V.Ivanchenko Salamanca1 Geant4: Hadronic Processes 1  Cross sections  Secondary generators  Nuclear interactions at rest  CHIPS model

V.Ivanchenko Salamanca2 Geant4 hadronics Model approach – cross sections and secondary generation are separated. Based of evaluated data libraries: ENDF, Jef, EFF, JENDL, FENDL, CENDL, ENSDF, Brond, and MENDL. Following models are exist now: Elastic cascade Chiral_inv_phase_space Pre-equilibrium High_energy parameterized Low_energy parameterized Isotope_production Neutron_hp Stopping Radiative_decay String fragmentation MARS-17

V.Ivanchenko Salamanca3 Geant4 Hadronics

V.Ivanchenko Salamanca4 Geant4 cross sections Cross elastic and inelastic cross sections are based on Geant3 data Advance parametrisations are provided for p, n, , e –, and   nuclear reactions To access the database on nuclear levels required for simulation of nuclear deexcitations environment variable should be defined: G4LEVELGAMMADATA G4NDL0.2 – without neutron transport G4NDL3.7 – with neutron transport

V.Ivanchenko Salamanca5 Hadronic PhysicsList  G4ParticleDefinition * n = G4Neutron::Neutron();  G4ProcessManager * m = n->GetProcessManager();  G4NeutronInelasticProcess * thePr = new G4NeutronInelasticProcess(“neuInelastic”);  m->AddDiscreteProcess(thePr);  thePr->GetCrossSectionDataStore()-> AddDataSet(new G4NeutronHPInelasticData());  thePr->RegisterMe(new G4NeutronHPInelasticModel())

V.Ivanchenko Salamanca6 Hadronic PhysicsList  Default cross sections are defined  Default models are not defined  Several models can be added to a process  Energy ranges of models must not intersect

V.Ivanchenko Salamanca7 Stopping of negatively charged particles  Negatively charged particles (  -,  -, K - ) loss their energy to ionization and captured by atomic nuclei  Excited nuclear emits nucleons  G4VRestProcess – abstract interface to these processes  They are implemented in G4 hadronic package  Electromagnetic interactions have to be taken into account as well

V.Ivanchenko Salamanca8 Negative muon stopping  The process was described by E.Fermi and E.Teller in 1947  Stopping  - is captured by the host atom into high orbital momentum state of the mesonic atom with a principal quantum number n  = (m  /m e ) 1/2  14  Then muon cascade down to K-shell of the mesonic atom  Auger transitions are dominant for higher orbits  For low orbits radiative dipole transitions dominate Z --

V.Ivanchenko Salamanca9 Negative muon stopping  As a result, Auger electrons and gamma-rays are emitted by the host atoms  On the K-shell muon decays or is captured by the nucleus  Life time is differ from that of free muon  For atom with Z = 11 these two processes have the same probability  The process G4MuonMinusCaptureAtRest can be used for G4 simulation

V.Ivanchenko Salamanca10 Stopping of  –  Negative pions are captured by atomic nucleus before the end of mesonic atom cascade  Two different models: evaporation and absorption describe the neutron spectrum

V.Ivanchenko Salamanca11 Stopping of pbar  Chiral Invariant Phase Space Model (CHIPS)  Branching ratios of final states are reproduced with very high accuracy  These data were not used in the model!

V.Ivanchenko Salamanca12 CHIPS model  Fragmentation of excited hadronic system into hadrons  Based on quark- parton model and asymptotic freedom approach  Assumes massless quarks  Use quark exchange probability and probability of hadronisation  Temperature of hadonic system is a fundamental parameter of the model

V.Ivanchenko Salamanca13 CHIPS model  The probability to find a system of N partons with the mass M at temperature T dW~M 2N-4 e -M/T dM  Automatic energy/ momentum balance  Residual nucleus production  Is applicable to all reactions  Is tuned inside G4 for   and pbar capture;  Is tuned for  -nuclear reactions (giant dipole resonance, delta resonance, and continum)

V.Ivanchenko Salamanca14 CHIPS model  Is tuned inside G4 for electron-nucleus interactions based on equivalent photons approach  Is not tuned for hadron nuclear interactions, need tuning or combining with other models responsible for scattering of incident hadrons on nuclei

V.Ivanchenko Salamanca15 Conclusion remarks  Geant4 toolkit includes a set of models to simulate hadron-nucleus interactions  Models are applicable to different use cases and to different energy ranges  To built optimal combinations of models and cross sections user should know what physics required for his/her application  It is the most complicate domain of G4!