The Architecture of MEG Simulation and Analysis Software

TL;DR

The paper describes the design and implementation of a modular, reusable software architecture for the MEG experiment, enabling efficient simulation and analysis despite limited human resources.

Contribution

It introduces a layered software framework using FORTRAN and C++ that simplifies development and promotes code reuse for complex physics data analysis.

Findings

Reusable software frameworks facilitated collaboration among physicists.

The architecture supported simulation, reconstruction, and analysis tasks effectively.

The system integrated GEANT 3 and ROOT libraries for visualization and data handling.

Abstract

MEG (Mu to Electron Gamma) is an experiment dedicated to search for the $\mu^+ \rightarrow e^+\gamma$ decay that is strongly suppressed in the Standard Model but predicted in several Super Symmetric extensions of it at an accessible rate. MEG is a small-size experiment ($\approx 50-60$ 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 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 programming skill. The offline software is based on two frameworks: {\bf REM} in FORTRAN 77 used for the event generation and detector simulation package {\bf GEM}, based on GEANT 3, and {\bf ROME} in C++ used in the readout simulation {\bf Bartender} and in the reconstruction and analysis program {\bf Analyzer}. Event display in the simulation is based on GEANT 3 graphic libraries and in the reconstruction on ROOT graphic libraries. Data are stored in different formats in various stage of the processing. The frameworks include utilities for input/output, database handling and format conversion transparent to the user.