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A Linear Collider Physics List for Geant4 Simulations

Victoria Linear Collider Workshop 28-31 July 2004 Dennis Wright (SLAC). A Linear Collider Physics List for Geant4 Simulations. Objectives. Provide a “standard” Geant4 physics list to be used in study of LC detectors Make the list easy to use and understand

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A Linear Collider Physics List for Geant4 Simulations

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  1. Victoria Linear Collider Workshop 28-31 July 2004 Dennis Wright (SLAC) ALinear Collider Physics List for Geant4 Simulations

  2. Objectives • Provide a “standard” Geant4 physics list to be used in study of LC detectors • Make the list easy to use and understand • Keep it up-to-date as new models become available • Validate as test beam data becomes available • Include it in LC Geant4 example (Makoto Asai)

  3. Physics List Design • Forsimplicity: • Provide only one list everyone can use • Specializedlistscouldbeaddedlater • Avoid hadronic list libraries • Thesearenice,buttoogeneralandsomewhatinvolved • Write out a “long-hand” physics list • DerivedfromG4VModularPhysicsList • Everythingcontainedin12files • Easytoseewhatprocesses/modelsareusedandhowtheyareinvoked

  4. Physics List Contents (1) • Allapplicable standardEManddecayprocesses (as available in Geant4 6.2) • HadronprocessesandmodelstakenfromtheQGSP_BERThadronicphysicslist: • For incident (p, K, p, n) energies of ~20 GeV to 100 TeV: • (QGS) Quark Gluon String + PRE (Precompound) models • For all others (L, S, anti-p, ...) with energies 20 GeV to 100 TeV: • HEP (High Energy Parameterized model) • For all particles with energies between 9.5 GeV to 20 GeV: • LEP (Low Energy Parameterized model)

  5. Physics List Contents (2) • For incident p, p, n with energies < 10 GeV • Bertini cascade model • For all others (K, anti-n, ...) with energies < 10 GeV • LEP • At rest processes for p-, K- absorption, anti-p, anti-n annihilation • Neutron capture, neutron-induced fission • Elastic hadron-nucleus scattering (same model for all hadrons) • Added processes for light ions (d, t, 3He, a) • Elastic scattering • LEP model for inelastic (d, t, a)

  6. Justification of Model Choices:20 GeV and Above • Threemodelstochoosefrom: • HEP : works for all particles • QGS, FTF : work for p, K, p, n only • Use testbeam data to decide: • e/pratiofrom Atlas HEC prefers QGS, HEP • No data yet to say if QGS is better than HEP • Choose QGS because: • It is more thoroughly validated • It is based more on physics than parameterization • So use QGS for p, K, p, n, HEP for all others

  7. Fig.1 • F

  8. Fig. 2 • D

  9. Justification of Model Choices:Below 20 GeV • Between10and20GeV,onlyonemodelavailable: LEP • Below10GeV,threemodelstochoosefrom: • Low energy parameterized (LEP) : for all particles • Bertini cascade: for p, p, n only • Binary cascade: for p, p, n only • Pion production reactions clearly eliminate LEP • Bertini and Binary equally good, Bertini 8x faster • So LEP plus Bertini cascade required in list

  10. Fig. 3 • S

  11. Fig. 4 • W

  12. Plans • Add gamma- and electro-nuclear processes/models • Extend Bertini cascade to kaons • Add hadronic interactions for light ions (to replace LEP) • Validation gap: 1 – 15 GeV • Eagerly awaiting HARP publication • Looking for other test beam data in this range

  13. Maintenance and Use • Physics list will be maintained in FreeHEP CVS • Anyone can get it: • cvs -d :pserver:anonymous@cvs.freehep.org:/cvs/lcd LCPhys • Better models, bug fixes will be included as available • Questions, problems to • dwright@slac.stanford.edu

  14. Geant4 Highlights at Release 6.2 • RunManager • Now modularized, easier to embed in a framework • Event • Links between pre-assigned decay products and primary maintained • User information can be attached to event in G4VUserEventInformation (also track, vertex, particle and region) • Geometry • First steps taken to abstract navigator -> other, quite different steppers will soon be enabled • New default values for tracking in EM field -> improved accuracy • Divisions (ala Geant3) introduced

  15. Geant4 Highlights at Release 6.2 • Visualization • New HepRep XML driver for HepRep2 • New visualization commands • Remove obsolete OPACS driver • Environments • MOMO Java tools now included (geometry and physics editors) • Biasing • Importance, weight-window methods available • Co-works with scoring • EM processes • Example physics lists available

  16. Coming Highlights from Release 7.0 • “Unknown” particle class • Propagated in a field, through materials • Appears as a track/trajectory • Will decay if and only if pre-assigned decay channel is defined for that track • PDG compliance for particle numbers • Geometry • Mixing of placements and parameterized volumes • Twisted trapezoid shape • Reflection of parameterized volumes

  17. Coming Highlights from Release 7.0 • EM processes • Performanceanalysisandoptimizationofshowers • Hadronic processes • Revised physics lists based on new/updated models • NLD1 example • Demonstrates use of “unknown particle”, region user information, linking of primary particles, tracks, trajectories, hits • Includes physics list previously discussed • Currently available at http://www.slac.stanford.edu/~asai/NLD1/ • Will be extended example in release

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