Upgrade of CMS Endcap Calorimeters and Silicon Sensor Characterization

After 14 years of data taking CMS detector at the LHC has suffered radiation damage in some sub-detectors due to particle radiation from proton-proton collisions. Due to this radiation damage and the 10-fold increase in luminosity at the HL-LHC, extensive upgrades and refurbishments are planned for the CMS experiment in the coming years. This thesis covers the radiation damage in the CMS calorimeter endcaps and the upgrade to high-granularity calorimeter (HGCAL), which will replace the existing electromagnetic and hadronic calorimeters in the endcaps. In addition to the electrical characterization of the silicon sensors to be used in HGCAL, the quality control steps and analysis of the hexaboards where the sensors will be placed are also included in this thesis. Hexaboards are PCBs containing the front-end electronics for the silicon hexagonal module consisting of silicon sensor, Kapton foil and base plate. Technical specifications of hexaboards are given in the thesis. In addition to the detailed discussion of the techniques and setups used for the electrical characterization of silicon sensors, HGCAL's test strategy for silicon sensors is also included. The active parts of HGCAL are silicon sensors and scintillators. This thesis includes the analysis of silicon sensors. The Phase-2 upgrade project at CMS will improve the detector systems to provide the required physics performance under the challenging conditions at HL-LHC. The installation of the upgraded detector systems is planned to be completed at LS3, scheduled between 2026 and 2028.