The detector simulation of the L3 experiment at LEP

The L3 simulation program, based on the GEANT3 package, has been intensively used to produce the events needed for the L3 analysis. After six years of operation of the L3 detector over 30 million events have been fully simulated in the L3 setup. The simulation having to match the precision reached in the experiment, a lot of effort has been put to reach the best agreement of the simulated data with the real detector response. In addition to the careful tuning of the GEANT tracking parameters many time dependent effects which affect the response of the detector, like dead channels and inefficiencies, have been taken into account. The design principles and the general organization of the program are described and comparisons of the simulation with the data recorded by the L3 experiment are shown. The current status of our experience in simulating a large number of events is also reviewed