Muon reconstruction and physics commissioning of the CMS experiment with cosmic muons
Abstract
In this thesis, the first physics measurements using the Compact Muon Solenoid (CMS) at the Large Hadron Collider (LHC) are presented. These physics measurements were performed using cosmic ray muons traversing the CMS detector. The CMS detector is optimized for the detection of muons and the results presented here also have a purpose of helping in the commissioning of the detector for the LHC collisions. Two analyses were conducted; the first is a measurement of the charge ratio of positive to negative muons, and the second is a measurement of the differential and absolute flux of incident cosmic rays. The charge ratio measurement was made using both the muon and tracking detectors and is highlighted by its data-driven method. The charge ratio over the momentum range starting from 10 GeV were measured at the detector center and then transferred to the earth's surface. The flux measurement was performed using the muon system only and more relied on Monte Carlo samples. The flux was measured over the momentum range from 15 GeV to over 1 TeV at the CMS outer surface and then transferred to the earth's surface. These measurements required the development of specialized reconstruction and analysis tools since cosmic rays pass through the CMS detector in a different pattern than the particles from the LHC collisions. Good precision and agreement with previous experiments was observed. These measurements demonstrate the capability of the CMS detector for physics analyses and are the first physics result of the CMS collaboration. Besides the cosmic muon analyses, an analysis of Monte Carlo samples, with full detector simulation and reconstruction of collisions at 10 TeV, was performed. This analysis focused on the fundamental Drell-Yan process as an essential part of discovery physics in the dimuon channel. The results show that it is possible to measure the cross section precisely with the first 100 pb-1 data from the LHC, and the systematic uncertainty is dominated by the expected uncertainty in the luminosity measurement.
Degree
Ph.D.
Advisors
Neumeister, Purdue University.
Subject Area
Particle physics
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