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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 /// 27 /// >> 28 // $Id$ >> 29 // GEANT4 tag $Name: geant4-09-01-ref-00 $ 28 // 30 // 29 // 31 // 30 // ------------------------------------------- 32 // -------------------------------------------------------------- 31 // 33 // 32 // Author: A. Forti 34 // Author: A. Forti 33 // Maria Grazia Pia (Maria.Grazia.Pia@ 35 // Maria Grazia Pia (Maria.Grazia.Pia@cern.ch) 34 // 36 // 35 // History: 37 // History: 36 // -------- 38 // -------- 37 // 02/03/1999 A. Forti 1st implementation 39 // 02/03/1999 A. Forti 1st implementation 38 // 14.03.2000 Veronique Lefebure; 40 // 14.03.2000 Veronique Lefebure; 39 // Change initialisation of lowestEnergyLimit 41 // Change initialisation of lowestEnergyLimit from 1.22 to 1.022. 40 // Note that the hard coded value 1.022 should 42 // Note that the hard coded value 1.022 should be used instead of 41 // 2*electron_mass_c2 in order to agree with t 43 // 2*electron_mass_c2 in order to agree with the value of the data bank EPDL97 42 // 24.04.01 V.Ivanchenko remove RogueWave 44 // 24.04.01 V.Ivanchenko remove RogueWave 43 // 27.07.01 F.Longo correct bug in energy dist 45 // 27.07.01 F.Longo correct bug in energy distribution 44 // 21.01.03 V.Ivanchenko Cut per region 46 // 21.01.03 V.Ivanchenko Cut per region 45 // 25.03.03 F.Longo fix in angular distributio 47 // 25.03.03 F.Longo fix in angular distribution of e+/e- 46 // 24.04.03 V.Ivanchenko - Cut per region mfpt 48 // 24.04.03 V.Ivanchenko - Cut per region mfpt 47 // 49 // 48 // ------------------------------------------- 50 // -------------------------------------------------------------- 49 51 50 #include "G4LowEnergyGammaConversion.hh" 52 #include "G4LowEnergyGammaConversion.hh" 51 53 52 #include "Randomize.hh" 54 #include "Randomize.hh" 53 #include "G4PhysicalConstants.hh" 55 #include "G4PhysicalConstants.hh" 54 #include "G4SystemOfUnits.hh" 56 #include "G4SystemOfUnits.hh" 55 #include "G4ParticleDefinition.hh" 57 #include "G4ParticleDefinition.hh" 56 #include "G4Track.hh" 58 #include "G4Track.hh" 57 #include "G4Step.hh" 59 #include "G4Step.hh" 58 #include "G4ForceCondition.hh" 60 #include "G4ForceCondition.hh" 59 #include "G4Gamma.hh" 61 #include "G4Gamma.hh" 60 #include "G4Electron.hh" 62 #include "G4Electron.hh" 61 #include "G4DynamicParticle.hh" 63 #include "G4DynamicParticle.hh" 62 #include "G4VParticleChange.hh" 64 #include "G4VParticleChange.hh" 63 #include "G4ThreeVector.hh" 65 #include "G4ThreeVector.hh" 64 #include "G4Positron.hh" 66 #include "G4Positron.hh" 65 #include "G4IonisParamElm.hh" 67 #include "G4IonisParamElm.hh" 66 #include "G4Material.hh" 68 #include "G4Material.hh" 67 #include "G4RDVCrossSectionHandler.hh" 69 #include "G4RDVCrossSectionHandler.hh" 68 #include "G4RDCrossSectionHandler.hh" 70 #include "G4RDCrossSectionHandler.hh" 69 #include "G4RDVEMDataSet.hh" 71 #include "G4RDVEMDataSet.hh" 70 #include "G4RDVDataSetAlgorithm.hh" 72 #include "G4RDVDataSetAlgorithm.hh" 71 #include "G4RDLogLogInterpolation.hh" 73 #include "G4RDLogLogInterpolation.hh" 72 #include "G4RDVRangeTest.hh" 74 #include "G4RDVRangeTest.hh" 73 #include "G4RDRangeTest.hh" 75 #include "G4RDRangeTest.hh" 74 #include "G4MaterialCutsCouple.hh" 76 #include "G4MaterialCutsCouple.hh" 75 77 76 G4LowEnergyGammaConversion::G4LowEnergyGammaCo 78 G4LowEnergyGammaConversion::G4LowEnergyGammaConversion(const G4String& processName) 77 : G4VDiscreteProcess(processName), 79 : G4VDiscreteProcess(processName), 78 lowEnergyLimit(1.022000*MeV), 80 lowEnergyLimit(1.022000*MeV), 79 highEnergyLimit(100*GeV), 81 highEnergyLimit(100*GeV), 80 intrinsicLowEnergyLimit(1.022000*MeV), 82 intrinsicLowEnergyLimit(1.022000*MeV), 81 intrinsicHighEnergyLimit(100*GeV), 83 intrinsicHighEnergyLimit(100*GeV), 82 smallEnergy(2.