[968] | 1 | // |
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| 2 | // ******************************************************************** |
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| 3 | // * License and Disclaimer * |
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| 4 | // * * |
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| 5 | // * The Geant4 software is copyright of the Copyright Holders of * |
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| 6 | // * the Geant4 Collaboration. It is provided under the terms and * |
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| 7 | // * conditions of the Geant4 Software License, included in the file * |
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| 8 | // * LICENSE and available at http://cern.ch/geant4/license . These * |
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| 9 | // * include a list of copyright holders. * |
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| 10 | // * * |
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| 11 | // * Neither the authors of this software system, nor their employing * |
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| 12 | // * institutes,nor the agencies providing financial support for this * |
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| 13 | // * work make any representation or warranty, express or implied, * |
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| 14 | // * regarding this software system or assume any liability for its * |
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| 15 | // * use. Please see the license in the file LICENSE and URL above * |
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| 16 | // * for the full disclaimer and the limitation of liability. * |
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| 17 | // * * |
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| 18 | // * This code implementation is the result of the scientific and * |
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| 19 | // * technical work of the GEANT4 collaboration. * |
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| 20 | // * By using, copying, modifying or distributing the software (or * |
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| 21 | // * any work based on the software) you agree to acknowledge its * |
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| 22 | // * use in resulting scientific publications, and indicate your * |
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| 23 | // * acceptance of all terms of the Geant4 Software license. * |
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| 24 | // ******************************************************************** |
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| 25 | // |
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[1055] | 26 | // $Id: G4eBremsstrahlungRelModel.cc,v 1.14 2009/04/09 18:41:18 vnivanch Exp $ |
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| 27 | // GEANT4 tag $Name: geant4-09-03-beta-cand-01 $ |
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[968] | 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: G4eBremsstrahlungRelModel |
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| 35 | // |
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| 36 | // Author: Andreas Schaelicke |
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| 37 | // |
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| 38 | // Creation date: 12.08.2008 |
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| 39 | // |
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| 40 | // Modifications: |
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| 41 | // |
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| 42 | // 13.11.08 add SetLPMflag and SetLPMconstant methods |
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| 43 | // 13.11.08 change default LPMconstant value |
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| 44 | // |
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| 45 | // Main References: |
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| 46 | // Y.-S.Tsai, Rev. Mod. Phys. 46 (1974) 815; Rev. Mod. Phys. 49 (1977) 421. |
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| 47 | // S.Klein, Rev. Mod. Phys. 71 (1999) 1501. |
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| 48 | // T.Stanev et.al., Phys. Rev. D25 (1982) 1291. |
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| 49 | // M.L.Ter-Mikaelian, High-energy Electromagnetic Processes in Condensed Media, Wiley, 1972. |
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| 50 | // |
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| 51 | // ------------------------------------------------------------------- |
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| 52 | // |
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| 53 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 54 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 55 | |
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| 56 | #include "G4eBremsstrahlungRelModel.hh" |
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| 57 | #include "G4Electron.hh" |
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| 58 | #include "G4Positron.hh" |
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| 59 | #include "G4Gamma.hh" |
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| 60 | #include "Randomize.hh" |
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| 61 | #include "G4Material.hh" |
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| 62 | #include "G4Element.hh" |
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| 63 | #include "G4ElementVector.hh" |
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| 64 | #include "G4ProductionCutsTable.hh" |
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| 65 | #include "G4ParticleChangeForLoss.hh" |
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| 66 | #include "G4LossTableManager.hh" |
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| 67 | |
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| 68 | |
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| 69 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 70 | |
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| 71 | const G4double G4eBremsstrahlungRelModel::xgi[]={ 0.0199, 0.1017, 0.2372, 0.4083, |
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| 72 | 0.5917, 0.7628, 0.8983, 0.9801 }; |
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| 73 | const G4double G4eBremsstrahlungRelModel::wgi[]={ 0.0506, 0.1112, 0.1569, 0.1813, |
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| 74 | 0.1813, 0.1569, 0.1112, 0.0506 }; |
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| 75 | const G4double G4eBremsstrahlungRelModel::Fel_light[] = {0., 5.31 , 4.79 , 4.74 , 4.71} ; |
