[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: G4LivermoreComptonModel.cc,v 1.6 2009/04/18 18:29:34 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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[1055] | 29 | // |
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| 30 | // Author: Sebastien Inserti |
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| 31 | // 30 October 2008 |
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| 32 | // |
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| 33 | // History: |
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| 34 | // -------- |
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| 35 | // 18 Apr 2009 V Ivanchenko Cleanup initialisation and generation of secondaries: |
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| 36 | // - apply internal high-energy limit only in constructor |
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| 37 | // - do not apply low-energy limit (default is 0) |
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| 38 | // - remove GetMeanFreePath method and table |
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| 39 | // - added protection against numerical problem in energy sampling |
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| 40 | // - use G4ElementSelector |
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[968] | 41 | |
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| 42 | #include "G4LivermoreComptonModel.hh" |
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| 43 | |
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| 44 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 45 | |
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| 46 | using namespace std; |
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| 47 | |
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| 48 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 49 | |
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| 50 | G4LivermoreComptonModel::G4LivermoreComptonModel(const G4ParticleDefinition*, |
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[1055] | 51 | const G4String& nam) |
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| 52 | :G4VEmModel(nam),isInitialised(false),meanFreePathTable(0), |
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| 53 | scatterFunctionData(0),crossSectionHandler(0) |
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[968] | 54 | { |
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[1055] | 55 | lowEnergyLimit = 250 * eV; |
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[968] | 56 | highEnergyLimit = 100 * GeV; |
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[1055] | 57 | // SetLowEnergyLimit(lowEnergyLimit); |
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[968] | 58 | SetHighEnergyLimit(highEnergyLimit); |
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| 59 | |
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[1055] | 60 | verboseLevel=0 ; |
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[968] | 61 | // Verbosity scale: |
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| 62 | // 0 = nothing |
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| 63 | // 1 = warning for energy non-conservation |
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| 64 | // 2 = details of energy budget |
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| 65 | // 3 = calculation of cross sections, file openings, sampling of atoms |
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| 66 | // 4 = entering in methods |
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[1055] | 67 | |
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| 68 | if( verboseLevel>0 ) { |
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| 69 | G4cout << "Livermore Compton model is constructed " << G4endl |
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| 70 | << "Energy range: " |
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| 71 | << lowEnergyLimit / eV << " eV - " |
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| 72 | << highEnergyLimit / GeV << " GeV" |
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| 73 | << G4endl; |
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| 74 | } |
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[968] | 75 | } |
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| 76 | |
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| 77 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 78 | |
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| 79 | G4LivermoreComptonModel::~G4LivermoreComptonModel() |
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| 80 | { |
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[1055] | 81 | if (crossSectionHandler) delete crossSectionHandler; |
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| 82 | if (scatterFunctionData) delete scatterFunctionData; |
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[968] | 83 | } |
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| 84 | |
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| 85 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 86 | |
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| 87 | void G4LivermoreComptonModel::Initialise(const G4ParticleDefinition* particle, |
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[1055] | 88 | const G4DataVector& cuts) |
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[968] | 89 | { |
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| 90 | if (verboseLevel > 3) |
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| 91 | G4cout << "Calling G4LivermoreComptonModel::Initialise()" << G4endl; |
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| 92 | |
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[1055] | 93 | if (crossSectionHandler) |
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| 94 | { |
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| 95 | crossSectionHandler->Clear(); |
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| 96 | delete crossSectionHandler; |
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| 97 | } |
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[968] | 98 | |
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| 99 | // Reading of data files - all materials are read |
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| 100 | |
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| 101 | crossSectionHandler = new G4CrossSectionHandler; |
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| 102 | crossSectionHandler->Clear(); |
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| 103 | G4String crossSectionFile = "comp/ce-cs-"; |
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| 104 | crossSectionHandler->LoadData(crossSectionFile); |
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| 105 | |
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| 106 | G4VDataSetAlgorithm* scatterInterpolation = new G4LogLogInterpolation; |
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| 107 | G4String scatterFile = "comp/ce-sf-"; |
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| 108 | scatterFunctionData = new G4CompositeEMDataSet(scatterInterpolation, 1., 1.); |
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| 109 | scatterFunctionData->LoadData(scatterFile); |
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| 110 | |
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| 111 | // For Doppler broadening |
