[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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[1315] | 26 | // $Id: G4MuPairProductionModel.cc,v 1.45 2010/06/01 15:21:59 vnivanch Exp $ |
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[1337] | 27 | // GEANT4 tag $Name: geant4-09-04-beta-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: 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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[961] | 106 | particle(0), |
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| 107 | factorForCross(4.*fine_structure_const*fine_structure_const |
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[819] | 108 | *classic_electr_radius*classic_electr_radius/(3.*pi)), |
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| 109 | sqrte(sqrt(exp(1.))), |
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| 110 | currentZ(0), |
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[961] | 111 | fParticleChange(0), |
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| 112 | minPairEnergy(4.*electron_mass_c2), |
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| 113 | lowestKinEnergy(1.*GeV), |
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[819] | 114 | nzdat(5), |
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| 115 | ntdat(8), |
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| 116 | nbiny(1000), |
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| 117 | nmaxElements(0), |
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| 118 | ymin(-5.), |
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| 119 | ymax(0.), |
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| 120 | dy((ymax-ymin)/nbiny), |
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| 121 | samplingTablesAreFilled(false) |
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| 122 | { |
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| 123 | SetLowEnergyLimit(minPairEnergy); |
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[961] | 124 | nist = G4NistManager::Instance(); |
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[819] | 125 | |
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| 126 | theElectron = G4Electron::Electron(); |
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| 127 | thePositron = G4Positron::Positron(); |
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| 128 | |
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| 129 | if(p) SetParticle(p); |
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| 130 | } |
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| 131 | |
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| 132 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 133 | |
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| 134 | G4MuPairProductionModel::~G4MuPairProductionModel() |
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| 135 | {} |
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| 136 | |
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| 137 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 138 | |
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[1055] | 139 | G4double G4MuPairProductionModel::MinEnergyCut(const G4ParticleDefinition*, |
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| 140 | const G4MaterialCutsCouple* ) |
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| 141 | { |
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| 142 | return minPairEnergy; |
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| 143 | } |
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| 144 | |
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| 145 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 146 | |
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| 147 | G4double G4MuPairProductionModel::MaxSecondaryEnergy(const G4ParticleDefinition*, |
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| 148 | G4double kineticEnergy) |
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| 149 | { |
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| 150 | G4double maxPairEnergy = kineticEnergy + particleMass*(1.0 - 0.75*sqrte*z13); |
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| 151 | return maxPairEnergy; |
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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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[819] | 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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[1055] | 163 | if(!fParticleChange) fParticleChange = GetParticleChangeForLoss(); |
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[819] | 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 G4MuPairProductionModel::ComputeDEDXPerVolume( |
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| 169 | const G4Material* material, |
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| 170 | const G4ParticleDefinition*, |
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| 171 | G4double kineticEnergy, |
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| 172 | G4double cutEnergy) |
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| 173 | { |
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| 174 | G4double dedx = 0.0; |
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[961] | 175 | if (cutEnergy <= minPairEnergy || kineticEnergy <= lowestKinEnergy) |
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[819] | 176 | return dedx; |
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| 177 | |
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| 178 | const G4ElementVector* theElementVector = material->GetElementVector(); |
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| 179 | const G4double* theAtomicNumDensityVector = |
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| 180 | material->GetAtomicNumDensityVector(); |
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| 181 | |
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| 182 | // loop for elements in the material |
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| 183 | for (size_t i=0; i<material->GetNumberOfElements(); i++) { |
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| 184 | G4double Z = (*theElementVector)[i]->GetZ(); |
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| 185 | SetCurrentElement(Z); |
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| 186 | G4double tmax = MaxSecondaryEnergy(particle, kineticEnergy); |
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| 187 | G4double loss = ComputMuPairLoss(Z, kineticEnergy, cutEnergy, tmax); |
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| 188 | dedx += loss*theAtomicNumDensityVector[i]; |
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| 189 | } |
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| 190 | if (dedx < 0.) dedx = 0.; |
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| 191 | return dedx; |
