Optimising the multiplex factor of the frequency domain multiplexed readout of the TES-based microcalorimeter imaging array for the X-IFU instrument on the Athena Xray observatory

摘要

Athena is a space-based X-ray observatory intended for exploration of the hotand energetic universe. One of the science instruments on Athena will be theX-ray Integrated Field Unit (X-IFU), which is a cryogenic X-ray spectrometer,based on a large cryogenic imaging array of Transition Edge Sensors (TES) basedmicrocalorimeters operating at a temperature of 100mK. The imaging arrayconsists of 3800 pixels providing 2.5 eV spectral resolution, and covers afield of view with a diameter of of 5 arc minutes. Multiplexed readout of thecryogenic microcalorimeter array is essential to comply with the cooling powerand complexity constraints on a space craft. Frequency domain multiplexing hasbeen under development for the readout of TES-based detectors for this purpose,not only for the X-IFU detector arrays but also for TES-based bolometer arraysfor the Safari instrument of the Japanese SPICA observatory. This paperdiscusses the design considerations which are applicable to optimise themultiplex factor within the boundary conditions as set by the space craft. Morespecifically, the interplay between the science requirements such as pixeldynamic range, pixel speed, and cross talk, and the space craft requirementssuch as the power dissipation budget, available bandwidth, and electromagneticcompatibility will be discussed.