The future European Space Agency's X-ray space observatory Athena (0.2 - 12 keV) will need a 50 mK cryogenic focal plane anti-coincidence detector for the spectrometer X-IFU as the TES array of the spectrometer alone is not able to distinguish between target X-ray photons and background particles depositing energy in the detector band, thus limiting the instrument sensitivity.
We developed some Cryogenic Anticoincidence (CryoAC) detector prototypes with a 1 cm2 large-area suspended silicon absorber (500 µm thick) sensed by an array of transition edge, iridium gold bilayer, sensors (TESs) with a 100 mK superconducting transition. The TES array is directly fabricated on the silicon radiation absorber and functions as a thermal calorimeter whose temperature is restored through micromachined silicon bridges to the heat sink.
The planar configuration of the detector with the Silicon as substrate and absorber of the TES gave us the possibility to invistigate the signal generation when a particle interacts with the silicon mass. Thus, is possible to design detector in two different operating conditions: few TES to sense only the termal equilibrium signal or an array of many TES to sense the a-thermal transient signal. Our model and simulations together with measurements shows that the rise of a group of energetic phonons at the point where the event occurred spread the energy of the particle over the entire absorber. With the possibility to detect a-thermal phonons of lower energy distant from the interaction point giving a fast detector with spectroscopic capability. We will present the model and its comparison with measurements.
L. Ferrari barusso et al. IEEE 2023
M. D'Andrea et al. 2021
M. Biasotti JLTP 2019
M. D'Andrea et al. 2019
C. Macculi et al. JLTP 2019
Authors would acknowledge Mrs M. Rigano and Mr. A. Bevilacqua, F. Siccardi and L. Parodi for the thecnical support and ASI for funding