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The Cryogenic AntiCoincidence detector (CryoAC) of ATHENA X-IFU is designed to reduce the particle background of the instrument and to enable the mission science goals. It is a 4-pixel silicon microcalorimeter sensed by an Ir/Au TES network. We have developed the CryoAC demonstration model, a prototype aimed to probe the critical technologies of the detector, i.e., the suspended absorber with an active area of 1 cm2; the low energy threshold of 20 keV; and the operation connected to a 50 mK thermal bath with a power dissipation less than 40 nW. Here, we report the test performed on the first CryoAC DM sample (namely, the AC-S10 prototype), showing that it is fully compliant with its requirements. [ABSTRACT FROM AUTHOR]

The 50 mK cryogenic focal plane anti-coincidence detector of the Athena X-ray observatory (CryoAC) is a silicon suspended absorber sensed by a network of about 400 Ir/Au Transition Edge Sensors (TES) and connected through silicon bridges to a surrounding silicon frame plated with gold (rim). The device is shaped by Deep Reactive Ion Etching (DRIE) from a single silicon wafer of 500 μ m. There are two different possible geometries: a single Monolithic absorber and a Segmented one with 4 distinct absorber structures. As part of the payload of space mission the detector must resist to several mechanical excitation. We have tested a set of structural prototypes of the CryoAC vibrating several hexagonal silicon samples by using the vibrational mask provided by SRON which is responsible for FPA design. The aim is to have a first information on the mechanical response of the silicon bridges that connect the absorber to the rim, to start a trade-off over the two geometries and to validate the elastic-mechanical response. [ABSTRACT FROM AUTHOR]