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The current projects of future X-rays space telescopes foresee high resolving power transition edge sensor (TES) micro-calorimeters arrays as focal plane instrument. In order to full exploit their sensitivity in the space environment, they need an anticoincidence detector to reject the background due to cosmic charged particles. High-energy protons (> 150 MeV) and other charged particle may release in the X-ray calorimeter, the same energy of the X-rays sources under observation. We report the description of the last prototype based on TES calorimeter where a 1-cm2 silicon chip is used as both substrate and absorber. The readout is made of 96 iridium/gold TESs uniformly distributed on its surface and parallel wired. In this paper, we will describe the design, with the preliminary phonon dynamics simulation, the fabrication, of first demonstration model for the ATHENA space telescope project. [ABSTRACT FROM AUTHOR]

ATHENA is the L2 mission selected by ESA to pursue the science theme 'Hot and Energetic Universe.' One of the two focal plane instruments is the X-ray Integral Field Unit, an array of TES microcalorimeters operated at T $$<$$ 100 mK. To allow the X-ray photons focused by the telescope to reach the detector, windows have to be opened on the cryostat thermal shields. X-ray transparent filters need to be mounted on these open windows to attenuate the IR radiation from warm surfaces, to attenuate RF electromagnetic interferences on TES sensors and SQUID electronics, and to protect the detector from contamination. This paper reviews the ongoing activities driving the design of the X-IFU thermal filters. [ABSTRACT FROM AUTHOR]

The TES cryogenic detectors, due to their high spectral resolution and imaging capability in the soft X-ray domain, are the reference devices for the next proposed space missions whose aims are to characterize the spectra of faint or diffuse sources. ATHENA is the re-scoped IXO mission, and one of its focal plane instrument is the X-ray Microcalorimeter Spectrometer (XMS) working in the energy range 0.3-10 keV. XMS will be able to achieve the proposed scientific goals if a background lower than 0.02 cts/cm/s/keV is guaranteed. The studies performed by GEANT4 simulations depict a scenario where it is mandatory to use an active Anti-Coincidence (AC) to reduce the expected background in the L2 orbit down to the required level. This is possible using a cryogenic AC detector able to provide a rejection efficiency of about 99%. We are developing for this purpose a TES-based detector made by Silicon absorbers (total assembled area about 1 cm and 300 μm thick) and sensed by a Ir:Au TES. All the work done for IXO is applicable to ATHENA, with more margins due to the smaller area required for the detector. Here we present the results obtained from different samples, as a step towards the final detector design. [ABSTRACT FROM AUTHOR]