A Precise Measurement of the Lifetime of $B^{0}_{d}$-mesons, Measurement of $CP$-violation Parameters of $B_{s}^{0}$-mesons, the ATLAS Experiment at the LHC, and Development of Silicon Detectors for Future Particle Physics Experiments

A series of connected research projects has been carried out for the purpose of seeking physics phenomena beyond the Standard Model. These consist of a precise measurement of the lifetime of a short-lived $b$-hadron, the $B^{0}_\mathrm{d}$; preparations for measurements of $CP$-violating parameters in $B^{0}_\mathrm{s}$ decays; development of triggers that select $b$-hadron events; development of new instruments for improved precision in detecting fundamental particles; and monitoring and mitigating the effect of radiation on the detectors, which is inescapable in their operating environment. Datasets collected by the ATLAS detector at the Large Hadron Collider (LHC) are used for the analyses involving the decays of $b$-hadrons. These analyses are supplemented by a detailed study of the evolution of the radiation effects in the current and upgraded ATLAS Pixel Detectors, using a radiation damage model and improving the model with the data collected at high luminosities. In the end, a set of comprehensive quality control tests, which include electrical and mechanical tests, has been carried out on the modules of the ATLAS Upgrade Pixel Detector.