Hadronic Physics & Reference Physics Lists

1. HadronicPhysics & Reference Physics Lists MC-PAD Tutorial DESY, Hamburg, January 2010 Gunter Folger

2. Outline • Overview of hadronic physics • processes, cross sections, models • Elastic scattering • Inelastic scattering • From high energy down to rest • Reference Physics Lists Gunter Folger / CERN

3. Introduction • Hadronic interaction is interaction of hadron with nucleus • strong interaction • QCD is theory for strong interaction, so far no solution at low energies • Simulation of hadronic interactions relies on • Phenomenologial models, inspired by theory • Parameterized models, using data and physical meaningful extrapolation • Fully data driven approach • Applicability of models in general are limited • range of energy • Incident particles types • Some to a range of nuclei Gunter Folger / CERN

4. CHIPS At rest Absorption K, anti-p Photo-nuclear, lepto-nuclear (CHIPS) High precision neutron Evaporation Pre- compound FTF String Fermi breakup Multifragment QG String de-excitation Binary cascade Radioactive Decay Bertini cascade Fission HEP LEP 1 MeV 10 MeV 100 MeV 1 GeV 10 GeV 100 GeV 1 TeV Hadronic Process/Model Inventorysketch, not all shown Gunter Folger / CERN

5. particle particle particle particle at rest process 1 in-flight process 2 process 3 model 1 model 2 . . model n c.s. set 1 c.s. set 2 . . c.s. set n Cross section datastore Energyrange manager process manager HadronicProcesses, Models, and CrossSections • Hadronic process may be implemented • directly as part of the process, or • Separating final state generation(models) and cross sections • For models and cross sections there often is a choice of models or datasets • Physics detail vs. cpu performance • Choice of models and cross section dataset possible via • Mangement of cross section store • Model or energy range manager Gunter Folger / CERN

6. Cross Sections • Default cross section sets are provided for each type of hadronic process for all hadrons • elastic, inelastic, fission, capture • can be overridden or completely replaced • Common Interface to different types of cross section sets • some contain only a few numbers to parameterize cross section • some represent large databases • some are purely theoretical Gunter Folger / CERN

7. Alternative Cross Sections • Low energy neutrons • G4NDL available as Geant4 distribution data files • Available with or without thermal cross sections • “High energy” neutron and proton reaction • 14 MeV < E < 20 GeV, Axen-Wellisch systematics • Barashenkov evaluation ( up to 1TeV) • Simplified Glauber-Gribov Ansatz ( E > ~GeV ) • Pion reaction cross sections • Barashenkov evaluation (up to 1TeV) • Simplified Glauber-Gribov Ansatz (E > ~GeV ) • Ion-nucleus reaction cross sections • Good for E/A < 10 GeV • In general, except for G4NDL, no cross section for specific final states provided • User can easily implement cross section and model Gunter Folger / CERN

8. GetCrossSection() sees last set loaded for energy range Load sequence Set4 Set3 Set2 Set1 Baseline Set Energy Cross Section Management Gunter Folger / CERN

9. Elastic Interactions Gunter Folger / CERN

10. Hadron Elastic ScatteringProcesses • G4HadronElasticProcess • Used in LHEP, uses G4LElastic model • G4UHadronElasticProcess • Uses G4HadronElastic model, combined model • p,n use G4QElastic • Pion with E > 1GeV use G4HElastic • G4LElastic otherwise • Options available to change settings, expert use Gunter Folger / CERN

11. Inelastic Interactions Gunter Folger / CERN

12. TeVhadron dE/dx~ A1/3 GeV ~GeV - ~100 MeV ~10 MeV to thermal ~100MeV - ~10 MeV Hadronic Interactions from TeV - meV Gunter Folger / CERN

13. Model returned by GetHadronicInteraction() 1 1+3 3 Error 2 Error Error Error 2 Model 5 Model 3 Model 4 Model 2 Energy Model 1 Model Management Gunter Folger / CERN

14. String Models – QGS and FTF • For incident p, n,π,K • QGS model also for high energy  when CHIPS model is connected • QGS ~10 GeV < E < 50 TeV • FTF ~ 4 GeV < E < 50 TeV • Models handle: • selection of collision partners • splitting of nucleons into quarks and diquarks • formation and excitation of strings • String hadronization needs to be provided • Damaged nucleus remains. Another Geant4 model must be added for nuclear fragmentation and de-excitation • pre-compound model, • CHIPS for nuclear fragmentation • Binary Cascade and precompound for re-scattering and deexcitation Gunter Folger / CERN

