The CMS Detector

The second part of the thesis focusses on the construction and commissioning of the CMS pixel barrel detector, the central part of the CMS detector with about 48 million readout channels. The CMS pixel detector allows to measure secondary vertices with high precision and thus plays a key role in the analysis of events with Z -quarks. 

The integration of the CMS pixel barrel detector has been accomplished within about two years before it was installed into the CMS detector in Summer 2008. The large effort in commissioning and calibration resulted in the successful and stable operation of the CMS pixel detector during cosmic and proton-proton collision data taking. 

The CMS experiment—one of the four large LHC experiments— is a general-purpose detector designed to optimally exploit the physics potential of the LHC. Located inside the superconducting solenoid, which provides a 3.8 Tesla held, are the hadronic and electromagnetic calorimeters as well as the tracking system. The latter is based on silicon pixels and silicon strip detectors, with a total sUicon area of 210 m. A multi-layer muon system embedded in the return yoke outside the solenoid completes the CMS detector. 

In addition to their impact on the pixel operation, the results of the work described in this thesis also set the stage for new analysis techniques using the CMS detector. The results also provide an excellent example of the close link between the development of forefront technologies and major progress in fundamental science, by exploiting the new energy frontier offered by the LHC. 

Even though the CMS detector is primarily designed for high transverse momentum physics, it is very well suited for heavy flavor physics thanks to the muon system with the potential to identify low transverse momentum muons and the excellent tracking detectors. In particular, CMS features a novel three-layer silicon pixel detector which allows for a precise and efficient reconstruction of secondary vertices from heavy flavor decays. 

In December 2009 proton-proton collisions at the LHC were recorded with the CMS detector for the first time. The eollisions happened at a center-of-mass energy of /s = 900 GeV and = 2.36 TeV. The data collected during the first LHC running period... 

On March 30, 2010, the first proton-proton collisions at a center-of-mass energy of /s = 7 TeV happened at the LHC. The data statistics recorded by the CMS detector during the first months of data-taking allows for a first measurement of the inclusive -quark production cross-section at the LHC [1], The preliminary result has been presented at the 35th International Conference on High Energy Physics [2],... 

In the first two sections the development of the testing procedure is described, before the construction of the BPIX detector is addressed. In particular the technique for mounting the modules on the support structure, the assembly of the detector control and readout electronics on the supply tube and the integration of the final system are explained. The following section focusses on the installation of the BPIX detector into the CMS detector. In the last section the results of the system tests are discussed and the performance of the BPIX during the first running period is reviewed. The chapter concludes with a summary. 

The goal of the cosmic data taking with the CMS detector is the commissioning and calibration of the individual subdetectors, the alignment of the tracking detectors and the muon chambers and the testing of the DAQ system. 

The muon system is the outermost part of the CMS detector. The magnet return yoke is equipped with gaseous detector chambers for muon identification and momentum measurement. In the barrel, the muon stations are arranged in five separate iron wheels... 

Fig. 2.10 View of one quarter of the CMS detector illustrating the layout of the muon system in...

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