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A ROOT Tool for 3D Event Visualization in ATLAS Calorimeters

A ROOT Tool for 3D Event Visualization in ATLAS Calorimeters. Luciano Andrade José de Seixas. Federal University of Rio de Janeiro/COPPE. Outline. The LHC and ATLAS detector. ATLAS calorimeter system. Trigger system and Level 2 Trigger RoI. Commissioning phase with cosmics.

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A ROOT Tool for 3D Event Visualization in ATLAS Calorimeters

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  1. A ROOT Tool for 3D Event Visualization in ATLAS Calorimeters Luciano Andrade José de Seixas Federal University of Rio de Janeiro/COPPE

  2. Outline • The LHC and ATLAS detector. • ATLAS calorimeter system. • Trigger system and Level 2 Trigger RoI. • Commissioning phase with cosmics. • The visualization tool. • Some problems found by this tool. • Conclusion and To-Do list.

  3. The LHC and ATLAS Detector • LHC - it is being finished at CERN. • ATLAS - high granularity, TBytes/sec of data. • Trigger system – to save only relevant events. Eletromagnetic Calorimeter Hadronic Calorimeter Muon Chambers Inner Detector

  4. ATLAS Calorimeter System Electromagnetic - LArg Inner detector Electromagnetic Calorimeter • Liquid argon as detection medium. • Charged particles generate eletromagnetic showers. • Electric field captures free electrons → signal pulse. Hadronic - TileCal • Scintillating tiles. • Iron to absorv the energy. • Energetic hadrons interact with the tiles → light generation. • Photomultipliers transform the light in a electrical signal. Hadronic Calorimeter

  5. Calorimeter Segmentation Hadronic Electromagnetic • 64 Modules in φcoordinate. • Two readout channels by cell. • 10,000 readout channels. • Three layers. • 100,000 readout channels. • Four layers.

  6. Trigger System 1 GHz Level 1 Trigger 100 kHz Region of Interest (RoI) (Region with signal information) Level 2 Trigger RoI algorithm was checked with this visualization tool (simulated data) 1 kHz Event Filter 100 Hz

  7. Commissioning with cosmic muons Trigger tower • Use of a standalone coincidence board. • Bypass the Trigger System. • Back-to-back coincidence – projective events. • Use TileCal Trigger Towers. • Commissioning of the calorimeters with real data. coincidence board 1 2 dicriminator logic OR trigger Logic AND dicriminator logic OR 3 4

  8. The Visualization Tool - Motivation • Three-dimensional event visualization of the Calorimeter cells. • Tool used in the commissioning phase. • Simple and intuitive way to look for potential problems. • Easy connection with reconstructed data (ROOT). • Two versions: • Hadron Calorimeter specific. • Combined Eletromagnetic/Hadron Calorimeters. • Analysis examples: • Track visualization for cosmics – real data. • Level 2 Trigger RoI debug - simulated data.

  9. TileCal Specific Tool - Overview • ROOT macro (TileCosmicView.C). • Input → standard TileCal reconstruction nTuple. To open the nTuple Standard Root GL Viewer Graphic User Interface (GUI) some activated cells cosmic track TileCal

  10. Features • Fast response. • Color palette adjustment. • Threshold by cell energy. • Show individual PMTs. • Cell selection with mouse. • Projective views. • Show ADC counts. • Rotate and zoom.

  11. Combined Calorimeter Tool - Overview • ROOT macro (CaloGeoView.C). • Input → standard Athena reconstruction nTuple. Standard Root GL Viewer Graphic User Interface (GUI) Example of a Level 2 Trigger RoI visualization

  12. Features Example of cosmic event reconstruction (real data) log scale green palette - Eletromagnetic hot palette - Hadronic

  13. Detecting Problems – Cell Imbalance TileCal cells have two readout channels Cell PMT left PMT right cell with asymmetric energy

  14. Detecting Problems – noisy modules TileCal module LBA45 with high pedestals in most of the cells

  15. Threshold by Cell Energy Level 2 Trigger RoI seen from inside of the detector buttom to force same threshold activated cells Low threshold in the Eletromagnetic Calorimeter (all cells are showed)

  16. Threshold by Cell Energy Level 2 Trigger RoI seen from inside of the detector Threshold at 50 MeV (LArg detector)

  17. Threshold by Cell Energy Level 2 Trigger RoI seen from inside of the detector energy of some activated cells Threshold at 2 GeV (only activated cells are showed)

  18. Identifying Problems – Level 2 RoI last cells (high eta) with wrong values wrong cell information after fix the problem before fix the problem

  19. Conclusion & To do list • Easy way to go through the events and check for problems. • Needs only Root (v5.14.00). • Easy to run and to modify. • No need to recompile. • It has helped commissioning phase with cosmic. • Some bugs in the L2 Trigger algorithms has been found with this tool. • Next steps: Include LArg EndCap and Inner Detector.

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