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Hadronic Physics & Reference Physics Lists Geant4 Tutorial Annecy, November 2008 Gunter Folger.

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Presentation on theme: "Hadronic Physics & Reference Physics Lists Geant4 Tutorial Annecy, November 2008 Gunter Folger."— Presentation transcript:

1 Hadronic Physics & Reference Physics Lists Geant4 Tutorial Annecy, November 2008 Gunter Folger

2 Geant4 course, Annecy 2008Gunter Folger / CERN 2 Outline Overview of hadronic physics processes, cross sections, models hadronic framework and organization Elastic scattering Inelastic scattering From rest to high energy Reference Physics Lists

3 Geant4 course, Annecy 2008Gunter 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

4 Geant4 course, Annecy 2008Gunter Folger / CERN 4 Hadronic Processes, Models, and Cross Sections Hadronic process may be implemented directly as part of the process, or in terms of 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 particle Energy range manager process manager 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 data store particle

5 Geant4 course, Annecy 2008Gunter Folger / CERN 5 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 Different types of cross section sets some contain only a few numbers to parameterize cross section some represent large databases some are purely theoretical

6 Geant4 course, Annecy 2008Gunter Folger / CERN 6 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

7 Geant4 course, Annecy 2008Gunter Folger / CERN 7 Cross Section Management Set 1 Set 2 Set 3 Set 4 GetCrossSection() sees last set loaded for energy range Energy Load sequence Baseline Set

8 Geant4 course, Annecy 2008Gunter Folger / CERN8 Modeling interactions

9 Geant4 course, Annecy 2008Gunter Folger / CERN 9 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

10 Geant4 course, Annecy 2008Gunter Folger / CERN 10 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

11 Geant4 course, Annecy 2008Gunter Folger / CERN 11 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)

12 Geant4 course, Annecy 2008Gunter Folger / CERN 12 Hadronic Model Inventory sketch, not all shown 1 MeV 10 MeV 100 MeV 1 GeV 10 GeV 100 GeV 1 TeV LEP HEP ( up to 15 TeV) Photon Evap Multifragment Fermi breakup Fission Evaporation Pre- compound Bertini cascade Binary cascade QG String (up to 100 TeV) FTF String (up to 100 TeV) High precision neutron At rest Absorption  K, anti-p Photo-nuclear, electro-nuclear CHIPS (gamma) CHIPS LE pp, pn Rad. Decay 12

13 Geant4 course, Annecy 2008Gunter Folger / CERN 13 Model Management Model 1Model 2 Model 3Model 4 Model 5 11+33Error2 2 Model returned by GetHadronicInteraction() Energy

14 Geant4 course, Annecy 2008Gunter Folger / CERN 14 Hadronic Model Organization At restIn flightDirect implementations Cross sectionsModelsIsotope productionEvent biasing Direct impl. Theory framework High energy Spallation framework CascadePrecompound Direct impl. Frag function impl. Process Direct impl. Transport utilityString parton String fragmenation util. Evaporation util. Direct impl. Frag function intfc Direct impl.

15 Geant4 course, Annecy 2008Gunter Folger / CERN 15 Hadron Elastic Scattering (1) G4HadronElasticProcess Used in LHEP, uses G4LElastic G4UHadronElasticProcess Uses G4HadronElastic model G4HadronElastic, combined model P,n use G4QElastic Pion with E > 1GeV use G4HElastic G4LElastic otherwise Options available to change settings, expert use

16 Geant4 course, Annecy 2008Gunter Folger / CERN 16 Hadron Elastic Scattering (2) G4LElastic, origin in Gheisha models Simple parameterization of cross sections and angular distribution Applicable for all long lived hadrons at all energies G4QElastic New parameterization of cross section in function of E, t, (A,Z); t is momentum transfer (p – p’) 2 (Mandelstam variable) Applicable for proton and neutron at all energies G4DiffuseElastic Scattering particle (wave) on nucleus viewed as black disk with diffuse edge Applicable p, n, pi, K, lambda, … G4HElastic Glauber model for elastic scattering Applicable for all stable hadrons G4LEpp/G4LEnp taken from detailed phase-shift analysis by SAID for (p,p), (n,n)/(n,p), (p,n) :, good up to 1.2 GeV

17 Geant4 course, Annecy 2008Gunter Folger / CERN17 Inelastic Interactions

18 Geant4 course, Annecy 2008Gunter Folger / CERN 18 Hadronic Interactions from TeV - meV dE/dx ~ A 1/3 GeV TeV hadron ~ GeV - ~100 MeV ~100 MeV - ~10 MeV ~10 MeV to thermal

19 Geant4 course, Annecy 2008Gunter Folger / CERN 19 At Rest Most Hadrons are unstable Only proton and anti-proton are stable! I.e hadrons, except protons have Decay() 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