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| 76 | const G4double G4eBremsstrahlungRelModel::Finel_light[] = {0., 6.144 , 5.621 , 5.805 , 5.924} ; |
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| 77 | |
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| 78 | |
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| 79 | using namespace std; |
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| 80 | |
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| 81 | G4eBremsstrahlungRelModel::G4eBremsstrahlungRelModel(const G4ParticleDefinition* p, |
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| 82 | const G4String& name) |
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| 83 | : G4VEmModel(name), |
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| 84 | particle(0), |
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| 85 | fXiLPM(0), fPhiLPM(0), fGLPM(0), |
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| 86 | isElectron(true), |
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| 87 | fMigdalConstant(classic_electr_radius*electron_Compton_length*electron_Compton_length*4.0*pi), |
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| 88 | fLPMconstant(fine_structure_const*electron_mass_c2*electron_mass_c2/(4.*pi*hbarc)*0.5), |
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| 89 | bremFactor(fine_structure_const*classic_electr_radius*classic_electr_radius*16./3.), |
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| 90 | use_completescreening(true),isInitialised(false) |
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| 91 | { |
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| 92 | if(p) SetParticle(p); |
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| 93 | theGamma = G4Gamma::Gamma(); |
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| 94 | |
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| 95 | minThreshold = 1.0*keV; |
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| 96 | SetLowEnergyLimit(GeV); |
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| 97 | |
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| 98 | nist = G4NistManager::Instance(); |
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| 99 | InitialiseConstants(); |
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| 100 | |
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| 101 | SetLPMFlag(true); |
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| 102 | } |
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| 103 | |
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| 104 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 105 | |
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| 106 | void G4eBremsstrahlungRelModel::InitialiseConstants() |
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| 107 | { |
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| 108 | facFel = log(184.15); |
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| 109 | facFinel = log(1194.); |
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| 110 | |
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| 111 | preS1 = 1./(184.15*184.15); |
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| 112 | logTwo = log(2.); |
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| 113 | } |
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| 114 | |
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| 115 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 116 | |
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| 117 | G4eBremsstrahlungRelModel::~G4eBremsstrahlungRelModel() |
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| 118 | { |
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| 119 | } |
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| 120 | |
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| 121 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 122 | |
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| 123 | void G4eBremsstrahlungRelModel::SetParticle(const G4ParticleDefinition* p) |
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| 124 | { |
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| 125 | particle = p; |
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| 126 | particleMass = p->GetPDGMass(); |
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| 127 | if(p == G4Electron::Electron()) isElectron = true; |
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| 128 | else isElectron = false; |
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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 | G4double G4eBremsstrahlungRelModel::MinEnergyCut(const G4ParticleDefinition*, |
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| 134 | const G4MaterialCutsCouple*) |
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| 135 | { |
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| 136 | return minThreshold; |
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| 137 | } |
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| 138 | |
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| 139 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 140 | |
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| 141 | void G4eBremsstrahlungRelModel::SetupForMaterial(const G4ParticleDefinition*, |
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| 142 | const G4Material* mat, G4double kineticEnergy) |
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| 143 | { |
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| 144 | densityFactor = mat->GetElectronDensity()*fMigdalConstant; |
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| 145 | lpmEnergy = mat->GetRadlen()*fLPMconstant; |
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| 146 | |
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| 147 | // Threshold for LPM effect (i.e. below which LPM hidden by density effect) |
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| 148 | if (LPMFlag()) |
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| 149 | energyThresholdLPM=sqrt(densityFactor)*lpmEnergy; |
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| 150 | else |
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| 151 | energyThresholdLPM=1.e39; // i.e. do not use LPM effect |
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| 152 | |
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| 153 | // calculate threshold for density effect |
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| 154 | kinEnergy = kineticEnergy; |
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| 155 | totalEnergy = kineticEnergy + particleMass; |
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| 156 | densityCorr = densityFactor*totalEnergy*totalEnergy; |
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| 157 | |
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| 158 | // define critical gamma energies (important for integration/dicing) |
