Studies of the electromagnetic calorimeter and direct photon production at the CMS detector

This thesis describes work carried out on the Compact Muon Solenoid (CMS) experiment for the Large Hadron Collider at CERN. Studies of the prototype of the electromagnetic calorimeter are described. The energy resolution has been evaluated for the 7 x 7 lead tungstate crystal matrix . The energy resolution achieved was: #sigma#/E = 4.5%/#sq root#E #+-# 0.31%. An investigation of the response of eight prototype crystals to irradiation is also presented. This thesis describes in detail the first study of direct photon production at CMS. Event simulation and methods of reducing the background to the direct photon signal are presented. This work demonstrates that this process may he used to distinguish between different parameterisations of the gluon distribution. The sensitivity is such that a few days worth of data taking at low luminosity will be sufficient for this type of analysis at CMS. (author)Available from British Library Document Supply Centre-DSC:DXN028036 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo