Searches for $\textit{CP}$ violation in $D^{0} \to K_{S}^{0} K \pi$ decays with the Energy test method, module assembly and commissioning for the LHCb VELO Upgrade

A search for Charge Parity (CP) violation is performed in $D^{0} \to K_{S}^{0} K \pi$ decays with the Energy Test (ET) method, an unbinned model independent statistical method pioneered by the University of Manchester. This decay channel is a golden candidate for further CP violation discovery in the charm sector with a maximum predicted asymmetry as large as 0.003. The selection criteria and ET robustness tests are described, as well as control channel studied that confirmed the reliability of the method and excluded the presence of significant sources of bias in the signal sample. A visualisation tool is illustrated, which would allow to locate the phase space region contributing the most to CP violation effects, if found. The results are compatible with CP symmetry. The VELO Upgrade is a brand new detector replacing the old VErtex LOcator, which played a crucial role in the reconstruction of primary and secondary vertices of interaction contributing to the many outstanding results delivered by the LHCb detector. The VELO Upgrade characteristics and modules assembly procedure are explained, along with their validation setup and procedure, followed by a report on the grading criteria used to classify each module. As the glue attaching the sensors to the cooling structure is responsible for the heat management of the modules, the results of the R&D effort carried out on the choice and assessment of the ideal production glue are illustrated. The High Voltage project developed during detector commissioning at CERN is described, specifically the Current vs Voltage (IV) scan panels and the Storck database implementation. The information extracted from the IV scans taken during 2022 allowed to carry out the first radiation damage estimation on the sensors after a the first year of data-taking.