20 Geant4 course, Annecy 2008Gunter Folger / CERN 20 Capture Processes At Rest Capture Processes G4MuonMinusCaptureAtRest G4PionMinusAbsorptionAtRest G4KaonMinusAbsorption G4AntiProtonAnnihilationAtRest G4AntiNeutronAnnihilationAtRest Alternative model implemented in CHIPS G4QCaptureAtRest  Applies to all negative particles, and anti-nucleon Neutron with E < ~30 MeV can also be captured G4HadronCaptureProcess uses following models: G4LCapture (mainly for neutrons), simple + fast G4NeutronHPCapture (specifically for neutrons), detailed cross sections, slow

21 Geant4 course, Annecy 2008Gunter Folger / CERN 21 Using Capture processes // Muon minus aProcMan = G4MuonMinus::MuonMinus()->GetProcessManager(); G4MuonMinusCaptureAtRest * theMuonMinusAbsorption = new G4MuonMinusCaptureAtRest(); aProcMan->AddRestProcess(theMuonMinusAbsorption); // PionMinus aProcMan = G4PionMinus::PionMinus()->GetProcessManager(); G4PionMinusAbsorptionAtRest * thePionMinusAbsorption = new G4PionMinusAbsorptionAtRest(); aProcMan->AddRestProcess(thePionMinusAbsorption); … etc…, OR using CHIPS process // Using Chips Capture Process aProcMan = G4PionMinus::PionMinus()->GetProcessManager(); G4QCaptureAtRest * hProcess = new G4QCaptureAtRest(); aProcMan ->AddRestProcess(hProcess);

22 Geant4 course, Annecy 2008Gunter Folger / CERN 22 Low energy neutron transport NeutronHP 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

23 Geant4 course, Annecy 2008Gunter Folger / CERN 23 How to Use G4Processmanager * procMan = G4Neutron::Neutron()->GetProcessManager; G4HadronElasticProcess * aP = new G4HadronElasticProcess G4NeutronHPElastic * HPElastic = new G4NeutronHPElastic; HPElastic->SetMinEnergy(0); HPElastic->SetMaxEnergy(20*MeV); G4NeutronHPElasticData* HPElasticData = new G4NeutronHPElasticData; aP->AddDataSet(HPElasticData); aP->RegisterMe(HPElastic); ProcMan->AddDiscreteProcess(aP); … etc for the other processes

24 Geant4 course, Annecy 2008Gunter Folger / CERN 24 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

25 Geant4 course, Annecy 2008Gunter Folger / CERN 25 Using the PreCompoundModel G4Processmanager * procMan = G4Neutron::Neutron()->GetProcessManager; // equilibrium decay G4ExcitationHandler* theHandler = new G4ExcitationHandler; // preequilibrium G4PrecompoundModel* preModel = new G4PrecompoundModel(theHandler); //Create equilibrium decay models and assign to Precompound model G4NeutronInelasticProcess* nProc = new G4NeutronInelasticProcess; // Register model to process, process to particle nProc->RegisterMe(preModel); procMan->AddDiscreteProcess(nProc);

26 Geant4 course, Annecy 2008Gunter Folger / CERN 26 Cascade models ( 100 MeV – GeVs )

27 Geant4 course, Annecy 2008Gunter Folger / CERN 27 Bertini Cascade Model 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, K 0 S,  +         valid for incident energies of 0 – 10 GeV

28 Geant4 course, Annecy 2008Gunter Folger / CERN 28 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

29 Geant4 course, Annecy 2008Gunter Folger / CERN 29 Using the Bertini Cascade G4CascadeInterface* bertini = new G4CascadeInterface() G4ProtonInelasticProcess* pproc = new G4ProtonInelasticProcess(); pproc -> RegisterMe(bertini); proton_manager -> AddDiscreteProcess(pproc);

30 Geant4 course, Annecy 2008Gunter Folger / CERN 30 Binary Cascade Modeling sequence similar to Bertini, except that Nucleus consists of nucleons hadron-nucleon collisions  handled by forming resonances which then decay according to their quantum numbers  Elastic scattering on nucleons particles follow curved trajectories in nuclear potential PreCompound model is used for nuclear de-excitation after cascading phase In Geant4 the Binary cascade model is currently used for incident p, n and  valid for incident p, n from 0 to 10 GeV valid for incident      from 0 to 1.3 GeV A variant of the model, G4BinaryLightIonReaction, is valid for incident light ions or higher if target is made of light nuclei

31 Geant4 course, Annecy 2008Gunter Folger / CERN 31 Using the Binary Cascade Invocation sequence Binary cascade G4BinaryCascade* binary = new G4BinaryCascade(); G4ProtonInelasticProcess* pproc = new G4ProtonInelasticProcess(); pproc -> RegisterMe(binary); proton_manager -> AddDiscreteProcess(pproc); Invocation sequence BinaryLightIonReaction G4BinaryLightIonReaction* ionBinary = new G4BinaryLightIonReaction; G4IonInelasticProcess* ionProc = new G4IonInelasticProcess; ionProc->RegisterMe(ionBinary); genericIonManager->AddDiscreteProcess(ionProc);