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| 159 | klpm=totalEnergy*totalEnergy/lpmEnergy; |
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| 160 | kp=sqrt(densityCorr); |
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| 161 | |
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| 162 | } |
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| 163 | |
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| 164 | |
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| 165 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 166 | |
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| 167 | void G4eBremsstrahlungRelModel::Initialise(const G4ParticleDefinition* p, |
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| 168 | const G4DataVector& cuts) |
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| 169 | { |
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| 170 | if(p) SetParticle(p); |
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| 171 | |
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| 172 | highKinEnergy = HighEnergyLimit(); |
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| 173 | lowKinEnergy = LowEnergyLimit(); |
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| 174 | |
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| 175 | currentZ = 0.; |
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| 176 | |
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| 177 | InitialiseElementSelectors(p, cuts); |
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| 178 | |
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| 179 | if(isInitialised) return; |
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[1055] | 180 | fParticleChange = GetParticleChangeForLoss(); |
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[968] | 181 | isInitialised = true; |
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| 182 | } |
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| 183 | |
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| 184 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 185 | |
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| 186 | G4double G4eBremsstrahlungRelModel::ComputeDEDXPerVolume( |
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| 187 | const G4Material* material, |
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| 188 | const G4ParticleDefinition* p, |
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| 189 | G4double kineticEnergy, |
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| 190 | G4double cutEnergy) |
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| 191 | { |
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| 192 | if(!particle) SetParticle(p); |
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| 193 | if(kineticEnergy < lowKinEnergy) return 0.0; |
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| 194 | G4double cut = std::min(cutEnergy, kineticEnergy); |
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| 195 | if(cut == 0.0) return 0.0; |
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| 196 | |
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| 197 | SetupForMaterial(particle, material,kineticEnergy); |
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| 198 | |
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| 199 | const G4ElementVector* theElementVector = material->GetElementVector(); |
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| 200 | const G4double* theAtomicNumDensityVector = material->GetAtomicNumDensityVector(); |
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| 201 | |
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| 202 | G4double dedx = 0.0; |
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| 203 | |
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| 204 | // loop for elements in the material |
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| 205 | for (size_t i=0; i<material->GetNumberOfElements(); i++) { |
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| 206 | |
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| 207 | G4VEmModel::SetCurrentElement((*theElementVector)[i]); |
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| 208 | SetCurrentElement((*theElementVector)[i]->GetZ()); |
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| 209 | |
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| 210 | dedx += theAtomicNumDensityVector[i]*currentZ*currentZ*ComputeBremLoss(cut); |
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| 211 | } |
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| 212 | dedx *= bremFactor; |
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| 213 | |
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| 214 | |
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| 215 | return dedx; |
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| 216 | } |
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| 217 | |
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| 218 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 219 | |
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| 220 | G4double G4eBremsstrahlungRelModel::ComputeBremLoss(G4double cut) |
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| 221 | { |
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| 222 | G4double loss = 0.0; |
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| 223 | |
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| 224 | // number of intervals and integration step |
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| 225 | G4double vcut = cut/totalEnergy; |
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| 226 | G4int n = (G4int)(20*vcut) + 3; |
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| 227 | G4double delta = vcut/G4double(n); |
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| 228 | |
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| 229 | G4double e0 = 0.0; |
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| 230 | G4double xs; |
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| 231 | |
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| 232 | // integration |
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| 233 | for(G4int l=0; l<n; l++) { |
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| 234 | |
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| 235 | for(G4int i=0; i<8; i++) { |
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| 236 | |
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| 237 | G4double eg = (e0 + xgi[i]*delta)*totalEnergy; |
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| 238 | |
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| 239 | if(totalEnergy > energyThresholdLPM) { |
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| 240 | xs = ComputeRelDXSectionPerAtom(eg); |
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| 241 | } else { |