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| 112 | shellData.SetOccupancyData(); |
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| 113 | G4String file = "/doppler/shell-doppler"; |
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| 114 | shellData.LoadData(file); |
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| 115 | |
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| 116 | if (verboseLevel > 2) |
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| 117 | G4cout << "Loaded cross section files for Livermore Compton model" << G4endl; |
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| 118 | |
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[1055] | 119 | InitialiseElementSelectors(particle,cuts); |
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[968] | 120 | |
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[1055] | 121 | if( verboseLevel>0 ) { |
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| 122 | G4cout << "Livermore Compton model is initialized " << G4endl |
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| 123 | << "Energy range: " |
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| 124 | << LowEnergyLimit() / eV << " eV - " |
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| 125 | << HighEnergyLimit() / GeV << " GeV" |
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| 126 | << G4endl; |
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| 127 | } |
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| 128 | // |
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[968] | 129 | if(isInitialised) return; |
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[1055] | 130 | fParticleChange = GetParticleChangeForGamma(); |
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[968] | 131 | isInitialised = true; |
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| 132 | } |
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| 133 | |
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| 134 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 135 | |
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| 136 | G4double G4LivermoreComptonModel::ComputeCrossSectionPerAtom( |
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| 137 | const G4ParticleDefinition*, |
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| 138 | G4double GammaEnergy, |
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| 139 | G4double Z, G4double, |
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| 140 | G4double, G4double) |
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| 141 | { |
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| 142 | if (verboseLevel > 3) |
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| 143 | G4cout << "Calling ComputeCrossSectionPerAtom() of G4LivermoreComptonModel" << G4endl; |
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| 144 | |
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[1055] | 145 | if (GammaEnergy < lowEnergyLimit || GammaEnergy > highEnergyLimit) return 0.0; |
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| 146 | |
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| 147 | G4double cs = crossSectionHandler->FindValue(G4int(Z), GammaEnergy); |
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[968] | 148 | return cs; |
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| 149 | } |
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| 150 | |
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| 151 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 152 | |
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| 153 | void G4LivermoreComptonModel::SampleSecondaries(std::vector<G4DynamicParticle*>* fvect, |
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[1055] | 154 | const G4MaterialCutsCouple* couple, |
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| 155 | const G4DynamicParticle* aDynamicGamma, |
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| 156 | G4double, G4double) |
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[968] | 157 | { |
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[1055] | 158 | |
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[968] | 159 | // The scattered gamma energy is sampled according to Klein - Nishina formula. |
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| 160 | // then accepted or rejected depending on the Scattering Function multiplied |
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| 161 | // by factor from Klein - Nishina formula. |
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| 162 | // Expression of the angular distribution as Klein Nishina |
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| 163 | // angular and energy distribution and Scattering fuctions is taken from |
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| 164 | // D. E. Cullen "A simple model of photon transport" Nucl. Instr. Meth. |
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| 165 | // Phys. Res. B 101 (1995). Method of sampling with form factors is different |
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| 166 | // data are interpolated while in the article they are fitted. |
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| 167 | // Reference to the article is from J. Stepanek New Photon, Positron |
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| 168 | // and Electron Interaction Data for GEANT in Energy Range from 1 eV to 10 |
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| 169 | // TeV (draft). |
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| 170 | // The random number techniques of Butcher & Messel are used |
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| 171 | // (Nucl Phys 20(1960),15). |
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| 172 | |
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[1055] | 173 | G4double photonEnergy0 = aDynamicGamma->GetKineticEnergy(); |
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[968] | 174 | |
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[1055] | 175 | if (verboseLevel > 3) { |
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| 176 | G4cout << "G4LivermoreComptonModel::SampleSecondaries() E(MeV)= " |
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| 177 | << photonEnergy0/MeV << " in " << couple->GetMaterial()->GetName() |
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| 178 | << G4endl; |
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| 179 | } |
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[968] | 180 | |
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[1055] | 181 | // low-energy gamma is absorpted by this process |
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| 182 | if (photonEnergy0 <= lowEnergyLimit) |
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| 183 | { |
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[968] | 184 | fParticleChange->ProposeTrackStatus(fStopAndKill); |
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| 185 | fParticleChange->SetProposedKineticEnergy(0.); |
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| 186 | fParticleChange->ProposeLocalEnergyDeposit(photonEnergy0); |
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| 187 | return ; |
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[1055] | 188 | } |
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[968] | 189 | |
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| 190 | G4double e0m = photonEnergy0 / electron_mass_c2 ; |
