Pedro Arce (CERN/CIEMAT) GEANT4 CMS SIMULATION Pedro Arce (CERN/CIEMAT) GEANT4 delta review 02 CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT)

CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT) Outline OSCAR functionality OSCAR/GEANT4 robustness and performance Physics comparisons CMS - GEANT4 interaction 2002 GEANT4 delta review 02 CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT)

CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT) OSCAR functionality Geometry: All CMS detectors Also several testbeams Currently moving to geometry in XML database, common to Simulation/Reconstruction/Visualisation All geometry converted from GEANT3 geometry Detailed checking in progress Thorough comparison of GEANT3 and GEANT4 geometry done All materials, volumes and touchables properties Positions of touchable centres Material budget CMS Overlap Detection Tool (now in GEANT4) GEANT4 delta review 02 CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT)

CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT) Geometry for OSCAR Future way: automatically building GEANT4 geometry from XML files XML based Detector Description Language (XML DDL) - Single description inter- face for the ideal detector - Generic description . Materials . Geometry . Component approach - Attaching specific Information to . Components . Subsets of Volumes - Human editable/readable /expandable GEANT4 delta review 02 CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT)

View of 180 Higgs event simulated in CMS Tracker detector Sliced view of CMS barrel detectors View of CMS muon system View of 180 Higgs event simulated in CMS Tracker detector GEANT4 delta review 02 CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT)

CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT) OSCAR functionality Primary generator: CMS particle gun: Scan in , , energy Random in , , energy Interface with HEPEVT ASCII files Interface with PYTHIA ntuples Long-life particles: select to simulate then before decaying or simulate decay products Persistency: Hits Primary generator particles Selected tracks Use CMS framework (COBRA) Using Objectivity, moving to ROOT GEANT4 delta review 02 CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT)

CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT) OSCAR functionality Interactive visualisation is done with IGUANA Visualise any GEANT4 Geometry Select by logical volumes / by individual copies / by category Picking, slices GEANT4 command line A wizard to guide through OSCAR settings 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 Integrated with overlap detection Hits, in the near future GEANT4 delta review 02 CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT)

Example extension (a trivial wizard) IGUANA viewer displaying 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 GEANT4 delta review 02 CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT)

OSCAR functionality Physics: Electromagnetic processes needed at LHC Hadronic processes needed at LHC CMS Physics Technical Design Report is planned to be written using OSCAR (due 2005) OSCAR milestone Summer 2003: “Reproduce the physics results of the GEANT3 simulation with the same performance” Physics Cuts: Production cuts per material Minimum kinetic energy cuts per material Still to be investigated if we really need them Time of flight cut GEANT4 delta review 02 CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT)

CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT) OSCAR functionality UserActions: Several user actions of the same type loadable on demand Framework: COBRA manages the main() and takes care of persistency Now OSCAR is being reengineered to achieve full integration with CMS Framework Documentation: User’s Guide updated for each release Several Tutorials on the web For OSCAR developers For Physics Reconstruction software developers For Summer Students GEANT4 delta review 02 CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT)

CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT) OSCAR functionality Future developments: GEANT4e as GEANE replacement (error propagation for track fitting) Under progress GFLASH for fast simulation RTAG/G4 discussion Summary: OSCAR is ready for physics validation studies GEANT4 delta review 02 CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT)

OSCAR/GEANT4 robustness Several problems found: Particles loop between two volumes  push them by 0.01 mm Several G4Exception found: solved by CMS team or/and with the help of GEANT4 team  >10000 pp events without crashing New G4Exception found recently in geant4.4.1.p01: currently under investigation with the help of GEANT4 (see progress by delta review....) GEANT4 delta review 02 CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT)

GEANT4 vs GEANT3 Time Performance - Full events in full CMS: H / tte / Z - All CMS geometry - 3D TOSCA magnetic field - Production and tracking cuts as in CMSIM (GEANT3) - geant4.4.0.ref02 - Pentium III 850 Mhz, 640 Mb CMSIM(GEANT3) OSCAR(GEANT4) G4/G3 - H (10 events) 318 seconds 583 seconds 1.83 - tte (10 events) 919 seconds 2125 seconds 2.31 - Z (10 events) 480 seconds 1240 seconds 2.58 GEANT4 delta review 02 CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT)

CMSIM(GEANT3) - OSCAR(GEANT4) comparison Central Tracker Number of rechits per track vs eta Cmsim 122 OSCAR 1 3 2 pre 03 RecHits 100 GeV Pt muons in region ||<2.5 resolution vs eta GEANT4 delta review 02 CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT)