32 Geant4 course, Annecy 2008Gunter Folger / CERN 32 Liege Cascade model Well established code in nuclear physics Well tested for spallation studies Uses ABLA code for nuclear de-excitation Valid for p, n, pions up to 2-3 GeV Not applicable to light nuclei ( A< 12-16) Authors collaborate with Geant4 to re- write code in C++ First version will be released with 9.2 in December 2008 ABLA is included as well

33 Geant4 course, Annecy 2008Gunter Folger / CERN 33 LEP (0-40 GeV), HEP (25GeV – TeVs) CM Frame

34 Geant4 course, Annecy 2008Gunter Folger / CERN 34 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

35 Geant4 course, Annecy 2008Gunter Folger / CERN 35 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);

36 Geant4 course, Annecy 2008Gunter Folger / CERN 36 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

37 Geant4 course, Annecy 2008Gunter Folger / CERN 37 String Model Algorithm Build up 3-dimensional model of nucleus Large -factor collapses nucleus to 2 dimensions Calculate impact parameter with all nucleons Calculate hadron-nucleon collision probabilities use Gaussian density distributions for hadrons and nucleons Form strings String formation and fragmentation into hadrons

38 Geant4 course, Annecy 2008Gunter Folger / CERN 38 Quark Gluon String Model 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

39 Geant4 course, Annecy 2008Gunter Folger / CERN 39 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

40 Geant4 course, Annecy 2008Gunter Folger / CERN 40 Longitudinal String Fragmentation String extends between constituents Break string by inserting q-qbar pair according to u : d : s : qq = 1 : 1 : 0.27 : 0.1 At break -> new string + hadron Created hadron gets longitudinal momentum from sampling fragmentation functions Gaussian Pt, = 0.5 GeV

41 Geant4 course, Annecy 2008Gunter Folger / CERN 41 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);

42 Geant4 course, Annecy 2008Gunter Folger / CERN 42 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

43 Geant4 course, Annecy 2008Gunter Folger / CERN 43 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 T C : model parameter which relates the quasmon mass to the number n of its partons: M 2 Q = 4n(n-1)T 2 C => M Q ~ 2nT C T C = 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

44 Geant4 course, Annecy 2008Gunter Folger / CERN 44 CHIPS Applications u,d,s quarks treated symmetrically (all massless) model can produce kaons, but s suppression parameter is needed,  suppression parameter also required real s-quark mass is taken into account by using masses of strange hadrons CHIPS is a universal method for fragmentation of excited nuclei (containing quasmons). Unique, initial interactions were developed for: interactions at rest such as   - capture, pbar annihilation gamma- and lepto-nuclear reactions hadron-nuclear interaction in-flight are in progress Anti-proton annihilation on p and   capture at rest in a nucleus illustrate two CHIPS modelling sequences

45 Geant4 course, Annecy 2008Gunter Folger / CERN 45 Skipping Electro-nuclear interacions Ion induced interactions Already mentioned Binary light ion cascade QMD model under development Wilson Abrasion/Ablation models available EM Dissociation model Isotope production model Radioactive decay

46 Geant4 course, Annecy 2008Gunter Folger / CERN 46 Summary hadronics Geant4 hadronic physics allows user to choose how a physics process should be implemented: cross sections models Many processes, models and cross sections to choose from hadronic framework makes it easier for users to add his own cross section or model Recent improvements new additions in FTF model Precompound and de-excitation models New Liege cascade implementation, including ABLA Elastic scattering Cross sections

47 Geant4 course, Annecy 2008Gunter Folger / CERN 47 Physics Lists Hadronic Physics lists provided by Geant4 help users in difficult task to compose a complete and consistent set of cross sections, processes, and models for all particles Rely on experience of hadronic developers Advanced examples provide lists for specific cases Reference physics lists attempt to cover many use cases

48 Geant4 course, Annecy 2008Gunter Folger / CERN 48 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  New FTF_BIC is promising alternative 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 results Documentation available from user support page Physics Lists User forum for questions and feedback

49 Geant4 course, Annecy 2008Gunter Folger / CERN 49 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…

50 Geant4 course, Annecy 2008Gunter Folger / CERN 50 Using Reference physics In main(), pass a physics list to runManager: G4VUserPhysicsListG4VUserPhysicsList* physics = new FTF_BIC; runManager->SetUserInitialization(physics);

51 Geant4 course, Annecy 2008Gunter Folger / CERN 51 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

52 Geant4 course, Annecy 2008Gunter Folger / CERN 52 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 Physics lists help users chosing hadronic 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 http://geant4.fnal.gov/hadronic_validation/validation_plots.htm

53 Geant4 course, Annecy 2008Gunter Folger / CERN53 Backup slides

54 Geant4 course, Annecy 2008Gunter Folger / CERN 54 Fission Processes G4HadronFissionProcess can use three models: G4LFission (mostly for neutrons) G4NeutronHPFission (specifically for neutrons) G4ParaFissionModel New spontaneous fission model from LLNL available soon

55 Geant4 course, Annecy 2008Gunter Folger / CERN 55 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)

56 Geant4 course, Annecy 2008Gunter Folger / CERN 56 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


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