[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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| 26 | // $Id: G4MuPairProductionModel.cc,v 1.35 2007/10/11 13:52:04 vnivanch Exp $ |
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| 27 | // GEANT4 tag $Name: geant4-09-01-patch-02 $ |
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| 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: G4MuPairProductionModel |
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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: 24.06.2002 |
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| 39 | // |
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| 40 | // Modifications: |
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| 41 | // |
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| 42 | // 04-12-02 Change G4DynamicParticle constructor in PostStep (V.Ivanchenko) |
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| 43 | // 23-12-02 Change interface in order to move to cut per region (V.Ivanchenko) |
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| 44 | // 24-01-03 Fix for compounds (V.Ivanchenko) |
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| 45 | // 27-01-03 Make models region aware (V.Ivanchenko) |
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| 46 | // 13-02-03 Add model (V.Ivanchenko) |
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| 47 | // 06-06-03 Fix in cross section calculation for high energy (V.Ivanchenko) |
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| 48 | // 20-10-03 2*xi in ComputeDDMicroscopicCrossSection (R.Kokoulin) |
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| 49 | // 8 integration points in ComputeDMicroscopicCrossSection |
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| 50 | // 12-01-04 Take min cut of e- and e+ not its sum (V.Ivanchenko) |
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| 51 | // 10-02-04 Update parameterisation using R.Kokoulin model (V.Ivanchenko) |
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| 52 | // 28-04-04 For complex materials repeat calculation of max energy for each |
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| 53 | // material (V.Ivanchenko) |
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| 54 | // 01-11-04 Fix bug inside ComputeDMicroscopicCrossSection (R.Kokoulin) |
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| 55 | // 08-04-05 Major optimisation of internal interfaces (V.Ivantchenko) |
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| 56 | // 03-08-05 Add SetParticle method (V.Ivantchenko) |
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| 57 | // 23-10-05 Add protection in sampling of e+e- pair energy needed for |
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| 58 | // low cuts (V.Ivantchenko) |
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| 59 | // 13-02-06 Add ComputeCrossSectionPerAtom (mma) |
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| 60 | // 24-04-07 Add protection in SelectRandomAtom method (V.Ivantchenko) |
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| 61 | // 12-05-06 Updated sampling (use cut) in SelectRandomAtom (A.Bogdanov) |
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| 62 | // 11-10-07 Add ignoreCut flag (V.Ivanchenko) |
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| 63 | |
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| 64 | // |
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| 65 | // Class Description: |
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| 66 | // |
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| 67 | // |
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| 68 | // ------------------------------------------------------------------- |
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| 69 | // |
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| 70 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 71 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 72 | |
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| 73 | #include "G4MuPairProductionModel.hh" |
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| 74 | #include "G4Electron.hh" |
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| 75 | #include "G4Positron.hh" |
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| 76 | #include "G4MuonMinus.hh" |
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| 77 | #include "G4MuonPlus.hh" |
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| 78 | #include "Randomize.hh" |
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| 79 | #include "G4Material.hh" |
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| 80 | #include "G4Element.hh" |
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| 81 | #include "G4ElementVector.hh" |
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| 82 | #include "G4ProductionCutsTable.hh" |
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| 83 | #include "G4ParticleChangeForLoss.hh" |
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| 84 | #include "G4ParticleChangeForGamma.hh" |
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| 85 | |
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| 86 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 87 | |
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| 88 | // static members |
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| 89 | // |
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| 90 | G4double G4MuPairProductionModel::zdat[]={1., 4., 13., 29., 92.}; |
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| 91 | G4double G4MuPairProductionModel::adat[]={1.01, 9.01, 26.98, 63.55, 238.03}; |
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| 92 | G4double G4MuPairProductionModel::tdat[]={1.e3, 1.e4, 1.e5, 1.e6, 1.e7, 1.e8, |
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| 93 | 1.e9, 1.e10}; |
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| 94 | G4double G4MuPairProductionModel::xgi[]={ 0.0199, 0.1017, 0.2372, 0.4083, |
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| 95 | 0.5917, 0.7628, 0.8983, 0.9801 }; |
