Thesis defense of Holger Stevens

This thesis presents studies towards the LHCb detector upgrade for the LHC Run III. Mostly the entire detector is renewed to profit from the changed beam conditions. Two of the main changes are a fivefold instantaneous luminosity and a pure software trigger. Because of the higher luminosity, the track density is increased. Therefore, components with higher granularity are used, and one of them is the SciFi tracker. It is made of 250 μm thick scintillating fibres. The light output of this fibres decreases through radiation damages and natural material ageing. These effects are added to the detector simulation. Thereby the tracking efficiency of the SciFi is simulated for the entire planned lifetime. The first stage of the LHCb software trigger reduces the incoming data-rate of 40 Tbit s−1 by a factor of 40. The necessary computations are paralellisable, and for this reason, a GPU based implementation is suitable. A GPU version of the SciFi hit decoder was implemented during the baseline architecture change process from PU to GPU. The LHCb detector has a diamond-sensor based safety system, which monitors the LHC beam. This system is renewed in parallel to the detector upgrade. Measurements towards the diamond sensor efficiency characterisation with a strontium source are presented.

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