A ROOT Tool for 3D Event Visualization in ATLAS Calorimeters

The ATLAS (A Toroidal LHC ApparatuS) detector is being tested with cosmic rays before LHC (Large Hadron Collider) starts its full operation by the midle of the year 2008. For the ongoing commissioning phase, it is necessary to develop specific tools that can perform efficient cosmic ray data analysis. An important issue for final analysis is to provide a way to visualize cosmic muon tracks and the corresponding activated cells in the detector, so that one can check visually the coherence of the reconstructed data and seek for potential problems. This work presents a 3D visualization tool for cosmic muon track visualization based on activated cells in the highly segmented ATLAS calorimeter system. This tool was developed in the ROOT framework, which allows a smooth integration between specifics analyses from ATLAS community and the visualization tool. This tool uses the ROOT embedded geometry package to create the ATLAS calorimeter, cell by cell, and provides routines to fill calorimeter cells with the reconstructed data information. Energy thresholds can be set by the user so that only relevant information is displayed. The tool structure and some applicationand with reconstructed data are presented.