15. Cascade models ( 100 MeV – GeVs ) • Bertini Cascade • Binary Cascade • INCL/ABLA Gunter Folger / CERN

16. BertiniCascadeModels • The Bertini model is a classical cascade: • it is a solution to the Boltzman equation on average • no scattering matrix calculated • can be traced back to some of the earliest codes (1960s) • Core code: • elementary particle collider: uses free-space cross sections to generate secondaries • cascade in nuclear medium • pre-equilibrium and equilibrium decay of residual nucleus • 3-D model of nucleus consisting of shells of different nuclear density • In Geant4 the Bertini model is currently used for p, n, L , K0S , + • valid for incident energies of 0 – 10 GeV Gunter Folger / CERN

17. Precompound Model • G4PreCompoundModel is used for nucleon-nucleus interactions at low energy and as a nuclear de-excitation model within higher-energy codes • valid for incident p, n from 0 to 170 MeV • takes a nucleus from a highly-excited set of particle-hole states down to equilibrium energy by emitting p, n, d, t, 3He, alpha • once equilibrium state is reached, four other models are invoked via G4ExcitationHandler to take care of nuclear evaporation and breakup • these models not currently callable by users • The parameterized and cascade models all have nuclear de-excitation models embedded Gunter Folger / CERN

18. Low energy neutron transportNeutronHP • Data driven models for low energy neutrons, E< 20 MeV, down to thermal • Elastic, capture, inelastic, fission • Inelastic includes several explicit channels • Based on data library derived from several evaluated neutron data libraries Gunter Folger / CERN

19. At Rest • Most Hadrons are unstable • Only proton and anti-proton are stable! • I.e hadrons, except protons have Decay process • Negative particles and neutrons can be captured (neutron, μ-), absorbed (π-, K-) by, or annihilate (anti-proton, anti-neutron) in nucleus • In general this modeled as a two step reaction • Particle interacts with nucleons or decays within nucleus • Exited nucleus will evaporate nucleons and photons to reach ground state Gunter Folger / CERN

20. Skipping • HEP and LEP models • CHIPS • Electro-nuclear interactions • Ion induced interactions • Binary light ion cascade • QMD model • Wilson Abrasion/Ablation models available • EM Dissociation model • Isotope production model • Radioactive decay Gunter Folger / CERN

21. Summary hadronics • Geant4 hadronic physics framework allows for physics process implemented as: • Process • cross sections plus model, or combination of models • Many processes, models and cross sections to choose from • hadronic framework also allows users to add his own cross section or model • Recent improvements and additions in • FTF model • Precompound and de-excitation models • Liege cascade implementation, including ABLA • Elastic scattering • Cross sections • Not shown: Validation of models and cross sections • http://geant4.fnal.gov/hadronic_validation/validation_plots.htm Gunter Folger / CERN

22. Physics Lists - Physics Choices • User has the final say on the physics chosen for the simulation. He/she must: • identify the relevant particles and select for each particle type the physics processes • validate the selection for the application area • ‘PhysicsList’representthiscollection • Deciding or creating the physics list is the user's responsibility • reference physics lists are provided by Geant4 • are continuously-tested and widely used configurations (eg QGSP_BERT, adopted by LHC experiments as default) • other ‘educated-guess’ configurations for use as starting points • ‘Builders’ provided combining certain physics, e.g. EM physics Gunter Folger / CERN

23. Reference Physics Lists (1) • Reference physics lists attempt to cover a wide range of use cases • Extensive validation by LHC experiments for simulation hadronic showers • QGSP_BERT, or QGSP_BERT_EMV current favorite • Recent FTF improvements: FTFP_BERT is promising alternative • Medical Community • Comparison to TARC experiment testing neutron production and transport demonstrates good agreement • QGSP_BIC_HP, QGSP_BERT_HP • user feedback, e.g. vi hypernews, is welcome • Users responsible for validating applicability to specific domain Gunter Folger / CERN

24. Reference physics lists (2) • Reference Physics Lists use modular design • Reuse builders for several physics lists • Evolve lists following developments in G4 • New options first offered in experimental lists • Adopting mature options in production lists • Sharing of physics lists between users • LHC experiments required common physics settings supported by G4 • Sharing of experience, validation, etc… • Documentation under user support page • Physics Lists User forum • for questions and feedback Gunter Folger / CERN