*MeV) 84 smallEnergy(2.*MeV) 83 85 84 { 86 { 85 if (lowEnergyLimit < intrinsicLowEnergyLimit 87 if (lowEnergyLimit < intrinsicLowEnergyLimit || 86 highEnergyLimit > intrinsicHighEnergyLim 88 highEnergyLimit > intrinsicHighEnergyLimit) 87 { 89 { 88 G4Exception("G4LowEnergyGammaConversion: 90 G4Exception("G4LowEnergyGammaConversion::G4LowEnergyGammaConversion()", 89 "OutOfRange", FatalException 91 "OutOfRange", FatalException, 90 "Energy limit outside intrin 92 "Energy limit outside intrinsic process validity range!"); 91 } 93 } 92 94 93 // The following pointer is owned by G4DataH 95 // The following pointer is owned by G4DataHandler 94 96 95 crossSectionHandler = new G4RDCrossSectionHa 97 crossSectionHandler = new G4RDCrossSectionHandler(); 96 crossSectionHandler->Initialise(0,1.0220*MeV 98 crossSectionHandler->Initialise(0,1.0220*MeV,100.*GeV,400); 97 meanFreePathTable = 0; 99 meanFreePathTable = 0; 98 rangeTest = new G4RDRangeTest; 100 rangeTest = new G4RDRangeTest; 99 101 100 if (verboseLevel > 0) 102 if (verboseLevel > 0) 101 { 103 { 102 G4cout << GetProcessName() << " is crea 104 G4cout << GetProcessName() << " is created " << G4endl 103 << "Energy range: " 105 << "Energy range: " 104 << lowEnergyLimit / MeV << " MeV - " 106 << lowEnergyLimit / MeV << " MeV - " 105 << highEnergyLimit / GeV << " GeV" 107 << highEnergyLimit / GeV << " GeV" 106 << G4endl; 108 << G4endl; 107 } 109 } 108 } 110 } 109 111 110 G4LowEnergyGammaConversion::~G4LowEnergyGammaC 112 G4LowEnergyGammaConversion::~G4LowEnergyGammaConversion() 111 { 113 { 112 delete meanFreePathTable; 114 delete meanFreePathTable; 113 delete crossSectionHandler; 115 delete crossSectionHandler; 114 delete rangeTest; 116 delete rangeTest; 115 } 117 } 116 118 117 void G4LowEnergyGammaConversion::BuildPhysicsT 119 void G4LowEnergyGammaConversion::BuildPhysicsTable(const G4ParticleDefinition& ) 118 { 120 { 119 121 120 crossSectionHandler->Clear(); 122 crossSectionHandler->Clear(); 121 G4String crossSectionFile = "pair/pp-cs-"; 123 G4String crossSectionFile = "pair/pp-cs-"; 122 crossSectionHandler->LoadData(crossSectionFi 124 crossSectionHandler->LoadData(crossSectionFile); 123 125 124 delete meanFreePathTable; 126 delete meanFreePathTable; 125 meanFreePathTable = crossSectionHandler->Bui 127 meanFreePathTable = crossSectionHandler->BuildMeanFreePathForMaterials(); 126 } 128 } 127 129 128 G4VParticleChange* G4LowEnergyGammaConversion: 130 G4VParticleChange* G4LowEnergyGammaConversion::PostStepDoIt(const G4Track& aTrack, 129 const G4Step& aStep) 131 const G4Step& aStep) 130 { 132 { 131 // The energies of the e+ e- secondaries are s 133 // The energies of the e+ e- secondaries are sampled using the Bethe - Heitler 132 // cross sections with Coulomb correction. A m 134 // cross sections with Coulomb correction. A modified version of the random 133 // number techniques of Butcher & Messel is us 135 // number techniques of Butcher & Messel is used (Nuc Phys 20(1960),15). 134 136 135 // Note 1 : Effects due to the breakdown of th 137 // Note 1 : Effects due to the breakdown of the Born approximation at low 136 // energy are ignored. 138 // energy are ignored. 