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| 96 | G4double G4MuPairProductionModel::wgi[]={ 0.0506, 0.1112, 0.1569, 0.1813, |
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| 97 | 0.1813, 0.1569, 0.1112, 0.0506 }; |
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| 98 | |
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| 99 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 100 | |
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| 101 | using namespace std; |
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| 102 | |
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| 103 | G4MuPairProductionModel::G4MuPairProductionModel(const G4ParticleDefinition* p, |
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| 104 | const G4String& nam) |
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| 105 | : G4VEmModel(nam), |
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| 106 | minPairEnergy(4.*electron_mass_c2), |
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| 107 | lowestKinEnergy(1.*GeV), |
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| 108 | factorForCross(4.*fine_structure_const*fine_structure_const |
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| 109 | *classic_electr_radius*classic_electr_radius/(3.*pi)), |
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| 110 | sqrte(sqrt(exp(1.))), |
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| 111 | currentZ(0), |
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| 112 | particle(0), |
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| 113 | nzdat(5), |
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| 114 | ntdat(8), |
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| 115 | nbiny(1000), |
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| 116 | nmaxElements(0), |
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| 117 | ymin(-5.), |
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| 118 | ymax(0.), |
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| 119 | dy((ymax-ymin)/nbiny), |
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| 120 | ignoreCut(false), |
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| 121 | samplingTablesAreFilled(false) |
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| 122 | { |
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| 123 | SetLowEnergyLimit(minPairEnergy); |
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| 124 | |
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| 125 | theElectron = G4Electron::Electron(); |
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| 126 | thePositron = G4Positron::Positron(); |
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| 127 | |
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| 128 | if(p) SetParticle(p); |
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| 129 | } |
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| 130 | |
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| 131 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 132 | |
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| 133 | G4MuPairProductionModel::~G4MuPairProductionModel() |
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| 134 | {} |
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| 135 | |
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| 136 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 137 | |
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| 138 | G4double G4MuPairProductionModel::MinEnergyCut(const G4ParticleDefinition*, |
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| 139 | const G4MaterialCutsCouple* ) |
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| 140 | { |
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| 141 | return minPairEnergy; |
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| 142 | } |
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| 143 | |
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| 144 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 145 | |
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| 146 | void G4MuPairProductionModel::SetParticle(const G4ParticleDefinition* p) |
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| 147 | { |
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| 148 | if(!particle) { |
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| 149 | particle = p; |
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| 150 | particleMass = particle->GetPDGMass(); |
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| 151 | } |
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| 152 | } |
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| 153 | |
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| 154 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 155 | |
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| 156 | void G4MuPairProductionModel::Initialise(const G4ParticleDefinition* p, |
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| 157 | const G4DataVector&) |
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| 158 | { |
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| 159 | if (!samplingTablesAreFilled) { |
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| 160 | if(p) SetParticle(p); |
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| 161 | MakeSamplingTables(); |
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| 162 | } |
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| 163 | if(pParticleChange) { |
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| 164 | if(ignoreCut) { |
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| 165 | gParticleChange = |
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| 166 | reinterpret_cast<G4ParticleChangeForGamma*>(pParticleChange); |
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| 167 | fParticleChange = 0; |
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| 168 | } else { |
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| 169 | fParticleChange = |