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| 192 | } |
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| 193 | |
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| 194 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 195 | |
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| 196 | G4double G4MuPairProductionModel::ComputMuPairLoss(G4double Z, |
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| 197 | G4double tkin, |
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| 198 | G4double cutEnergy, |
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| 199 | G4double tmax) |
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| 200 | { |
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| 201 | SetCurrentElement(Z); |
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| 202 | G4double loss = 0.0; |
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| 203 | |
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[961] | 204 | G4double cut = std::min(cutEnergy,tmax); |
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[819] | 205 | if(cut <= minPairEnergy) return loss; |
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| 206 | |
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| 207 | // calculate the rectricted loss |
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| 208 | // numerical integration in log(PairEnergy) |
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| 209 | G4double ak1=6.9; |
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| 210 | G4double ak2=1.0; |
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| 211 | G4double aaa = log(minPairEnergy); |
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| 212 | G4double bbb = log(cut); |
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| 213 | G4int kkk = (G4int)((bbb-aaa)/ak1+ak2); |
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| 214 | if (kkk > 8) kkk = 8; |
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| 215 | G4double hhh = (bbb-aaa)/(G4double)kkk; |
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| 216 | G4double x = aaa; |
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| 217 | |
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| 218 | for (G4int l=0 ; l<kkk; l++) |
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| 219 | { |
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| 220 | |
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| 221 | for (G4int ll=0; ll<8; ll++) |
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| 222 | { |
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| 223 | G4double ep = exp(x+xgi[ll]*hhh); |
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| 224 | loss += wgi[ll]*ep*ep*ComputeDMicroscopicCrossSection(tkin, Z, ep); |
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| 225 | } |
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| 226 | x += hhh; |
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| 227 | } |
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| 228 | loss *= hhh; |
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| 229 | if (loss < 0.) loss = 0.; |
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| 230 | return loss; |
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| 231 | } |
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| 232 | |
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| 233 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 234 | |
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| 235 | G4double G4MuPairProductionModel::ComputeMicroscopicCrossSection( |
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| 236 | G4double tkin, |
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| 237 | G4double Z, |
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| 238 | G4double cut) |
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| 239 | { |
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[961] | 240 | G4double cross = 0.; |
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[819] | 241 | SetCurrentElement(Z); |
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| 242 | G4double tmax = MaxSecondaryEnergy(particle, tkin); |
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| 243 | if (tmax <= cut) return cross; |
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| 244 | |
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| 245 | G4double ak1=6.9 ; |
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| 246 | G4double ak2=1.0 ; |
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| 247 | G4double aaa = log(cut); |
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| 248 | G4double bbb = log(tmax); |
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| 249 | G4int kkk = (G4int)((bbb-aaa)/ak1 + ak2); |
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| 250 | if(kkk > 8) kkk = 8; |
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| 251 | G4double hhh = (bbb-aaa)/float(kkk); |
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| 252 | G4double x = aaa; |
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| 253 | |
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| 254 | for(G4int l=0; l<kkk; l++) |
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| 255 | { |
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| 256 | for(G4int i=0; i<8; i++) |
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| 257 | { |
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| 258 | G4double ep = exp(x + xgi[i]*hhh); |
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| 259 | cross += ep*wgi[i]*ComputeDMicroscopicCrossSection(tkin, Z, ep); |
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| 260 | } |
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| 261 | x += hhh; |
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| 262 | } |
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| 263 | |
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| 264 | cross *=hhh; |
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| 265 | if(cross < 0.0) cross = 0.0; |
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| 266 | return cross; |
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| 267 | } |
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| 268 | |
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| 269 | G4double G4MuPairProductionModel::ComputeDMicroscopicCrossSection( |
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| 270 | G4double tkin, |
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| 271 | G4double Z, |
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| 272 | G4double pairEnergy) |
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| 273 | // Calculates the differential (D) microscopic cross section |
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| 274 | // using the cross section formula of R.P. Kokoulin (18/01/98) |
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| 275 | // Code modified by R.P. Kokoulin, V.N. Ivanchenko (27/01/04) |
