GEANT4 simulation of the ATLAS Muon Spectrometer

The Large Hadron Collider (LHC) at CERN will offer anunparallel opportunity to probe fundamental physics at an energy scale well beyond that reached by current experiments. The ATLAS detector is designed to fully exploit the potential of LHC providing high accuracy measurements in terms of mass and type identification of particles emerging from the LHC proton-proton collisions. Given the complexity of the apparatus in this demanding environment, an Object-Oriented(OO) methodology is required to manage the full detector simulation. The GEANT4 simulation of the ATLAS Muon Spectrometer(MS), implemented in a OO perspective, is an ambitious task since it deserves not only a very detailed description of the apparatus geometry, but also it covers issues connected to a fast but precise simulation and a correct implementation of the different detector responses. A report on the Muon Simulation activities during the last year is the content of the present paper