137 // Note 2 : The differential cross section imp 139 // Note 2 : The differential cross section implicitly takes account of 138 // pair creation in both nuclear and atomic el 140 // pair creation in both nuclear and atomic electron fields. However triplet 139 // prodution is not generated. 141 // prodution is not generated. 140 142 141 aParticleChange.Initialize(aTrack); 143 aParticleChange.Initialize(aTrack); 142 144 143 const G4MaterialCutsCouple* couple = aTrack. 145 const G4MaterialCutsCouple* couple = aTrack.GetMaterialCutsCouple(); 144 146 145 const G4DynamicParticle* incidentPhoton = aT 147 const G4DynamicParticle* incidentPhoton = aTrack.GetDynamicParticle(); 146 G4double photonEnergy = incidentPhoton->GetK 148 G4double photonEnergy = incidentPhoton->GetKineticEnergy(); 147 G4ParticleMomentum photonDirection = inciden 149 G4ParticleMomentum photonDirection = incidentPhoton->GetMomentumDirection(); 148 150 149 G4double epsilon ; 151 G4double epsilon ; 150 G4double epsilon0 = electron_mass_c2 / photo 152 G4double epsilon0 = electron_mass_c2 / photonEnergy ; 151 153 152 // Do it fast if photon energy < 2. MeV 154 // Do it fast if photon energy < 2. MeV 153 if (photonEnergy < smallEnergy ) 155 if (photonEnergy < smallEnergy ) 154 { 156 { 155 epsilon = epsilon0 + (0.5 - epsilon0) * 157 epsilon = epsilon0 + (0.5 - epsilon0) * G4UniformRand(); 156 } 158 } 157 else 159 else 158 { 160 { 159 // Select randomly one element in the cu 161 // Select randomly one element in the current material 160 const G4Element* element = crossSectionH 162 const G4Element* element = crossSectionHandler->SelectRandomElement(couple,photonEnergy); 161 163 162 if (element == 0) 164 if (element == 0) 163 { 165 { 164 G4cout << "G4LowEnergyGammaConversion::Pos 166 G4cout << "G4LowEnergyGammaConversion::PostStepDoIt - element = 0" << G4endl; 165 } 167 } 166 G4IonisParamElm* ionisation = element->G 168 G4IonisParamElm* ionisation = element->GetIonisation(); 167 if (ionisation == 0) 169 if (ionisation == 0) 168 { 170 { 169 G4cout << "G4LowEnergyGammaConversion::Pos 171 G4cout << "G4LowEnergyGammaConversion::PostStepDoIt - ionisation = 0" << G4endl; 170 } 172 } 171 173 172 // Extract Coulomb factor for this Eleme 174 // Extract Coulomb factor for this Element 173 G4double fZ = 8. * (ionisation->GetlogZ3 175 G4double fZ = 8. * (ionisation->GetlogZ3()); 174 if (photonEnergy > 50. * MeV) fZ += 8. * 176 if (photonEnergy > 50. * MeV) fZ += 8. * (element->GetfCoulomb()); 175 177 176 // Limits of the screening variable 178 // Limits of the screening variable 177 G4double screenFactor = 136. * epsilon0 179 G4double screenFactor = 136. * epsilon0 / (element->GetIonisation()->GetZ3()) ; 178 G4double screenMax = std::exp ((42.24 - 180 G4double screenMax = std::exp ((42.24 - fZ)/8.368) - 0.952 ; 179 G4double screenMin = std::min(4.*screenF 181 G4double screenMin = std::min(4.*screenFactor,screenMax) ; 180 182 181 // Limits of the energy sampling 183 // Limits of the energy sampling 182 G4double epsilon1 = 0.5 - 0.5 * std::sqr 184 G4double epsilon1 = 0.5 - 0.5 * std::sqrt(1. - screenMin / screenMax) ; 183 G4double epsilonMin = std::max(epsilon0, 185 G4double epsilonMin = std::max(epsilon0,epsilon1); 184 G4double epsilonRange = 0.5 - epsilonMin 186 G4double epsilonRange = 0.5 - epsilonMin ; 185 187 186 // Sample the energy rate of the created 188 // Sample the energy rate of the created electron (or positron) 187 G4double screen; 189 G4double screen; 188 G4double gReject ; 190 G4double gReject ; 189 191 190 G4double f10 = ScreenFunction1(screenMin 192 G4double f10 = ScreenFunction1(screenMin) - fZ; 191 G4double f20 = ScreenFunction2(screenMin 193 G4double f20 = ScreenFunction2(screenMin) - fZ; 192 G4double normF1 = std::max(f10 * epsilon 194 G4double normF1 = std::max(f10 * epsilonRange * epsilonRange,0.); 193 G4double normF2 = std::max(1.5 * f20,0.) 