Measurement of direct CP violation in the NA48 experiment

The 2 first chapters of this thesis are dedicated to the theoretical and experimental aspects of CP violation. The NA48 experiment is a third generation experiment like KTeV, NA48 has been designed to collect data concerning the simultaneous detection of the 4 decay modes: KL,S → ππ and to provide the measurement of the parameter of direct CP violation with an uncertainty nearing 2*10-4. The third chapter describes the experimental equipment of NA48 in CERN: the production of KL and KS beams, the tagging system, the detection system for K → π+π-, the detection system for K → π0π0, the data acquisition system, and the trigger system. Chapter 4 is dedicated to the selection and identification of events. Chapter 5 deals with specific problems concerning the detection of π+π-, it means: the dead time in the triggering system, the overflow of the chamber reading system and the inefficiency of shift chambers. Chapter 6 lists the different corrections and systematic errors concerning the double ratio R, and gives the following result: Re(ε'/ε=(14.4±2.6)*10-4 which is by itself, for the first time, an evidence of direct violation. (A.C.)