CERN Accelerating science

Since the start of Large Hadron Collider (LHC) particle collisions in 2008 all LHC experiments have provided data to understand the interactions between the fundamental particles. Out of the LHC experiments ALICE (A Large Ion Collider Experiment) is the dedicated heavy ion exper- iment, focusing on the study of Quark-Gluon Plasma (QGP) formed in the collisions between heavy ions. After extensive upgrade efforts to the detector setup to withstand the conditions set by the increased particle beam luminosity for the next physics run (Run 3), the ALICE experiment started collecting data again in 2022. After Run 3 there will be another upgrade that will include replacing the three innermost layers in the inner tracking system with a more precise tracker (ITS3) and adding a new forward calorimeter (FoCal) to the experiment. FoCal extends the physics analyses to the forward rapidities (near beam pipe) and includes the gluon saturation physics to the ALICE physics program. The gluon saturation is expected happen at low gluon momenta but it has not been observed experimentally yet. FoCal is expected to probe the saturation region and provide constraints to the theory calculations related to gluon distributions going near the saturation limit. In this thesis, I present the performance characterization of FoCal silicon pad sensors from two first FoCal test beams carried on during 2021 and 2022. For the main analysis in this thesis I have simulated the physics performance of $\pi^0-\pi^0$ correlations measured in FoCal. In addition, simulation results regarding the event plane performance of Fast Interaction Trigger (FIT), the new forward trigger installed for Run 3 are presented. The event plane is an estimator for the heavy ion collision reaction plane and is provided by FIT Run 3 onwards.