Since the end of 1997, P.G. plays a leading role to the design and the implementation of the barrel muon detector. This detector is composed of 250 drift tube (DT) chambers. In particular P.G. is one of the two responsibles for the design of the gas system and of the cooling system of the barrel muon detector and has been one of the main contributors to the preparation and writing of the CMS Muon Detector Technical Design Report. He is also one of the responsibles of the implementation of the Slow Controls system of the muon detector. P.G. has participated to several studies of prototypes DT chambers and has contributed to the development of the test laboratory in the old ISR tunnel at ISR, where all DTs are tested and verified before their final installation in CMS. He gave several presentations at internal meetings and invited talks at international conferences.