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1 // 1 2 // ******************************************* 3 // * License and Disclaimer 4 // * 5 // * The Geant4 software is copyright of th 6 // * the Geant4 Collaboration. It is provided 7 // * conditions of the Geant4 Software License 8 // * LICENSE and available at http://cern.ch/ 9 // * include a list of copyright holders. 10 // * 11 // * Neither the authors of this software syst 12 // * institutes,nor the agencies providing fin 13 // * work make any representation or warran 14 // * regarding this software system or assum 15 // * use. Please see the license in the file 16 // * for the full disclaimer and the limitatio 17 // * 18 // * This code implementation is the result 19 // * technical work of the GEANT4 collaboratio 20 // * By using, copying, modifying or distri 21 // * any work based on the software) you ag 22 // * use in resulting scientific publicati 23 // * acceptance of all terms of the Geant4 Sof 24 // ******************************************* 25 // 26 // 27 // ------------------------------------------- 28 // 29 // GEANT4 Class file 30 // 31 // 32 // File name: G4eplusTo2or3GammaModel 33 // 34 // Author: Vladimir Ivanchenko and Omrame 35 // 36 // Creation date: 29.03.2018 37 // 38 // 39 // ------------------------------------------- 40 // 41 //....oooOO0OOooo........oooOO0OOooo........oo 42 //....oooOO0OOooo........oooOO0OOooo........oo 43 44 45 #include "G4eplusTo2or3GammaModel.hh" 46 #include "G4eplusTo3GammaOKVIModel.hh" 47 #include "G4PhysicalConstants.hh" 48 #include "G4SystemOfUnits.hh" 49 #include "G4EmParameters.hh" 50 #include "G4TrackStatus.hh" 51 #include "G4Electron.hh" 52 #include "G4Positron.hh" 53 #include "G4Gamma.hh" 54 #include "G4DataVector.hh" 55 #include "G4PhysicsVector.hh" 56 #include "G4PhysicsLogVector.hh" 57 #include "G4RandomDirection.hh" 58 #include "Randomize.hh" 59 #include "G4ParticleChangeForGamma.hh" 60 #include "G4Log.hh" 61 #include "G4Exp.hh" 62 63 //....oooOO0OOooo........oooOO0OOooo........oo 64 65 G4PhysicsVector* G4eplusTo2or3GammaModel::fCro 66 G4PhysicsVector* G4eplusTo2or3GammaModel::f3GP 67 68 G4eplusTo2or3GammaModel::G4eplusTo2or3GammaMod 69 : G4VEmModel("eplusTo2or3gamma"), 70 fDeltaMin(0.001), 71 fDelta(fDeltaMin), 72 fGammaTh(CLHEP::MeV) 73 { 74 theGamma = G4Gamma::Gamma(); 75 fParticleChange = nullptr; 76 f3GModel = new G4eplusTo3GammaOKVIModel(); 77 SetTripletModel(f3GModel); 78 79 // instantiate vectors once 80 if (nullptr == fCrossSection) { 81 G4double emin = 10*CLHEP::eV; 82 G4double emax = 100*CLHEP::TeV; 83 G4int nbins = 20*G4lrint(std::log10(emax/e 84 fCrossSection = new G4PhysicsLogVector(emi 85 f3GProbability = new G4PhysicsLogVector(em 86 } 87 } 88 89 //....oooOO0OOooo........oooOO0OOooo........oo 90 91 G4eplusTo2or3GammaModel::~G4eplusTo2or3GammaMo 92 { 93 if (IsMaster()) { 94 delete fCrossSection; 95 delete f3GProbability; 96 fCrossSection = nullptr; 97 f3GProbability = nullptr; 98 } 99 } 100 101 //....oooOO0OOooo........oooOO0OOooo........oo 102 103 void G4eplusTo2or3GammaModel::Initialise(const 104 const G4DataVector& cuts) 105 { 106 // here particle change is set for the tripl 107 if (nullptr == fParticleChange) { 108 fParticleChange = GetParticleChangeForGamm 109 } 110 // initialialise 3-gamma model before new ru 111 f3GModel->Initialise(p, cuts); 112 fGammaTh = G4EmParameters::Instance()->Lowes 113 114 // initialise vectors 115 if (IsMaster()) { 116 std::size_t num = fCrossSection->GetVector 117 for (std::size_t i=0; i<num; ++i) { 118 G4double e = fCrossSection->Energy(i); 119 G4double cs2 = ComputeCrossSectionPerEle 120 G4double cs3 = f3GModel->ComputeCrossSec 121 cs2 += cs3; 122 fCrossSection->PutValue(i, cs2); 123 G4double y = (cs2 > 0.0) ? cs3/cs2 : 0.0 124 f3GProbability->PutValue(i, y); 125 } 126 fCrossSection->FillSecondDerivatives(); 127 f3GProbability->FillSecondDerivatives(); 128 } 129 } 130 131 //....oooOO0OOooo........oooOO0OOooo........oo 132 133 G4double 134 G4eplusTo2or3GammaModel::ComputeCrossSectionPe 135 { 136 // Calculates the cross section per electron 137 // photons from the Heilter formula with the 138 // annihilation channel. (A.A.) rho is chang 139 140 G4double ekin = std::max(CLHEP::eV, kinEne 141 G4double tau = ekin/CLHEP::electron_mass_ 142 G4double gam = tau + 1.0; 143 G4double gamma2 = gam*gam; 144 G4double bg2 = tau * (tau+2.0); 145 G4double bg = std::sqrt(bg2); 146 G4double rho = (gamma2+4.*gam+1.)*G4Log(gam+ 147 - (gam+3.)/(std::sqrt(gam*gam - 1.)); 148 G4double eGammaCMS = CLHEP::electron_mass_c2 149 fDelta = std::max(fDeltaMin, fGammaTh/eGamma 150 f3GModel->SetDelta(fDelta); 151 152 static const G4double pir2 = 153 CLHEP::pi*CLHEP::classic_electr_radius*CLH 154 G4double cross = (pir2*rho + alpha_rcl2*2.*G 155 156 return cross; 157 } 158 159 //....oooOO0OOooo........oooOO0OOooo........oo 160 161 G4double G4eplusTo2or3GammaModel::ComputeCross 162 const G4Pa 163 G4double k 164 G4double, G4double, G4double) 165 { 166 // Calculates the cross section per atom of 167 G4double cross = Z*fCrossSection->Value(kine 168 return cross; 169 } 170 171 //....oooOO0OOooo........oooOO0OOooo........oo 172 173 G4double G4eplusTo2or3GammaModel::CrossSection 174 const G4Material* material, 175 const G4ParticleDefinition*, 176 G4double kineticEnergy, 177 G4double, G4double) 178 { 179 // Calculates the cross section per volume o 180 G4double eDensity = material->GetElectronDen 181 G4double cross = eDensity*fCrossSection->Val 182 return cross; 183 } 184 185 //....oooOO0OOooo........oooOO0OOooo........oo 186 187 // Polarisation of gamma according to M.H.L.Pr 188 // Nature 4065 (1947) 435. 189 190 void G4eplusTo2or3GammaModel::SampleSecondarie 191 std::vector<G4DynamicParticle*>* 192 const G4M 193 const G4D 194 G4double, 195 { 196 // kill primary positron 197 fParticleChange->SetProposedKineticEnergy(0. 198 fParticleChange->ProposeTrackStatus(fStopAnd 199 200 // Case at rest not considered anymore 201 G4double posiKinEnergy = dp->GetKineticEnerg 202 G4LorentzVector lv(dp->GetMomentum(), 203 posiKinEnergy + 2*CLHEP::electron_mas 204 G4double eGammaCMS = 0.5 * lv.mag(); 205 206 if (G4UniformRand() < f3GProbability->Value( 207 fDelta = std::max(fDeltaMin, fGammaTh/eGam 208 f3GModel->SetDelta(fDelta); 209 f3GModel->SampleSecondaries(vdp, couple, d 210 return; 211 } 212 213 G4ThreeVector dir1 = G4RandomDirection(); 214 G4double phi = CLHEP::twopi * G4UniformRand( 215 G4double cosphi = std::cos(phi); 216 G4double sinphi = std::sin(phi); 217 G4ThreeVector pol1(cosphi, sinphi, 0.0); 218 pol1.rotateUz(dir1); 219 G4LorentzVector lv1(eGammaCMS*dir1, eGammaCM 220 221 G4ThreeVector pol2(-sinphi, cosphi, 0.0); 222 pol2.rotateUz(dir1); 223 224 // transformation to lab system 225 lv1.boost(lv.boostVector()); 226 lv -= lv1; 227 228 //!!! boost of polarisation vector is not ye 229 230 // use constructors optimal for massless par 231 auto aGamma1 = new G4DynamicParticle(G4Gamma 232 aGamma1->SetPolarization(pol1); 233 auto aGamma2 = new G4DynamicParticle(G4Gamma 234 aGamma2->SetPolarization(pol2); 235 236 vdp->push_back(aGamma1); 237 vdp->push_back(aGamma2); 238 } 239 240 //....oooOO0OOooo........oooOO0OOooo........oo 241