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Simulations for CBM CBM-India Meeting, Jammu, 12 February 2008

Simulations for CBM CBM-India Meeting, Jammu, 12 February 2008. V. Friese v.friese@gsi.de. Planned experiment. Running experiment. Input (Signal, Background). Required performance (S/B, SNR, eff.). Detector description. Input (Signal, Background). Simulation. Simulation.

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Simulations for CBM CBM-India Meeting, Jammu, 12 February 2008

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  1. Simulations for CBMCBM-India Meeting, Jammu, 12 February 2008 V. Friese v.friese@gsi.de

  2. Planned experiment Running experiment Input (Signal, Background) Required performance (S/B, SNR, eff.) Detector description Input (Signal, Background) Simulation Simulation Simulated signal Simulated signal Detector design Performance (acceptance, efficiency) Simulations: Why? V. Friese CBM-India, 12 February 2008 2

  3. Consequences: Many different detector designs / setups need being investigated The simulation framework must be flexible enough to enable an easy switch between geometries / digitisations Challenge in particular for reconstruction (data structures, ...) Simulations for detector design V. Friese CBM-India, 12 February 2008 3

  4. Event generator UrQMD, HSD, user defined, ... Particles (type, momentum, vertex) GEN Transport (MC) GEANT3, GEANT4, FLUKA, ... MCPoint, MCTrack MC Monte-Carlo Detector response simulation Digi RAW CBMROOT Reconstruction Hits, Tracks, Vertices EDS Analysis Histogram Simulation steps Step Data structures Data level Experiment DAQ V. Friese CBM-India, 12 February 2008 4

  5. CBMROOT is the CBM software framework for simulation, reconstruction and analysis It is based on (FAIR)ROOT and VMC Execution via ROOT macros Code is written in C++ Documentation system is DOXYGEN The (current) build system is cmake, the distribution system is subversion Supported platforms are (almost) all Linux flavours External packages used: GEANT3 GEANT4 ROOT CLHEP VMC PYTHIA CBMROOT V. Friese CBM-India, 12 February 2008 5

  6. CBMROOT and FAIRROOT CBMROOT detector specific (geometry, digitisation, ...) core (run manager, I/O, ...) CBMROOT FAIRROOT PANDAROOT V. Friese CBM-India, 12 February 2008 6

  7. Produces a list of particles, each with type, start vertex and momentum at start vertex, as input for the transport Available generator interfaces: Standalone (outside of the framework, with intermediate file) UrqmdGenerator (UrQMD output ftn14, ASCII) PlutoGemerator (PLUTO output, ROOT) ShieldGenerator (SHIELD output, ASCII) AsciiGenerator (self-written ASCII, defined format) Integrated (inside the framework, on the fly, without intermediate file) ParticleGenerator (single particles) BoxGenerator (particles with flat distribution in p, pt, y, φ) An arbitrary number of generators can be used at the same time Event generators V. Friese CBM-India, 12 February 2008 7

  8. FAIRROOT employs the concept of Virtual Monte Carlo (VMC): The user can choose between different transport engines Available engines: GEANT3 GEANT4 (FLUKA in preparation) The simulation run is controlled by the manager class CbmRunSim The output is a ROOT tree. Branches are CbmMCTrack (input + secondary tracks) and objects derived from CbmMCPoint CbmMvdPoint CbmStsPoint .... MC transport V. Friese CBM-India, 12 February 2008 8

  9. 1. Choose engine and create run MC Transport step by step 4. Define input CbmPrimaryGenerator* primGen = new CbmPrimaryGenerator(); CbmUrqmdGenerator* urqmdGen = new CbmUrqmdGenerator(inFile); primGen->AddGenerator(urqmdGen); fRun->SetGenerator(primGen); CbmRunSim* fRun = new CbmRunSim(); fRun->SetName("TGeant3"); // Transport engine fRun->SetOutputFile(outFile); // Output file CbmRuntimeDb* rtdb = fRun->GetRuntimeDb(); fRun->SetMaterials/"media.geo"); 2. Define detector geometry 5. ... and run CbmDetector* sts = new CbmSts("STS", kTRUE); sts->SetGeometryFileName(stsGeom); fRun->AddModule(sts); fRun->Run(nEvents); 3. Define magnetic field CbmFieldMap* magField = new CbmFieldMapSym3(fieldMap); magField->SetPosition(0., 0., fieldZ); magField->SetScale(fieldScale); fRun->SetField(magField); V. Friese CBM-India, 12 February 2008 9

  10. describes the detector response to the simulated MCTracks to be defined according to knowledge on the detector output: CbmDigi for each active channel workaround: HitProducer (e.g. Gaussian smearing of point) Detector simulation (digitisation) CbmStsPoint CbmStsPoint CbmStsDigitize CbmStsDigi CbmStsHitProducer CbmStsFindHits CbmStsHit CbmStsHit V. Friese CBM-India, 12 February 2008 10

  11. The CBM setup: electrons TOF TRD ECAL RICH STS + MVD magnet V. Friese CBM-India, 12 February 2008 11

  12. The CBM setup: muons ECAL TRD STS + MVD magnet V. Friese CBM-India, 12 February 2008 12

  13. Status of detector description V. Friese CBM-India, 12 February 2008 13

  14. Example: STS V. Friese CBM-India, 12 February 2008 14

  15. Example: MUCH V. Friese CBM-India, 12 February 2008 15

  16. is currently done in one step with digitisation (macro) manager class is CbmRunAna input is MC data (output of transport simulation) The user defines tasks which are initialised at the beginning of the run executed for each event finalised after the last event output is a ROOT tree with branches for all data structures registered to the run manager by the class Event reconstruction V. Friese CBM-India, 12 February 2008 16

  17. 1. Create run Reconstruction step by step CbmRunAna *run= new CbmRunAna(); run->SetInputFile(inFile); run->SetOutputFile(outFile); 2. Register task(s) CbmTask* stsDigitize = new CbmStsDigitize(iVerbose); run->AddTask(stsDigitize); 3. Initialise and start run run->LoadGeometry(); run->Init(); run->Run(0,nEvents); V. Friese CBM-India, 12 February 2008 17

  18. Available reconstruction algorithms V. Friese CBM-India, 12 February 2008 18

  19. Some results Track reconstruction efficiency in MVD+STS, CA algorithm V. Friese CBM-India, 12 February 2008 19

  20. Some more results RICH ring reconstruction with Hough transform V. Friese CBM-India, 12 February 2008 20

  21. Electron identification capabilities Composition of identified electrons Pion suppression V. Friese CBM-India, 12 February 2008 21

  22. Performance of di-electron measurements Low-mass vector mesons Acceptance for ρ meson V. Friese CBM-India, 12 February 2008 22

  23. Performance of di-electron measurements (2) Charmonia Acceptance for J/ψ meson V. Friese CBM-India, 12 February 2008 23

  24. Open charm results K- π+ D0, cτ=127 μm V. Friese CBM-India, 12 February 2008 24

  25. Open charm results (2) D+ ->K- ++ D0 ->K- - ++ c+ pK-+ V. Friese CBM-India, 12 February 2008 25

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