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EM Standard Physics Upgrade for Geant4 9.2

EM Standard Physics Upgrade for Geant4 9.2. V.N.Ivanchenko, 3 December 2008. J.Apostolakis, A.Bagulya, A.Bogdanov, S.Elles, V.Grichine, P.Gumplinger, O.Kadri, R.Kokoulin, M.Maire, A.Schaeliske, T.Toshito, L.Urban. Outline. List of new developments

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EM Standard Physics Upgrade for Geant4 9.2

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  1. EM Standard Physics Upgrade for Geant4 9.2 V.N.Ivanchenko, 3 December 2008

  2. J.Apostolakis, A.Bagulya, A.Bogdanov, S.Elles, V.Grichine, P.Gumplinger, O.Kadri, R.Kokoulin, M.Maire, A.Schaeliske, T.Toshito, L.Urban

  3. Outline List of new developments Highlights on upgrade of standard EM physics Bremsstrahlung Multiple Scattering Spline option ApplyCuts option Some validation results Conclusions 3

  4. New physics will available with g4 9.2 • Relativistic bremsstrahlung model for E > 1 GeV • Updated density effect • Hadron induced bremsstrahlung and e+e- pair production processes/models • Updated positron annihilation to hadrons • G4eMultipleScattering process with G4UrbanMscModel2 • G4MuMultipleScacttering process with G4WentzelVIModel • G4Cerenkov process updated • G4Scintillation process includes Birks low • ICRU’73 data are inserted • Ion ionisation updated

  5. New options and infrastructure components will be available with g4 9.2 • Spline option for physics tables • Option3 Standard Physics builder • Optimized for medical and space applications • New utility classes: • G4EmSaturation – Birks effect (used in G4Scintillation) • NIEL and gamma interactions • G4ElectronIonPair – helper class to sample of ionisation clusters at charge particle step using ICRU’31 approach • G4EmProcessSubType – enumerator of EM processes • G4EmConfigurator – helper class to configure EM models per energy range and G4Region

  6. Highlights on new developments which is available with 9.2

  7. Bremsstrahlung 287 GeV e- at Ta target (4%X0) • Added new relativistic model bremsstrahlung model for e± • Updated density and LPM effects • Applied above 1 GeV • Added new model for hadron bremsstrahlung and e+e- pair production • In predefined PhysLists for π± and protons

  8. New relativistic bremsstrahlung modelA.Schaeliscke, IEEE NSS, 2008 Bethe-Heitler formula with corrections Complete screening with Coulomb correction Valid for E > 1 GeV Density & LPM-Effect consistent combination a’la Ter-Mikaelian LPM old LPM new LPM off 287 GeV e- at Ta target (4%X0) Data from the CERN experiment: H.D.Hansen et al,PR D 69, 032001 (2004) 8

  9. Updated multiple scattering • New specialized process for e±G4eMultipleScattering • Uses G4UrbanMscModel2 tuned for electron data • FR = 0.04 • Old model G4UrbanMscModel is frozen • Validation versus data and alternative models: • G4WentzelVIModel • G4CoulombScattering

  10. Test of e- transport versus Sandia data(details in O.Kadri et al, NIM B258 (2007) 358) Sensitive to multiple scattering Directly connected with LHC calorimeters results Tuned Urban’s msc model#2 is best in describing data Label e-Msc, skin=3 Ta Al 10

  11. Upgrade of multiple scattering model Old default version will be kept for backward compatibility 11

  12. Spline option for Physics Tables Spline interpolation of dEdx, range and other tables Zoomed Bragg peak Default EM physics without spline (Opt0) strong cut dependence Non-statistical variations due to numerical instability Spline is activated (Opt3) Stable result 12

  13. “ApplyCuts” option • “ApplyCuts” was inside the package for a long time • By default is “false” • Production thresholds (cuts) are applied only for ionisation and bremsstrahlung • If “true” production thresholds are applied for all EM standard processes • Provides more fast simulation but may bias results if cuts are high (above 1 mm)

  14. ATLAS barrel type calorimeter • EMV and EMX in this plot use “ApplyCuts” • Default Physics List results unchanged • Cut on gamma processes (EMX) reduces accuracy of energy response but has no effect on EMV 14

  15. ATLAS HEC type calorimeter Visible energy increased by 0.5%

  16. CMS ECAL type calorimeter • 5x5 matrix of PW04 crystals • Reduced (~0.5%) energy deposition in central crystal both for the default and EMV Physics Lists • Result of upgrade of Urban multiple scattering model 16

  17. CPU benchmarking Static build on dedicated SLC4 PC no libraries from afs • CPU gain with 9.0 mainly due to c++ software cleanup • CPU gain with 9.2 due to optimization of physics • step limitation by multiple scattering • energy threshold for gamma processes 17

  18. Summary • There are number of modifications in EM standard in g4 9.2, it is expected: • better CPU performance and better agreement with test-beam • No change in total response and resolution for ECal • Minor increase of response in sampling calorimeters with low sampling fraction • Apply Cuts option may significantly improve CPU performance BUT • Should be applied with care • Cuts should be reviewed

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