Characterization of CryoAC Demonstration Model 1.1 Candidates for the Athena X-IFU Instrument

The Cryogenic AntiCoincidence detector (CryoAC) is a TES-based auxiliary detector designed to reduce the particle background of the X-IFU instrument onboard the Athena X-ray observatory. In preparation for integration with the Focal Plane Assembly (FPA), we characterized two nearly identical CryoAC Demonstration Models (DM143 and DM144, the latter being selected as DM1.1) to assess their performance and evaluate the replicability and robustness of the fabrication process. We present here the results of transition curve measurements, thermal conductance evaluation between the TES, the absorber, and the thermal bath, as well as current-voltage characterization. The performance was validated using both background particle events and shielded radioactive sources (<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">55</sup>Fe and <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">241</sup>Am).