Study of radiation damage and possible upgrade of the CMS ECAL Laser Monitoring system

The Electromagnetic Calorimeter (ECAL), one of the main subsystems of the CMS detector, measures the energies of electrons and photons. The ECAL consists of 75848 lead tungstate (PbWO4) crystals. The transparency of crystals is affected by irradiation, and the laser monitoring system is designed to measure the transparency changes for each ECAL crystal over time. In the future, the High-Luminosity LHC upgrade will increase the integrated luminosuty of the LHC and lead to higher radiation damage in all components of the CMS detector. In this work we report the proposed upgrade for the laser monitoring system and the results of computing crystal transparencies based on Run 2 data.