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| 191 | G4ParticleMomentum photonDirection0 = aDynamicGamma->GetMomentumDirection(); |
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| 192 | |
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| 193 | // Select randomly one element in the current material |
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[1055] | 194 | // G4int Z = crossSectionHandler->SelectRandomAtom(couple,photonEnergy0); |
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| 195 | const G4ParticleDefinition* particle = aDynamicGamma->GetDefinition(); |
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| 196 | const G4Element* elm = SelectRandomAtom(couple,particle,photonEnergy0); |
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| 197 | G4int Z = (G4int)elm->GetZ(); |
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[968] | 198 | |
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| 199 | G4double epsilon0 = 1. / (1. + 2. * e0m); |
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| 200 | G4double epsilon0Sq = epsilon0 * epsilon0; |
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| 201 | G4double alpha1 = -std::log(epsilon0); |
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| 202 | G4double alpha2 = 0.5 * (1. - epsilon0Sq); |
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| 203 | |
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| 204 | G4double wlPhoton = h_Planck*c_light/photonEnergy0; |
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| 205 | |
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| 206 | // Sample the energy of the scattered photon |
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| 207 | G4double epsilon; |
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| 208 | G4double epsilonSq; |
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| 209 | G4double oneCosT; |
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| 210 | G4double sinT2; |
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| 211 | G4double gReject; |
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| 212 | |
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| 213 | do |
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| 214 | { |
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| 215 | if ( alpha1/(alpha1+alpha2) > G4UniformRand()) |
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| 216 | { |
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[1055] | 217 | // std::pow(epsilon0,G4UniformRand()) |
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| 218 | epsilon = std::exp(-alpha1 * G4UniformRand()); |
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[968] | 219 | epsilonSq = epsilon * epsilon; |
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| 220 | } |
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| 221 | else |
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| 222 | { |
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| 223 | epsilonSq = epsilon0Sq + (1. - epsilon0Sq) * G4UniformRand(); |
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| 224 | epsilon = std::sqrt(epsilonSq); |
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| 225 | } |
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| 226 | |
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| 227 | oneCosT = (1. - epsilon) / ( epsilon * e0m); |
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| 228 | sinT2 = oneCosT * (2. - oneCosT); |
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| 229 | G4double x = std::sqrt(oneCosT/2.) / (wlPhoton/cm); |
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| 230 | G4double scatteringFunction = scatterFunctionData->FindValue(x,Z-1); |
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| 231 | gReject = (1. - epsilon * sinT2 / (1. + epsilonSq)) * scatteringFunction; |
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| 232 | |
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| 233 | } while(gReject < G4UniformRand()*Z); |
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| 234 | |
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| 235 | G4double cosTheta = 1. - oneCosT; |
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| 236 | G4double sinTheta = std::sqrt (sinT2); |
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| 237 | G4double phi = twopi * G4UniformRand() ; |
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| 238 | G4double dirx = sinTheta * std::cos(phi); |
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| 239 | G4double diry = sinTheta * std::sin(phi); |
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| 240 | G4double dirz = cosTheta ; |
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| 241 | |
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| 242 | // Doppler broadening - Method based on: |
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| 243 | // Y. Namito, S. Ban and H. Hirayama, |
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[1055] | 244 | // "Implementation of the Doppler Broadening of a Compton-Scattered Photon |
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| 245 | // into the EGS4 Code", NIM A 349, pp. 489-494, 1994 |
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[968] | 246 | |
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| 247 | // Maximum number of sampling iterations |
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| 248 | G4int maxDopplerIterations = 1000; |
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| 249 | G4double bindingE = 0.; |
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| 250 | G4double photonEoriginal = epsilon * photonEnergy0; |
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| 251 | G4double photonE = -1.; |
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| 252 | G4int iteration = 0; |
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| 253 | G4double eMax = photonEnergy0; |
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| 254 | do |
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| 255 | { |
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| 256 | iteration++; |
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| 257 | // Select shell based on shell occupancy |
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| 258 | G4int shell = shellData.SelectRandomShell(Z); |
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| 259 | bindingE = shellData.BindingEnergy(Z,shell); |
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| 260 | |
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| 261 | eMax = photonEnergy0 - bindingE; |
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| 262 | |
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[1055] | 263 | // Randomly sample bound electron momentum |
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| 264 | // (memento: the data set is in Atomic Units) |
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[968] | 265 | G4double pSample = profileData.RandomSelectMomentum(Z,shell); |
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| 266 | // Rescale from atomic units |
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| 267 | G4double pDoppler = pSample * fine_structure_const; |
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| 268 | G4double pDoppler2 = pDoppler * pDoppler; |
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| 269 | G4double var2 = 1. + oneCosT * e0m; |
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| 270 | G4double var3 = var2*var2 - pDoppler2; |