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| 242 | xs = ComputeDXSectionPerAtom(eg); |
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| 243 | } |
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| 244 | loss += wgi[i]*xs/(1.0 + densityCorr/(eg*eg)); |
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| 245 | } |
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| 246 | e0 += delta; |
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| 247 | } |
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| 248 | |
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| 249 | loss *= delta*totalEnergy; |
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| 250 | |
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| 251 | return loss; |
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| 252 | } |
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| 253 | |
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| 254 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 255 | |
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| 256 | G4double G4eBremsstrahlungRelModel::ComputeCrossSectionPerAtom( |
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| 257 | const G4ParticleDefinition* p, |
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| 258 | G4double kineticEnergy, |
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| 259 | G4double Z, G4double, |
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| 260 | G4double cutEnergy, |
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| 261 | G4double maxEnergy) |
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| 262 | { |
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| 263 | if(!particle) SetParticle(p); |
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| 264 | if(kineticEnergy < lowKinEnergy) return 0.0; |
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| 265 | G4double cut = std::min(cutEnergy, kineticEnergy); |
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| 266 | G4double tmax = std::min(maxEnergy, kineticEnergy); |
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| 267 | |
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| 268 | if(cut >= tmax) return 0.0; |
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| 269 | |
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| 270 | SetCurrentElement(Z); |
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| 271 | |
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| 272 | G4double cross = ComputeXSectionPerAtom(cut); |
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| 273 | |
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| 274 | // allow partial integration |
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| 275 | if(tmax < kinEnergy) cross -= ComputeXSectionPerAtom(tmax); |
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| 276 | |
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| 277 | cross *= Z*Z*bremFactor; |
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| 278 | |
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| 279 | return cross; |
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| 280 | } |
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| 281 | |
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| 282 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 283 | |
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| 284 | |
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| 285 | G4double G4eBremsstrahlungRelModel::ComputeXSectionPerAtom(G4double cut) |
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| 286 | { |
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| 287 | G4double cross = 0.0; |
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| 288 | |
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| 289 | // number of intervals and integration step |
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| 290 | G4double vcut = log(cut/totalEnergy); |
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| 291 | G4double vmax = log(kinEnergy/totalEnergy); |
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| 292 | G4int n = (G4int)(0.45*(vmax - vcut)) + 4; |
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| 293 | // n=1; // integration test |
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| 294 | G4double delta = (vmax - vcut)/G4double(n); |
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| 295 | |
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| 296 | G4double e0 = vcut; |
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| 297 | G4double xs; |
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| 298 | |
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| 299 | // integration |
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| 300 | for(G4int l=0; l<n; l++) { |
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| 301 | |
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| 302 | for(G4int i=0; i<8; i++) { |
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| 303 | |
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| 304 | G4double eg = exp(e0 + xgi[i]*delta)*totalEnergy; |
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| 305 | |
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| 306 | if(totalEnergy > energyThresholdLPM) { |
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| 307 | xs = ComputeRelDXSectionPerAtom(eg); |
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| 308 | } else { |
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| 309 | xs = ComputeDXSectionPerAtom(eg); |
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| 310 | } |
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| 311 | cross += wgi[i]*xs/(1.0 + densityCorr/(eg*eg)); |
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| 312 | } |
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| 313 | e0 += delta; |
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| 314 | } |
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| 315 | |
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| 316 | cross *= delta; |
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| 317 | |
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| 318 | return cross; |
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| 319 | } |
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| 320 | |
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| 321 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 322 | void G4eBremsstrahlungRelModel::CalcLPMFunctions(G4double k) |
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| 323 | { |
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| 324 | // *** calculate lpm variable s & sprime *** |
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| 325 | // Klein eqs. (78) & (79) |
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| 326 | G4double sprime = sqrt(0.125*k*lpmEnergy/(totalEnergy*(totalEnergy-k))); |
