[819] | 1 | // |
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| 2 | // ******************************************************************** |
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| 3 | // * License and Disclaimer * |
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| 4 | // * * |
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| 5 | // * The Geant4 software is copyright of the Copyright Holders of * |
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| 6 | // * the Geant4 Collaboration. It is provided under the terms and * |
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| 7 | // * conditions of the Geant4 Software License, included in the file * |
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| 8 | // * LICENSE and available at http://cern.ch/geant4/license . These * |
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| 9 | // * include a list of copyright holders. * |
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| 10 | // * * |
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| 11 | // * Neither the authors of this software system, nor their employing * |
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| 12 | // * institutes,nor the agencies providing financial support for this * |
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| 13 | // * work make any representation or warranty, express or implied, * |
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| 14 | // * regarding this software system or assume any liability for its * |
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| 15 | // * use. Please see the license in the file LICENSE and URL above * |
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| 16 | // * for the full disclaimer and the limitation of liability. * |
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| 17 | // * * |
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| 18 | // * This code implementation is the result of the scientific and * |
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| 19 | // * technical work of the GEANT4 collaboration. * |
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| 20 | // * By using, copying, modifying or distributing the software (or * |
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| 21 | // * any work based on the software) you agree to acknowledge its * |
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| 22 | // * use in resulting scientific publications, and indicate your * |
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| 23 | // * acceptance of all terms of the Geant4 Software license. * |
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| 24 | // ******************************************************************** |
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| 25 | // |
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[1055] | 26 | // $Id: G4eBremsstrahlungModel.cc,v 1.44 2009/04/09 18:41:18 vnivanch Exp $ |
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| 27 | // GEANT4 tag $Name: geant4-09-03-beta-cand-01 $ |
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[819] | 28 | // |
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| 29 | // ------------------------------------------------------------------- |
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| 30 | // |
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| 31 | // GEANT4 Class file |
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| 32 | // |
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| 33 | // |
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| 34 | // File name: G4eBremsstrahlungModel |
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| 35 | // |
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| 36 | // Author: Vladimir Ivanchenko on base of Laszlo Urban code |
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| 37 | // |
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| 38 | // Creation date: 03.01.2002 |
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| 39 | // |
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| 40 | // Modifications: |
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| 41 | // |
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| 42 | // 11-11-02 Fix division by 0 (V.Ivanchenko) |
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| 43 | // 04-12-02 Change G4DynamicParticle constructor in PostStep (V.Ivanchenko) |
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| 44 | // 23-12-02 Change interface in order to move to cut per region (V.Ivanchenko) |
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| 45 | // 24-01-03 Fix for compounds (V.Ivanchenko) |
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| 46 | // 27-01-03 Make models region aware (V.Ivanchenko) |
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| 47 | // 13-02-03 Add name (V.Ivanchenko) |
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| 48 | // 09-05-03 Fix problem of supression function + optimise sampling (V.Ivanchenko) |
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| 49 | // 20-05-04 Correction to ensure unit independence (L.Urban) |
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| 50 | // 08-04-05 Major optimisation of internal interfaces (V.Ivantchenko) |
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| 51 | // 03-08-05 Add extra protection at initialisation (V.Ivantchenko) |
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| 52 | // 07-02-06 public function ComputeCrossSectionPerAtom() (mma) |
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| 53 | // 21-03-06 Fix problem of initialisation in case when cuts are not defined (VI) |
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| 54 | // 27-03-06 Fix calculation of fl parameter at low energy (energy loss) (VI) |
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| 55 | // 15-02-07 correct LPMconstant by a factor 2, thanks to G. Depaola (mma) |
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[961] | 56 | // 09-09-08 MigdalConstant increased in (2pi)^2 times (A.Schaelicke) |
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[819] | 57 | // |
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| 58 | // Class Description: |
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| 59 | // |
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| 60 | // |
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| 61 | // ------------------------------------------------------------------- |
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| 62 | // |
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| 63 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 64 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 65 | |
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| 66 | #include "G4eBremsstrahlungModel.hh" |
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| 67 | #include "G4Electron.hh" |
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| 68 | #include "G4Positron.hh" |
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| 69 | #include "G4Gamma.hh" |
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| 70 | #include "Randomize.hh" |
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| 71 | #include "G4Material.hh" |
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| 72 | #include "G4Element.hh" |
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| 73 | #include "G4ElementVector.hh" |
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| 74 | #include "G4ProductionCutsTable.hh" |