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| 276 | { |
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| 277 | G4double bbbtf= 183. ; |
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| 278 | G4double bbbh = 202.4 ; |
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| 279 | G4double g1tf = 1.95e-5 ; |
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| 280 | G4double g2tf = 5.3e-5 ; |
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| 281 | G4double g1h = 4.4e-5 ; |
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| 282 | G4double g2h = 4.8e-5 ; |
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| 283 | |
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| 284 | G4double totalEnergy = tkin + particleMass; |
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| 285 | G4double residEnergy = totalEnergy - pairEnergy; |
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| 286 | G4double massratio = particleMass/electron_mass_c2 ; |
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| 287 | G4double massratio2 = massratio*massratio ; |
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| 288 | G4double cross = 0.; |
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| 289 | |
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| 290 | SetCurrentElement(Z); |
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| 291 | |
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| 292 | G4double c3 = 0.75*sqrte*particleMass; |
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| 293 | if (residEnergy <= c3*z13) return cross; |
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| 294 | |
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| 295 | G4double c7 = 4.*electron_mass_c2; |
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| 296 | G4double c8 = 6.*particleMass*particleMass; |
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| 297 | G4double alf = c7/pairEnergy; |
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| 298 | G4double a3 = 1. - alf; |
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| 299 | if (a3 <= 0.) return cross; |
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| 300 | |
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| 301 | // zeta calculation |
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| 302 | G4double bbb,g1,g2; |
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| 303 | if( Z < 1.5 ) { bbb = bbbh ; g1 = g1h ; g2 = g2h ; } |
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| 304 | else { bbb = bbbtf; g1 = g1tf; g2 = g2tf; } |
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| 305 | |
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| 306 | G4double zeta = 0; |
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| 307 | G4double zeta1 = 0.073*log(totalEnergy/(particleMass+g1*z23*totalEnergy))-0.26; |
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| 308 | if ( zeta1 > 0.) |
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| 309 | { |
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| 310 | G4double zeta2 = 0.058*log(totalEnergy/(particleMass+g2*z13*totalEnergy))-0.14; |
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| 311 | zeta = zeta1/zeta2 ; |
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| 312 | } |
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| 313 | |
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| 314 | G4double z2 = Z*(Z+zeta); |
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| 315 | G4double screen0 = 2.*electron_mass_c2*sqrte*bbb/(z13*pairEnergy); |
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| 316 | G4double a0 = totalEnergy*residEnergy; |
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| 317 | G4double a1 = pairEnergy*pairEnergy/a0; |
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| 318 | G4double bet = 0.5*a1; |
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| 319 | G4double xi0 = 0.25*massratio2*a1; |
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| 320 | G4double del = c8/a0; |
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| 321 | |
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| 322 | G4double rta3 = sqrt(a3); |
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| 323 | G4double tmnexp = alf/(1. + rta3) + del*rta3; |
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| 324 | if(tmnexp >= 1.0) return cross; |
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| 325 | |
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| 326 | G4double tmn = log(tmnexp); |
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| 327 | G4double sum = 0.; |
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| 328 | |
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| 329 | // Gaussian integration in ln(1-ro) ( with 8 points) |
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| 330 | for (G4int i=0; i<8; i++) |
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| 331 | { |
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| 332 | G4double a4 = exp(tmn*xgi[i]); // a4 = (1.-asymmetry) |
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| 333 | G4double a5 = a4*(2.-a4) ; |
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| 334 | G4double a6 = 1.-a5 ; |
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| 335 | G4double a7 = 1.+a6 ; |
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| 336 | G4double a9 = 3.+a6 ; |
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| 337 | G4double xi = xi0*a5 ; |
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| 338 | G4double xii = 1./xi ; |
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| 339 | G4double xi1 = 1.+xi ; |
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| 340 | G4double screen = screen0*xi1/a5 ; |
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| 341 | G4double yeu = 5.-a6+4.*bet*a7 ; |
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| 342 | G4double yed = 2.*(1.+3.*bet)*log(3.+xii)-a6-a1*(2.-a6) ; |
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| 343 | G4double ye1 = 1.+yeu/yed ; |
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| 344 | G4double ale=log(bbb/z13*sqrt(xi1*ye1)/(1.+screen*ye1)) ; |
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| 345 | G4double cre = 0.5*log(1.+2.25*z23*xi1*ye1/massratio2) ; |
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| 346 | G4double be; |
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| 347 | |
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| 348 | if (xi <= 1.e3) be = ((2.+a6)*(1.+bet)+xi*a9)*log(1.+xii)+(a5-bet)/xi1-a9; |
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| 349 | else be = (3.-a6+a1*a7)/(2.*xi); |
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| 350 | |
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| 351 | G4double fe = (ale-cre)*be; |
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| 352 | if ( fe < 0.) fe = 0. ; |
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| 353 | |
