Studies of Scintillator-Based Muon Triggers in CMS

The CMS experiment at the LHC will face challenges due to upgrades and improve- ments of the LHC in future. Especially, the upgrade towards the high luminosity LHC in 2025 with a foreseen center of mass energy of 14 TeV, an instantaneous luminosity of O(1035cm−2s−1) and the concurrent aging of and radiation damage to the detectors will have an impact on the fast CMS trigger system and the CMS sub-detectors. Es- pecially, the impact on the CMS muon system - and more particular on the drift tube (DT) system - is of vital interest. In order to respond to these challenges the performance of the DT system as part of the L1 muon trigger and the use of a scintillator-based muon trigger as supportive detector are analyzed in this thesis. First, the concept of such a scintillator-based muon trigger, the Muon Track fast Tag (MTT), as support for the DT trigger system, is presented. The conducted related R&D; is described. Exploiting the similarity of the MTT concept and the existing hadron outer calorimeter (HO), studies are presented that evaluate the impact of the challenges on the L1 Trigger as well as the potential of the HO detector as a possible response to these challenges. It is shown that the HO detector can be of help in case of DT detec- tor failures and it is able to improve the muon recognition of the DT detector in the L1 Trigger. The reduction of L1 muon ambiguities with the HO detector is found to be not feasible. The results, that were obtained using HO, are extrapolated towards the MTT concept. The MTT concept is rated as valuable backup solution that, however, will not increase the benefit above the HO detector in the presented application scenarios. After a summary of the performed analyses, the conclusion is drawn, that the HO de- tector should be included into the L1 Trigger decision. The initiated upgrade process of the HO integration into the L1 muon trigger, that was motivated by these studies, is presented. The preceding upgrade of HO with silicon-photomultipliers and the cor- responding commissioning are described. The thesis concludes with the presentation of first HO signals that are now received in the upgraded L1 muon trigger hardware component.