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| 75 | #include "G4DataVector.hh" |
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| 76 | #include "G4ParticleChangeForLoss.hh" |
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| 77 | |
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| 78 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 79 | |
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| 80 | using namespace std; |
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| 81 | |
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| 82 | G4eBremsstrahlungModel::G4eBremsstrahlungModel(const G4ParticleDefinition* p, |
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| 83 | const G4String& nam) |
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| 84 | : G4VEmModel(nam), |
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| 85 | particle(0), |
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| 86 | isElectron(true), |
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| 87 | probsup(1.0), |
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[961] | 88 | MigdalConstant(classic_electr_radius*electron_Compton_length*electron_Compton_length*4.0*pi), |
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[819] | 89 | LPMconstant(fine_structure_const*electron_mass_c2*electron_mass_c2/(4.*pi*hbarc)), |
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| 90 | isInitialised(false) |
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| 91 | { |
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| 92 | if(p) SetParticle(p); |
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| 93 | theGamma = G4Gamma::Gamma(); |
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| 94 | minThreshold = 1.0*keV; |
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| 95 | } |
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| 96 | |
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| 97 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 98 | |
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| 99 | G4eBremsstrahlungModel::~G4eBremsstrahlungModel() |
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| 100 | { |
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| 101 | size_t n = partialSumSigma.size(); |
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| 102 | if(n > 0) { |
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| 103 | for(size_t i=0; i<n; i++) { |
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| 104 | delete partialSumSigma[i]; |
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| 105 | } |
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| 106 | } |
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| 107 | } |
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| 108 | |
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| 109 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 110 | |
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| 111 | void G4eBremsstrahlungModel::SetParticle(const G4ParticleDefinition* p) |
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| 112 | { |
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| 113 | particle = p; |
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| 114 | if(p == G4Electron::Electron()) isElectron = true; |
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| 115 | else isElectron = false; |
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| 116 | } |
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| 117 | |
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| 118 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 119 | |
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| 120 | G4double G4eBremsstrahlungModel::MinEnergyCut(const G4ParticleDefinition*, |
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| 121 | const G4MaterialCutsCouple*) |
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| 122 | { |
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| 123 | return minThreshold; |
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| 124 | } |
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| 125 | |
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| 126 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 127 | |
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| 128 | void G4eBremsstrahlungModel::Initialise(const G4ParticleDefinition* p, |
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| 129 | const G4DataVector& cuts) |
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| 130 | { |
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| 131 | if(p) SetParticle(p); |
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| 132 | highKinEnergy = HighEnergyLimit(); |
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| 133 | lowKinEnergy = LowEnergyLimit(); |
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| 134 | const G4ProductionCutsTable* theCoupleTable= |
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| 135 | G4ProductionCutsTable::GetProductionCutsTable(); |
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| 136 | |
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| 137 | if(theCoupleTable) { |
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| 138 | G4int numOfCouples = theCoupleTable->GetTableSize(); |
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| 139 | |
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| 140 | G4int nn = partialSumSigma.size(); |
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| 141 | G4int nc = cuts.size(); |
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| 142 | if(nn > 0) { |
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| 143 | for (G4int ii=0; ii<nn; ii++){ |
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| 144 | G4DataVector* a=partialSumSigma[ii]; |
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| 145 | if ( a ) delete a; |
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| 146 | } |
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| 147 | partialSumSigma.clear(); |
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| 148 | } |
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| 149 | if(numOfCouples>0) { |
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| 150 | for (G4int i=0; i<numOfCouples; i++) { |
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| 151 | G4double cute = DBL_MAX; |
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| 152 | if(i < nc) cute = cuts[i]; |
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| 153 | const G4MaterialCutsCouple* couple = theCoupleTable->GetMaterialCutsCouple(i); |
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| 154 | const G4Material* material = couple->GetMaterial(); |
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| 155 | G4DataVector* dv = ComputePartialSumSigma(material, 0.5*highKinEnergy, |
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| 156 | std::min(cute, 0.25*highKinEnergy)); |
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| 157 | partialSumSigma.push_back(dv); |
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| 158 | } |
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| 159 | } |
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| 160 | } |
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| 161 | if(isInitialised) return; |
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[1055] | 162 | fParticleChange = GetParticleChangeForLoss(); |
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[819] | 163 | isInitialised = true; |
