Construction of the DarkSide-20k Dark Matter experiment. Novel simulation techniques and QA/QC software for massive light detectors production.

Dark Matter is one of the most enigmatic entities in the Universe, profoundly impacting cosmic structures despite being elusive to direct observation. This thesis is developed in the context of the direct search of Dark Matter with low background experiments, focusing on the construction of DarkSide-20k detector. I delineate the experiment's design, emphasising the use of liquid Argon as a detection medium and the experiment innovative Gadolinium-loaded plastic for neutron capture. Additionally, I discuss the pivotal role of Monte Carlo simulations in optimising experimental parameters and the implementation of CAD-based techniques for accurate volume representation in the experiment simulation. Furthermore, I elucidate the testing and assembly procedures of cryogenic Silicon PhotoMultipliers, crucial components for detecting liquid Argon scintillation and neutron signals.