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| 327 | |
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| 328 | G4double s1 = preS1*z23; |
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| 329 | G4double logS1 = 2./3.*lnZ-2.*facFel; |
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| 330 | G4double logTS1 = logTwo+logS1; |
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| 331 | |
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| 332 | xiLPM = 2.; |
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| 333 | |
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| 334 | if (sprime>1) |
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| 335 | xiLPM = 1.; |
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| 336 | else if (sprime>sqrt(2.)*s1) { |
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| 337 | G4double h = log(sprime)/logTS1; |
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| 338 | xiLPM = 1+h-0.08*(1-h)*(1-sqr(1-h))/logTS1; |
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| 339 | } |
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| 340 | |
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| 341 | G4double s = sprime/sqrt(xiLPM); |
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| 342 | |
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| 343 | // *** merging with density effect*** should be only necessary in region "close to" kp, e.g. k<100*kp |
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| 344 | // using Ter-Mikaelian eq. (20.9) |
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| 345 | G4double k2 = k*k; |
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| 346 | s = s * (1 + (densityCorr/k2) ); |
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| 347 | |
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| 348 | // recalculate Xi using modified s above |
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| 349 | // Klein eq. (75) |
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| 350 | xiLPM = 1.; |
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| 351 | if (s<=s1) xiLPM = 2.; |
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| 352 | else if ( (s1<s) && (s<=1) ) xiLPM = 1. + log(s)/logS1; |
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| 353 | |
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| 354 | |
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| 355 | // *** calculate supression functions phi and G *** |
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| 356 | // Klein eqs. (77) |
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| 357 | G4double s2=s*s; |
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| 358 | G4double s3=s*s2; |
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| 359 | G4double s4=s2*s2; |
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| 360 | |
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| 361 | if (s<0.1) { |
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| 362 | // high suppression limit |
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| 363 | phiLPM = 6.*s - 18.84955592153876*s2 + 39.47841760435743*s3 |
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| 364 | - 57.69873135166053*s4; |
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| 365 | gLPM = 37.69911184307752*s2 - 236.8705056261446*s3 + 807.7822389*s4; |
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| 366 | } |
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| 367 | else if (s<1.9516) { |
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| 368 | // intermediate suppression |
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| 369 | // using eq.77 approxim. valid s<2. |
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| 370 | phiLPM = 1.-exp(-6.*s*(1.+(3.-pi)*s) |
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| 371 | +s3/(0.623+0.795*s+0.658*s2)); |
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| 372 | if (s<0.415827397755) { |
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| 373 | // using eq.77 approxim. valid 0.07<s<2 |
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| 374 | G4double psiLPM = 1-exp(-4*s-8*s2/(1+3.936*s+4.97*s2-0.05*s3+7.50*s4)); |
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| 375 | gLPM = 3*psiLPM-2*phiLPM; |
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| 376 | } |
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| 377 | else { |
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| 378 | // using alternative parametrisiation |
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| 379 | G4double pre = -0.16072300849123999 + s*3.7550300067531581 + s2*-1.7981383069010097 |
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| 380 | + s3*0.67282686077812381 + s4*-0.1207722909879257; |
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| 381 | gLPM = tanh(pre); |
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| 382 | } |
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| 383 | } |
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| 384 | else { |
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| 385 | // low suppression limit valid s>2. |
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| 386 | phiLPM = 1. - 0.0119048/s4; |
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| 387 | gLPM = 1. - 0.0230655/s4; |
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| 388 | } |
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| 389 | |
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| 390 | // *** make sure suppression is smaller than 1 *** |
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| 391 | // *** caused by Migdal approximation in xi *** |
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| 392 | if (xiLPM*phiLPM>1. || s>0.57) xiLPM=1./phiLPM; |
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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 | |
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| 398 | G4double G4eBremsstrahlungRelModel::ComputeRelDXSectionPerAtom(G4double gammaEnergy) |
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| 399 | // Ultra relativistic model |
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| 400 | // only valid for very high energies, but includes LPM suppression |
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| 401 | // * complete screening |
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| 402 | { |
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| 403 | if(gammaEnergy < 0.0) return 0.0; |
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| 404 | |
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| 405 | G4double y = gammaEnergy/totalEnergy; |
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| 406 | G4double y2 = y*y*.25; |
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| 407 | G4double yone2 = (1.-y+2.*y2); |