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| 164 | } |
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| 165 | |
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| 166 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 167 | |
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| 168 | G4double G4eBremsstrahlungModel::ComputeDEDXPerVolume( |
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| 169 | const G4Material* material, |
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| 170 | const G4ParticleDefinition* p, |
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| 171 | G4double kineticEnergy, |
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| 172 | G4double cutEnergy) |
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| 173 | { |
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| 174 | if(!particle) SetParticle(p); |
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| 175 | if(kineticEnergy < lowKinEnergy) return 0.0; |
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| 176 | |
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| 177 | const G4double thigh = 100.*GeV; |
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| 178 | |
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| 179 | G4double cut = std::min(cutEnergy, kineticEnergy); |
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| 180 | |
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| 181 | G4double rate, loss; |
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| 182 | const G4double factorHigh = 36./(1450.*GeV); |
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| 183 | const G4double coef1 = -0.5; |
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| 184 | const G4double coef2 = 2./9.; |
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| 185 | |
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| 186 | const G4ElementVector* theElementVector = material->GetElementVector(); |
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| 187 | const G4double* theAtomicNumDensityVector = material->GetAtomicNumDensityVector(); |
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| 188 | |
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| 189 | G4double totalEnergy = kineticEnergy + electron_mass_c2; |
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| 190 | G4double dedx = 0.0; |
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| 191 | |
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| 192 | // loop for elements in the material |
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| 193 | for (size_t i=0; i<material->GetNumberOfElements(); i++) { |
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| 194 | |
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| 195 | G4double Z = (*theElementVector)[i]->GetZ(); |
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| 196 | G4double natom = theAtomicNumDensityVector[i]; |
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| 197 | |
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| 198 | // loss for MinKinEnergy<KineticEnergy<=100 GeV |
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| 199 | if (kineticEnergy <= thigh) { |
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| 200 | |
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| 201 | // x = log(totalEnergy/electron_mass_c2); |
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| 202 | loss = ComputeBremLoss(Z, kineticEnergy, cut) ; |
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| 203 | if (!isElectron) loss *= PositronCorrFactorLoss(Z, kineticEnergy, cut); |
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| 204 | |
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| 205 | // extrapolation for KineticEnergy>100 GeV |
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| 206 | } else { |
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| 207 | |
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| 208 | // G4double xhigh = log(thigh/electron_mass_c2); |
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| 209 | G4double cuthigh = thigh*0.5; |
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| 210 | |
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| 211 | if (cut < thigh) { |
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| 212 | |
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| 213 | loss = ComputeBremLoss(Z, thigh, cut) ; |
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| 214 | if (!isElectron) loss *= PositronCorrFactorLoss(Z, thigh, cut) ; |
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| 215 | rate = cut/totalEnergy; |
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| 216 | loss *= (1. + coef1*rate + coef2*rate*rate); |
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| 217 | rate = cut/thigh; |
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| 218 | loss /= (1.+coef1*rate+coef2*rate*rate); |
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| 219 | |
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| 220 | } else { |
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| 221 | |
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| 222 | loss = ComputeBremLoss(Z, thigh, cuthigh) ; |
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| 223 | if (!isElectron) loss *= PositronCorrFactorLoss(Z, thigh, cuthigh) ; |
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| 224 | rate = cut/totalEnergy; |
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| 225 | loss *= (1. + coef1*rate + coef2*rate*rate); |
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| 226 | loss *= cut*factorHigh; |
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| 227 | } |
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| 228 | } |
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| 229 | loss *= natom; |
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| 230 | |
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| 231 | G4double kp2 = MigdalConstant*totalEnergy*totalEnergy |
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| 232 | * (material->GetElectronDensity()) ; |
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| 233 | |
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| 234 | // now compute the correction due to the supression(s) |
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| 235 | G4double kmin = 1.*eV; |
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| 236 | G4double kmax = cut; |
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| 237 | |
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| 238 | if (kmax > kmin) { |
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| 239 | |
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| 240 | G4double floss = 0.; |
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| 241 | G4int nmax = 100; |
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| 242 | |
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| 243 | G4double vmin=log(kmin); |
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| 244 | G4double vmax=log(kmax) ; |
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| 245 | G4int nn = (G4int)(nmax*(vmax-vmin)/(log(highKinEnergy)-vmin)) ; |
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| 246 | G4double u,fac,c,v,dv ; |
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| 247 | if(nn > 0) { |
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| 248 | |
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| 249 | dv = (vmax-vmin)/nn ; |
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| 250 | v = vmin-dv ; |