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| 170 | reinterpret_cast<G4ParticleChangeForLoss*>(pParticleChange); |
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| 171 | gParticleChange = 0; |
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| 172 | } |
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| 173 | } else { |
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| 174 | fParticleChange = new G4ParticleChangeForLoss(); |
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| 175 | gParticleChange = 0; |
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| 176 | } |
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| 177 | } |
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| 178 | |
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| 179 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 180 | |
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| 181 | G4double G4MuPairProductionModel::ComputeDEDXPerVolume( |
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| 182 | const G4Material* material, |
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| 183 | const G4ParticleDefinition*, |
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| 184 | G4double kineticEnergy, |
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| 185 | G4double cutEnergy) |
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| 186 | { |
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| 187 | G4double dedx = 0.0; |
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| 188 | if (cutEnergy <= minPairEnergy || kineticEnergy <= lowestKinEnergy |
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| 189 | || ignoreCut) |
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| 190 | return dedx; |
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| 191 | |
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| 192 | const G4ElementVector* theElementVector = material->GetElementVector(); |
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| 193 | const G4double* theAtomicNumDensityVector = |
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| 194 | material->GetAtomicNumDensityVector(); |
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| 195 | |
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| 196 | // loop for elements in the material |
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| 197 | for (size_t i=0; i<material->GetNumberOfElements(); i++) { |
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| 198 | G4double Z = (*theElementVector)[i]->GetZ(); |
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| 199 | SetCurrentElement(Z); |
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| 200 | G4double tmax = MaxSecondaryEnergy(particle, kineticEnergy); |
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| 201 | G4double loss = ComputMuPairLoss(Z, kineticEnergy, cutEnergy, tmax); |
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| 202 | dedx += loss*theAtomicNumDensityVector[i]; |
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| 203 | } |
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| 204 | if (dedx < 0.) dedx = 0.; |
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| 205 | return dedx; |
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| 206 | } |
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| 207 | |
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| 208 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 209 | |
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| 210 | G4double G4MuPairProductionModel::ComputMuPairLoss(G4double Z, |
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| 211 | G4double tkin, |
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| 212 | G4double cutEnergy, |
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| 213 | G4double tmax) |
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| 214 | { |
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| 215 | SetCurrentElement(Z); |
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| 216 | G4double loss = 0.0; |
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| 217 | |
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| 218 | G4double cut = min(cutEnergy,tmax); |
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| 219 | if(cut <= minPairEnergy) return loss; |
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| 220 | |
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| 221 | // calculate the rectricted loss |
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| 222 | // numerical integration in log(PairEnergy) |
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| 223 | G4double ak1=6.9; |
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| 224 | G4double ak2=1.0; |
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| 225 | G4double aaa = log(minPairEnergy); |
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| 226 | G4double bbb = log(cut); |
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| 227 | G4int kkk = (G4int)((bbb-aaa)/ak1+ak2); |
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| 228 | if (kkk > 8) kkk = 8; |
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| 229 | G4double hhh = (bbb-aaa)/(G4double)kkk; |
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| 230 | G4double x = aaa; |
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| 231 | |
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| 232 | for (G4int l=0 ; l<kkk; l++) |
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| 233 | { |
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| 234 | |
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| 235 | for (G4int ll=0; ll<8; ll++) |
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| 236 | { |
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| 237 | G4double ep = exp(x+xgi[ll]*hhh); |
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| 238 | loss += wgi[ll]*ep*ep*ComputeDMicroscopicCrossSection(tkin, Z, ep); |
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| 239 | } |
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| 240 | x += hhh; |
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| 241 | } |
