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Geant4 in HARP

Learn about the HARP experiment at CERN and how Geant4 is used in the simulation, reconstruction, and event display. Explore topics such as trigger optimization and hadron production.

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Geant4 in HARP

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  1. Geant4 in HARP The Hadron Production Experiment at the PS, CERN V.Ivanchenko For the HARP Collaboration Geant4 User Workshop 14 November 2002

  2. Outline • HARP experiment • HARP software • Geant4 in Gaudi Framework • HARP Geant4 user interface • Trigger optimisation • Hadron production • Conclusions 14.11.02

  3. HARP Collaboration Università degli Studi e Sezione INFN, Bari, Italy Rutherford Appleton Laboratory, Chilton, Didcot, UK Institut für Physik, Universität Dortmund, Germany Joint Institute for Nuclear Research, JINR Dubna, Russia Università degli Studi e Sezione INFN, Ferrara, Italy CERN, Geneva, Switzerland Section de Physique, Université de Genève, Switzerland Laboratori Nazionali di Legnaro dell' INFN, Legnaro, Italy Institut de Physique Nucléaire, UCL, Louvain-la-Neuve, Belgium Università degli Studi e Sezione INFN, Milano, Italy P.N. Lebedev Institute of Physics (FIAN), Russian Academy of Sciences, Moscow, Russia Institute for Nuclear Research, Moscow, Russia Università "Federico II" e Sezione INFN, Napoli, Italy Nuclear and Astrophysics Laboratory, University of Oxford, UK Università degli Studi e Sezione INFN, Padova, Italy LPNHE, Université de Paris VI et VII, Paris, France Institute for High Energy Physics, Protvino, Russia Università "La Sapienza" e Sezione INFN Roma I, Roma, Italy Università degli Studi e Sezione INFN Roma III, Roma, Italy Dept. of Physics, University of Sheffield, UK Faculty of Physics, St Kliment Ohridski University, Sofia, Bulgaria Institute for Nuclear Research and Nuclear Energy, Academy of Sciences, Sofia, Bulgaria Università di Trieste e Sezione INFN 14.11.02

  4. HARP goals • Cross sections for protons and pions in the momentum range (1.5-15) GeV/c • The data for the neutrino factory source optimization • The data for calculation of meson flax from atmospheric neutrino • The data for K2K and MiniBooNE experiments • The data for Geant4 hadronic models 14.11.02

  5. TOF wall electron identifier cherenkov muon identifier spectrometer magnet forward trigger forward RPC TPC/RPC solenoid magnet drift chambers “characterized” beam Detector layout Large Acceptance and Particle ID Neutrino Factory: ~2-24 GeV Atmospheric meson flux: 2-100 GeV PS East Area beams: 1.5-15 GeV/c 14.11.02

  6. Large Angle detectors  12 GeV/c p RPC 14.11.02

  7. Forward Spectrometer: Drift Chambers Nomad Drift Chamber Module (4x3 planes) Nomad Drift Chamber Module (4x3 planes) A simple beam pion Nomad Drift Chamber Module (4x3 planes) Dipole Spectrometer TOF Wall Cherenkov Beam Cherenkov 14.11.02

  8. HARP at T9 14.11.02

  9. Approved in 1999 Construction from 2000 1st run 2001 (108 triggers) 2nd run 2002 (108 triggers) Software project from 2000 Component approach, OO design and c++ Geant4 is one of the main external packages for HARP Positive and negative beams Momentums: 1.5, 3, 5, 8, 10, 12.2, 15 GeV/c Solid targets: Be, C, Al, Cu, Sn, Ta, Pb Target depth in nuclear interaction length 2%, 5%, 100% Special targets: Al(K2K), Be (MiniBooNE) Liquid targets: H2O, H2/D2, O2/N2 HARP History & Strategy 14.11.02