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| 251 | |
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| 252 | for(G4int n=0; n<=nn; n++) { |
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| 253 | |
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| 254 | v += dv; |
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| 255 | u = exp(v); |
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| 256 | fac = u*SupressionFunction(material,kineticEnergy,u); |
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| 257 | fac *= probsup*(u*u/(u*u+kp2))+1.-probsup; |
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| 258 | if ((n==0)||(n==nn)) c=0.5; |
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| 259 | else c=1. ; |
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| 260 | fac *= c ; |
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| 261 | floss += fac ; |
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| 262 | } |
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| 263 | floss *=dv/(kmax-kmin); |
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| 264 | |
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| 265 | } else { |
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| 266 | floss = 1.; |
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| 267 | } |
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| 268 | if(floss > 1.) floss = 1.; |
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| 269 | // correct the loss |
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| 270 | loss *= floss; |
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| 271 | } |
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| 272 | dedx += loss; |
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| 273 | } |
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| 274 | if(dedx < 0.) dedx = 0.; |
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| 275 | return dedx; |
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| 276 | } |
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| 277 | |
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| 278 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 279 | |
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| 280 | G4double G4eBremsstrahlungModel::ComputeBremLoss(G4double Z, G4double T, |
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| 281 | G4double Cut) |
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| 282 | |
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| 283 | // compute loss due to soft brems |
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| 284 | { |
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| 285 | static const G4double beta=1.0, ksi=2.0; |
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| 286 | static const G4double clossh = 0.254 , closslow = 1./3. , alosslow = 1. ; |
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| 287 | static const G4double Tlim= 10.*MeV ; |
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| 288 | |
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| 289 | static const G4double xlim = 1.2 ; |
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| 290 | static const G4int NZ = 8 ; |
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| 291 | static const G4int Nloss = 11 ; |
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| 292 | static const G4double ZZ[NZ] = |
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| 293 | {2.,4.,6.,14.,26.,50.,82.,92.}; |
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| 294 | static const G4double coefloss[NZ][Nloss] = { |
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| 295 | // Z=2 |
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| 296 | { 0.98916, 0.47564, -0.2505, -0.45186, 0.14462, |
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| 297 | 0.21307, -0.013738, -0.045689, -0.0042914, 0.0034429, |
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| 298 | 0.00064189}, |
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| 299 | |
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| 300 | // Z=4 |
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| 301 | { 1.0626, 0.37662, -0.23646, -0.45188, 0.14295, |
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| 302 | 0.22906, -0.011041, -0.051398, -0.0055123, 0.0039919, |
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| 303 | 0.00078003}, |
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| 304 | // Z=6 |
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| 305 | { 1.0954, 0.315, -0.24011, -0.43849, 0.15017, |
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| 306 | 0.23001, -0.012846, -0.052555, -0.0055114, 0.0041283, |
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| 307 | 0.00080318}, |
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| 308 | |
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| 309 | // Z=14 |
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| 310 | { 1.1649, 0.18976, -0.24972, -0.30124, 0.1555, |
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| 311 | 0.13565, -0.024765, -0.027047, -0.00059821, 0.0019373, |
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| 312 | 0.00027647}, |
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| 313 | |
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| 314 | // Z=26 |
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| 315 | { 1.2261, 0.14272, -0.25672, -0.28407, 0.13874, |
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| 316 | 0.13586, -0.020562, -0.026722, -0.00089557, 0.0018665, |
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| 317 | 0.00026981}, |
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| 318 | |
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| 319 | // Z=50 |
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| 320 | { 1.3147, 0.020049, -0.35543, -0.13927, 0.17666, |
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| 321 | 0.073746, -0.036076, -0.013407, 0.0025727, 0.00084005, |
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| 322 | -1.4082e-05}, |
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| 323 | |
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| 324 | // Z=82 |
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| 325 | { 1.3986, -0.10586, -0.49187, -0.0048846, 0.23621, |
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| 326 | 0.031652, -0.052938, -0.0076639, 0.0048181, 0.00056486, |
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| 327 | -0.00011995}, |
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| 328 | |
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| 329 | // Z=92 |
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| 330 | { 1.4217, -0.116, -0.55497, -0.044075, 0.27506, |
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| 331 | 0.081364, -0.058143, -0.023402, 0.0031322, 0.0020201, |
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| 332 | 0.00017519} |
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| 333 | |
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| 334 | } ; |
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| 335 | static G4double aaa = 0.414; |
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| 336 | static G4double bbb = 0.345; |
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| 337 | static G4double ccc = 0.460; |
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| 338 | |
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| 339 | G4int iz = 0; |