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| 242 | loss *= hhh; |
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| 243 | if (loss < 0.) loss = 0.; |
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| 244 | return loss; |
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| 245 | } |
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| 246 | |
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| 247 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 248 | |
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| 249 | G4double G4MuPairProductionModel::ComputeMicroscopicCrossSection( |
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| 250 | G4double tkin, |
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| 251 | G4double Z, |
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| 252 | G4double cut) |
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| 253 | |
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| 254 | { |
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| 255 | G4double cross = 0. ; |
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| 256 | |
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| 257 | SetCurrentElement(Z); |
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| 258 | G4double tmax = MaxSecondaryEnergy(particle, tkin); |
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| 259 | |
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| 260 | if (tmax <= cut) return cross; |
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| 261 | |
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| 262 | G4double ak1=6.9 ; |
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| 263 | G4double ak2=1.0 ; |
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| 264 | G4double aaa = log(cut); |
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| 265 | G4double bbb = log(tmax); |
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| 266 | G4int kkk = (G4int)((bbb-aaa)/ak1 + ak2); |
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| 267 | if(kkk > 8) kkk = 8; |
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| 268 | G4double hhh = (bbb-aaa)/float(kkk); |
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| 269 | G4double x = aaa; |
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| 270 | |
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| 271 | for(G4int l=0; l<kkk; l++) |
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| 272 | { |
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| 273 | for(G4int i=0; i<8; i++) |
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| 274 | { |
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| 275 | G4double ep = exp(x + xgi[i]*hhh); |
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| 276 | cross += ep*wgi[i]*ComputeDMicroscopicCrossSection(tkin, Z, ep); |
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| 277 | } |
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| 278 | x += hhh; |
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| 279 | } |
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| 280 | |
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| 281 | cross *=hhh; |
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| 282 | if(cross < 0.0) cross = 0.0; |
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| 283 | return cross; |
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| 284 | } |
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| 285 | |
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| 286 | G4double G4MuPairProductionModel::ComputeDMicroscopicCrossSection( |
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| 287 | G4double tkin, |
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| 288 | G4double Z, |
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| 289 | G4double pairEnergy) |
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| 290 | // Calculates the differential (D) microscopic cross section |
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| 291 | // using the cross section formula of R.P. Kokoulin (18/01/98) |
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| 292 | // Code modified by R.P. Kokoulin, V.N. Ivanchenko (27/01/04) |
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| 293 | { |
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| 294 | G4double bbbtf= 183. ; |
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| 295 | G4double bbbh = 202.4 ; |
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| 296 | G4double g1tf = 1.95e-5 ; |
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| 297 | G4double g2tf = 5.3e-5 ; |
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| 298 | G4double g1h = 4.4e-5 ; |
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| 299 | G4double g2h = 4.8e-5 ; |
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| 300 | |
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| 301 | G4double totalEnergy = tkin + particleMass; |
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| 302 | G4double residEnergy = totalEnergy - pairEnergy; |
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| 303 | G4double massratio = particleMass/electron_mass_c2 ; |
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| 304 | G4double massratio2 = massratio*massratio ; |
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| 305 | G4double cross = 0.; |
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| 306 | |
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| 307 | SetCurrentElement(Z); |
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| 308 | |
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| 309 | G4double c3 = 0.75*sqrte*particleMass; |
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| 310 | if (residEnergy <= c3*z13) return cross; |
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| 311 | |
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| 312 | G4double c7 = 4.*electron_mass_c2; |
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| 313 | G4double c8 = 6.*particleMass*particleMass; |