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| 354 | G4double ymu = 4.+a6 +3.*bet*a7 ; |
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| 355 | G4double ymd = a7*(1.5+a1)*log(3.+xi)+1.-1.5*a6 ; |
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| 356 | G4double ym1 = 1.+ymu/ymd ; |
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| 357 | G4double alm_crm = log(bbb*massratio/(1.5*z23*(1.+screen*ym1))); |
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| 358 | G4double a10,bm; |
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| 359 | if ( xi >= 1.e-3) |
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| 360 | { |
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| 361 | a10 = (1.+a1)*a5 ; |
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| 362 | bm = (a7*(1.+1.5*bet)-a10*xii)*log(xi1)+xi*(a5-bet)/xi1+a10; |
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| 363 | } else { |
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| 364 | bm = (5.-a6+bet*a9)*(xi/2.); |
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| 365 | } |
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| 366 | |
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| 367 | G4double fm = alm_crm*bm; |
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| 368 | if ( fm < 0.) fm = 0. ; |
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| 369 | |
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| 370 | sum += wgi[i]*a4*(fe+fm/massratio2); |
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| 371 | } |
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| 372 | |
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| 373 | cross = -tmn*sum*factorForCross*z2*residEnergy/(totalEnergy*pairEnergy); |
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| 374 | |
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| 375 | return cross; |
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| 376 | } |
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| 377 | |
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| 378 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 379 | |
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| 380 | G4double G4MuPairProductionModel::ComputeCrossSectionPerAtom( |
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| 381 | const G4ParticleDefinition*, |
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| 382 | G4double kineticEnergy, |
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| 383 | G4double Z, G4double, |
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| 384 | G4double cutEnergy, |
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[961] | 385 | G4double maxEnergy) |
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[819] | 386 | { |
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| 387 | G4double cross = 0.0; |
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| 388 | if (kineticEnergy <= lowestKinEnergy) return cross; |
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| 389 | |
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[961] | 390 | SetCurrentElement(Z); |
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[1196] | 391 | |
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| 392 | G4double maxPairEnergy = MaxSecondaryEnergy(particle,kineticEnergy); |
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| 393 | G4double tmax = std::min(maxEnergy, maxPairEnergy); |
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| 394 | G4double cut = std::max(cutEnergy, minPairEnergy); |
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[961] | 395 | if (cut >= tmax) return cross; |
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[819] | 396 | |
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[961] | 397 | cross = ComputeMicroscopicCrossSection (kineticEnergy, Z, cut); |
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| 398 | if(tmax < kineticEnergy) { |
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| 399 | cross -= ComputeMicroscopicCrossSection(kineticEnergy, Z, tmax); |
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[819] | 400 | } |
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| 401 | return cross; |
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| 402 | } |
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| 403 | |
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| 404 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 405 | |
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| 406 | void G4MuPairProductionModel::MakeSamplingTables() |
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| 407 | { |
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| 408 | for (G4int iz=0; iz<nzdat; iz++) |
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| 409 | { |
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| 410 | G4double Z = zdat[iz]; |
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| 411 | SetCurrentElement(Z); |
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| 412 | |
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[961] | 413 | for (G4int it=0; it<ntdat; it++) { |
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| 414 | |
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[819] | 415 | G4double kineticEnergy = tdat[it]; |
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| 416 | G4double maxPairEnergy = MaxSecondaryEnergy(particle,kineticEnergy); |
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[961] | 417 | // G4cout << "Z= " << currentZ << " z13= " << z13 |
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| 418 | //<< " mE= " << maxPairEnergy << G4endl; |
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[819] | 419 | G4double CrossSection = 0.0 ; |
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| 420 | |
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[961] | 421 | if(maxPairEnergy > minPairEnergy) { |
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[819] | 422 | |
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[961] | 423 | G4double y = ymin - 0.5*dy ; |
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| 424 | G4double yy = ymin - dy ; |
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| 425 | G4double x = exp(y); |
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| 426 | G4double fac = exp(dy); |
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| 427 | G4double dx = exp(yy)*(fac - 1.0); |
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[819] | 428 | |
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[961] | 429 | G4double c = log(maxPairEnergy/minPairEnergy); |
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| 430 | |
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| 431 | for (G4int i=0 ; i<nbiny; i++) { |
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| 432 | y += dy ; |
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| 433 | if(c > 0.0) { |
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| 434 | x *= fac; |
