The end-to-end simulator of the ATHENA X-IFU Cryogenic AntiCoincidence detector (CryoAC)

• Published in: arXiv.org
• Main Authors: D'Andrea, Matteo, Macculi, Claudio, Lotti, Simone, Piro, Luigi, Argan, Andrea, Minervini, Gabriele, Torrioli, Guido, Chiarello, Fabio, Lorenzo Ferrari Barusso, Gatti, Flavio, Rigano, Manuela
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 19.07.2024
• Subjects: Algorithms; Arrays; Astronomical instruments; Calorimeters; Performance assessment; Physics - Instrumentation and Methods for Astrophysics; Sensors
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2407.14083

The X-IFU is one of the two instruments of ATHENA, the next ESA large X-ray observatory. It is a cryogenic spectrometer based on an array of TES microcalorimeters. To reduce the particle background, the TES array works in combination with a Cryogenic AntiCoincidence detector (CryoAC). The CryoAC is a 4-pixel detector, based on ~1 cm2 silicon absorbers sensed by Ir/Au TES. It is required to have a wide energy bandwidth (from 20 keV to ~1 MeV), high efficiency (< 0.014% missed particles), low dead-time (< 1%) and good time-tagging accuracy (10 us at 1 sigma). An end-to-end simulator of the CryoAC detector has been developed both for design and performance assessment, consisting of several modules. First, the in-flight flux of background particles is evaluated by Geant4 simulations. Then, the current flow in the TES is evaluated by solving the electro-thermal equations of microcalorimeters, and the detector output signal is generated by simulating the SQUID FLL dynamics. Finally, the output is analyzed by a high-efficiency trigger algorithm, producing the simulated CryoAC telemetry. Here, we present in detail this end-to-end simulator, and how we are using it to define the new CryoAC baseline configuration in the new Athena context.