Backsplash Effects on SPD and Flavour Tagging in LHCb

The LHCb experiment is to the study of B meson systems and CP violation. The Scintillator Pad Detector (SPD) is a part of the LHCb Calorimeters. The SPD is meant to perform the electron-photon separation at L0 trigger level. In this thesis, the performance of the SPD under backsplash effects is studied and measured. In a second part, related to the flavour tagging of B mesons, it is tested a method to extract dilutions from data using control channels, in particular, of the B0->JPsi Ks decay. This consists in classifying the events on what made them trigger and correct for phase space differences afterwards. Special care is taken for the JPsi->ee channels, which have bremsstrahlung photons that can trigger the event. This part also includes the development of selection algorithms for both control channels B0->JPsi(ee)K* and B+->JPsi(ee)K+ and a way to avoid the multiplicity of hits at reconstruction which affects the electron tag.