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| 408 | |
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| 409 | // ** form factors complete screening case ** |
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| 410 | |
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| 411 | // ** calc LPM functions -- include ter-mikaelian merging with density effect ** |
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| 412 | // G4double xiLPM, gLPM, phiLPM; // to be made member variables !!! |
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| 413 | CalcLPMFunctions(gammaEnergy); |
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| 414 | |
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| 415 | G4double mainLPM = xiLPM*(y2 * gLPM + yone2*phiLPM) * ( (Fel-fCoulomb) + Finel/currentZ ); |
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| 416 | G4double secondTerm = (1.-y)/12.*(1.+1./currentZ); |
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| 417 | |
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| 418 | G4double cross = mainLPM+secondTerm; |
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| 419 | return cross; |
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| 420 | } |
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| 421 | |
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| 422 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 423 | |
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| 424 | G4double G4eBremsstrahlungRelModel::ComputeDXSectionPerAtom(G4double gammaEnergy) |
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| 425 | // Relativistic model |
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| 426 | // only valid for high energies (and if LPM suppression does not play a role) |
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| 427 | // * screening according to thomas-fermi-Model (only valid for Z>5) |
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| 428 | // * no LPM effect |
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| 429 | { |
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| 430 | |
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| 431 | if(gammaEnergy < 0.0) return 0.0; |
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| 432 | |
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| 433 | G4double y = gammaEnergy/totalEnergy; |
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| 434 | |
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| 435 | G4double main=0.,secondTerm=0.; |
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| 436 | |
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| 437 | if (use_completescreening|| currentZ<5) { |
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| 438 | // ** form factors complete screening case ** |
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| 439 | main = (3./4.*y*y - y + 1.) * ( (Fel-fCoulomb) + Finel/currentZ ); |
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| 440 | secondTerm = (1.-y)/12.*(1.+1./currentZ); |
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| 441 | } |
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| 442 | else { |
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| 443 | // ** intermediate screening using Thomas-Fermi FF from Tsai only valid for Z>=5** |
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| 444 | G4double dd=100.*electron_mass_c2*y/(totalEnergy-gammaEnergy); |
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| 445 | G4double gg=dd*z13; |
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| 446 | G4double eps=dd*z23; |
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| 447 | G4double phi1=Phi1(gg,currentZ), phi1m2=Phi1M2(gg,currentZ); |
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| 448 | G4double psi1=Psi1(eps,currentZ), psi1m2=Psi1M2(eps,currentZ); |
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| 449 | |
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| 450 | main = (3./4.*y*y - y + 1.) * ( (0.25*phi1-1./3.*lnZ-fCoulomb) + (0.25*psi1-2./3.*lnZ)/currentZ ); |
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| 451 | secondTerm = (1.-y)/8.*(phi1m2+psi1m2/currentZ); |
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| 452 | } |
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| 453 | G4double cross = main+secondTerm; |
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| 454 | return cross; |
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| 455 | } |
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| 456 | |
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| 457 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 458 | |
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| 459 | void G4eBremsstrahlungRelModel::SampleSecondaries( |
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| 460 | std::vector<G4DynamicParticle*>* vdp, |
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| 461 | const G4MaterialCutsCouple* couple, |
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| 462 | const G4DynamicParticle* dp, |
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| 463 | G4double cutEnergy, |
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| 464 | G4double maxEnergy) |
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| 465 | { |
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| 466 | G4double kineticEnergy = dp->GetKineticEnergy(); |
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| 467 | if(kineticEnergy < lowKinEnergy) return; |
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| 468 | G4double cut = std::min(cutEnergy, kineticEnergy); |
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| 469 | G4double emax = std::min(maxEnergy, kineticEnergy); |
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| 470 | if(cut >= emax) return; |
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| 471 | |
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| 472 | SetupForMaterial(particle, couple->GetMaterial(),kineticEnergy); |
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| 473 | |
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| 474 | const G4Element* elm = |
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| 475 | SelectRandomAtom(couple,particle,kineticEnergy,cut,emax); |
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| 476 | SetCurrentElement(elm->GetZ()); |
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| 477 | |
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| 478 | kinEnergy = kineticEnergy; |
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| 479 | totalEnergy = kineticEnergy + particleMass; |
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| 480 | densityCorr = densityFactor*totalEnergy*totalEnergy; |
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| 481 | G4ThreeVector direction = dp->GetMomentumDirection(); |
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| 482 | |
