The performance of SCT128A ASICs when reading out silicon sensors and a study of $B^{0}_{s}\to D^{+-}_{s} \pi^{-+}$ at LHCb

LHCb is a future detector which will take data at the CERN Large Hadron Collider proton-proton collider. It is optimized for B physics and will make precision measurements of CP violation parameters and flavour mixing. Measurements of time-dependent asymmetries and decay rates require accurate reconstruction of the B meson production and decay vertices; this is achieved with a silicon microstrip VErtex LOcator (VELO). In this thesis, an overview of silicon strip detectors (SSDs) is given and the choice of sensor technology at LHCb justified. Data from beam tests in which prototype VELO SSDs were read out using SCT128A electronics are presented and analysed. The time response of the system is measured and the implications for LHC-speed readout are discussed. The effect of detector input capacitance is investigated. Measurements of the mass and width differences of the Bs mass eigenstates, Delta M_s and Delta Gamma_s, will be possible at LHCb. Recent theoretical predictions for these parameters are given and it is shown that observation of a significantly smaller value of |Delta Gamma_s| would imply new physics beyond the Standard Model. These parameters may be extracted using Bs --> Ds- (K+ K- pi-) pi+ decay rates. A selection algorithm for this channel is developed using simulated events produced with the LHCb simulation program SICb. A specialized detector simulation is used to estimate the sensitivity to Delta M_s and Delta Gamma_s at LHCb. Their statistical uncertainties for a range of possible parameter values are determined. Possible sources of systematic error are investigated and discussed.