Ageing Studies on the Drift Tubes of the Muon Spectrometer and Observability of MSSM Heavy Higgses via a Sparticle decay Mode

This Ph.D. thesis summarized the work performed in INFN Cosenza group within the ATLAS Muon Collaboration. This work is a representative cross section of the different aspects to the preparation of a modern day high energy physics experiment. An important part is dedicated to the testing of specialized detector elements. And the experiment's discovery potential for signatures of new theoretical proposal is evaluated. The thesis is divided into three parts. The first part, made up of the first three chapters, is an introduction about the theoretical and the experimental background of the two main work I have performed during the doctoral period. The second part, the fourth chapter, is about the main work I have dealt with, the ageing problem of the Monitored Drift Tube detectors, which make up the Muon Spectrometer. And the last third part, the fifth chapter, is about the study of an MSSM Higgs bosons decay mode into sparticles.