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| 435 | dx*= fac; |
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| 436 | G4double ep = minPairEnergy*exp(c*x) ; |
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| 437 | CrossSection += |
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| 438 | ep*dx*ComputeDMicroscopicCrossSection(kineticEnergy, Z, ep); |
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| 439 | } |
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| 440 | ya[i] = y; |
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| 441 | proba[iz][it][i] = CrossSection; |
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| 442 | } |
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| 443 | |
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| 444 | } else { |
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| 445 | for (G4int i=0 ; i<nbiny; i++) { |
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| 446 | proba[iz][it][i] = CrossSection; |
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| 447 | } |
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[819] | 448 | } |
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| 449 | |
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| 450 | ya[nbiny]=ymax; |
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| 451 | proba[iz][it][nbiny] = CrossSection; |
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| 452 | |
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| 453 | } |
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| 454 | } |
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| 455 | samplingTablesAreFilled = true; |
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| 456 | } |
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| 457 | |
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| 458 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 459 | |
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[1196] | 460 | void |
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| 461 | G4MuPairProductionModel::SampleSecondaries(std::vector<G4DynamicParticle*>* vdp, |
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| 462 | const G4MaterialCutsCouple* couple, |
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| 463 | const G4DynamicParticle* aDynamicParticle, |
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| 464 | G4double tmin, |
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| 465 | G4double tmax) |
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[819] | 466 | { |
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| 467 | G4double kineticEnergy = aDynamicParticle->GetKineticEnergy(); |
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[1315] | 468 | G4double totalEnergy = kineticEnergy + particleMass; |
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| 469 | G4double totalMomentum = |
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| 470 | sqrt(kineticEnergy*(kineticEnergy + 2.0*particleMass)); |
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[819] | 471 | |
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[1315] | 472 | G4ThreeVector partDirection = aDynamicParticle->GetMomentumDirection(); |
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| 473 | |
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[819] | 474 | G4int it; |
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[1315] | 475 | for(it=1; it<ntdat; ++it) {if(kineticEnergy <= tdat[it]) break;} |
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| 476 | if(it == ntdat) { --it; } |
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[819] | 477 | G4double dt = log(kineticEnergy/tdat[it-1])/log(tdat[it]/tdat[it-1]); |
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| 478 | |
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| 479 | // select randomly one element constituing the material |
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[1315] | 480 | const G4Element* anElement = |
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| 481 | SelectRandomAtom(kineticEnergy, dt, it, couple, tmin); |
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[819] | 482 | SetCurrentElement(anElement->GetZ()); |
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| 483 | |
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| 484 | // define interval of enegry transfer |
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| 485 | G4double maxPairEnergy = MaxSecondaryEnergy(particle,kineticEnergy); |
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| 486 | G4double maxEnergy = std::min(tmax, maxPairEnergy); |
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| 487 | G4double minEnergy = std::max(tmin, minPairEnergy); |
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[961] | 488 | |
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[1315] | 489 | if(minEnergy >= maxEnergy) { return; } |
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[819] | 490 | //G4cout << "emin= " << minEnergy << " emax= " << maxEnergy |
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| 491 | // << " minPair= " << minPairEnergy << " maxpair= " << maxPairEnergy |
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| 492 | // << " ymin= " << ymin << " dy= " << dy << G4endl; |
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| 493 | |
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| 494 | // select bins |
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| 495 | G4int iymin = 0; |
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| 496 | G4int iymax = nbiny-1; |
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| 497 | if( minEnergy > minPairEnergy) |
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| 498 | { |
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| 499 | G4double xc = log(minEnergy/minPairEnergy)/log(maxPairEnergy/minPairEnergy); |
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| 500 | iymin = (G4int)((log(xc) - ymin)/dy); |
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| 501 | if(iymin >= nbiny) iymin = nbiny-1; |
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| 502 | else if(iymin < 0) iymin = 0; |
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| 503 | xc = log(maxEnergy/minPairEnergy)/log(maxPairEnergy/minPairEnergy); |
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| 504 | iymax = (G4int)((log(xc) - ymin)/dy) + 1; |
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| 505 | if(iymax >= nbiny) iymax = nbiny-1; |
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| 506 | else if(iymax < 0) iymax = 0; |
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| 507 | } |
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| 508 | |
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| 509 | // sample e-e+ energy, pair energy first |
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| 510 | G4int iz, iy; |
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| 511 | |
