of a resonator can be set by adjusting the resonator length and the geometry of the coupling capacitor. We simulate the electromagnetic properties of different coupler geometries to find a proper resonator design matching our readout requirements. Since both fr and Ql depend strongly on the accuracy of the physical resonator dimensions, we optimise the microfabrication process in order to minimise fabrication inaccuracies. In addition, to minimise the influence of stray light, the kinetic inductance and tunnelling systems causing low-frequency phase noise, we investigate different superconducting materials. In this contribution, we present different aspects related to the optimisation of our superconducting resonators.