The reduction techniques of the particle background for the ATHENA X-IFU instrument at L2 orbit: Geant4 and the CryoAC

We present the particle background reduction techniques aimed to increase the X-IFU sensitivity, which is reduced by primary protons of both solar and Cosmic Rays origin, and secondary electrons. The adopted solutions involve Monte Carlo simulation by both Geant4 toolkit related to the "expected" background at L2 orbit through the payload mass model and the ray tracing technique to evaluate the soft protons components focused by the optics to the main detector, and the development of an active Cryogenic AntiCoincidence detector and a passive electron shielding to meet the scientific requirements.