Progress in the Development of Frequency-Domain Multiplexing for the X-ray Integral Field Unit on Board the Athena Mission

• Published in: Journal of low temperature physics 2020-05, Vol.199 (3-4), p.737-744
• Main Authors: Akamatsu, H., Gottardi, L., Kuur, J. van der, Vries, C. P. de, Bruijn, M. P., Chervenak, J. A., Kiviranta, M., Linden, A. J. van den, Jackson, B. D., Miniussi, A., Ravensberg, K., Sakai, K., Smith, S. J., Wakeham, N.
• Format: Article
• Language: English
• Subjects: Alternating current; Bias; Characterization and Evaluation of Materials; Condensed Matter Physics; Energy resolution; Frequency division multiplexing; Frequency domain analysis; Integrals; Low temperature physics; Magnetic Materials; Magnetism; Physics; Physics (General); Physics and Astronomy; Pixels; Room temperature
• ISSN: 0022-2291; 1573-7357
• DOI: 10.1007/s10909-020-02351-3

Frequency-domain multiplexing (FDM) is the baseline readout system for the X-ray Integral Field Unit on board the Athena mission. Under the FDM scheme, TESs are coupled to a passive LC filter and biased with alternating current (AC bias) at MHz frequencies. Using high-quality-factor LC filters and room-temperature electronics developed at SRON and low-noise two-stage SQUID amplifiers provided by VTT, we have recently demonstrated good performance with the FDM readout of Mo/Au TES calorimeters with Au/Bi absorbers. We have achieved a performance requested for the demonstration model with the single-pixel AC bias ( ΔE = 1.8 eV ) and nine-pixel multiplexing ( ΔE = 2.6 eV ) modes. We have also demonstrated 14-pixel multiplexing with an average energy resolution of 3.3 eV, which is limited by nonfundamental issues related to FDM readout in our laboratory setup.