25. Using Reference physics • In main(), pass a physics list to runManager: • #include “QGSP_BERT.hh” • G4VUserPhysicsList* physicsList = new QGSP_BERT; • runManager->SetUserInitialization(physicsList); Gunter Folger / CERN

26. Summary – Physics Lists • Physics list provided and supported by Geant4 • Help users • Share experience • Follow developments in Geant4 • Reduce risk of missing physics, • or using wrong models for specific type of application Gunter Folger / CERN

27. Summary • Hadronic physics offers models use • Parameterized modeling • Detailed theory inspired models • Precise data driven models • Offer choice of physics detail, • at expense of CPU performance • Continuing improvement in modeling • Reference Physics lists help users building or choosing physics • Did not show • Extensive validation effort going on in hadronics • See still incomplete list in:http://geant4.fnal.gov/hadronic_validation/validation_plots.htm Gunter Folger / CERN

28. Backup slides Gunter Folger / CERN

29. Modeling interactions Gunter Folger / CERN

30. Hadronic Models – Data Driven • Characterized by lots of data • cross section • angular distribution • multiplicity • etc. • To get interaction length and final state, models interpolate data • cross section, coefficients of Legendre polynomials • Examples • neutrons (E < 20 MeV) • coherent elastic scattering (pp, np, nn) • Radioactive decay Gunter Folger / CERN

31. Hadronic Models - Parameterized • Depend mostly on fits to data and some theoretical distributions • Examples: • Low Energy Parameterized (LEP) for < 50 GeV • High Energy Parameterized (HEP) for > 20 GeV • Each type refers to a collection of models • Both derived from GHEISHA model used in Geant3 • Core code: • hadron fragmentation • cluster formation and fragmentation • nuclear de-excitation Gunter Folger / CERN

32. Hadronic Models – Theory Driven • Based on phenomenological theory models • less limited by need for detailed experimental data • Experimental data used mostly for validation • Final states determined by sampling theoretical distributions or parameterizations of experimental data • Examples: • quark-gluon string (projectiles with E > 20 GeV) • intra-nuclear cascade (intermediate energies) • nuclear de-excitation and breakup • chiral invariant phase space (up to a few GeV) Gunter Folger / CERN

33. QuarkGluonStringModel • Two or more strings may be stretched between partons within hadrons • strings from cut cylindrical Pomerons • Parton interaction leads to color coupling of valence quarks • sea quarks included too • Partons connected by quark gluon strings, which hadronize Gunter Folger / CERN

34. Fritiof Model • String formation via scattering of projectile on nucleons • momentum is exchanged, increases mass of projectile and/or nucleon • Sucessive interactions further increase projectile mass • Excited off shell particle viewed as string • Lund string fragmentation functions used • FTF model has been significantly improved in the last year Gunter Folger / CERN

35. BertiniCascadeModel • The Bertini model is a classical cascade: • it is a solution to the Boltzman equation on average • no scattering matrix calculated • can be traced back to some of the earliest codes (1960s) • Core code: • elementary particle collider: uses free-space cross sections to generate secondaries • cascade in nuclear medium • pre-equilibrium and equilibrium decay of residual nucleus • 3-D model of nucleus consisting of shells of different nuclear density • In Geant4 the Bertini model is currently used for p, n, L , K0S , + • valid for incident energies of 0 – 10 GeV Gunter Folger / CERN

36. Bertini Cascade (text version) • Modeling sequence: • incident particle penetrates nucleus, is propagated in a density-dependent nuclear potential • all hadron-nucleon interactions based on free-space cross sections, angular distributions, but no interaction if Pauli exclusion not obeyed • each secondary from initial interaction is propagated in nuclear potential until it interacts or leaves nucleus • during the cascade, particle-hole exciton states are collected • pre-equilibrium decay occurs using exciton states • next, nuclear breakup, evaporation, or fission models Gunter Folger / CERN

37. Using the Bertini Cascade • G4CascadeInterface* bertini = new G4CascadeInterface() • G4ProtonInelasticProcess* pproc = new G4ProtonInelasticProcess(); • pproc -> RegisterMe(bertini); • proton_manager -> AddDiscreteProcess(pproc); Gunter Folger / CERN

