System performance of a cryogenic test-bed for the time-division multiplexing readout for Athena X-IFU

SRON is developing the Focal Plane Assembly (FPA) for the X-ray Integral Field Unit (X-IFU) of the Athena observatory, ESA’s next L2-class mission slated to launch in 2037. X-IFU willallow spectroscopy with high-energy resolution (< 4 eV at energies up to 7 keV) and high-spatial resolution (< 9’’) over the energies from 0.2 keV to 12 keV, employing an arrayof 1536 Transition-Edge Sensors (TES) covering a field of view of 4’. The Demonstration Model (DM) of the FPA will use Time Domain Multiplexing (TDM) to readout the detectors.The TDM technology will be provided by NIST, while the TES array will be provided by NASA-GSFC. We report on tests performed at SRON of a prototype system with TDM readout provided by NIST and NASA-GSFC. This TDM system used a longer flex harness than previous lab 8x32 systems between the cold SQUID read-out and the room temperature electronics, as required for the reformulated X-IFU design. We measured system performance consistent with shorter harness measurements and models, validating the longer harness length for X-IFU.