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| 483 | // G4double fmax= fMax; |
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| 484 | G4bool highe = true; |
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| 485 | if(totalEnergy < energyThresholdLPM) highe = false; |
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| 486 | |
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| 487 | G4double xmin = log(cut*cut + densityCorr); |
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| 488 | G4double xmax = log(emax*emax + densityCorr); |
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| 489 | G4double gammaEnergy, f, x; |
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| 490 | |
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| 491 | do { |
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| 492 | x = exp(xmin + G4UniformRand()*(xmax - xmin)) - densityCorr; |
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| 493 | if(x < 0.0) x = 0.0; |
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| 494 | gammaEnergy = sqrt(x); |
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| 495 | if(highe) f = ComputeRelDXSectionPerAtom(gammaEnergy); |
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| 496 | else f = ComputeDXSectionPerAtom(gammaEnergy); |
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| 497 | |
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| 498 | if ( f > fMax ) { |
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| 499 | G4cout << "### G4eBremsstrahlungRelModel Warning: Majoranta exceeded! " |
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| 500 | << f << " > " << fMax |
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| 501 | << " Egamma(MeV)= " << gammaEnergy |
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| 502 | << " E(mEV)= " << kineticEnergy |
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| 503 | << G4endl; |
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| 504 | } |
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| 505 | |
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| 506 | } while (f < fMax*G4UniformRand()); |
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| 507 | |
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| 508 | // |
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| 509 | // angles of the emitted gamma. ( Z - axis along the parent particle) |
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| 510 | // |
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| 511 | // universal distribution suggested by L. Urban |
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| 512 | // (Geant3 manual (1993) Phys211), |
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| 513 | // derived from Tsai distribution (Rev Mod Phys 49,421(1977)) |
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| 514 | |
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| 515 | G4double u; |
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| 516 | const G4double a1 = 0.625 , a2 = 3.*a1 , d = 27. ; |
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| 517 | |
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| 518 | if (9./(9.+d) > G4UniformRand()) u = - log(G4UniformRand()*G4UniformRand())/a1; |
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| 519 | else u = - log(G4UniformRand()*G4UniformRand())/a2; |
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| 520 | |
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| 521 | G4double theta = u*particleMass/totalEnergy; |
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| 522 | G4double sint = sin(theta); |
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| 523 | G4double phi = twopi * G4UniformRand(); |
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| 524 | G4ThreeVector gammaDirection(sint*cos(phi),sint*sin(phi), cos(theta)); |
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| 525 | gammaDirection.rotateUz(direction); |
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| 526 | |
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| 527 | // create G4DynamicParticle object for the Gamma |
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| 528 | G4DynamicParticle* g = new G4DynamicParticle(theGamma,gammaDirection, |
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| 529 | gammaEnergy); |
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| 530 | vdp->push_back(g); |
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| 531 | |
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| 532 | G4double totMomentum = sqrt(kineticEnergy*(totalEnergy + electron_mass_c2)); |
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| 533 | G4ThreeVector dir = totMomentum*direction - gammaEnergy*gammaDirection; |
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| 534 | direction = dir.unit(); |
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| 535 | |
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| 536 | // energy of primary |
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| 537 | G4double finalE = kineticEnergy - gammaEnergy; |
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| 538 | |
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| 539 | // stop tracking and create new secondary instead of primary |
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| 540 | if(gammaEnergy > SecondaryThreshold()) { |
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| 541 | fParticleChange->ProposeTrackStatus(fStopAndKill); |
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| 542 | fParticleChange->SetProposedKineticEnergy(0.0); |
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| 543 | G4DynamicParticle* el = |
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| 544 | new G4DynamicParticle(const_cast<G4ParticleDefinition*>(particle), |
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| 545 | direction, finalE); |
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| 546 | vdp->push_back(el); |
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| 547 | |
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| 548 | // continue tracking |
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| 549 | } else { |
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| 550 | fParticleChange->SetProposedMomentumDirection(direction); |
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| 551 | fParticleChange->SetProposedKineticEnergy(finalE); |
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| 552 | } |
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| 553 | } |
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| 554 | |
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| 555 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 556 | |
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| 557 | |
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