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[1315] | 512 | for(iz=1; iz<nzdat; ++iz) { if(currentZ <= zdat[iz]) { break; } } |
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| 513 | if(iz == nzdat) { --iz; } |
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[819] | 514 | |
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| 515 | G4double dz = log(currentZ/zdat[iz-1])/log(zdat[iz]/zdat[iz-1]); |
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| 516 | |
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| 517 | G4double pmin = InterpolatedIntegralCrossSection(dt,dz,iz,it,iymin,currentZ); |
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| 518 | G4double pmax = InterpolatedIntegralCrossSection(dt,dz,iz,it,iymax,currentZ); |
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| 519 | |
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| 520 | G4double p = pmin+G4UniformRand()*(pmax - pmin); |
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| 521 | |
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| 522 | // interpolate sampling vector; |
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| 523 | G4double p1 = pmin; |
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| 524 | G4double p2 = pmin; |
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[1315] | 525 | for(iy=iymin+1; iy<=iymax; ++iy) { |
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[819] | 526 | p1 = p2; |
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| 527 | p2 = InterpolatedIntegralCrossSection(dt, dz, iz, it, iy, currentZ); |
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| 528 | if(p <= p2) break; |
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| 529 | } |
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| 530 | // G4cout << "iy= " << iy << " iymin= " << iymin << " iymax= " |
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| 531 | // << iymax << " Z= " << currentZ << G4endl; |
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| 532 | G4double y = ya[iy-1] + dy*(p - p1)/(p2 - p1); |
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| 533 | |
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| 534 | G4double PairEnergy = minPairEnergy*exp(exp(y) |
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| 535 | *log(maxPairEnergy/minPairEnergy)); |
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| 536 | |
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[1315] | 537 | if(PairEnergy < minEnergy) { PairEnergy = minEnergy; } |
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| 538 | if(PairEnergy > maxEnergy) { PairEnergy = maxEnergy; } |
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[819] | 539 | |
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| 540 | // sample r=(E+-E-)/PairEnergy ( uniformly .....) |
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| 541 | G4double rmax = |
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| 542 | (1.-6.*particleMass*particleMass/(totalEnergy*(totalEnergy-PairEnergy))) |
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| 543 | *sqrt(1.-minPairEnergy/PairEnergy); |
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| 544 | G4double r = rmax * (-1.+2.*G4UniformRand()) ; |
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| 545 | |
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| 546 | // compute energies from PairEnergy,r |
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| 547 | G4double ElectronEnergy = (1.-r)*PairEnergy*0.5; |
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| 548 | G4double PositronEnergy = PairEnergy - ElectronEnergy; |
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| 549 | |
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[1315] | 550 | // The angle of the emitted virtual photon is sampled |
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| 551 | // according to the muon bremsstrahlung model |
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| 552 | |
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| 553 | G4double gam = totalEnergy/particleMass; |
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| 554 | G4double gmax = gam*std::min(1.0, totalEnergy/PairEnergy - 1.0); |
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| 555 | G4double gmax2= gmax*gmax; |
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| 556 | G4double x = G4UniformRand()*gmax2/(1.0 + gmax2); |
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[819] | 557 | |
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[1315] | 558 | G4double theta = sqrt(x/(1.0 - x))/gam; |
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| 559 | G4double sint = sin(theta); |
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| 560 | G4double phi = twopi * G4UniformRand() ; |
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| 561 | G4double dirx = sint*cos(phi), diry = sint*sin(phi), dirz = cos(theta) ; |
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[819] | 562 | |
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[1315] | 563 | G4ThreeVector gDirection(dirx, diry, dirz); |
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| 564 | gDirection.rotateUz(partDirection); |
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[819] | 565 | |
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[1315] | 566 | // the angles of e- and e+ assumed to be the same as virtual gamma |
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[819] | 567 | |
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| 568 | // create G4DynamicParticle object for the particle1 |
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[1315] | 569 | G4DynamicParticle* aParticle1 = |
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| 570 | new G4DynamicParticle(theElectron, gDirection, |
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| 571 | ElectronEnergy - electron_mass_c2); |
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[819] | 572 | |
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| 573 | // create G4DynamicParticle object for the particle2 |
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| 574 | G4DynamicParticle* aParticle2 = |
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[1315] | 575 | new G4DynamicParticle(thePositron, gDirection, |
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[819] | 576 | PositronEnergy - electron_mass_c2); |
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| 577 | |
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| 578 | // primary change |
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| 579 | kineticEnergy -= (ElectronEnergy + PositronEnergy); |
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[961] | 580 | fParticleChange->SetProposedKineticEnergy(kineticEnergy); |
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[819] | 581 | |
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[1315] | 582 | partDirection *= totalMomentum; |
