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Abstract

New experiments, designed to test the Standard Model of particle physics with unprecedented precision and to search for physics beyond, push detector technologies to their limits. The Mu3e experiment searches for the charged lepton flavor violating decay μ+ → e+e−e+ with a branching ratio sensitivity of better than 1 ·10−16. This decay is suppressed in the StandardModel to unobservable levels but can be sizable in models beyond the Standard Model. The Mu3e detector consists of a thin pixel spectrometer combined with scintillating detectors to measure the vertex, momentum and time of the decay particles. Requirements on rate and material budget cannot be fulfilled by classical pixel sensors and demand the development of a novel pixel technology: high-voltage monolithic active pixel sensors (HV-MAPS). Two important steps towards a final pixel detector are discussed within the scope of this thesis: the characterization of two HV-MAPS prototypes from the MUPIX family and the development of a tracking telescope based on HV-MAPS with online monitoring, tracking and efficiency calculation for particle rates above 10 MHz. Using the telescope it is shown that the transition from the small-scale MUPIX7 to the full-scale MUPIX8 has been successful. Sensor characterization studies of the MUPIX8 show efficiencies above 99% at noise rates below 0.4 Hz/pixel over a large threshold range as well as a time resolution of 6.5 ns after time-walk corrections, thus fulfilling allMu3e sensor requirements. Additionally, the radiation tolerance of the MUPIX7 has been demonstrated up to a fluence of 1.5 ·10+15 24 GeV p/cm2.