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| 340 | G4double delz = 1.e6; |
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| 341 | for (G4int ii=0; ii<NZ; ii++) |
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| 342 | { |
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| 343 | G4double dz = std::abs(Z-ZZ[ii]); |
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| 344 | if(dz < delz) { |
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| 345 | iz = ii; |
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| 346 | delz = dz; |
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| 347 | } |
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| 348 | } |
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| 349 | |
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| 350 | G4double xx = log10(T/MeV); |
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| 351 | G4double fl = 1.; |
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| 352 | |
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| 353 | if (xx <= xlim) |
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| 354 | { |
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| 355 | xx /= xlim; |
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| 356 | G4double yy = 1.0; |
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| 357 | fl = 0.0; |
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| 358 | for (G4int j=0; j<Nloss; j++) { |
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| 359 | fl += yy+coefloss[iz][j]; |
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| 360 | yy *= xx; |
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| 361 | } |
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| 362 | if (fl < 0.00001) fl = 0.00001; |
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| 363 | else if (fl > 1.0) fl = 1.0; |
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| 364 | } |
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| 365 | |
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| 366 | G4double loss; |
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| 367 | G4double E = T+electron_mass_c2 ; |
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| 368 | |
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| 369 | loss = Z*(Z+ksi)*E*E/(T+E)*exp(beta*log(Cut/T))*(2.-clossh*exp(log(Z)/4.)); |
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| 370 | if (T <= Tlim) loss /= exp(closslow*log(Tlim/T)); |
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| 371 | if( T <= Cut) loss *= exp(alosslow*log(T/Cut)); |
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| 372 | // correction |
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| 373 | loss *= (aaa+bbb*T/Tlim)/(1.+ccc*T/Tlim); |
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| 374 | loss *= fl; |
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| 375 | loss /= Avogadro; |
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| 376 | |
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| 377 | return loss; |
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| 378 | } |
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| 379 | |
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| 380 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 381 | |
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| 382 | G4double G4eBremsstrahlungModel::PositronCorrFactorLoss(G4double Z, |
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| 383 | G4double kineticEnergy, G4double cut) |
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| 384 | |
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| 385 | //calculates the correction factor for the energy loss due to bremsstrahlung for positrons |
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| 386 | //the same correction is in the (discrete) bremsstrahlung |
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| 387 | |
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| 388 | { |
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| 389 | static const G4double K = 132.9416*eV ; |
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| 390 | static const G4double a1=4.15e-1, a3=2.10e-3, a5=54.0e-5 ; |
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| 391 | |
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| 392 | G4double x = log(kineticEnergy/(K*Z*Z)), x2 = x*x, x3 = x2*x; |
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| 393 | G4double eta = 0.5+atan(a1*x+a3*x3+a5*x3*x2)/pi; |
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| 394 | G4double e0 = cut/kineticEnergy; |
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| 395 | |
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| 396 | G4double factor = 0.0; |
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| 397 | if (e0 < 1.0) { |
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| 398 | factor=log(1.-e0)/eta; |
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| 399 | factor=exp(factor); |
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| 400 | } |
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| 401 | factor = eta*(1.-factor)/e0; |
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| 402 | |
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| 403 | return factor; |
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| 404 | } |
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| 405 | |
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| 406 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 407 | |
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| 408 | G4double G4eBremsstrahlungModel::CrossSectionPerVolume( |
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| 409 | const G4Material* material, |
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| 410 | const G4ParticleDefinition* p, |
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| 411 | G4double kineticEnergy, |
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| 412 | G4double cutEnergy, |
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| 413 | G4double maxEnergy) |
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| 414 | { |
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| 415 | if(!particle) SetParticle(p); |
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| 416 | G4double cross = 0.0; |
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| 417 | G4double tmax = min(maxEnergy, kineticEnergy); |
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| 418 | G4double cut = max(cutEnergy, minThreshold); |
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| 419 | if(cut >= tmax) return cross; |
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| 420 | |
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| 421 | const G4ElementVector* theElementVector = material->GetElementVector(); |
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| 422 | const G4double* theAtomNumDensityVector = material->GetAtomicNumDensityVector(); |
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| 423 | G4double dum=0.; |
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| 424 | |
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| 425 | for (size_t i=0; i<material->GetNumberOfElements(); i++) { |
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| 426 | |
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| 427 | cross += theAtomNumDensityVector[i] * ComputeCrossSectionPerAtom(p, |
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| 428 | kineticEnergy, (*theElementVector)[i]->GetZ(), dum, cut); |
