Development of frequency domain multiplexing for the X-ray Integral Field Unit (X-IFU) on the Athena

• Published in: arXiv.org 2016-11
• Main Authors: Akamatsu, Hiroki, Gottardi, Luciano, van der Kuur, Jan, de Vries, Cor P, Ravensberg, Kevin, Adams, Joseph S, Bandler, Simon R, Bruijn, Marcel P, Chervenak, James A, Kilbourne, Caroline A, Kiviranta, Mikko, A J van den Linden, Jackson, Brian D, Smith, Stephen J
• Format: Article
• Language: English
• Subjects: Arrays; Bias; Calorimeters; Energy resolution; Frequency division multiplexing; Frequency domain analysis; Integrals; Pixels; Q factors; Quantum efficiency; Spectral resolution
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1611.00956

We are developing the frequency domain multiplexing (FDM) read-out of transition-edge sensor (TES) microcalorimeters for the X-ray Integral Field Unit (X-IFU) instrument on board of the future European X-Ray observatory Athena. The X-IFU instrument consists of an array of \(\sim\)3840 TESs with a high quantum efficiency (\(>\)90 \%) and spectral resolution \(\Delta E\)=2.5 eV \(@\) 7 keV (\(E/\Delta E\sim\)2800). FDM is currently the baseline readout system for the X-IFU instrument. 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. An integrated noise equivalent power resolution of about 2.0 eV at 1.7 MHz has been demonstrated with a pixel from a new TES array from NASA/Goddard (GSFC-A2). We have achieved X-ray energy resolutions \(\sim\)2.5 eV at AC bias frequency at 1.7 MHz in the single pixel read-out. We have also demonstrated for the first time an X-ray energy resolution around 3.0 eV in a 6 pixel FDM read-out with TES array (GSFC-A1). In this paper we report on the single pixel performance of these microcalorimeters under MHz AC bias, and further results of the performance of these pixels under FDM.