Geant4 Simulations of TES Detectors in the ATHENA and IAXO Experiments

Abstract: 

Francesco Monastra's seminar is based on his master's thesis work on Monte Carlo analysis of Transition-Edge Sensor (TES) microcalorimeters and evaluation of particle backgrounds that can compromise their performance, both during ground-based characterization campaigns and for future space missions.

In his work the Geant4 toolkit was used to quantify the contribution of particle fluxes on two ground-based experimental setups: the DM-127 detector of INAF/IAPS and the XFDM array of SRON. The simulations included:

1. Cosmic ray swarms: evaluation of flux and secondary interaction in the surrounding environment.
2. Environmental radioactivity (NORMs): simulation of natural radionuclides present on site, and radioisotope traces within the constituent materials of the cryostats.
3. Multi-stage Monte Carlo: For the XFDM case, a two-stage Monte Carlo was developed, with implementation of simulated flux normalization and volume scaling techniques to ensure consistency with experimental data. 

This work allowed the experimental results to be reproduced in both environments, confirming several assumptions that had been made by the experimental groups, identifying several critical issues in the treatment of the experimental data, and identifying the steps necessary for the continuation of the activity.