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| 429 | if (tmax < kineticEnergy) { |
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| 430 | cross -= theAtomNumDensityVector[i] * ComputeCrossSectionPerAtom(p, |
---|
| 431 | kineticEnergy, (*theElementVector)[i]->GetZ(), dum, tmax); |
---|
| 432 | } |
---|
| 433 | } |
---|
| 434 | |
---|
| 435 | // now compute the correction due to the supression(s) |
---|
| 436 | |
---|
| 437 | G4double kmax = tmax; |
---|
| 438 | G4double kmin = cut; |
---|
| 439 | |
---|
| 440 | G4double totalEnergy = kineticEnergy+electron_mass_c2 ; |
---|
| 441 | G4double kp2 = MigdalConstant*totalEnergy*totalEnergy |
---|
| 442 | *(material->GetElectronDensity()); |
---|
| 443 | |
---|
| 444 | G4double fsig = 0.; |
---|
| 445 | G4int nmax = 100; |
---|
| 446 | G4double vmin=log(kmin); |
---|
| 447 | G4double vmax=log(kmax) ; |
---|
| 448 | G4int nn = (G4int)(nmax*(vmax-vmin)/(log(highKinEnergy)-vmin)); |
---|
| 449 | G4double u,fac,c,v,dv,y ; |
---|
| 450 | if(nn > 0) { |
---|
| 451 | |
---|
| 452 | dv = (vmax-vmin)/nn ; |
---|
| 453 | v = vmin-dv ; |
---|
| 454 | for(G4int n=0; n<=nn; n++) { |
---|
| 455 | |
---|
| 456 | v += dv; |
---|
| 457 | u = exp(v); |
---|
| 458 | fac = SupressionFunction(material, kineticEnergy, u); |
---|
| 459 | y = u/kmax; |
---|
| 460 | fac *= (4.-4.*y+3.*y*y)/3.; |
---|
| 461 | fac *= probsup*(u*u/(u*u+kp2))+1.-probsup; |
---|
| 462 | |
---|
| 463 | if ((n==0)||(n==nn)) c=0.5; |
---|
| 464 | else c=1. ; |
---|
| 465 | |
---|
| 466 | fac *= c; |
---|
| 467 | fsig += fac; |
---|
| 468 | } |
---|
| 469 | y = kmin/kmax ; |
---|
| 470 | fsig *=dv/(-4.*log(y)/3.-4.*(1.-y)/3.+0.5*(1.-y*y)); |
---|
| 471 | |
---|
| 472 | } else { |
---|
| 473 | |
---|
| 474 | fsig = 1.; |
---|
| 475 | } |
---|
| 476 | if (fsig > 1.) fsig = 1.; |
---|
| 477 | |
---|
| 478 | // correct the cross section |
---|
| 479 | cross *= fsig; |
---|
| 480 | |
---|
| 481 | return cross; |
---|
| 482 | } |
---|
| 483 | |
---|
| 484 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
---|
| 485 | |
---|
| 486 | G4double G4eBremsstrahlungModel::ComputeCrossSectionPerAtom( |
---|
| 487 | const G4ParticleDefinition*, |
---|
| 488 | G4double kineticEnergy, |
---|
| 489 | G4double Z, G4double, |
---|
| 490 | G4double cut, G4double) |
---|
| 491 | |
---|
| 492 | // Calculates the cross section per atom in GEANT4 internal units. |
---|
| 493 | // |
---|
| 494 | |
---|
| 495 | { |
---|
| 496 | G4double cross = 0.0 ; |
---|
| 497 | if ( kineticEnergy < 1*keV || kineticEnergy < cut) return cross; |
---|
| 498 | |
---|
| 499 | static const G4double ksi=2.0, alfa=1.00; |
---|
| 500 | static const G4double csigh = 0.127, csiglow = 0.25, asiglow = 0.020*MeV ; |
---|
| 501 | static const G4double Tlim = 10.*MeV ; |
---|
| 502 | |
---|
| 503 | static const G4double xlim = 1.2 ; |
---|
| 504 | static const G4int NZ = 8 ; |
---|
| 505 | static const G4int Nsig = 11 ; |
---|
| 506 | static const G4double ZZ[NZ] = |
---|
| 507 | {2.,4.,6.,14.,26.,50.,82.,92.} ; |
---|
| 508 | static const G4double coefsig[NZ][Nsig] = { |
---|
| 509 | // Z=2 |
---|
| 510 | { 0.4638, 0.37748, 0.32249, -0.060362, -0.065004, |
---|
| 511 | -0.033457, -0.004583, 0.011954, 0.0030404, -0.0010077, |
---|
| 512 | -0.00028131}, |
---|
| 513 | |
---|
| 514 | // Z=4 |
---|
| 515 | { 0.50008, 0.33483, 0.34364, -0.086262, -0.055361, |
---|
| 516 | -0.028168, -0.0056172, 0.011129, 0.0027528, -0.00092265, |
---|
| 517 | -0.00024348}, |
---|
| 518 | |
---|
| 519 | // Z=6 |
---|
| 520 | { 0.51587, 0.31095, 0.34996, -0.11623, -0.056167, |
---|
| 521 | -0.0087154, 0.00053943, 0.0054092, 0.00077685, -0.00039635, |
---|
| 522 | -6.7818e-05}, |
---|
| 523 | |
---|
| 524 | // Z=14 |
---|
| 525 | { 0.55058, 0.25629, 0.35854, -0.080656, -0.054308, |
---|
| 526 | -0.049933, -0.00064246, 0.016597, 0.0021789, -0.001327, |
---|
| 527 | -0.00025983}, |
---|
| 528 | |
---|
| 529 | // Z=26 |
---|
| 530 | { 0.5791, 0.26152, 0.38953, -0.17104, -0.099172, |
---|
| 531 | 0.024596, 0.023718, -0.0039205, -0.0036658, 0.00041749, |
---|
| 532 | 0.00023408}, |
---|
| 533 | |
---|
| 534 | // Z=50 |
---|
| 535 | { 0.62085, 0.27045, 0.39073, -0.37916, -0.18878, |
---|
| 536 | 0.23905, 0.095028, -0.068744, -0.023809, 0.0062408, |
---|
| 537 | 0.0020407}, |
---|
| 538 | |
---|
| 539 | // Z=82 |
---|
| 540 | { 0.66053, 0.24513, 0.35404, -0.47275, -0.22837, |
---|
| 541 | 0.35647, 0.13203, -0.1049, -0.034851, 0.0095046, |
---|
| 542 | 0.0030535}, |
---|
| 543 | |
---|
| 544 | // Z=92 |
---|
| 545 | { 0.67143, 0.23079, 0.32256, -0.46248, -0.20013, |
---|
| 546 | 0.3506, 0.11779, -0.1024, -0.032013, 0.0092279, |
---|
| 547 | 0.0028592} |
---|
| 548 | |
---|
| 549 | } ; |
---|
| 550 | |
---|
| 551 | G4int iz = 0 ; |
---|
| 552 | G4double delz = 1.e6 ; |
---|
| 553 | for (G4int ii=0; ii<NZ; ii++) |
---|
| 554 | { |
---|
| 555 | G4double absdelz = std::abs(Z-ZZ[ii]); |
---|
| 556 | if(absdelz < delz) |
---|
| 557 | { |
---|
| 558 | iz = ii ; |
---|
| 559 | delz = absdelz; |
---|
| 560 | } |
---|
| 561 | } |
---|
| 562 | |
---|
| 563 | G4double xx = log10(kineticEnergy/MeV) ; |
---|
| 564 | G4double fs = 1. ; |
---|
| 565 | |
---|
| 566 | if (xx <= xlim) { |
---|
| 567 | |
---|
| 568 | fs = coefsig[iz][Nsig-1] ; |
---|
| 569 | for (G4int j=Nsig-2; j>=0; j--) { |
---|
| 570 | |
---|
| 571 | fs = fs*xx+coefsig[iz][j] ; |
---|
| 572 | } |
---|
| 573 | if(fs < 0.) fs = 0.; |
---|
| 574 | } |
---|
| 575 | |
---|
| 576 | cross = Z*(Z+ksi)*(1.-csigh*exp(log(Z)/4.))*pow(log(kineticEnergy/cut),alfa); |
---|
| 577 | |
---|
| 578 | if (kineticEnergy <= Tlim) |
---|
| 579 | cross *= exp(csiglow*log(Tlim/kineticEnergy)) |
---|
| 580 | *(1.+asiglow/(sqrt(Z)*kineticEnergy)); |
---|
| 581 | |
---|
| 582 | if (!isElectron) |
---|
| 583 | cross *= PositronCorrFactorSigma(Z, kineticEnergy, cut); |
---|
| 584 | |
---|
| 585 | cross *= fs/Avogadro ; |
---|
| 586 | |
---|
| 587 | if (cross < 0.) cross = 0.; |
---|
| 588 | return cross; |
---|
| 589 | } |
---|
| 590 | |
---|
| 591 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
---|
| 592 | |
---|
| 593 | G4double G4eBremsstrahlungModel::PositronCorrFactorSigma( G4double Z, |
---|
| 594 | G4double kineticEnergy, G4double cut) |
---|
| 595 | |
---|
| 596 | //Calculates the correction factor for the total cross section of the positron |
---|
| 597 | // bremsstrahl. |
---|
| 598 | // Eta is the ratio of positron to electron energy loss by bremstrahlung. |
---|
| 599 | // A parametrized formula from L. Urban is used to estimate eta. It is a fit to |
---|
| 600 | // the results of L. Kim & al: Phys Rev. A33,3002 (1986) |
---|
| 601 | |
---|
| 602 | { |
---|
| 603 | static const G4double K = 132.9416*eV; |
---|
| 604 | static const G4double a1 = 4.15e-1, a3 = 2.10e-3, a5 = 54.0e-5; |
---|
| 605 | |
---|
| 606 | G4double x = log(kineticEnergy/(K*Z*Z)); |
---|
| 607 | G4double x2 = x*x; |
---|
| 608 | G4double x3 = x2*x; |
---|
| 609 | G4double eta = 0.5 + atan(a1*x + a3*x3 + a5*x3*x2)/pi ; |
---|
| 610 | G4double alfa = (1. - eta)/eta; |
---|
| 611 | return eta*pow((1. - cut/kineticEnergy), alfa); |
---|
| 612 | } |
---|
| 613 | |
---|
| 614 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
---|
| 615 | |
---|
| 616 | G4DataVector* G4eBremsstrahlungModel::ComputePartialSumSigma( |
---|
| 617 | const G4Material* material, |
---|
| 618 | G4double kineticEnergy, |
---|
| 619 | G4double cut) |
---|
| 620 | |
---|
| 621 | // Build the table of cross section per element. |
---|
| 622 | //The table is built for MATERIALS. |
---|
| 623 | // This table is used by DoIt to select randomly an element in the material. |
