Development of a silicon pixel tracker for the measurement of the differential charm cross~section of 400 GeV/c proton collisions on a SHiP-like thick target

The Search for Hidden Particles (SHiP) experiment is proposed to search for weakly interacting particles in a beam-dump setup with a 400 GeV/c proton beam of unprecedented intensity at the CERN SPS. An important parameter in modeling signal and background is the charm production cross section in the SHiP target, which is not known with sufficient precision and has in fact never been measured for cascade production. The SHiP-charm experiment is designed to measure the charm cross section in a thick target, where cascade production dominates. The experiment is proposed for the same SPS beam as SHiP. The experiment has a moving target, instrumented with nuclear emulsions for direct observation of production and decay of charmed hadrons, followed by a spectrometer. It is crucial for the experiment to timestamp tracks and vertices in the nuclear emulsion for accurate event reconstruction. Within the scope of this work, a pixel tracker, placed directly downstream of the target as part of the spectrometer, has been built and operated in an optimisation testbeam for SHiP-charm. As first electronic detector in the setup the pixel tracker is connecting observed tracks and vertices in the emulsion with electronic, timestamped events in the spectrometer. The detector setup is presented, the performance of the pixel tracker is discussed, and the matching of pixel tracker events with tracks and vertices detected in the emulsion target is presented in this thesis.