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Please see the license in the file LICENSE and URL above * 16 // * for the full disclaimer and the limitatio 16 // * for the full disclaimer and the limitation of liability. * 17 // * 17 // * * 18 // * This code implementation is the result 18 // * This code implementation is the result of the scientific and * 19 // * technical work of the GEANT4 collaboratio 19 // * technical work of the GEANT4 collaboration. * 20 // * By using, copying, modifying or distri 20 // * By using, copying, modifying or distributing the software (or * 21 // * any work based on the software) you ag 21 // * any work based on the software) you agree to acknowledge its * 22 // * use in resulting scientific publicati 22 // * use in resulting scientific publications, and indicate your * 23 // * acceptance of all terms of the Geant4 Sof 23 // * acceptance of all terms of the Geant4 Software license. * 24 // ******************************************* 24 // ******************************************************************** 25 // 25 // 26 // 26 // 27 // Author: D.H. Wright 27 // Author: D.H. Wright 28 // Date: 1 May 2012 28 // Date: 1 May 2012 29 // 29 // 30 // Description: model for electron and positro 30 // Description: model for electron and positron interaction with nuclei 31 // using the equivalent photon sp 31 // using the equivalent photon spectrum. A real gamma is 32 // produced from the virtual phot 32 // produced from the virtual photon spectrum and is then 33 // interacted hadronically by the 33 // interacted hadronically by the Bertini cascade at low 34 // energies. At high energies th 34 // energies. At high energies the gamma is treated as a 35 // pi0 and interacted with the nu 35 // pi0 and interacted with the nucleus using the FTFP model. 36 // The electro- and photo-nuclear 36 // The electro- and photo-nuclear cross sections of 37 // M. Kossov are used to generate 37 // M. Kossov are used to generate the virtual photon 38 // spectrum. 38 // spectrum. 39 // 39 // 40 40 41 #include "G4ElectroVDNuclearModel.hh" 41 #include "G4ElectroVDNuclearModel.hh" 42 42 43 #include "G4PhysicalConstants.hh" 43 #include "G4PhysicalConstants.hh" 44 #include "G4SystemOfUnits.hh" 44 #include "G4SystemOfUnits.hh" 45 45 46 #include "G4ElectroNuclearCrossSection.hh" 46 #include "G4ElectroNuclearCrossSection.hh" 47 #include "G4PhotoNuclearCrossSection.hh" 47 #include "G4PhotoNuclearCrossSection.hh" 48 #include "G4CrossSectionDataSetRegistry.hh" 48 #include "G4CrossSectionDataSetRegistry.hh" 49 49 50 #include "G4CascadeInterface.hh" 50 #include "G4CascadeInterface.hh" 51 #include "G4TheoFSGenerator.hh" 51 #include "G4TheoFSGenerator.hh" 52 #include "G4GeneratorPrecompoundInterface.hh" 52 #include "G4GeneratorPrecompoundInterface.hh" 53 #include "G4ExcitationHandler.hh" 53 #include "G4ExcitationHandler.hh" 54 #include "G4PreCompoundModel.hh" 54 #include "G4PreCompoundModel.hh" 55 #include "G4LundStringFragmentation.hh" 55 #include "G4LundStringFragmentation.hh" 56 #include "G4ExcitedStringDecay.hh" 56 #include "G4ExcitedStringDecay.hh" 57 #include "G4FTFModel.hh" 57 #include "G4FTFModel.hh" 58 58 59 #include "G4HadFinalState.hh" 59 #include "G4HadFinalState.hh" 60 #include "G4HadronicInteractionRegistry.hh" 60 #include "G4HadronicInteractionRegistry.hh" 61 #include "G4PhysicsModelCatalog.hh" 61 #include "G4PhysicsModelCatalog.hh" 62 62 63 #include "G4ElectroNuclearCrossSection.hh" << 64 #include "G4PhotoNuclearCrossSection.hh" << 65 #include "G4GammaNuclearXS.hh" << 66 << 67 << 68 G4ElectroVDNuclearModel::G4ElectroVDNuclearMod 63 G4ElectroVDNuclearModel::G4ElectroVDNuclearModel() 69 : G4HadronicInteraction("G4ElectroVDNuclearMo 64 : G4HadronicInteraction("G4ElectroVDNuclearModel"), 70 leptonKE(0.0), photonEnergy(0.0), photonQ2( 65 leptonKE(0.0), photonEnergy(0.0), photonQ2(0.0), secID(-1) 71 { 66 { 72 SetMinEnergy(0.0); 67 SetMinEnergy(0.0); 73 SetMaxEnergy(1*PeV); 68 SetMaxEnergy(1*PeV); 74 << 75 electroXS = 69 electroXS = 76 (G4ElectroNuclearCrossSection*)G4CrossSect 70 (G4ElectroNuclearCrossSection*)G4CrossSectionDataSetRegistry::Instance()-> 77 GetCrossSectionDataSet(G4ElectroNuclearCro 71 GetCrossSectionDataSet(G4ElectroNuclearCrossSection::Default_Name()); 78 if ( electroXS == nullptr ) { << 79 electroXS = new G4ElectroNuclearCrossSecti << 80 } << 81 << 82 gammaXS = 72 gammaXS = 83 (G4PhotoNuclearCrossSection*)G4CrossSectio 73 (G4PhotoNuclearCrossSection*)G4CrossSectionDataSetRegistry::Instance()-> 84 GetCrossSectionDataSet(G4PhotoNuclearCross 74 GetCrossSectionDataSet(G4PhotoNuclearCrossSection::Default_Name()); 85 if ( gammaXS == nullptr ) { << 86 gammaXS = << 87 (G4GammaNuclearXS*)G4CrossSectionDataSet << 88 GetCrossSectionDataSet(G4GammaNuclearXS: << 89 if ( gammaXS == nullptr ) { << 90 gammaXS = new G4PhotoNuclearCrossSection << 91 } << 92 } << 93 75 94 // reuse existing pre-compound model 76 // reuse existing pre-compound model 95 G4GeneratorPrecompoundInterface* precoInterf 77 G4GeneratorPrecompoundInterface* precoInterface 96 = new G4GeneratorPrecompoundInterface(); 78 = new G4GeneratorPrecompoundInterface(); 97 G4HadronicInteraction* p = 79 G4HadronicInteraction* p = 98 G4HadronicInteractionRegistry::Instance()- 80 G4HadronicInteractionRegistry::Instance()->FindModel("PRECO"); 99 G4VPreCompoundModel* pre = static_cast<G4VPr 81 G4VPreCompoundModel* pre = static_cast<G4VPreCompoundModel*>(p); 100 if(!pre) { pre = new G4PreCompoundModel(); } 82 if(!pre) { pre = new G4PreCompoundModel(); } 101 precoInterface->SetDeExcitation(pre); 83 precoInterface->SetDeExcitation(pre); 102 84 103 // string model 85 // string model 104 ftfp = new G4TheoFSGenerator(); 86 ftfp = new G4TheoFSGenerator(); 105 ftfp->SetTransport(precoInterface); 87 ftfp->SetTransport(precoInterface); 106 theFragmentation = new G4LundStringFragmenta 88 theFragmentation = new G4LundStringFragmentation(); 107 theStringDecay = new G4ExcitedStringDecay(th 89 theStringDecay = new G4ExcitedStringDecay(theFragmentation); 108 G4FTFModel* theStringModel = new G4FTFModel( 90 G4FTFModel* theStringModel = new G4FTFModel(); 109 theStringModel->SetFragmentationModel(theStr 91 theStringModel->SetFragmentationModel(theStringDecay); 110 ftfp->SetHighEnergyGenerator(theStringModel) 92 ftfp->SetHighEnergyGenerator(theStringModel); 111 93 112 // Build Bertini model 94 // Build Bertini model 113 bert = new G4CascadeInterface(); 95 bert = new G4CascadeInterface(); 114 96 115 // Creator model ID 97 // Creator model ID 116 secID = G4PhysicsModelCatalog::GetModelID( " 98 secID = G4PhysicsModelCatalog::GetModelID( "model_" + GetModelName() ); 117 } 99 } 118 100 119 G4ElectroVDNuclearModel::~G4ElectroVDNuclearMo 101 G4ElectroVDNuclearModel::~G4ElectroVDNuclearModel() 120 { 102 { 121 delete theFragmentation; 103 delete theFragmentation; 122 delete theStringDecay; 104 delete theStringDecay; 123 } 105 } 124 106 125 void G4ElectroVDNuclearModel::ModelDescription 107 void G4ElectroVDNuclearModel::ModelDescription(std::ostream& outFile) const 126 { 108 { 127 outFile << "G4ElectroVDNuclearModel handles 109 outFile << "G4ElectroVDNuclearModel handles the inelastic scattering\n" 128 << "of e- and e+ from nuclei using t 110 << "of e- and e+ from nuclei using the equivalent photon\n" 129 << "approximation in which the incom 111 << "approximation in which the incoming lepton generates a\n" 130 << "virtual photon at the electromag 112 << "virtual photon at the electromagnetic vertex, and the\n" 131 << "virtual photon is converted to a 113 << "virtual photon is converted to a real photon. At low\n" 132 << "energies, the photon interacts d 114 << "energies, the photon interacts directly with the nucleus\n" 133 << "using the Bertini cascade. At h 115 << "using the Bertini cascade. At high energies the photon\n" 134 << "is converted to a pi0 which inte 116 << "is converted to a pi0 which interacts using the FTFP\n" 135 << "model. The electro- and gamma-n 117 << "model. The electro- and gamma-nuclear cross sections of\n" 136 << "M. Kossov are used to generate t 118 << "M. Kossov are used to generate the virtual photon spectrum\n"; 137 } 119 } 138 120 139 121 140 G4HadFinalState* 122 G4HadFinalState* 141 G4ElectroVDNuclearModel::ApplyYourself(const G 123 G4ElectroVDNuclearModel::ApplyYourself(const G4HadProjectile& aTrack, 142 G4Nucle 124 G4Nucleus& targetNucleus) 143 { 125 { 144 // Set up default particle change (just re 126 // Set up default particle change (just returns initial state) 145 theParticleChange.Clear(); 127 theParticleChange.Clear(); 146 theParticleChange.SetStatusChange(isAlive) 128 theParticleChange.SetStatusChange(isAlive); 147 leptonKE = aTrack.GetKineticEnergy(); 129 leptonKE = aTrack.GetKineticEnergy(); 148 theParticleChange.SetEnergyChange(leptonKE 130 theParticleChange.SetEnergyChange(leptonKE); 149 theParticleChange.SetMomentumChange(aTrack 131 theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit() ); 150 132 151 // Set up sanity checks for real photon pr 133 // Set up sanity checks for real photon production 152 G4DynamicParticle lepton(aTrack.GetDefinit 134 G4DynamicParticle lepton(aTrack.GetDefinition(), aTrack.Get4Momentum() ); 153 135 154 // Need to call GetElementCrossSection bef 136 // Need to call GetElementCrossSection before calling GetEquivalentPhotonEnergy. 155 const G4Material* mat = aTrack.GetMaterial << 137 G4Material* mat = 0; 156 G4int targZ = targetNucleus.GetZ_asInt(); 138 G4int targZ = targetNucleus.GetZ_asInt(); 157 electroXS->GetElementCrossSection(&lepton, 139 electroXS->GetElementCrossSection(&lepton, targZ, mat); 158 140 159 photonEnergy = electroXS->GetEquivalentPho 141 photonEnergy = electroXS->GetEquivalentPhotonEnergy(); 160 // Photon energy cannot exceed lepton ener 142 // Photon energy cannot exceed lepton energy 161 if (photonEnergy < leptonKE) { 143 if (photonEnergy < leptonKE) { 162 photonQ2 = electroXS->GetEquivalentPho 144 photonQ2 = electroXS->GetEquivalentPhotonQ2(photonEnergy); 163 G4double dM = G4Proton::Proton()->GetP 145 G4double dM = G4Proton::Proton()->GetPDGMass() + G4Neutron::Neutron()->GetPDGMass(); 164 // Photon 146 // Photon 