Evaluation of the LHCb RICH detectors and a measurement of the CKM angle $\gamma$

Abstract

The future LHCb experiment at the Large Hadron Collider (LHC) at CERN will perform precision measurements of CP violation parameters in the neutral B systems. In this thesis the performance of the LHCb RICH system is evaluated, and the feasibility of a measurement of the CP violation parameter #gamma#, using the decays B_d"0 #-># D*"-#pi#"+, B_d"0 #-># D*"-#pi#"+ and their CP conjugates, is investigated. Efficient methods for the reconstruction of B_d"0 #-># D*"-#pi#"+ decays at LHCb are developed. Using the GEANT-based LHCb detector simulation program SICb, the reconstruction efficiencies and signal to background ratios are estimated. It is demonstrated that the decay channel B_d"0 #-># D*"-#pi#"+ can provide a precision in #gamma# of a few degrees after one year of LHCb data taking. A full-scale prototype of the LHCb RICH 2 detector has been tested in a testbeam at CERN in Summer 1998. It is shown to work according to expectation, in particular in the defining aspects of a RICH detector, the photon yield and the Cherenkov angle resolution. These results demonstrate that the LHCb RICH detectors are well understood and give confidence in the model of the RICH system used in the simulation studies for LHCb detector optimisation. In a testbeam in Summer 1999 a RICH prototype was tested using a 3x3 cluster of Multi-anode Photo Multiplier Tubes equipped with lenses. The tubes were read out within the LHC bunch-crossing interval of 25 ns for the first time. It is demonstrated that the MaPMT performs well and is a suitable photodetector for the LHCb RICH. (author)Available from British Library Document Supply Centre-DSC:D213936 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo