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Simulation Framework and XML Detector
Description for the CMS Experiment
ARCE Pedro1,2, BANERJEE Sunanda3, BOCCALI
Tomasso4, CASE Michael5, De ROECK Albert2, LARA
Vicente2, LIENDL Martin2,6, NIKITENKO Alexander7,
SCHRODER Matthias2, STRAESSNER Arno2, Van LINGEN
Frank2, WELLISCH Hans-Peter2, WENZEL
Hans8 1CIEMAT, Madrid, Spain, 2CERN, Geneva,
Switzerland, 3Tata Institute, Bombay, India,
4INFN Bari, Italy, 5UC Davis, USA, 6HEPHY,
Vienna, Austria, 7Imperial College, UK,
8Fermilab, Chicago, USA (for the CMS
Collaboration) ACAT 2002, Moscow, 23th June 2002
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Outline

• GEANT4 simulation framework (OSCAR)
• OSCAR IGUANA Visualisation
• OSCAR Physics comparison
• GEANT4 Performance comparison
• DDD scope
• Basic aspects and architecture
• Document structuring
• Summary

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CMS Simulation Reconstruction
User Analysis
User Analysis
ORCA
FAMOS
CMSIM
OODB
ZebraFZ
CMSjet
OSCAR
FAMOS
CMSIM
Ntuple
Monte-Carlo generator
Monte-Carlo generator
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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!

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Shoot geantinos
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View of CMS muon system
Sliced view of CMS barrel detectors
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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

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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

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OSCAR - IGUANA
Overlap detection
Example extension (a trivial wizard) Queried from
plug-in database, loaded on request and bound to
IGUANA G4 Run Manager
Control of arbitrary GEANT4 tree
Correlated Picking
IGUANA viewer displaying OpenInventor scene
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CMS magnetic field in IGUANA
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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

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GEANT4/GEANT3 simu. ORCA reco.
CMS central tracker
Single ? events
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GEANT4/GEANT3 simu. ORCA reco.
CMS muon system
Single ? events
phi_sim - phi_rec
eta_sim - eta_rec
Pt_sim - Pt_rec
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GEANT4/GEANT3 ECAL comparisons
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OSCAR Time Performance
Full events in full CMS gt 10000 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
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H????? in all CMS (10 Events)
- CMSIM (442828 tracks)
No Tracks
Initial track energy

• OSCAR (427136 tracks)

MeV
- CMSIM (442828 tracks)
No Tracks

• OSCAR (427136 tracks)

Track length
MeV
mm
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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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