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| 314 | G4double alf = c7/pairEnergy; |
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| 315 | G4double a3 = 1. - alf; |
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| 316 | if (a3 <= 0.) return cross; |
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| 317 | |
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| 318 | // zeta calculation |
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| 319 | G4double bbb,g1,g2; |
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| 320 | if( Z < 1.5 ) { bbb = bbbh ; g1 = g1h ; g2 = g2h ; } |
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| 321 | else { bbb = bbbtf; g1 = g1tf; g2 = g2tf; } |
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| 322 | |
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| 323 | G4double zeta = 0; |
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| 324 | G4double zeta1 = 0.073*log(totalEnergy/(particleMass+g1*z23*totalEnergy))-0.26; |
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| 325 | if ( zeta1 > 0.) |
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| 326 | { |
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| 327 | G4double zeta2 = 0.058*log(totalEnergy/(particleMass+g2*z13*totalEnergy))-0.14; |
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| 328 | zeta = zeta1/zeta2 ; |
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| 329 | } |
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| 330 | |
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| 331 | G4double z2 = Z*(Z+zeta); |
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| 332 | G4double screen0 = 2.*electron_mass_c2*sqrte*bbb/(z13*pairEnergy); |
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| 333 | G4double a0 = totalEnergy*residEnergy; |
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| 334 | G4double a1 = pairEnergy*pairEnergy/a0; |
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| 335 | G4double bet = 0.5*a1; |
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| 336 | G4double xi0 = 0.25*massratio2*a1; |
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| 337 | G4double del = c8/a0; |
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| 338 | |
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| 339 | G4double rta3 = sqrt(a3); |
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| 340 | G4double tmnexp = alf/(1. + rta3) + del*rta3; |
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| 341 | if(tmnexp >= 1.0) return cross; |
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| 342 | |
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| 343 | G4double tmn = log(tmnexp); |
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| 344 | G4double sum = 0.; |
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| 345 | |
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| 346 | // Gaussian integration in ln(1-ro) ( with 8 points) |
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| 347 | for (G4int i=0; i<8; i++) |
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| 348 | { |
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| 349 | G4double a4 = exp(tmn*xgi[i]); // a4 = (1.-asymmetry) |
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| 350 | G4double a5 = a4*(2.-a4) ; |
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| 351 | G4double a6 = 1.-a5 ; |
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| 352 | G4double a7 = 1.+a6 ; |
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| 353 | G4double a9 = 3.+a6 ; |
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| 354 | G4double xi = xi0*a5 ; |
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| 355 | G4double xii = 1./xi ; |
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| 356 | G4double xi1 = 1.+xi ; |
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| 357 | G4double screen = screen0*xi1/a5 ; |
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| 358 | G4double yeu = 5.-a6+4.*bet*a7 ; |
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| 359 | G4double yed = 2.*(1.+3.*bet)*log(3.+xii)-a6-a1*(2.-a6) ; |
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| 360 | G4double ye1 = 1.+yeu/yed ; |
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| 361 | G4double ale=log(bbb/z13*sqrt(xi1*ye1)/(1.+screen*ye1)) ; |
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| 362 | G4double cre = 0.5*log(1.+2.25*z23*xi1*ye1/massratio2) ; |
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| 363 | G4double be; |
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| 364 | |
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| 365 | if (xi <= 1.e3) be = ((2.+a6)*(1.+bet)+xi*a9)*log(1.+xii)+(a5-bet)/xi1-a9; |
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| 366 | else be = (3.-a6+a1*a7)/(2.*xi); |
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| 367 | |
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| 368 | G4double fe = (ale-cre)*be; |
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| 369 | if ( fe < 0.) fe = 0. ; |
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| 370 | |
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| 371 | G4double ymu = 4.+a6 +3.*bet*a7 ; |
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| 372 | G4double ymd = a7*(1.5+a1)*log(3.+xi)+1.-1.5*a6 ; |
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| 373 | G4double ym1 = 1.+ymu/ymd ; |
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| 374 | G4double alm_crm = log(bbb*massratio/(1.5*z23*(1.+screen*ym1))); |
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| 375 | G4double a10,bm; |
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| 376 | if ( xi >= 1.e-3) |
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| 377 | { |
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| 378 | a10 = (1.+a1)*a5 ; |
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| 379 | bm = (a7*(1.+1.5*bet)-a10*xii)*log(xi1)+xi*(a5-bet)/xi1+a10; |
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| 380 | } else { |
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| 381 | bm = (5.-a6+bet*a9)*(xi/2.); |