---|
| 624 | { |
---|
| 625 | G4int nElements = material->GetNumberOfElements(); |
---|
| 626 | const G4ElementVector* theElementVector = material->GetElementVector(); |
---|
| 627 | const G4double* theAtomNumDensityVector = material->GetAtomicNumDensityVector(); |
---|
| 628 | G4double dum = 0.; |
---|
| 629 | |
---|
| 630 | G4DataVector* dv = new G4DataVector(); |
---|
| 631 | |
---|
| 632 | G4double cross = 0.0; |
---|
| 633 | |
---|
| 634 | for (G4int i=0; i<nElements; i++ ) { |
---|
| 635 | |
---|
| 636 | cross += theAtomNumDensityVector[i] * ComputeCrossSectionPerAtom( particle, |
---|
| 637 | kineticEnergy, (*theElementVector)[i]->GetZ(), dum, cut); |
---|
| 638 | dv->push_back(cross); |
---|
| 639 | } |
---|
| 640 | return dv; |
---|
| 641 | } |
---|
| 642 | |
---|
| 643 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
---|
| 644 | |
---|
| 645 | void G4eBremsstrahlungModel::SampleSecondaries(std::vector<G4DynamicParticle*>* vdp, |
---|
| 646 | const G4MaterialCutsCouple* couple, |
---|
| 647 | const G4DynamicParticle* dp, |
---|
| 648 | G4double tmin, |
---|
| 649 | G4double maxEnergy) |
---|
| 650 | // The emitted gamma energy is sampled using a parametrized formula |
---|
| 651 | // from L. Urban. |
---|
| 652 | // This parametrization is derived from : |
---|
| 653 | // cross-section values of Seltzer and Berger for electron energies |
---|
| 654 | // 1 keV - 10 GeV, |
---|
| 655 | // screened Bethe Heilter differential cross section above 10 GeV, |
---|
| 656 | // Migdal corrections in both case. |
---|
| 657 | // Seltzer & Berger: Nim B 12:95 (1985) |
---|
| 658 | // Nelson, Hirayama & Rogers: Technical report 265 SLAC (1985) |
---|
| 659 | // Migdal: Phys Rev 103:1811 (1956); Messel & Crawford: Pergamon Press (1970) |
---|
| 660 | // |
---|
| 661 | // A modified version of the random number techniques of Butcher&Messel is used |
---|
| 662 | // (Nuc Phys 20(1960),15). |
---|
| 663 | { |
---|
| 664 | G4double kineticEnergy = dp->GetKineticEnergy(); |
---|
| 665 | G4double tmax = min(maxEnergy, kineticEnergy); |
---|
| 666 | if(tmin >= tmax) return; |
---|
| 667 | |
---|
| 668 | // |
---|
| 669 | // GEANT4 internal units. |
---|
| 670 | // |
---|
| 671 | static const G4double |
---|
| 672 | ah10 = 4.67733E+00, ah11 =-6.19012E-01, ah12 = 2.02225E-02, |
---|
| 673 | ah20 =-7.34101E+00, ah21 = 1.00462E+00, ah22 =-3.20985E-02, |
---|
| 674 | ah30 = 2.93119E+00, ah31 =-4.03761E-01, ah32 = 1.25153E-02; |
---|
| 675 | |
---|
| 676 | static const G4double |
---|
| 677 | bh10 = 4.23071E+00, bh11 =-6.10995E-01, bh12 = 1.95531E-02, |
---|
| 678 | bh20 =-7.12527E+00, bh21 = 9.69160E-01, bh22 =-2.74255E-02, |
---|
| 679 | bh30 = 2.69925E+00, bh31 =-3.63283E-01, bh32 = 9.55316E-03; |
---|
| 680 | |
---|
| 681 | static const G4double |
---|
| 682 | al00 =-2.05398E+00, al01 = 2.38815E-02, al02 = 5.25483E-04, |
---|
| 683 | al10 =-7.69748E-02, al11 =-6.91499E-02, al12 = 2.22453E-03, |
---|
| 684 | al20 = 4.06463E-02, al21 =-1.01281E-02, al22 = 3.40919E-04; |
---|
| 685 | |
---|
| 686 | static const G4double |
---|
| 687 | bl00 = 1.04133E+00, bl01 =-9.43291E-03, bl02 =-4.54758E-04, |
---|
| 688 | bl10 = 1.19253E-01, bl11 = 4.07467E-02, bl12 =-1.30718E-03, |
---|
| 689 | bl20 =-1.59391E-02, bl21 = 7.27752E-03, bl22 =-1.94405E-04; |
---|
| 690 | |
---|
| 691 | static const G4double tlow = 1.*MeV; |
---|
| 692 | |
---|
| 693 | G4double gammaEnergy; |
---|
| 694 | G4bool LPMOK = false; |
---|
| 695 | const G4Material* material = couple->GetMaterial(); |
---|
| 696 | |
---|
| 697 | // select randomly one element constituing the material |
---|
| 698 | const G4Element* anElement = SelectRandomAtom(couple); |
---|
| 699 | |
---|
| 700 | // Extract Z factors for this Element |
---|
| 701 | G4double lnZ = 3.*(anElement->GetIonisation()->GetlogZ3()); |
---|
| 702 | G4double FZ = lnZ* (4.- 0.55*lnZ); |
---|
| 703 | G4double ZZ = anElement->GetIonisation()->GetZZ3(); |
---|
| 704 | |
---|
| 705 | // limits of the energy sampling |
---|
| 706 | G4double totalEnergy = kineticEnergy + electron_mass_c2; |
---|
| 707 | G4ThreeVector direction = dp->GetMomentumDirection(); |
---|
| 708 | G4double xmin = tmin/kineticEnergy; |
---|
| 709 | G4double xmax = tmax/kineticEnergy; |
---|
| 710 | G4double kappa = 0.0; |
---|
| 711 | if(xmax >= 1.) xmax = 1.; |
---|
| 712 | else kappa = log(xmax)/log(xmin); |
---|
| 713 | G4double epsilmin = tmin/totalEnergy; |
---|
| 714 | G4double epsilmax = tmax/totalEnergy; |
---|
| 715 | |
---|
| 716 | // Migdal factor |
---|
| 717 | G4double MigdalFactor = (material->GetElectronDensity())*MigdalConstant |
---|
| 718 | / (epsilmax*epsilmax); |
---|
| 719 | |
---|
| 720 | G4double x, epsil, greject, migdal, grejmax, q; |
---|
| 721 | G4double U = log(kineticEnergy/electron_mass_c2); |
---|
| 722 | G4double U2 = U*U; |
---|
| 723 | |
---|
| 724 | // precalculated parameters |
---|
| 725 | G4double ah, bh; |
---|
| 726 | G4double screenfac = 0.0; |
---|
| 727 | |
---|
| 728 | if (kineticEnergy > tlow) { |
---|
| 729 | |
---|
| 730 | G4double ah1 = ah10 + ZZ* (ah11 + ZZ* ah12); |
---|
| 731 | G4double ah2 = ah20 + ZZ* (ah21 + ZZ* ah22); |
---|
| 732 | G4double ah3 = ah30 + ZZ* (ah31 + ZZ* ah32); |
---|
| 733 | |
---|
| 734 | G4double bh1 = bh10 + ZZ* (bh11 + ZZ* bh12); |
---|
| 735 | G4double bh2 = bh20 + ZZ* (bh21 + ZZ* bh22); |
---|
| 736 | G4double bh3 = bh30 + ZZ* (bh31 + ZZ* bh32); |
---|
| 737 | |
---|
| 738 | ah = 1. + (ah1*U2 + ah2*U + ah3) / (U2*U); |
---|
| 739 | bh = 0.75 + (bh1*U2 + bh2*U + bh3) / (U2*U); |
---|
| 740 | |
---|
| 741 | // limit of the screening variable |
---|
| 742 | screenfac = |
---|
| 743 | 136.*electron_mass_c2/((anElement->GetIonisation()->GetZ3())*totalEnergy); |
---|
| 744 | G4double screenmin = screenfac*epsilmin/(1.-epsilmin); |
---|
| 745 | |
---|
| 746 | // Compute the maximum of the rejection function |
---|
| 747 | G4double F1 = max(ScreenFunction1(screenmin) - FZ ,0.); |
---|
| 748 | G4double F2 = max(ScreenFunction2(screenmin) - FZ ,0.); |
---|
| 749 | grejmax = (F1 - epsilmin* (F1*ah - bh*epsilmin*F2))/(42.392 - FZ); |
---|
| 750 | |
---|
| 751 | } else { |
---|
| 752 | |
---|
| 753 | G4double al0 = al00 + ZZ* (al01 + ZZ* al02); |
---|
| 754 | G4double al1 = al10 + ZZ* (al11 + ZZ* al12); |
---|
| 755 | G4double al2 = al20 + ZZ* (al21 + ZZ* al22); |
---|
| 756 | |
---|
| 757 | G4double bl0 = bl00 + ZZ* (bl01 + ZZ* bl02); |
---|
| 758 | G4double bl1 = bl10 + ZZ* (bl11 + ZZ* bl12); |
---|
| 759 | G4double bl2 = bl20 + ZZ* (bl21 + ZZ* bl22); |
---|
| 760 | |
---|
| 761 | ah = al0 + al1*U + al2*U2; |
---|
| 762 | bh = bl0 + bl1*U + bl2*U2; |
---|
| 763 | |
---|
| 764 | // Compute the maximum of the rejection function |
---|
| 765 | grejmax = max(1. + xmin* (ah + bh*xmin), 1.+ah+bh); |
---|
| 766 | G4double xm = -ah/(2.*bh); |
---|
| 767 | if ( xmin < xm && xm < xmax) grejmax = max(grejmax, 1.+ xm* (ah + bh*xm)); |
---|
| 768 | } |
---|
| 769 | |
---|
| 770 | // |
---|
| 771 | // sample the energy rate of the emitted gamma for e- kin energy > 1 MeV |
---|
| 772 | // |
---|
| 773 | |
---|
| 774 | do { |
---|
| 775 | if (kineticEnergy > tlow) { |
---|
| 776 | do { |
---|
| 777 | q = G4UniformRand(); |
---|
| 778 | x = pow(xmin, q + kappa*(1.0 - q)); |
---|
| 779 | epsil = x*kineticEnergy/totalEnergy; |
---|
| 780 | G4double screenvar = screenfac*epsil/(1.0-epsil); |
---|
| 781 | G4double F1 = max(ScreenFunction1(screenvar) - FZ ,0.); |
---|
| 782 | G4double F2 = max(ScreenFunction2(screenvar) - FZ ,0.); |
---|
| 783 | migdal = (1. + MigdalFactor)/(1. + MigdalFactor/(x*x)); |
---|