  10. Software architecture DetResponse Reconstruction HarpUI Simulation Event Selector Objy Persistency DetRep ObjyHarp ObjectCnv HarpDD HarpEvent Gaudi Framework DAQ ROOT GEANT4 CLHEP + STL HEPODBMS Objectivity DATE 14.11.02

  11. Geant4 geometry description is used for simulation, reconstruction, and event display Extrapolator provides propagation of reconstructed tracks between subdetectors Magnetic field in solenoid, dipole, and T9 beam line ASCII files with a few tags (CMS): Logical volume Boolean operation Positioning Replica Positioning of parameterized volumes Rotations Materials Mixtures Geant4 Detector Description 14.11.02

  12. Geant4 in Gaudi Framework • Gaudi Framework from LHCb • Geant4 geometry is built for all offline applications (HARP geometry service) • HARP RunManager inherits from G4RunManager with public method HarpBeamOn(G4int), which is activated by Gaudi algorithm HsSimAlg • HsSimAlg is responsible for definition of • Primary generator • Physics • UI interface to G4 • Random numbers and G4 event loop 14.11.02

  13. Geant4 UI interface • Initialization of simulation (HsSimAlg) by Gaudi jobOptions - ASCII macro file • G4 UI commands can be submitted • Before run • After run • Before event • After event • G4 standard commands • HARP specific commands for • Event generator options • Cuts • Hadron production options 14.11.02

  14. HARP Geant4 simulation • Sensitive Detectors, Stepping and Tracking actions are defined for subsystems independently • Hits are stored in Gaudi Event Store • Digitization is separated from hit production • Digi are stored in Gaudi Event Store in the format of Reconstruction hits and can be processed as experimental data 14.11.02

  15. NDC Detector Response McVertex GEANT4 HdrNdcMCDigiAlg McParticle HdrNdcSD McBaseHit HdrNdcMCHitAlg McNdcHit NdcHit Gaudi 14.11.02

  16. Detector Response Simulation EM Calorimeter Ndc 3 GeV Data MC 14.11.02

  17. HARP event generators • Standard generator “HARPgun” • G4GeneralParticleSource • ASCII input, filled from experimental events • T9 beam line simulation – 72 meters of PS beam transport from the target to T9 hall have been performed. The mail goal: to control beam parameters. 14.11.02

  18. HARP background study • In 2001 experiment background was 4 times higher than expectations • In order to understand the background special Geant4 study was performed • Beam parameters were extracted from the data using MWPC and beam counters • Simulation were done with and without target • Background events were traced back 14.11.02

  19. Results of background study • Main sources of background are following: • Multiple scattering on beam counters and TPC walls (29 %) • Bremsstrahlung of beam electrons/positrons on beam counters and TPC walls with further conversion on other walls (33 %) • -electron production on beam counters and TPC walls (26 %) • -electrons production in air (12 %) • Simple shielding is not effective! • As a result the program to optimize HARP trigger for 2002 run have been formulated 14.11.02

  20. Hadron Production • The process of hadron production is designed. It is active only in the target and only for primary track • Interaction point is forced to be distributed along the target • One of the following secondary generators can be used: • “Elastic” – user defined angular distribution • “Exclusive” – user defined final state • Parametrised (GHEISHA) • Chiral invariant phase space (CHIPS) • String fragmetation + CHIPS 14.11.02

  21. Benchmark for G4 hadron physics • A benchmark is designed to study G4 hadronic generators • The goals: • Analysis strategy • Acceptance calculation • Studying hadronic generators • Gaudi framework is used • No secondary interactions • One can study: • Multiplicity of final states • Inclusive spectra • Angular distributions • Invariant masses 14.11.02

  22. Conclusions • HARP data taking have been completed in 2002 • Currently the calibration and alignment of HARP subsystems are in progress • Geant4 simulation of HARP is working and used as for calibration and for subdetector studies • Geant4 was used for trigger optimization • The results of HARP experiment will be utilized in Geant4 for testing and tuning of hadronic models in the momentum range 1.5-15 GeV/c 14.11.02

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