ACAT ’02 CMS GEANT4 Sim. & Detector Desc. Pedro Arce(CERN/CIEMAT) 1 Simulation Framework and XML Detector Description for the CMS Experiment ARCE Pedro 1,2, BANERJEE Sunanda 3, BOCCALI Tomasso 4, CASE Michael 5, De ROECK Albert 2, LARA Vicente 2, LIENDL Martin 2,6, NIKITENKO Alexander 7, SCHRODER Matthias 2, STRAESSNER Arno 2, Van LINGEN Frank 2, WELLISCH Hans-Peter 2, WENZEL Hans 8 1 CIEMAT, Madrid, Spain, 2 CERN, Geneva, Switzerland, 3 Tata Institute, Bombay, India, 4 INFN Bari, Italy, 5 UC Davis, USA, 6 HEPHY, Vienna, Austria, 7 Imperial College, UK, 8 Fermilab, Chicago, USA (for the CMS Collaboration) ACAT 2002, Moscow, 23th June 2002

ACAT ’02 CMS GEANT4 Sim. & Detector Desc. Pedro Arce(CERN/CIEMAT) 2 Outline GEANT4 simulation framework (OSCAR) OSCAR – IGUANA Visualisation OSCAR Physics comparison GEANT4 Performance comparison DDD scope Basic aspects and architecture Document structuring Summary

ACAT ’02 CMS GEANT4 Sim. & Detector Desc. Pedro Arce(CERN/CIEMAT) 3 CMS Simulation & Reconstruction Monte-Carlo generator Ntuple ZebraFZ CMSIM CMSjet User Analysis Monte-Carlo generator OODB OSCAR ORCA User Analysis FAMOS

ACAT ’02 CMS GEANT4 Sim. & Detector Desc. Pedro Arce(CERN/CIEMAT) 4 GEANT4 Simulation (OSCAR) Geometry: All geometry up-to-date Currently moving to geometry in XML database, common to Simulation/Reconstruction/Visualisation Detailed checking in progress  CMS Overlap Detection Tool GEANT4 expects: (a) Daughters of the same mother must not intersect each other (b) Daughters of the same mother must be fully contained in their mother (c) some refinements of the above in case of replication and parameterisation If these conditions hold for every mother-volume and the first level of daughters therein, the geometry is OK!

ACAT ’02 CMS GEANT4 Sim. & Detector Desc. Pedro Arce(CERN/CIEMAT) 5 Shoot geantinos

ACAT ’02 CMS GEANT4 Sim. & Detector Desc. Pedro Arce(CERN/CIEMAT) 6 View of CMS muon systemSliced view of CMS barrel detectors

ACAT ’02 CMS GEANT4 Sim. & Detector Desc. Pedro Arce(CERN/CIEMAT) 7 OSCAR Primary generator: CMS particle gun: Scan in , , energy Random in , , energy Interface with HEPEVT ASCII files Interface with PYTHIA ntuples Persistency: Hits Primary generator particles Selected tracks Using Objectivity, moving to ROOT

ACAT ’02 CMS GEANT4 Sim. & Detector Desc. Pedro Arce(CERN/CIEMAT) 8 OSCAR - IGUANA  Interactive visualisation is done with IGUANA (see poster in this Conference) Visualise any GEANT4 Geometry Select by logical volumes / by individual copies / by category Show volume/object details/properties Picking, slicing GEANT4 command line A wizard to guide through OSCAR settings Integrated with overlap detection Adding other extensions is trivial (e.g. GUIs like overlap detection) Visualise Tracks Visualise magnetic field 2D plane that can be rotated Field direction as an arrow Field intensity as colour

ACAT ’02 CMS GEANT4 Sim. & Detector Desc. Pedro Arce(CERN/CIEMAT) 9 OSCAR - IGUANA Correlated Picking Example extension (a trivial wizard) Queried from plug-in database, loaded on request and bound to IGUANA G4 Run Manager IGUANA viewer displaying OpenInventor scene Control of arbitrary GEANT4 tree Overlap detection

ACAT ’02 CMS GEANT4 Sim. & Detector Desc. Pedro Arce(CERN/CIEMAT) 10 CMS magnetic field in IGUANA

ACAT ’02 CMS GEANT4 Sim. & Detector Desc. Pedro Arce(CERN/CIEMAT) 11 OSCAR Physics: Electromagnetic processes needed at LHC Hadronic processes needed at LHC CMS Physics Technical Design Report is planned to be written using OSCAR (due december 2004) OSCAR milestone June 2003: “Reproduce the physics results of the GEANT3 simulation with the same performance”

ACAT ’02 CMS GEANT4 Sim. & Detector Desc. Pedro Arce(CERN/CIEMAT) 12 GEANT4/GEANT3 simu. + ORCA reco. CMS central tracker Single  events

ACAT ’02 CMS GEANT4 Sim. & Detector Desc. Pedro Arce(CERN/CIEMAT) 13 GEANT4/GEANT3 simu. + ORCA reco. CMS muon system Single  events phi_sim - phi_rec eta_sim - eta_rec Pt_sim - Pt_rec

ACAT ’02 CMS GEANT4 Sim. & Detector Desc. Pedro Arce(CERN/CIEMAT) 14 GEANT4/GEANT3 ECAL comparisons

ACAT ’02 CMS GEANT4 Sim. & Detector Desc. Pedro Arce(CERN/CIEMAT) 15 Full events in full CMS > events without crashing - H , tt  e, Z  - All CMS geometry - 3D TOSCA magnetic field - Production and tracking cuts as in CMSIM - geant4.4.0.ref02 - Pentium III 850 Mhz, 640 Mb OSCAR Time Performance

ACAT ’02 CMS GEANT4 Sim. & Detector Desc. Pedro Arce(CERN/CIEMAT) 16 H  in all CMS (10 Events) OSCAR ( tracks) - CMSIM ( tracks) MeV Initial track energy mm OSCAR ( tracks) - CMSIM ( tracks) Track length MeV No Tracks

ACAT ’02 CMS GEANT4 Sim. & Detector Desc. Pedro Arce(CERN/CIEMAT) 17 Time performance - H  (10 events) CMSIM: 439k tracks 318 seconds OSCAR: 400k tracks 583 seconds (1.83) - tt  e (10 events) CMSIM: 1809k tracks 919 seconds OSCAR: 1159k tracks 2125 seconds (2.31) - Z  (10 events) CMSIM: 1105k tracks 480 seconds OSCAR: 941k tracks 1240 seconds (2.58) No GEANT4 optimization done yet!

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