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| 583 | partDirection -= (aParticle1->GetMomentum() + aParticle2->GetMomentum()); |
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| 584 | partDirection = partDirection.unit(); |
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| 585 | fParticleChange->SetProposedMomentumDirection(partDirection); |
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| 586 | |
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| 587 | // add secondary |
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[819] | 588 | vdp->push_back(aParticle1); |
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| 589 | vdp->push_back(aParticle2); |
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| 590 | } |
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| 591 | |
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| 592 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 593 | |
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| 594 | const G4Element* G4MuPairProductionModel::SelectRandomAtom( |
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| 595 | G4double kinEnergy, G4double dt, G4int it, |
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| 596 | const G4MaterialCutsCouple* couple, G4double tmin) |
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| 597 | { |
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| 598 | // select randomly 1 element within the material |
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| 599 | |
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| 600 | const G4Material* material = couple->GetMaterial(); |
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| 601 | size_t nElements = material->GetNumberOfElements(); |
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| 602 | const G4ElementVector* theElementVector = material->GetElementVector(); |
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| 603 | if (nElements == 1) return (*theElementVector)[0]; |
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| 604 | |
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| 605 | if(nElements > nmaxElements) { |
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| 606 | nmaxElements = nElements; |
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| 607 | partialSum.resize(nmaxElements); |
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| 608 | } |
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| 609 | |
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| 610 | const G4double* theAtomNumDensityVector=material->GetAtomicNumDensityVector(); |
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| 611 | |
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| 612 | G4double sum = 0.0; |
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[1196] | 613 | G4double dl; |
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[819] | 614 | |
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| 615 | size_t i; |
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| 616 | for (i=0; i<nElements; i++) { |
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| 617 | G4double Z = ((*theElementVector)[i])->GetZ(); |
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| 618 | SetCurrentElement(Z); |
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| 619 | G4double maxPairEnergy = MaxSecondaryEnergy(particle,kinEnergy); |
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| 620 | G4double minEnergy = std::max(tmin, minPairEnergy); |
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[1196] | 621 | dl = 0.0; |
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| 622 | if(minEnergy < maxPairEnergy) { |
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[819] | 623 | |
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[1196] | 624 | G4int iz; |
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| 625 | for(iz=1; iz<nzdat; iz++) {if(Z <= zdat[iz]) break;} |
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| 626 | if(iz == nzdat) iz--; |
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| 627 | G4double dz = log(Z/zdat[iz-1])/log(zdat[iz]/zdat[iz-1]); |
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[819] | 628 | |
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[1196] | 629 | G4double sigcut; |
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| 630 | if(minEnergy <= minPairEnergy) |
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| 631 | sigcut = 0.; |
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| 632 | else |
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| 633 | { |
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| 634 | G4double xc = log(minEnergy/minPairEnergy)/log(maxPairEnergy/minPairEnergy); |
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| 635 | G4int iy = (G4int)((log(xc) - ymin)/dy); |
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| 636 | if(iy < 0) iy = 0; |
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| 637 | if(iy >= nbiny) iy = nbiny-1; |
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| 638 | sigcut = InterpolatedIntegralCrossSection(dt,dz,iz,it,iy, Z); |
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| 639 | } |
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| 640 | |
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| 641 | G4double sigtot = InterpolatedIntegralCrossSection(dt,dz,iz,it,nbiny,Z); |
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| 642 | dl = (sigtot - sigcut)*theAtomNumDensityVector[i]; |
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[819] | 643 | } |
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| 644 | // protection |
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| 645 | if(dl < 0.0) dl = 0.0; |
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| 646 | sum += dl; |
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| 647 | partialSum[i] = sum; |
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| 648 | } |
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| 649 | |
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| 650 | G4double rval = G4UniformRand()*sum; |
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| 651 | for (i=0; i<nElements; i++) { |
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| 652 | if(rval<=partialSum[i]) return (*theElementVector)[i]; |
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| 653 | } |
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| 654 | |
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| 655 | return (*theElementVector)[nElements - 1]; |
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| 656 | |
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| 657 | } |
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| 658 | |
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| 659 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 660 | |
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| 661 | |
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