Study of the differential Higgs boson production in the diphoton decay channel with CMS and characterisation and calibration of detector modules for the phase1 upgrade of the pixel detector

The data collected by the CMS experiment at CERN in proton-proton collisions during 2016 are analyzed to characterize the Higgs boson in its decay channel to two photons. The signal strengths relative to the standard model cross section are measured inclusively and for individual production modes, employing an event categorization optimized for the best precision. Production cross sections are then measured in a fiducial phase space,differentially with respect to the Higgs boson production and decay kinematic properties.The cross section is also measured inclusively in the fiducial phase space, as well as insub-regions enriched in events originating from specific production modes (ttH, VH). Forthese measurements, an approach aiming at minimizing the model dependence of themeasurements is adopted. The measurements are found to be in agreement with the standard model predictions, within experimental and theoretical uncertainties. A new upgraded pixel detector has been installed in the Compact Muon Solenoid (CMS) experiment in early 2017. The upgraded detector, while introducing several improvements with respect to the previous system, allows highly-efficient data taking at the increasing instantaneous luminosities of the LHC. The procedures designed to thoroughly test and calibrate the 1200+ detector modules are presented in this thesis, together with the quality criteria defined to identify modules suitable for installation in the final system.The results of the module production are reviewed, with a focus on modules employed for the construction of the second layer of the central part of the detector.