Evolution of the CMS ECAL performance and R&D Studies for Calorimetry Options at High Luminosity LHC

In this thesis the evolution of the CMS ECAL Calorimeter performance during the HL-LHC operating condition is estimated. A detailed picture of radiation damage in lead tungstate crystals is obtained with the analysis of beam test data. Given the necessity of the upgrade of the CMS endcap calorimeters, new scintillators which can withstand high levels of radiation have been study as candidates for calorimetry application under HL-LHC conditions. In particular, results obtained in test beam with calorimetric module made of brass and LuAG:Ce single crystalline fibers are presented.