165 if (photonEnergy > photonQ2/dM) { 147 if (photonEnergy > photonQ2/dM) { 166 // Produce recoil lepton and trans 148 // Produce recoil lepton and transferred photon 167 G4DynamicParticle* transferredPhot 149 G4DynamicParticle* transferredPhoton = CalculateEMVertex(aTrack, targetNucleus); 168 // Interact gamma with nucleus 150 // Interact gamma with nucleus 169 if (transferredPhoton) CalculateHa 151 if (transferredPhoton) CalculateHadronicVertex(transferredPhoton, targetNucleus); 170 } 152 } 171 } 153 } 172 return &theParticleChange; 154 return &theParticleChange; 173 } 155 } 174 156 175 157 176 G4DynamicParticle* 158 G4DynamicParticle* 177 G4ElectroVDNuclearModel::CalculateEMVertex(con 159 G4ElectroVDNuclearModel::CalculateEMVertex(const G4HadProjectile& aTrack, 178 G4N 160 G4Nucleus& targetNucleus) 179 { 161 { 180 G4DynamicParticle photon(G4Gamma::Gamma(), p 162 G4DynamicParticle photon(G4Gamma::Gamma(), photonEnergy, 181 G4ThreeVector(0.,0. 163 G4ThreeVector(0.,0.,1.) ); 182 164 183 // Get gamma cross section at Q**2 = 0 (real 165 // Get gamma cross section at Q**2 = 0 (real gamma) 184 G4int targZ = targetNucleus.GetZ_asInt(); 166 G4int targZ = targetNucleus.GetZ_asInt(); 185 const G4Material* mat = aTrack.GetMaterial() << 167 G4Material* mat = 0; 186 G4double sigNu = 168 G4double sigNu = 187 gammaXS->GetElementCrossSection(&photon, t 169 gammaXS->GetElementCrossSection(&photon, targZ, mat); 188 170 189 // Change real gamma energy to equivalent en 171 // Change real gamma energy to equivalent energy and get cross section at that energy 190 G4double dM = G4Proton::Proton()->GetPDGMass 172 G4double dM = G4Proton::Proton()->GetPDGMass() + G4Neutron::Neutron()->GetPDGMass(); 191 photon.SetKineticEnergy(photonEnergy - photo 173 photon.SetKineticEnergy(photonEnergy - photonQ2/dM); 192 G4double sigK = 174 G4double sigK = 193 gammaXS->GetElementCrossSection(&photon, t 175 gammaXS->GetElementCrossSection(&photon, targZ, mat); 194 G4double rndFraction = electroXS->GetVirtual 176 G4double rndFraction = electroXS->GetVirtualFactor(photonEnergy, photonQ2); 195 177 196 // No gamma produced, return null ptr 178 // No gamma produced, return null ptr 197 if (sigNu*G4UniformRand() > sigK*rndFraction 179 if (sigNu*G4UniformRand() > sigK*rndFraction) return 0; 198 180 199 // Scatter the lepton 181 // Scatter the lepton 200 G4double mProj = aTrack.GetDefinition()->Get 182 G4double mProj = aTrack.GetDefinition()->GetPDGMass(); 201 G4double mProj2 = mProj*mProj; 183 G4double mProj2 = mProj*mProj; 202 G4double iniE = leptonKE + mProj; 184 G4double iniE = leptonKE + mProj; // Total energy of incident lepton 203 G4double finE = iniE - photonEnergy; 185 G4double finE = iniE - photonEnergy; // Total energy of scattered lepton 204 theParticleChange.SetEnergyChange(finE-mProj 186 theParticleChange.SetEnergyChange(finE-mProj); 205 G4double iniP = std::sqrt(iniE*iniE-mProj2); 187 G4double iniP = std::sqrt(iniE*iniE-mProj2); // Incident lepton momentum 206 G4double finP = std::sqrt(finE*finE-mProj2); 188 G4double finP = std::sqrt(finE*finE-mProj2); // Scattered lepton momentum 207 G4double cost = (iniE*finE - mProj2 - photon 189 G4double cost = (iniE*finE - mProj2 - photonQ2/2.)/iniP/finP; // cos(theta) from Q**2 208 if (cost > 1.) cost= 1.; 190 if (cost > 1.) cost= 1.; 209 if (cost < -1.) cost=-1.; 191 if (cost < -1.) cost=-1.; 210 G4double sint = std::sqrt(1.