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Abstract

The Mu3e experiment searches for the charged lepton flavour violating decay μ+ →e+e−e+ with the goal to find or exclude the decay above a branching ratio of 1 ×10−16. In a first phase of the experiment a reduced muon decay rate of 1×108Hz is used which allows to reach a single event sensitivity of 2×10−15. With high particle rates and the low energy of the decay particles, the experiment imposes strong limitations on its material budget. For this reason the pixel tracker modules are designed with a thickness of 0.1% of a radiation length. The only pixel sensor technology which provides high rate capability, while allowing to thin the sensor down to 50 μm are high voltage monolithic active pixel sensors (HV-MAPS). In this thesis the first full-scale pixel sensor for the Mu3e experiment, MuPix10, is described and first results from its characterisation are presented. The focus of this work is on two specific developments. The first one is a novel slow control interface is developed, tailored to the MuPix chip, with the goal of minimising the amount of required differential pairs used for the sensor configuration. The resulting interface requires no additional differential lines as it incorporates the syncronous reset signal and takes its place. The new interface allows to configure a 9-chip pixel tracker module with chip-individual configuration in less then 400 ms. The second topic is the optimisation of the signal line routing scheme of the sensor with the goal to suppress crosstalk effects and reduce the row address dependent time delays, that have been observed in MuPix8. Subsequently, models are developed to gain a deeper understanding of the effects. The new routing scheme reduces the crosstalk probability from an expected average value of 18% to 2.5%. Furthermore, the time spread of the row dependent pixel delay is halved from 40 ns to 20 ns.