The focal plane assembly for the Athena X ray Integral Field Unit instrument
This paper summarizes a preliminary design concept for the focal plane assembly of the X ray Integral Field Unit on the Athena spacecraft, an imaging microcalorimeter that will enable high spectral resolution imaging and point source spectroscopy. The instrument's sensor array will be a 3840 pixel transition edge sensor (TES) microcalorimeter array, with a frequency domain multiplexed SQUID readout system allowing this large format sensor array to be operated within the thermal constraints of the instrument's cryogenic system. A second TES detector will be operated in close proximity to the sensor array to detect cosmic rays and secondary particles passing through the sensor array for off line coincidence detection to identify and reject events caused by the in orbit high energy particle background. The detectors, operating at 55 mK, or less, will be thermally isolated from the instrument cryostat's 2 K stage, while shielding and filtering within the FPA will allow the instrument's sensitive sensor array to be operated in the expected environment during both on ground testing and in flight operation, including straylight from the cryostat environment, low energy photons entering through the X ray aperture, low frequency magnetic fields, and high frequency electric fields.
Astronomical Telescopes Instrumentation