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| 382 | } |
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| 383 | |
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| 384 | G4double fm = alm_crm*bm; |
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| 385 | if ( fm < 0.) fm = 0. ; |
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| 386 | |
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| 387 | sum += wgi[i]*a4*(fe+fm/massratio2); |
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| 388 | } |
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| 389 | |
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| 390 | cross = -tmn*sum*factorForCross*z2*residEnergy/(totalEnergy*pairEnergy); |
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| 391 | |
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| 392 | return cross; |
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| 393 | } |
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| 394 | |
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| 395 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 396 | |
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| 397 | G4double G4MuPairProductionModel::ComputeCrossSectionPerAtom( |
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| 398 | const G4ParticleDefinition*, |
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| 399 | G4double kineticEnergy, |
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| 400 | G4double Z, G4double, |
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| 401 | G4double cutEnergy, |
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| 402 | G4double) |
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| 403 | { |
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| 404 | G4double cut = max(minPairEnergy,cutEnergy); |
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| 405 | if(ignoreCut) cut = minPairEnergy; |
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| 406 | G4double cross = ComputeMicroscopicCrossSection (kineticEnergy, Z, cut); |
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| 407 | return cross; |
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| 408 | } |
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| 409 | |
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| 410 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 411 | |
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| 412 | G4double G4MuPairProductionModel::CrossSectionPerVolume( |
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| 413 | const G4Material* material, |
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| 414 | const G4ParticleDefinition*, |
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| 415 | G4double kineticEnergy, |
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| 416 | G4double cutEnergy, |
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| 417 | G4double maxEnergy) |
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| 418 | { |
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| 419 | G4double cross = 0.0; |
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| 420 | if (kineticEnergy <= lowestKinEnergy) return cross; |
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| 421 | |
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| 422 | maxEnergy += particleMass; |
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| 423 | |
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| 424 | const G4ElementVector* theElementVector = material->GetElementVector(); |
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| 425 | const G4double* theAtomNumDensityVector = material-> |
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| 426 | GetAtomicNumDensityVector(); |
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| 427 | |
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| 428 | for (size_t i=0; i<material->GetNumberOfElements(); i++) { |
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| 429 | G4double Z = (*theElementVector)[i]->GetZ(); |
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| 430 | SetCurrentElement(Z); |
---|
| 431 | G4double tmax = min(maxEnergy,MaxSecondaryEnergy(particle, kineticEnergy)); |
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| 432 | G4double cut = max(minPairEnergy,cutEnergy); |
---|
| 433 | if(ignoreCut) cut = minPairEnergy; |
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| 434 | if(cut < tmax) { |
---|
| 435 | G4double cr = ComputeMicroscopicCrossSection(kineticEnergy, Z, cut) |
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| 436 | - ComputeMicroscopicCrossSection(kineticEnergy, Z, tmax); |
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| 437 | |
---|
| 438 | cross += theAtomNumDensityVector[i] * cr; |
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| 439 | } |
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| 440 | } |
---|
| 441 | return cross; |
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| 442 | } |
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| 443 | |
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| 444 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 445 | |
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| 446 | void G4MuPairProductionModel::MakeSamplingTables() |
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| 447 | { |
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| 448 | for (G4int iz=0; iz<nzdat; iz++) |
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| 449 | { |
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| 450 | G4double Z = zdat[iz]; |
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| 451 | SetCurrentElement(Z); |
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| 452 | |
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| 453 | for (G4int it=0; it<ntdat; it++) |
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| 454 | { |
---|
| 455 | G4double kineticEnergy = tdat[it]; |
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| 456 | G4double maxPairEnergy = MaxSecondaryEnergy(particle,kineticEnergy); |
