An analysis of the performance of the Compact Muon Solenoid Endcap Muon Chambers

Nicole M Ippolito, Purdue University

Abstract

In the fall of 2006, the Compact Muon Solenoid, one of the two multi-purpose detectors built along the Large Hadron Collider ring, was used to collect data in a full magnetic field of 4 Tesla. This series of runs was the so-named Magnet Test-Cosmic Challenge (or MTCC). For the first time, some sector of all sub-detectors were included in the data chain. Many terabytes of data was collected during this approximately month-long endeavor. The analysis of some subset of this data is considered herein. All work focused on the achievements made by the Cathode-Strip Chambers, which are part of the Endcap Muon system. Two major areas were considered: the resolution being achieved by the CSC's using the reconstruction software at the time of the MTCC, and the possibility of momentum reconstruction from the local tracks within the CSC's, removed from other parts of the detector. This thesis is divided into a number of different chapters. In chapter 1, the physics which the LHC hopes to achieve is discussed in some general sense. Chapter 2 delves into the background physics of cosmic ray muons-their origin, and some typical behavior that one would expect to see in an analysis such as this. Chapter 3 breaks down the CMS detector into the various subsystems which it is comprised of. Chapter 4 discusses the involvement with the hardware-namely the commissioning of the detector. Chapter 5 discusses some a preliminary analysis which was performed during the spring and summer of 2006-before the MTCC data had been collected. Chapters 6 and 7 then delve into the work which comprises the bulk of this analysis. The first task, that of the determining the resolution of the chambers from the cosmic data, is discussed in detail in chapter 6, along with improvements that could be considered. It was determined that the chambers are performing close to the design tolerances they were built to achieve, provided somewhat stringent cuts in the data set are made. The design of the chambers calls for a resolution of 150 microns with values of around 200 microns with appropriate cuts being measured at this time. The reconstruction of the cosmic muon momentum spectrum is discussed in chapter 7, along with the significant difficulties which arise from attempting to work with the CSC's alone. Nonetheless the momentum and energy were found to have a peak at 4 GeV and 4 GeV/c respectively, which is on-par with the expected values. For the full discussions on each of these topics, please see chapters 6 and 7.

Degree

Ph.D.

Advisors

Gutay, Purdue University.

Subject Area

Particle physics

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