MEG simulation and analysis software

MEG (Mu to Electron Gamma) is an experiment dedicated to search for the μ⁺ → e⁺γ decay that is strongly suppressed in the Standard Model. MEG is a small-size experiment (≈ 50-60 physicists at any time) with a life span of about 10 years. The limited human resource available, in particular in the core offline group, emphasized the importance of reusing software and exploiting already existing expertise. Great care has been devoted to provide a simple system that hides implementation details to the average programmer. That allowed many members of the collaboration to contribute to the development of the software of the experiment with limited technical skill. The software architecture is based on two frameworks: REM in FORTRAN 77 used for the event generation and detector simulation package GEM, based on GEANT 3, and ROME in C++ used in the readout simulation Bartender, reconstruction and analysis program Analyzer. Event display in the simulation is realized relying on GEANT graphics libraries and in the reconstruction on ROOT graphics libraries. Data are stored in different formats in various stage of the processing. The frameworks include utilities for input/output and format conversion transparent to the user.