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| 457 | |
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| 458 | G4double CrossSection = 0.0 ; |
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| 459 | |
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| 460 | G4double y = ymin - 0.5*dy ; |
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| 461 | G4double yy = ymin - dy ; |
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| 462 | G4double x = exp(y); |
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| 463 | G4double fac = exp(dy); |
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| 464 | G4double dx = exp(yy)*(fac - 1.0); |
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| 465 | |
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| 466 | G4double c = log(maxPairEnergy/minPairEnergy); |
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| 467 | |
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| 468 | for (G4int i=0 ; i<nbiny; i++) |
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| 469 | { |
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| 470 | y += dy ; |
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| 471 | if(c > 0.0) { |
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| 472 | x *= fac; |
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| 473 | dx*= fac; |
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| 474 | G4double ep = minPairEnergy*exp(c*x) ; |
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| 475 | CrossSection += ep*dx*ComputeDMicroscopicCrossSection( |
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| 476 | kineticEnergy, Z, ep); |
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| 477 | } |
---|
| 478 | ya[i] = y; |
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| 479 | proba[iz][it][i] = CrossSection; |
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| 480 | } |
---|
| 481 | |
---|
| 482 | ya[nbiny]=ymax; |
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| 483 | |
---|
| 484 | proba[iz][it][nbiny] = CrossSection; |
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| 485 | |
---|
| 486 | } |
---|
| 487 | } |
---|
| 488 | samplingTablesAreFilled = true; |
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| 489 | } |
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| 490 | |
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| 491 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 492 | |
---|
| 493 | void G4MuPairProductionModel::SampleSecondaries(std::vector<G4DynamicParticle*>* vdp, |
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| 494 | const G4MaterialCutsCouple* couple, |
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| 495 | const G4DynamicParticle* aDynamicParticle, |
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| 496 | G4double tmin, |
---|
| 497 | G4double tmax) |
---|
| 498 | { |
---|
| 499 | G4double kineticEnergy = aDynamicParticle->GetKineticEnergy(); |
---|
| 500 | G4double totalEnergy = kineticEnergy + particleMass ; |
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| 501 | G4ParticleMomentum ParticleDirection = |
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| 502 | aDynamicParticle->GetMomentumDirection(); |
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| 503 | |
---|
| 504 | G4int it; |
---|
| 505 | for(it=1; it<ntdat; it++) {if(kineticEnergy <= tdat[it]) break;} |
---|
| 506 | if(it == ntdat) it--; |
---|
| 507 | G4double dt = log(kineticEnergy/tdat[it-1])/log(tdat[it]/tdat[it-1]); |
---|
| 508 | |
---|
| 509 | // select randomly one element constituing the material |
---|
| 510 | const G4Element* anElement = SelectRandomAtom(kineticEnergy, dt, it, couple, tmin); |
---|
| 511 | SetCurrentElement(anElement->GetZ()); |
---|
| 512 | |
---|
| 513 | // define interval of enegry transfer |
---|
| 514 | G4double maxPairEnergy = MaxSecondaryEnergy(particle,kineticEnergy); |
---|
| 515 | G4double maxEnergy = std::min(tmax, maxPairEnergy); |
---|
| 516 | G4double minEnergy = std::max(tmin, minPairEnergy); |
---|
| 517 | if(ignoreCut)minEnergy = minPairEnergy; |
---|
| 518 | if(minEnergy >= maxEnergy) return; |
---|
| 519 | //G4cout << "emin= " << minEnergy << " emax= " << maxEnergy |
---|
| 520 | // << " minPair= " << minPairEnergy << " maxpair= " << maxPairEnergy |
---|
| 521 | // << " ymin= " << ymin << " dy= " << dy << G4endl; |
---|
| 522 | |
---|
| 523 | // select bins |
---|
| 524 | G4int iymin = 0; |
---|
| 525 | G4int iymax = nbiny-1; |
---|
| 526 | if( minEnergy > minPairEnergy) |
---|
| 527 | { |
---|
| 528 | G4double xc = log(minEnergy/minPairEnergy)/log(maxPairEnergy/minPairEnergy); |
---|
| 529 | iymin = (G4int)((log(xc) - ymin)/dy); |
---|
| 530 | if(iymin >= nbiny) iymin = nbiny-1; |
---|
| 531 | else if(iymin < 0) iymin = 0; |
---|
| 532 | xc = log(maxEnergy/minPairEnergy)/log(maxPairEnergy/minPairEnergy); |
---|
| 533 | iymax = (G4int)((log(xc) - ymin)/dy) + 1; |
---|
| 534 | if(iymax >= nbiny) iymax = nbiny-1; |
---|
| 535 | else if(iymax < 0) iymax = 0; |
---|
| 536 | } |
---|
| 537 | |
---|
| 538 | // sample e-e+ energy, pair energy first |
---|
| 539 | G4int iz, iy; |
---|
| 540 | |
---|
| 541 | for(iz=1; iz<nzdat; iz++) {if(currentZ <= zdat[iz]) break;} |
---|
| 542 | if(iz == nzdat) iz--; |
---|
| 543 | |
---|
| 544 | G4double dz = log(currentZ/zdat[iz-1])/log(zdat[iz]/zdat[iz-1]); |
---|
| 545 | |
---|
| 546 | G4double pmin = InterpolatedIntegralCrossSection(dt,dz,iz,it,iymin,currentZ); |
---|
| 547 | G4double pmax = InterpolatedIntegralCrossSection(dt,dz,iz,it,iymax,currentZ); |
---|
| 548 | |
---|
| 549 | G4double p = pmin+G4UniformRand()*(pmax - pmin); |
---|
| 550 | |
---|
| 551 | // interpolate sampling vector; |
---|
| 552 | G4double p1 = pmin; |
---|
| 553 | G4double p2 = pmin; |
---|
| 554 | for(iy=iymin+1; iy<=iymax; iy++) { |
---|
| 555 | p1 = p2; |
---|
| 556 | p2 = InterpolatedIntegralCrossSection(dt, dz, iz, it, iy, currentZ); |
---|
| 557 | if(p <= p2) break; |
---|
| 558 | } |
---|
| 559 | // G4cout << "iy= " << iy << " iymin= " << iymin << " iymax= " |
---|
| 560 | // << iymax << " Z= " << currentZ << G4endl; |