38. LEP, HEP models • Parameterized models, based on Gheisha • Modeling sequence: • initial interaction of hadron with nucleon in nucleus • highly excited hadron is fragmented into more hadrons • particles from initial interaction divided into forward and backward clusters in CM • another cluster of backward going nucleons added to account for intra-nuclear cascade • clusters are decayed into pions and nucleons • remnant nucleus is de-excited by emission of p, n, d, t, alpha • The LEP and HEP models valid for p, n, , t, d • LEP valid for incident energies of 0 – ~30 GeV • HEP valid for incident energies of ~10 GeV – 15 TeV Gunter Folger / CERN

39. Using the LEP and HEP models • G4ProtonInelasticProcess* pproc = new G4ProtonInelasticProcess(); • G4LEProtonInelastic* LEproton = new G4LEProtonInelastic(); • G4HEProtonInelastic* HEproton = new G4HEProtonInelastic(); • HEproton -> SetMinEnergy(25*GeV); • LEproton -> SetMaxEnergy(55*GeV); • pproc -> RegisterMe(LEproton); • pproc -> RegisterMe(HEproton); • proton_manager -> AddDiscreteProcess(pproc); Gunter Folger / CERN

40. Chiral Invariant Phase Space (CHIPS) • Origin: M.V. Kosov (CERN, ITEP) • Use: • capture of negatively charged hadrons at rest • anti-baryon nuclear interactions • gamma- and lepto-nuclear reactions • back end (nuclear fragmentation part) of QGSC model Gunter Folger / CERN

41. Chiral Invariant Phase Space (CHIPS) • Quasmon: an ensemble of massless partons uniformly distributed in invariant phase space • a 3D bubble of quark-parton plasma • can be any excited hadron system or ground state hadron • u,d,s quarks treated symmetrically (all massless) • Critical temperature TC : model parameter which relates the quasmon mass to the number n of its partons: • M2Q = 4n(n-1)T2C => MQ ~ 2nTC • TC = 180 – 200 MeV • Quark fusion hadronization: two quark-partons may combine to form an on-mass-shell hadron • Quark exchange hadronization: quarks from quasmon and neighbouring nucleon may trade places Gunter Folger / CERN

42. Using QGS or FTF model • G4TheoFSGenerator * theHEModel = new G4TheoFSGenerator(); • G4FTFModel * theStringModel = new G4FTFModel(); • G4ExcitedStringDecay * theStringFrag =new G4ExcitedStringDecay(new G4LundStringFragmentation()); • theStringModel->SetFragmentationModel(theStringFrag); • theHEModel->SetTransport(new G4BinaryCascade()); • theHEModel->SetMinEnergy(4.*GeV); • theHEModel->SetMaxEnergy(100*TeV); • theHEModel->SetHighEnergyGenerator(theStringModel); • // reduce use of casacde to below 5 GeV • // theCasacdeModel->SetMaxEnergy(5*GeV); • protonInelasticprocess->RegisterMe(theHEModel); Gunter Folger / CERN

43. Fission Processes • G4HadronFissionProcess can use three models: • G4LFission (mostly for neutrons) • G4NeutronHPFission (specifically for neutrons) • G4ParaFissionModel • New spontaneous fission model from LLNL • available soon Gunter Folger / CERN

44. Isotope Production • Useful for activation studies • Covers primary neutron energies from 100 MeV down to thermal • Can be run parasitically with other models • G4NeutronIsotopeProduction is currently available • G4ProtonIsotopeProduction not yet completed • To use: • G4NeutronInelasticProcess nprocess;G4NeutronIsotopeProduction nmodel;nprocess.RegisterIsotopeProductionModel(&nmodel); • Remember to set environment variable to point to G4NDL (Geant4 neutron data library) Gunter Folger / CERN

45. Reference physics lists (2) • Naming scheme • LHEP lists use parameterized HEP and LEP models • QGS / FTF list use string models for high energy interactions • LEP parameterized model for lower energies • Model used for nuclear de-excitation is indicated by • P for precompound • C for Chips model • Nothing for use of Binary, if followed _BIC, e.g. QGS_BIC • _BERT, _BIC add the use of cascade for lower energy ( < ~10 GeV) for p, n, and pions and Kaons for BERT • _HP indicates use of low energy neutron transport • _EMV, _EMX indicate electromagnetic options Gunter Folger / CERN