Study of Dissipative Losses in AC-Biased Mo/Au Bilayer Transition-Edge Sensors

• Published in: Journal of low temperature physics Vol. 193; no. 4-Mar; pp. 356 - 364
• Main Authors: Sakai, K., Adams, J. S., Bandler, S. R., Chervenak, J. A., Datesman, A. M., Eckart, M. E., Finkbeiner, F. M., Kelley, R. L., Kilbourne, C. A., Miniussi, A. R., Porter, F. S., Sadleir, J. S., Smith, S. J., Wakeham, N. A., Wassell, E. J., Yoon, W., Akamatsu, H., Bruijn, M. P., Gottardi, L., Jackson, B. D., Kuur, J. van der, Leeuwen, B. J. van, Linden, A. J. van der, Weers, H. J. van, Kiviranta, M.
• Format: Journal Article
• Language: English
• Published: Goddard Space Flight Center Springer Verlag 01.11.2018; Springer US; Springer Nature B.V
• Subjects: ABSORPTION; Astrophysics; Bias; CALORIMETERS; Characterization and Evaluation of Materials; Condensed Matter Physics; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Dependence; EDDY CURRENTS; FINITE ELEMENT METHOD; FREQUENCY DEPENDENCE; Gold; Instrumentation And Photography; LAYERS; Low temperature physics; Magnetic Materials; Magnetism; METALS; NOISE; Physics; Physics and Astronomy; Pixels; Sensor arrays; SENSORS; X RADIATION; X ray absorption; X-rays; Transition-edge sensors; Microcalorimeters; Frequency-division multiplexing; Eddy current heating
• ISSN: 0022-2291; 1573-7357; 1573-7357
• DOI: 10.1007/s10909-018-2002-4

We are developing kilo-pixel arrays of transition-edge sensors (TESs) for the X-ray Integral Field Unit on ESA's (European Space Agency's) Athena observatory. Previous measurements of AC-biased Mo/Au TESs have highlighted a frequency-dependent loss mechanism that results in broader transitions and worse spectral performance compared to the same devices measured under DC (Direct Current) bias. In order to better understand the nature of this loss, we are now studying TES pixels in different geometric configurations. We present measurements on devices of different sizes and with different metal features used for noise mitigation and X-ray absorption. Our results show how the loss mechanism is strongly dependent upon the amount of metal in close proximity to the sensor and can be attributed to induced eddy current coupling to these features. We present a finite element model that successfully reproduces the magnitude and geometry dependence of the losses. Using this model, we present mitigation strategies that should reduce the losses to an acceptable level.