First Test of the Performance of CMS Muon Chambers inside the Barrel Yoke von

The Compact Muon Solenoid (CMS) is a multi purpose experimental particle de-tector at the Large Hardon Collider (LHC). The goal of this experiment is to do fundamental research in particle physics and in particular to prove the validity of the Higgs model. The CMS muon barrel system provides a precise measurement of the position and the momentum of high energy muons. It consists of 250 drift tube chambers, with rectangular drift cells filled with a gas mixture of 85%Ar and 15%CO2. Each chamber is equipped with on-chamber readout and trigger electron-ics. The chambers for the innermost station have been produced at the Physics In-stitute IIIA at the RWTH University. After installing the chambers at their final position inside the barrel return yoke for the CMS solenoid magnet, cosmic muons have been recorded individually for all chambers and used to evaluate the detector performance, as this is the last chance to easily access the chambers for hardware in-terventions. These data also provide a good opportunity to study the reconstruction algorithms and to verify the chamber performance. In this diploma thesis the work and studies from the chamber commissioning is presented, as well as reconstruction and performance studies. ii