| 784 | greject = migdal*(F1 - epsil* (ah*F1 - bh*epsil*F2))/(42.392 - FZ); |
---|
| 785 | /* |
---|
| 786 | if ( greject > grejmax ) { |
---|
| 787 | G4cout << "### G4eBremsstrahlungModel Warning: Majoranta exceeded! " |
---|
| 788 | << greject << " > " << grejmax |
---|
| 789 | << " x= " << x |
---|
| 790 | << " e= " << kineticEnergy |
---|
| 791 | << G4endl; |
---|
| 792 | } |
---|
| 793 | */ |
---|
| 794 | } while( greject < G4UniformRand()*grejmax ); |
---|
| 795 | |
---|
| 796 | } else { |
---|
| 797 | |
---|
| 798 | do { |
---|
| 799 | q = G4UniformRand(); |
---|
| 800 | x = pow(xmin, q + kappa*(1.0 - q)); |
---|
| 801 | migdal = (1. + MigdalFactor)/(1. + MigdalFactor/(x*x)); |
---|
| 802 | greject = migdal*(1. + x* (ah + bh*x)); |
---|
| 803 | /* |
---|
| 804 | if ( greject > grejmax ) { |
---|
| 805 | G4cout << "### G4eBremsstrahlungModel Warning: Majoranta exceeded! " |
---|
| 806 | << greject << " > " << grejmax |
---|
| 807 | << " x= " << x |
---|
| 808 | << " e= " << kineticEnergy |
---|
| 809 | << G4endl; |
---|
| 810 | } |
---|
| 811 | */ |
---|
| 812 | } while( greject < G4UniformRand()*grejmax ); |
---|
| 813 | } |
---|
| 814 | /* |
---|
| 815 | if(x > 0.999) { |
---|
| 816 | G4cout << "### G4eBremsstrahlungModel Warning: e= " << kineticEnergy |
---|
| 817 | << " tlow= " << tlow |
---|
| 818 | << " x= " << x |
---|
| 819 | << " greject= " << greject |
---|
| 820 | << " grejmax= " << grejmax |
---|
| 821 | << " migdal= " << migdal |
---|
| 822 | << G4endl; |
---|
| 823 | // if(x >= 1.0) G4Exception("X=1"); |
---|
| 824 | } |
---|
| 825 | */ |
---|
| 826 | gammaEnergy = x*kineticEnergy; |
---|
| 827 | |
---|
[961] | 828 | if (LPMFlag()) { |
---|
[819] | 829 | // take into account the supression due to the LPM effect |
---|
| 830 | if (G4UniformRand() <= SupressionFunction(material,kineticEnergy, |
---|
| 831 | gammaEnergy)) |
---|
| 832 | LPMOK = true; |
---|
| 833 | } |
---|
| 834 | else LPMOK = true; |
---|
| 835 | |
---|
| 836 | } while (!LPMOK); |
---|
| 837 | |
---|
| 838 | // |
---|
| 839 | // angles of the emitted gamma. ( Z - axis along the parent particle) |
---|
| 840 | // |
---|
| 841 | // universal distribution suggested by L. Urban |
---|
| 842 | // (Geant3 manual (1993) Phys211), |
---|
| 843 | // derived from Tsai distribution (Rev Mod Phys 49,421(1977)) |
---|
| 844 | |
---|
| 845 | G4double u; |
---|
| 846 | const G4double a1 = 0.625 , a2 = 3.*a1 , d = 27. ; |
---|
| 847 | |
---|
| 848 | if (9./(9.+d) > G4UniformRand()) u = - log(G4UniformRand()*G4UniformRand())/a1; |
---|
| 849 | else u = - log(G4UniformRand()*G4UniformRand())/a2; |
---|
| 850 | |
---|
| 851 | G4double theta = u*electron_mass_c2/totalEnergy; |
---|
| 852 | |
---|
| 853 | G4double sint = sin(theta); |
---|
| 854 | |
---|
| 855 | G4double phi = twopi * G4UniformRand() ; |
---|
| 856 | |
---|
| 857 | G4ThreeVector gammaDirection(sint*cos(phi),sint*sin(phi), cos(theta)); |
---|
| 858 | gammaDirection.rotateUz(direction); |
---|
| 859 | |
---|
| 860 | // create G4DynamicParticle object for the Gamma |
---|
| 861 | G4DynamicParticle* g = new G4DynamicParticle(theGamma,gammaDirection, |
---|
| 862 | gammaEnergy); |
---|
| 863 | vdp->push_back(g); |
---|
| 864 | |
---|
| 865 | G4double totMomentum = sqrt(kineticEnergy*(totalEnergy + electron_mass_c2)); |
---|
| 866 | G4ThreeVector dir = totMomentum*direction - gammaEnergy*gammaDirection; |
---|
| 867 | direction = dir.unit(); |
---|
| 868 | |
---|
| 869 | // energy of primary |
---|
| 870 | G4double finalE = kineticEnergy - gammaEnergy; |
---|
| 871 | |
---|
| 872 | // stop tracking and create new secondary instead of primary |
---|
[961] | 873 | if(gammaEnergy > SecondaryThreshold()) { |
---|
[819] | 874 | fParticleChange->ProposeTrackStatus(fStopAndKill); |
---|
| 875 | fParticleChange->SetProposedKineticEnergy(0.0); |
---|
| 876 | G4DynamicParticle* el = |
---|
| 877 | new G4DynamicParticle(const_cast<G4ParticleDefinition*>(particle), |
---|
| 878 | direction, finalE); |
---|
| 879 | vdp->push_back(el); |
---|
| 880 | |
---|
| 881 | // continue tracking |
---|
| 882 | } else { |
---|
| 883 | fParticleChange->SetProposedMomentumDirection(direction); |
---|
| 884 | fParticleChange->SetProposedKineticEnergy(finalE); |
---|
| 885 | } |
---|
| 886 | } |
---|
| 887 | |
---|
| 888 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
---|
| 889 | |
---|
| 890 | const G4Element* G4eBremsstrahlungModel::SelectRandomAtom( |
---|
| 891 | const G4MaterialCutsCouple* couple) |
---|
| 892 | { |
---|
| 893 | // select randomly 1 element within the material |
---|
| 894 | |
---|
| 895 | const G4Material* material = couple->GetMaterial(); |
---|
| 896 | G4int nElements = material->GetNumberOfElements(); |
---|
| 897 | const G4ElementVector* theElementVector = material->GetElementVector(); |
---|
| 898 | |
---|
| 899 | const G4Element* elm = 0; |
---|
| 900 | |
---|
| 901 | if(1 < nElements) { |
---|
| 902 | |
---|
| 903 | G4DataVector* dv = partialSumSigma[couple->GetIndex()]; |
---|
| 904 | G4double rval = G4UniformRand()*((*dv)[nElements-1]); |
---|
| 905 | |
---|
| 906 | for (G4int i=0; i<nElements; i++) { |
---|
| 907 | if (rval <= (*dv)[i]) elm = (*theElementVector)[i]; |
---|
| 908 | } |
---|
| 909 | if(!elm) { |
---|
| 910 | G4cout << "G4eBremsstrahlungModel::SelectRandomAtom: Warning -" |
---|
| 911 | << " no elements found in " |
---|
| 912 | << material->GetName() |
---|
| 913 | << G4endl; |
---|
| 914 | elm = (*theElementVector)[0]; |
---|
| 915 | } |
---|
| 916 | } else elm = (*theElementVector)[0]; |
---|
| 917 | |
---|
| 918 | SetCurrentElement(elm); |
---|
| 919 | return elm; |
---|
| 920 | } |
---|
| 921 | |
---|
| 922 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
---|
| 923 | |
---|
| 924 | G4double G4eBremsstrahlungModel::SupressionFunction(const G4Material* material, |
---|
| 925 | G4double kineticEnergy, G4double gammaEnergy) |
---|
| 926 | { |
---|
| 927 | // supression due to the LPM effect+polarisation of the medium/ |
---|
| 928 | // supression due to the polarisation alone |
---|
| 929 | |
---|
| 930 | |
---|
| 931 | G4double totEnergy = kineticEnergy+electron_mass_c2 ; |
---|
| 932 | G4double totEnergySquare = totEnergy*totEnergy ; |
---|
| 933 | |
---|
| 934 | G4double LPMEnergy = LPMconstant*(material->GetRadlen()) ; |
---|
| 935 | |
---|
| 936 | G4double gammaEnergySquare = gammaEnergy*gammaEnergy ; |
---|
| 937 | |
---|
| 938 | G4double electronDensity = material->GetElectronDensity(); |
---|
| 939 | |
---|
| 940 | G4double sp = gammaEnergySquare/ |
---|
| 941 | (gammaEnergySquare+MigdalConstant*totEnergySquare*electronDensity); |
---|
| 942 | |
---|
| 943 | G4double supr = 1.0; |
---|
| 944 | |
---|
[961] | 945 | if (LPMFlag()) { |
---|
[819] | 946 | |
---|
| 947 | G4double s2lpm = LPMEnergy*gammaEnergy/totEnergySquare; |
---|
| 948 | |
---|
| 949 | if (s2lpm < 1.) { |
---|
| 950 | |
---|
| 951 | G4double LPMgEnergyLimit = totEnergySquare/LPMEnergy ; |
---|
| 952 | G4double LPMgEnergyLimit2 = LPMgEnergyLimit*LPMgEnergyLimit; |
---|
| 953 | G4double splim = LPMgEnergyLimit2/ |
---|
| 954 | (LPMgEnergyLimit2+MigdalConstant*totEnergySquare*electronDensity); |
---|
| 955 | G4double w = 1.+1./splim ; |
---|
| 956 | |
---|
| 957 | if ((1.-sp) < 1.e-6) w = s2lpm*(3.-sp); |
---|
| 958 | else w = s2lpm*(1.+1./sp); |
---|
| 959 | |
---|
| 960 | supr = (sqrt(w*w+4.*s2lpm)-w)/(sqrt(w*w+4.)-w) ; |
---|
| 961 | supr /= sp; |
---|
| 962 | } |
---|
| 963 | |
---|
| 964 | } |
---|
| 965 | return supr; |
---|
| 966 | } |
---|
| 967 | |
---|
| 968 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
---|
| 969 | |
---|
| 970 | |
---|