195 G4double normF2 = std::max(1.5 * f20,0.); 194 196 195 do { 197 do { 196 if (normF1 / (normF1 + normF2) > G4UniformRa 198 if (normF1 / (normF1 + normF2) > G4UniformRand() ) 197 { 199 { 198 epsilon = 0.5 - epsilonRange * std::pow( 200 epsilon = 0.5 - epsilonRange * std::pow(G4UniformRand(), 0.3333) ; 199 screen = screenFactor / (epsilon * (1. - 201 screen = screenFactor / (epsilon * (1. - epsilon)); 200 gReject = (ScreenFunction1(screen) - fZ) 202 gReject = (ScreenFunction1(screen) - fZ) / f10 ; 201 } 203 } 202 else 204 else 203 { 205 { 204 epsilon = epsilonMin + epsilonRange * G4 206 epsilon = epsilonMin + epsilonRange * G4UniformRand(); 205 screen = screenFactor / (epsilon * (1 - 207 screen = screenFactor / (epsilon * (1 - epsilon)); 206 gReject = (ScreenFunction2(screen) - fZ) 208 gReject = (ScreenFunction2(screen) - fZ) / f20 ; 207 } 209 } 208 } while ( gReject < G4UniformRand() ); 210 } while ( gReject < G4UniformRand() ); 209 211 210 } // End of epsilon sampling 212 } // End of epsilon sampling 211 213 212 // Fix charges randomly 214 // Fix charges randomly 213 215 214 G4double electronTotEnergy; 216 G4double electronTotEnergy; 215 G4double positronTotEnergy; 217 G4double positronTotEnergy; 216 218 217 if (CLHEP::RandBit::shootBit()) 219 if (CLHEP::RandBit::shootBit()) 218 { 220 { 219 electronTotEnergy = (1. - epsilon) * pho 221 electronTotEnergy = (1. - epsilon) * photonEnergy; 220 positronTotEnergy = epsilon * photonEner 222 positronTotEnergy = epsilon * photonEnergy; 221 } 223 } 222 else 224 else 223 { 225 { 224 positronTotEnergy = (1. - epsilon) * pho 226 positronTotEnergy = (1. - epsilon) * photonEnergy; 225 electronTotEnergy = epsilon * photonEner 227 electronTotEnergy = epsilon * photonEnergy; 226 } 228 } 227 229 228 // Scattered electron (positron) angles. ( Z 230 // Scattered electron (positron) angles. ( Z - axis along the parent photon) 229 // Universal distribution suggested by L. Ur 231 // Universal distribution suggested by L. Urban (Geant3 manual (1993) Phys211), 230 // derived from Tsai distribution (Rev. Mod. 232 // derived from Tsai distribution (Rev. Mod. Phys. 49, 421 (1977) 231 233 232 G4double u; 234 G4double u; 233 const G4double a1 = 0.625; 235 const G4double a1 = 0.625; 234 G4double a2 = 3. * a1; 236 G4double a2 = 3. * a1; 235 // G4double d = 27. ; 237 // G4double d = 27. ; 236 238 237 // if (9. / (9. + d) > G4UniformRand()) 239 // if (9. / (9. + d) > G4UniformRand()) 238 if (0.25 > G4UniformRand()) 240 if (0.25 > G4UniformRand()) 239 { 241 { 240 u = - std::log(G4UniformRand() * G4Unifo 242 u = - std::log(G4UniformRand() * G4UniformRand()) / a1 ; 241 } 243 } 242 else 244 else 243 { 245 { 244 u = - std::log(G4UniformRand() * G4Unifo 246 u = - std::log(G4UniformRand() * G4UniformRand()) / a2 ; 245 } 247 } 246 248 247 G4double thetaEle = u*electron_mass_c2/elect 249 G4double thetaEle = u*electron_mass_c2/electronTotEnergy; 248 G4double thetaPos = u*electron_mass_c2/posit 250 G4double thetaPos = u*electron_mass_c2/positronTotEnergy; 249 G4double phi = twopi * G4UniformRand(); 251 G4double phi = twopi * G4UniformRand(); 250 252 251 G4double