-cost*cost); 192 G4double sint = std::sqrt(1.-cost*cost); 211 193 212 G4ThreeVector dir = aTrack.Get4Momentum().ve 194 G4ThreeVector dir = aTrack.Get4Momentum().vect().unit(); 213 G4ThreeVector ortx = dir.orthogonal().unit() 195 G4ThreeVector ortx = dir.orthogonal().unit(); // Ortho-normal to scattering plane 214 G4ThreeVector orty = dir.cross(ortx); 196 G4ThreeVector orty = dir.cross(ortx); // Third unit vector 215 G4double phi = twopi*G4UniformRand(); 197 G4double phi = twopi*G4UniformRand(); 216 G4double sinx = sint*std::sin(phi); 198 G4double sinx = sint*std::sin(phi); 217 G4double siny = sint*std::cos(phi); 199 G4double siny = sint*std::cos(phi); 218 G4ThreeVector findir = cost*dir+sinx*ortx+si 200 G4ThreeVector findir = cost*dir+sinx*ortx+siny*orty; 219 theParticleChange.SetMomentumChange(findir); 201 theParticleChange.SetMomentumChange(findir); // change lepton direction 220 202 221 // Create a gamma with momentum equal to mom 203 // Create a gamma with momentum equal to momentum transfer 222 G4ThreeVector photonMomentum = iniP*dir - fi 204 G4ThreeVector photonMomentum = iniP*dir - finP*findir; 223 G4DynamicParticle* gamma = new G4DynamicPart 205 G4DynamicParticle* gamma = new G4DynamicParticle(G4Gamma::Gamma(), 224 206 photonEnergy, photonMomentum); 225 return gamma; 207 return gamma; 226 } 208 } 227 209 228 210 229 void 211 void 230 G4ElectroVDNuclearModel::CalculateHadronicVert 212 G4ElectroVDNuclearModel::CalculateHadronicVertex(G4DynamicParticle* incident, 231 213 G4Nucleus& target) 232 { 214 { 233 G4HadFinalState* hfs = 0; 215 G4HadFinalState* hfs = 0; 234 G4double gammaE = incident->GetTotalEnergy() 216 G4double gammaE = incident->GetTotalEnergy(); 235 217 236 if (gammaE < 10*GeV) { 218 if (gammaE < 10*GeV) { 237 G4HadProjectile projectile(*incident); 219 G4HadProjectile projectile(*incident); 238 hfs = bert->ApplyYourself(projectile, targ 220 hfs = bert->ApplyYourself(projectile, target); 239 } else { 221 } else { 240 // At high energies convert incident gamma 222 // At high energies convert incident gamma to a pion 241 G4double piMass = G4PionZero::PionZero()-> 223 G4double piMass = G4PionZero::PionZero()->GetPDGMass(); 242 G4double piMom = std::sqrt(gammaE*gammaE - 224 G4double piMom = std::sqrt(gammaE*gammaE - piMass*piMass); 243 G4ThreeVector piMomentum(incident->GetMome 225 G4ThreeVector piMomentum(incident->GetMomentumDirection() ); 244 piMomentum *= piMom; 226 piMomentum *= piMom; 245 G4DynamicParticle theHadron(G4PionZero::Pi 227 G4DynamicParticle theHadron(G4PionZero::PionZero(), piMomentum); 246 G4HadProjectile projectile(theHadron); 228 G4HadProjectile projectile(theHadron); 247 hfs = ftfp->ApplyYourself(projectile, targ 229 hfs = ftfp->ApplyYourself(projectile, target); 248 } 230 } 249 231 250 delete incident; 232 delete incident; 251 233 252 // Assign the creator model ID to the second 234 // Assign the creator model ID to the secondaries 253 for ( size_t i = 0; i < hfs->GetNumberOfSeco 235 for ( size_t i = 0; i < hfs->GetNumberOfSecondaries(); ++i ) { 254 hfs->GetSecondary( i )->SetCreatorModelID( 236 hfs->GetSecondary( i )->SetCreatorModelID( secID ); 255 } 237 } 256 238 257 // Copy secondaries from sub-model to model 239 // Copy secondaries from sub-model to model 258 theParticleChange.AddSecondaries(hfs); 240 theParticleChange.AddSecondaries(hfs); 259 } 241 } 260 242 261 243