---|
| 561 | G4double y = ya[iy-1] + dy*(p - p1)/(p2 - p1); |
---|
| 562 | |
---|
| 563 | G4double PairEnergy = minPairEnergy*exp(exp(y) |
---|
| 564 | *log(maxPairEnergy/minPairEnergy)); |
---|
| 565 | |
---|
| 566 | if(PairEnergy < minEnergy) PairEnergy = minEnergy; |
---|
| 567 | if(PairEnergy > maxEnergy) PairEnergy = maxEnergy; |
---|
| 568 | |
---|
| 569 | // sample r=(E+-E-)/PairEnergy ( uniformly .....) |
---|
| 570 | G4double rmax = |
---|
| 571 | (1.-6.*particleMass*particleMass/(totalEnergy*(totalEnergy-PairEnergy))) |
---|
| 572 | *sqrt(1.-minPairEnergy/PairEnergy); |
---|
| 573 | G4double r = rmax * (-1.+2.*G4UniformRand()) ; |
---|
| 574 | |
---|
| 575 | // compute energies from PairEnergy,r |
---|
| 576 | G4double ElectronEnergy = (1.-r)*PairEnergy*0.5; |
---|
| 577 | G4double PositronEnergy = PairEnergy - ElectronEnergy; |
---|
| 578 | |
---|
| 579 | // angles of the emitted particles ( Z - axis along the parent particle) |
---|
| 580 | // (mean theta for the moment) |
---|
| 581 | |
---|
| 582 | // |
---|
| 583 | // scattered electron (positron) angles. ( Z - axis along the parent photon) |
---|
| 584 | // |
---|
| 585 | // universal distribution suggested by L. Urban |
---|
| 586 | // (Geant3 manual (1993) Phys211), |
---|
| 587 | // derived from Tsai distribution (Rev Mod Phys 49,421(1977)) |
---|
| 588 | // G4cout << "Ee= " << ElectronEnergy << " Ep= " << PositronEnergy << G4endl; |
---|
| 589 | G4double u; |
---|
| 590 | const G4double a1 = 0.625 , a2 = 3.*a1 , d = 27. ; |
---|
| 591 | |
---|
| 592 | if (9./(9.+d) >G4UniformRand()) u= - log(G4UniformRand()*G4UniformRand())/a1; |
---|
| 593 | else u= - log(G4UniformRand()*G4UniformRand())/a2; |
---|
| 594 | |
---|
| 595 | G4double TetEl = u*electron_mass_c2/ElectronEnergy; |
---|
| 596 | G4double TetPo = u*electron_mass_c2/PositronEnergy; |
---|
| 597 | G4double Phi = twopi * G4UniformRand(); |
---|
| 598 | G4double dxEl= sin(TetEl)*cos(Phi),dyEl= sin(TetEl)*sin(Phi),dzEl=cos(TetEl); |
---|
| 599 | G4double dxPo=-sin(TetPo)*cos(Phi),dyPo=-sin(TetPo)*sin(Phi),dzPo=cos(TetPo); |
---|
| 600 | |
---|
| 601 | G4ThreeVector ElectDirection (dxEl, dyEl, dzEl); |
---|
| 602 | ElectDirection.rotateUz(ParticleDirection); |
---|
| 603 | |
---|
| 604 | // create G4DynamicParticle object for the particle1 |
---|
| 605 | G4DynamicParticle* aParticle1= new G4DynamicParticle(theElectron, |
---|
| 606 | ElectDirection, |
---|
| 607 | ElectronEnergy - electron_mass_c2); |
---|
| 608 | |
---|
| 609 | G4ThreeVector PositDirection (dxPo, dyPo, dzPo); |
---|
| 610 | PositDirection.rotateUz(ParticleDirection); |
---|
| 611 | |
---|
| 612 | // create G4DynamicParticle object for the particle2 |
---|
| 613 | G4DynamicParticle* aParticle2 = |
---|
| 614 | new G4DynamicParticle(thePositron, |
---|
| 615 | PositDirection, |
---|
| 616 | PositronEnergy - electron_mass_c2); |
---|
| 617 | |
---|
| 618 | // primary change |
---|
| 619 | kineticEnergy -= (ElectronEnergy + PositronEnergy); |
---|
| 620 | if(fParticleChange) |
---|
| 621 | fParticleChange->SetProposedKineticEnergy(kineticEnergy); |
---|
| 622 | else |
---|
| 623 | gParticleChange->SetProposedKineticEnergy(kineticEnergy); |
---|
| 624 | |
---|
| 625 | vdp->push_back(aParticle1); |
---|
| 626 | vdp->push_back(aParticle2); |
---|
| 627 | } |
---|
| 628 | |
---|
| 629 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
---|
| 630 | |
---|
| 631 | const G4Element* G4MuPairProductionModel::SelectRandomAtom( |
---|
| 632 | G4double kinEnergy, G4double dt, G4int it, |
---|
| 633 | const G4MaterialCutsCouple* couple, G4double tmin) |
---|
| 634 | { |
---|
| 635 | // select randomly 1 element within the material |
---|
| 636 | |
---|
| 637 | const G4Material* material = couple->GetMaterial(); |
---|
| 638 | size_t nElements = material->GetNumberOfElements(); |
---|
| 639 | const G4ElementVector* theElementVector = material->GetElementVector(); |
---|
| 640 | if (nElements == 1) return (*theElementVector)[0]; |
---|
| 641 | |
---|
| 642 | if(nElements > nmaxElements) { |
---|
| 643 | nmaxElements = nElements; |
---|
| 644 | partialSum.resize(nmaxElements); |
---|
| 645 | } |
---|
| 646 | |
---|
| 647 | const G4double* theAtomNumDensityVector=material->GetAtomicNumDensityVector(); |
---|
| 648 | |
---|
| 649 | G4double sum = 0.0; |
---|
| 650 | |
---|
| 651 | size_t i; |
---|
| 652 | for (i=0; i<nElements; i++) { |
---|
| 653 | G4double Z = ((*theElementVector)[i])->GetZ(); |
---|
| 654 | SetCurrentElement(Z); |
---|
| 655 | G4double maxPairEnergy = MaxSecondaryEnergy(particle,kinEnergy); |
---|
| 656 | G4double minEnergy = std::max(tmin, minPairEnergy); |
---|
| 657 | if(ignoreCut)minEnergy = minPairEnergy; |
---|
| 658 | |
---|
| 659 | G4int iz; |
---|
| 660 | for(iz=1; iz<nzdat; iz++) {if(Z <= zdat[iz]) break;} |
---|
| 661 | if(iz == nzdat) iz--; |
---|
| 662 | G4double dz = log(Z/zdat[iz-1])/log(zdat[iz]/zdat[iz-1]); |
---|
| 663 | |
---|
| 664 | G4double sigcut; |
---|
| 665 | if(minEnergy <= minPairEnergy) |
---|
| 666 | sigcut = 0.; |
---|
| 667 | else |
---|
| 668 | { |
---|
| 669 | G4double xc = log(minEnergy/minPairEnergy)/log(maxPairEnergy/minPairEnergy); |
---|
| 670 | G4int iy = (G4int)((log(xc) - ymin)/dy); |
---|
| 671 | if(iy < 0) iy = 0; |
---|
| 672 | if(iy >= nbiny) iy = nbiny-1; |
---|
| 673 | sigcut = InterpolatedIntegralCrossSection(dt,dz,iz,it,iy, Z); |
---|
| 674 | } |
---|
| 675 | |
---|
| 676 | G4double sigtot = InterpolatedIntegralCrossSection(dt,dz,iz,it,nbiny,Z); |
---|
| 677 | G4double dl = (sigtot - sigcut)*theAtomNumDensityVector[i]; |
---|
| 678 | |
---|
| 679 | // protection |
---|
| 680 | if(dl < 0.0) dl = 0.0; |
---|
| 681 | sum += dl; |
---|
| 682 | partialSum[i] = sum; |
---|
| 683 | } |
---|
| 684 | |
---|
| 685 | G4double rval = G4UniformRand()*sum; |
---|
| 686 | for (i=0; i<nElements; i++) { |
---|
| 687 | if(rval<=partialSum[i]) return (*theElementVector)[i]; |
---|
| 688 | } |
---|
| 689 | |
---|
| 690 | return (*theElementVector)[nElements - 1]; |
---|
| 691 | |
---|
| 692 | } |
---|
| 693 | |
---|
| 694 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
---|
| 695 | |
---|
| 696 | |
---|