dxEle= std::sin(thetaEle)*std::cos( 253 G4double dxEle= std::sin(thetaEle)*std::cos(phi),dyEle= std::sin(thetaEle)*std::sin(phi),dzEle=std::cos(thetaEle); 252 G4double dxPos=-std::sin(thetaPos)*std::cos( 254 G4double dxPos=-std::sin(thetaPos)*std::cos(phi),dyPos=-std::sin(thetaPos)*std::sin(phi),dzPos=std::cos(thetaPos); 253 255 254 256 255 // Kinematics of the created pair: 257 // Kinematics of the created pair: 256 // the electron and positron are assumed to 258 // the electron and positron are assumed to have a symetric angular 257 // distribution with respect to the Z axis a 259 // distribution with respect to the Z axis along the parent photon 258 260 259 G4double localEnergyDeposit = 0. ; 261 G4double localEnergyDeposit = 0. ; 260 262 261 aParticleChange.SetNumberOfSecondaries(2) ; 263 aParticleChange.SetNumberOfSecondaries(2) ; 262 G4double electronKineEnergy = std::max(0.,el 264 G4double electronKineEnergy = std::max(0.,electronTotEnergy - electron_mass_c2) ; 263 265 264 // Generate the electron only if with large 266 // Generate the electron only if with large enough range w.r.t. cuts and safety 265 267 266 G4double safety = aStep.GetPostStepPoint()-> 268 G4double safety = aStep.GetPostStepPoint()->GetSafety(); 267 269 268 if (rangeTest->Escape(G4Electron::Electron() 270 if (rangeTest->Escape(G4Electron::Electron(),couple,electronKineEnergy,safety)) 269 { 271 { 270 G4ThreeVector electronDirection (dxEle, 272 G4ThreeVector electronDirection (dxEle, dyEle, dzEle); 271 electronDirection.rotateUz(photonDirecti 273 electronDirection.rotateUz(photonDirection); 272 274 273 G4DynamicParticle* particle1 = new G4Dyn 275 G4DynamicParticle* particle1 = new G4DynamicParticle (G4Electron::Electron(), 274 electronDirection, 276 electronDirection, 275 electronKineEnergy); 277 electronKineEnergy); 276 aParticleChange.AddSecondary(particle1) 278 aParticleChange.AddSecondary(particle1) ; 277 } 279 } 278 else 280 else 279 { 281 { 280 localEnergyDeposit += electronKineEnergy 282 localEnergyDeposit += electronKineEnergy ; 281 } 283 } 282 284 283 // The e+ is always created (even with kinet 285 // The e+ is always created (even with kinetic energy = 0) for further annihilation 284 G4double positronKineEnergy = std::max(0.,po 286 G4double positronKineEnergy = std::max(0.,positronTotEnergy - electron_mass_c2) ; 285 287 286 // Is the local energy deposit correct, if t 288 // Is the local energy deposit correct, if the positron is always created? 287 if (! (rangeTest->Escape(G4Positron::Positro 289 if (! (rangeTest->Escape(G4Positron::Positron(),couple,positronKineEnergy,safety))) 288 { 290 { 289 localEnergyDeposit += positronKineEnergy 291 localEnergyDeposit += positronKineEnergy ; 290 positronKineEnergy = 0. ; 292 positronKineEnergy = 0. ; 291 } 293 } 292 294 293 G4ThreeVector positronDirection (dxPos, dyPo 295 G4ThreeVector positronDirection (dxPos, dyPos, dzPos); 294 positronDirection.rotateUz(photonDirection); 296 positronDirection.rotateUz(photonDirection); 295 297 296 // Create G4DynamicParticle object for the p 298 // Create G4DynamicParticle object for the particle2 297 G4DynamicParticle* particle2 = new G4Dynamic 299 G4DynamicParticle* particle2 = new G4DynamicParticle(G4Positron::Positron(), 298 positronDirection, positron 300 positronDirection, positronKineEnergy); 299 aParticleChange.AddSecondary(particle2) ; 301 aParticleChange.AddSecondary(particle2) ; 300 302 301 aParticleChange.ProposeLocalEnergyDeposit(lo 303 