Advanced Studies on RPCs

The purpose of the present work is to to investigate the properties of the RPCs detectors with particular reference to the high rate operation that is more and more required by the experiments at present and future hadron colliders. This purpose brings in a natural way to investigate on RPC detector physics and to develop a more complete working model including the avalanche saturation phenomenon that was not accounted for in previous simulations. After a short presentation of the ATLAS experiment, with particular emphasis on the muon physics (chapter 1), RPCs are presented in their historical development. The behaviour of RPCs high rate is studied in chapter 3, where a working model based on global parameters as applied voltage, working current, incident particle flux and counting rate, and electrode plate resistivity. The results of this analysis are the basis of the Logistic Saturated Avalanche Model that is developed in chapter 4. This model explains the previous experimental results, and correctly predicts measurable physical quantities as the total charge to prompt charge ratio. This permits to implement an accurate detector simulation and can be the base for a deeper comprehension of the discharge process in a uniform field. The last chapter is dedicated to the systematic study of the detector ageing problems that are analyzed both on fully assembled detectors and on some of the individual components. One of the principa l contributions to the measured detector performance loss is evidenced and a possible solution is tested,with encouraging results.