CMSIM(GEANT3) - OSCAR(GEANT4) comparison: Muon System reconstructed – generator quantities 5-200 GeV Pt muons in region ||<2.4 GEANT4 delta review 02 CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT)

CMSIM(GEANT3) - OSCAR(GEANT4) comparison: EM calorimeter GEANT4 delta review 02 CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT)

CMSIM(GEANT3) - OSCAR(GEANT4) comparison: EM calorimeter GEANT4 delta review 02 CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT)

CMSIM(GEANT3) - OSCAR(GEANT4) comparison: EM calorimeter GEANT4 delta review 02 CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT)

ECAL + HCAL testbeam: GEANT3 - GEANT4 comparison 1996 Testbeam Setup for CMS HCAL A test module of copper absorber plates with scintillator tile sampling exposed to pions, electrons and muons 28 scintillator plates with absorber of varying thickness in between A prototype lead tungstate crystal electromagnetic calorimeter Direction of magnetic field was parallel to the face of the scintillator plates (cms HCAL Barrel configuration) Energies: 225 GeV muons (for calibration), 10 to 300 GeV pions, 10 to 300 GeV electrons Magnetic Field: 0, 0.75, 1.5, 3 tesla Configuration: Only HCAL or ECAL + HCAL 5000 events were taken for each setup Response of the Calorimeter was studied as a function of: Magnetic field: effect on scintillator Absorber thickness: optimisation of resolution versus containment Absorber depth: energy containment Electromagnetic Calorimeter contribution: e/ effects GEANT4 delta review 02 CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT)

ECAL + HCAL testbeam: GEANT3 - GEANT4 comparison GEANT4 4.0.p02 100 GeV pi+ 0 Tesla ECAL+HCAL GEANT4 delta review 02 CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT)

ECAL + HCAL testbeam: GEANT3 - GEANT4 comparison 100 GeV e- 0 Tesla HCAL GEANT4 delta review 02 CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT)

ECAL + HCAL testbeam: GEANT3 - GEANT4 comparison pi+ 0 Tesla ECAL+HCAL Events with MIP in ECAL Events with shower in ECAL GEANT4 delta review 02 CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT)

ECAL + HCAL testbeam: GEANT3 - GEANT4 comparison pi+ 0 Tesla ECAL+HCAL Events with MIP in ECAL Events with shower in ECAL GEANT4 delta review 02 CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT)

CMS - GEANT4 interaction 2002 CMS requirements as presented in GEANT4 TSB meeting of 6/2/02 Problems with stuck particles/G4Exceptions: Quite good answer from GEANT4 teams. Most problems resolved Implementation of reflections Done end 2001 Some bugs found, solved after several months Long lived particles: setting decay time Already in GEANT4: communication problem Cuts per material/volume Cuts per material done by CMS  released in GEANT4 as a fast temporary solution More diagnostic/debug tools, e.g. for Geometry checks. Others? CMS Overlap Detection Tool included in GEANT4 release as an example in June release GEANT4 tracking optimization in parameterized volumes Done for June release GEANT4 delta review 02 CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT)

CMS - GEANT4 interaction 2002 Hadronic Model Issues (Testing-Review Documentation / information flow / Starting defaults for LHC experiments / Fluka?) Documentation updated with GEANT4 releases Consistent and explained physics lists provided Response quite satisfactory Updated documentation Physics Reference Manual and User´s Guide for Application Developers updated User´s Guide for Toolkit Developers under deep revision Fast simulation program (e.g. GFLASH in GEANT4) Under discussion by GEANT4 and RTAG SWIG/Python interface Under study GEANE equivalent in GEANT4: error propagation for track fitting Under progress by CMS team Many ‘smaller’ bugs reported & removed GEANT4 delta review 02 CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT)

CMS - GEANT4 interaction 2002 New requirements Parameterization of reflected volumes Measure and improve time performance Problems with stuck particles/G4Exceptions Improve advanced documentation GEANT4e requirements Write own G4Navigator Make public G4TrackingManager Allow particles increasing energy GEANT4 delta review 02 CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT)

CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT) Summary OSCAR is technically complete to start with physics studies Some comparisons vs CMS GEANT3 simulation started Some problems found, but solved by CMS + GEANT4 Some TestBeam comparison started: Show reasonable agreement with data Slightly better than GEANT3 Others to be done: ECAL TB ‘99, ECAL TB ‘02, ECAL+HCALTB ‘99, HCAL ‘02, Tracker ´02 Next months: systematic comparison with GEANT3 simulation Plan to move to GEANT4 simulation by Summer 2003 GEANT4 response to CMS requirements and problems has been in general satisfactory GEANT4 delta review 02 CMS GEANT4 Simulation Pedro Arce (CERN/CIEMAT)