aParticleChange.ProposeLocalEnergyDeposit(localEnergyDeposit) ; 302 304 303 // Kill the incident photon 305 // Kill the incident photon 304 aParticleChange.ProposeMomentumDirection(0., 306 aParticleChange.ProposeMomentumDirection(0.,0.,0.) ; 305 aParticleChange.ProposeEnergy(0.) ; 307 aParticleChange.ProposeEnergy(0.) ; 306 aParticleChange.ProposeTrackStatus(fStopAndK 308 aParticleChange.ProposeTrackStatus(fStopAndKill) ; 307 309 308 // Reset NbOfInteractionLengthLeft and retu 310 // Reset NbOfInteractionLengthLeft and return aParticleChange 309 return G4VDiscreteProcess::PostStepDoIt(aTra 311 return G4VDiscreteProcess::PostStepDoIt(aTrack,aStep); 310 } 312 } 311 313 312 G4bool G4LowEnergyGammaConversion::IsApplicabl 314 G4bool G4LowEnergyGammaConversion::IsApplicable(const G4ParticleDefinition& particle) 313 { 315 { 314 return ( &particle == G4Gamma::Gamma() ); 316 return ( &particle == G4Gamma::Gamma() ); 315 } 317 } 316 318 317 G4double G4LowEnergyGammaConversion::GetMeanFr 319 G4double G4LowEnergyGammaConversion::GetMeanFreePath(const G4Track& track, 318 G4double, // previousStepSize 320 G4double, // previousStepSize 319 G4ForceCondition*) 321 G4ForceCondition*) 320 { 322 { 321 const G4DynamicParticle* photon = track.GetD 323 const G4DynamicParticle* photon = track.GetDynamicParticle(); 322 G4double energy = photon->GetKineticEnergy() 324 G4double energy = photon->GetKineticEnergy(); 323 const G4MaterialCutsCouple* couple = track.G 325 const G4MaterialCutsCouple* couple = track.GetMaterialCutsCouple(); 324 size_t materialIndex = couple->GetIndex(); 326 size_t materialIndex = couple->GetIndex(); 325 327 326 G4double meanFreePath; 328 G4double meanFreePath; 327 if (energy > highEnergyLimit) meanFreePath = 329 if (energy > highEnergyLimit) meanFreePath = meanFreePathTable->FindValue(highEnergyLimit,materialIndex); 328 else if (energy < lowEnergyLimit) meanFreePa 330 else if (energy < lowEnergyLimit) meanFreePath = DBL_MAX; 329 else meanFreePath = meanFreePathTable->FindV 331 else meanFreePath = meanFreePathTable->FindValue(energy,materialIndex); 330 return meanFreePath; 332 return meanFreePath; 331 } 333 } 332 334 333 G4double G4LowEnergyGammaConversion::ScreenFun 335 G4double G4LowEnergyGammaConversion::ScreenFunction1(G4double screenVariable) 334 { 336 { 335 // Compute the value of the screening functi 337 // Compute the value of the screening function 3*phi1 - phi2 336 338 337 G4double value; 339 G4double value; 338 340 339 if (screenVariable > 1.) 341 if (screenVariable > 1.) 340 value = 42.24 - 8.368 * std::log(screenVar 342 value = 42.24 - 8.368 * std::log(screenVariable + 0.952); 341 else 343 else 342 value = 42.392 - screenVariable * (7.796 - 344 value = 42.392 - screenVariable * (7.796 - 1.961 * screenVariable); 343 345 344 return value; 346 return value; 345 } 347 } 346 348 347 G4double G4LowEnergyGammaConversion::ScreenFun 349 G4double G4LowEnergyGammaConversion::ScreenFunction2(G4double screenVariable) 348 { 350 { 349 // Compute the value of the screening functi 351 // Compute the value of the screening function 1.5*phi1 - 0.5*phi2 350 352 351 G4double value; 353 G4double value; 352 354 353 if (screenVariable > 1.) 355 if (screenVariable > 1.) 354 value = 42.24 - 8.368 * std::log(screenVar 356 value = 42.24 - 8.368 * std::log(screenVariable + 0.952); 355 else 357 else 356 value = 41.405 - screenVariable * (5.828 - 358 value = 41.405 - screenVariable * (5.828 - 0.8945 * screenVariable); 357 359 358 return value; 360 return value; 359 } 361 } 360 362