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Status and Plans for Geant4 Physics

Status and Plans for Geant4 Physics. Linear Collider Simulation Workshop III 2-5 June 2004 Dennis Wright (SLAC). Outline. Electromagnetic Physics status and plans validation plots Hadronic Physics status and plans validation plots.

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Status and Plans for Geant4 Physics

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  1. Status and Plans for Geant4 Physics Linear Collider Simulation Workshop III 2-5June2004 DennisWright(SLAC)

  2. Outline • ElectromagneticPhysics • statusandplans • validationplots • HadronicPhysics • status and plans • validation plots

  3. Electromagnetic Physics: Model Approach • Currentstatus: • ionization,bremsstrahlung,multiplescatteringarecoupledduetorelianceonpre-calculatedenergylosstables • Goal: • de-couplethembyabstractingcommonbehavior • allowmultiplephysicsmodelstobeappliedtoeachprocess • allowmodelstobedefinedforgivengeometricregionorenergy • Example: • canchooseG4MollerBhabhaModelforenergylossandproductionofdeltas by e+/e- • OrG4PAIModelfordeltaproductionbyheavychargedparticles

  4. Electromagnetic Physics: Multiple Scattering • MigrationtoModelApproachwastohavebeentransparenttouser,but bugs were introducedinGeant46.0 • width of angular distribution in MS became too large by 30% • only muons and hadrons were affected • electrons OK • other bugs as well: • mu ionization cross section 10% too small • infinite loop for particles stopping in very low density gas • ProblemsfixedbyGeant4 6.1 => don't use 6.0!

  5. Electromagnetic Physics: Multiple Scattering • Newfeatures: • improved transformation between geometric and true path length • use Highland formula for Gaussian part of angular distribution for electrons • option to allow backscattering at boundaries • Plans: • Develop MS processes which are specific to muons and ions

  6. Electromagnetic Physics: Other Processes • Muionization • addition of radiative corrections for energies above 1 GeV • accurarcy of energy loss at high energy improved from 10% to 2% • Mu pair production • updated parameterizations for E > 1 TeV • Precision of diff. cross section parameterization improved from 30% to 5% • New processes: • above 1 TeV) • e+e-(high energy) • Old EM processes kept in 52

  7. Compton ScatteringData, G4LowE , G4standard

  8. Stopping Power Data, G4LowE, G4Standard

  9. Photoelectric EffectData, G4LowE, G4Standard

  10. Pair ProductionData, G4LowE, G4Standard

  11. Multiple Scattering (1)

  12. Proton energy Target Data 0 (mr) Geant4 0(mr) 1.984MeV 3.42mg/cm2 Al 35.6(1.9) 35.4 158.6MeV 1.82g/cm2 Pb 24.00(.24) 23.88 158.6MeV 1.82g/cm2Be 6.39(.18) 6.46 174GeV 0.58g/cm2Pb 0.0213(.0029) 0.0213 Multiple Scattering (2)

  13. Bhabhascatteringdata Geant4 BaBar EM Calorimeter (EM shower shapes)

  14. Hadronic Physics Lists • Choosing the right combination of models is a complex task: • many models to choose from • must mix and match according to physics goals • Hadronic physics lists developed to make the job easier • really just educated guesses • meant as starting point for user to develop tailored physics list • 24hadronicphysicslistscurrentlyprovided • 19 physics lists categorized according to 14 use cases • url: http://cmsdoc.cern.ch/~hpw/GHAD/HomePage/ • all can be downloaded and installed as part of toolkit in directory parallel to source

  15. Hadronic Physics Lists: Linear Collider • LHEP • low energy parameterized + high energy parameterized models • fast • relatively easy to use • not particularly good results below a few GeV • LHEP_GN • gamma- and electro-nuclear suite added • QGSP_BERT • quark gluon string + Bertini cascade • better results • medium speed

  16. Hadronic Physics Lists: Linear Collider • QGSP_BIC • quark gluon string + binary cascade models • best results overall • slowest • GQSP_HP, LHEP_HP • high-precision neutron model added • good for LC neutron fluxes

  17. Hadronic Model Development • Cascademodels • extend Bertini cascade to include kaons • improve NN elastic and charge-exchange cross sections in Binary cascade • optimize Binary and Bertini cascades for use in calorimeter physics lists • Stringmodels • reduce lower bound for QGS model to 6 GeV • include anti-proton induced reactions • attempt to improve shower shapes • Chiral Invariant Phase Space model • improvednucleonstructurefunctions • include neutrino-induced reactions

  18. Hadronic Process Validation and Plans • Physicstesting • thintargettests (comparing single Geant4 process with data) • fullsetuptests (full physics and full geometry) • Statistical testing • Tooearly,manymodelsstillunderdevelopment • Regression • Some tests done currently, more are planned

  19. Gammasfrom14MeVNeutronCaptureonU(Datadrivenmodel)

  20. Elastic Kaon Scatteringat 800 MeV/c

  21. Production from 730 MeV p(LEP Model)

  22.  Production from 730 MeV p(Bertini Model)

  23. Multiplicity in pp -> Xat 200 GeV/c (QGS Model)

  24. Cross section for p Li ->  + Xat 400 GeV (QGS Model)

  25. Atlas HEC (e/ ratio)

  26. Validation at Experiments • ATLAS • Testbeamstudies • BaBar • Runningexperiment • Geant4inproductionfortwoyears • GLAST • Cosmic ray balloon tests • HARP • Runningtestbeam experiment • ResultstobeusedtovalidateGeant4thintargetstudies

  27. HARP Experiment and Goals • pand beams between1.5and15GeV/c on solid targets (Be through Pb) and liquid targets (H2 ,D2 ,N2 , H2O) • Provide a systematic study of hadron production cross sections • Willprovidemuch-neededdataforGeant4hadronicmodelvalidationandtuning • Data taking complete, analysis underway

  28. Summary • Electromagneticphysics • model approach migration continues (bugs fixed) • new models to be added • statistical and regression tests being performed • several processes are being extended • Hadronicphysics • hadronic physics lists available as a first step toward developing a detailed physics list • model development continues • validation of hadronicphysics continues

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