LO CICERO, UGOUGOLO CICEROBARBERA, MarcoMarcoBARBERA2023-02-272023-02-272022http://hdl.handle.net/20.500.12386/33903The authors wish to thank Lionel Jacques, Philippe Peille, Joern Wilms, Roland den Hartog, for their inputs to the work.The aim of this technical note is to describe the approach used to calculate the photon shot noise contribution to the energy resolution budget, and to present results from different simulated configurations driving the current preliminary design of the thermal filters in the X-IFU cryostat. The simple code used for the THF conceptual design available at the I-PRR has now migrated into a sophisticated ray-tracing code capable of simulating different configurations of the filter stack environment, allowing to perform a trade-off analysis, failure analysis, and estimating the impact of different sources of uncertainties in the implemented modeling.ELETTRONICOenResearch reportFIS/05 - ASTRONOMIA E ASTROFISICAERC sectors::Physical Sciences and Engineering::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation::PE9_17 Instrumentation – telescopes, detectors and techniques