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| 271 | G4double var4 = var2 - pDoppler2 * cosTheta; |
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| 272 | G4double var = var4*var4 - var3 + pDoppler2 * var3; |
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| 273 | if (var > 0.) |
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| 274 | { |
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| 275 | G4double varSqrt = std::sqrt(var); |
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| 276 | G4double scale = photonEnergy0 / var3; |
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| 277 | // Random select either root |
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| 278 | if (G4UniformRand() < 0.5) photonE = (var4 - varSqrt) * scale; |
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| 279 | else photonE = (var4 + varSqrt) * scale; |
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| 280 | } |
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| 281 | else |
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| 282 | { |
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| 283 | photonE = -1.; |
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| 284 | } |
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| 285 | } while ( iteration <= maxDopplerIterations && |
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| 286 | (photonE < 0. || photonE > eMax || photonE < eMax*G4UniformRand()) ); |
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| 287 | |
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| 288 | // End of recalculation of photon energy with Doppler broadening |
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| 289 | // Revert to original if maximum number of iterations threshold has been reached |
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| 290 | |
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| 291 | if (iteration >= maxDopplerIterations) |
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| 292 | { |
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| 293 | photonE = photonEoriginal; |
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| 294 | bindingE = 0.; |
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| 295 | } |
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| 296 | |
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| 297 | // Update G4VParticleChange for the scattered photon |
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| 298 | |
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| 299 | G4ThreeVector photonDirection1(dirx,diry,dirz); |
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| 300 | photonDirection1.rotateUz(photonDirection0); |
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| 301 | fParticleChange->ProposeMomentumDirection(photonDirection1) ; |
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| 302 | |
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| 303 | G4double photonEnergy1 = photonE; |
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| 304 | |
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| 305 | if (photonEnergy1 > 0.) |
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[1055] | 306 | { |
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| 307 | fParticleChange->SetProposedKineticEnergy(photonEnergy1) ; |
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| 308 | } |
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[968] | 309 | else |
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[1055] | 310 | { |
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| 311 | photonEnergy1 = 0.; |
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| 312 | fParticleChange->SetProposedKineticEnergy(0.) ; |
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| 313 | fParticleChange->ProposeTrackStatus(fStopAndKill); |
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| 314 | } |
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[968] | 315 | |
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| 316 | // Kinematics of the scattered electron |
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| 317 | G4double eKineticEnergy = photonEnergy0 - photonEnergy1 - bindingE; |
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[1055] | 318 | |
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| 319 | // protection against negative final energy: no e- is created |
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| 320 | if(eKineticEnergy < 0.0) { |
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| 321 | fParticleChange->ProposeLocalEnergyDeposit(photonEnergy0 - photonEnergy1); |
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| 322 | return; |
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| 323 | } |
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[968] | 324 | G4double eTotalEnergy = eKineticEnergy + electron_mass_c2; |
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| 325 | |
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| 326 | G4double electronE = photonEnergy0 * (1. - epsilon) + electron_mass_c2; |
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| 327 | G4double electronP2 = electronE*electronE - electron_mass_c2*electron_mass_c2; |
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| 328 | G4double sinThetaE = -1.; |
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| 329 | G4double cosThetaE = 0.; |
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| 330 | if (electronP2 > 0.) |
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| 331 | { |
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| 332 | cosThetaE = (eTotalEnergy + photonEnergy1 )* (1. - epsilon) / std::sqrt(electronP2); |
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| 333 | sinThetaE = -1. * sqrt(1. - cosThetaE * cosThetaE); |
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| 334 | } |
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| 335 | |
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| 336 | G4double eDirX = sinThetaE * std::cos(phi); |
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| 337 | G4double eDirY = sinThetaE * std::sin(phi); |
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| 338 | G4double eDirZ = cosThetaE; |
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| 339 | |
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| 340 | G4ThreeVector eDirection(eDirX,eDirY,eDirZ); |
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| 341 | eDirection.rotateUz(photonDirection0); |
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| 342 | |
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[1055] | 343 | // SI - The range test has been removed wrt original G4LowEnergyCompton class |
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[968] | 344 | |
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| 345 | fParticleChange->ProposeLocalEnergyDeposit(bindingE); |
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| 346 | |
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[1055] | 347 | G4DynamicParticle* dp = new G4DynamicParticle (G4Electron::Electron(), |
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| 348 | eDirection,eKineticEnergy) ; |
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[968] | 349 | fvect->push_back(dp); |
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| 350 | } |
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| 351 | |
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