| 1 | //
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| 2 | // ********************************************************************
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| 3 | // * License and Disclaimer *
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| 4 | // * *
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| 5 | // * The Geant4 software is copyright of the Copyright Holders of *
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| 6 | // * the Geant4 Collaboration. It is provided under the terms and *
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| 7 | // * conditions of the Geant4 Software License, included in the file *
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| 8 | // * LICENSE and available at http://cern.ch/geant4/license . These *
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| 9 | // * include a list of copyright holders. *
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| 10 | // * *
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| 11 | // * Neither the authors of this software system, nor their employing *
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| 12 | // * institutes,nor the agencies providing financial support for this *
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| 13 | // * work make any representation or warranty, express or implied, *
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| 14 | // * regarding this software system or assume any liability for its *
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| 15 | // * use. Please see the license in the file LICENSE and URL above *
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| 16 | // * for the full disclaimer and the limitation of liability. *
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| 17 | // * *
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| 18 | // * This code implementation is the result of the scientific and *
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| 19 | // * technical work of the GEANT4 collaboration. *
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| 20 | // * By using, copying, modifying or distributing the software (or *
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| 21 | // * any work based on the software) you agree to acknowledge its *
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| 22 | // * use in resulting scientific publications, and indicate your *
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| 23 | // * acceptance of all terms of the Geant4 Software license. *
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| 24 | // ********************************************************************
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| 25 | //
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| 26 | // $Id: G4LivermorePolarizedComptonModel.cc,v 1.6 2009/05/03 08:29:55 sincerti Exp $
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| 27 | // GEANT4 tag $Name: geant4-09-03-cand-01 $
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| 28 | //
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| 29 | // History:
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| 30 | // --------
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| 31 | // 02 May 2009 S Incerti as V. Ivanchenko proposed in G4LivermoreComptonModel.cc
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| 32 | //
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| 33 | // Cleanup initialisation and generation of secondaries:
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| 34 | // - apply internal high-energy limit only in constructor
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| 35 | // - do not apply low-energy limit (default is 0)
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| 36 | // - remove GetMeanFreePath method and table
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| 37 | // - added protection against numerical problem in energy sampling
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| 38 | // - use G4ElementSelector
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| 39 |
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| 40 | #include "G4LivermorePolarizedComptonModel.hh"
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| 41 |
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| 42 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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| 43 |
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| 44 | using namespace std;
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| 45 |
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| 46 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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| 47 |
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| 48 | G4LivermorePolarizedComptonModel::G4LivermorePolarizedComptonModel(const G4ParticleDefinition*,
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| 49 | const G4String& nam)
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| 50 | :G4VEmModel(nam),isInitialised(false),meanFreePathTable(0),scatterFunctionData(0),crossSectionHandler(0)
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| 51 | {
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| 52 | lowEnergyLimit = 250 * eV;
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| 53 | highEnergyLimit = 100 * GeV;
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| 54 | //SetLowEnergyLimit(lowEnergyLimit);
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| 55 | SetHighEnergyLimit(highEnergyLimit);
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| 56 |
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| 57 | verboseLevel= 0;
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| 58 | // Verbosity scale:
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| 59 | // 0 = nothing
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| 60 | // 1 = warning for energy non-conservation
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| 61 | // 2 = details of energy budget
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| 62 | // 3 = calculation of cross sections, file openings, sampling of atoms
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| 63 | // 4 = entering in methods
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| 64 |
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| 65 | if( verboseLevel>0 ) {
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| 66 | G4cout << "Livermore Polarized Compton is constructed " << G4endl
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| 67 | << "Energy range: "
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| 68 | << lowEnergyLimit / eV << " eV - "
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| 69 | << highEnergyLimit / GeV << " GeV"
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| 70 | << G4endl;
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| 71 | }
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| 72 | }
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| 73 |
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| 74 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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| 75 |
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| 76 | G4LivermorePolarizedComptonModel::~G4LivermorePolarizedComptonModel()
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| 77 | {
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| 78 | if (meanFreePathTable) delete meanFreePathTable;
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| 79 | if (crossSectionHandler) delete crossSectionHandler;
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| 80 | if (scatterFunctionData) delete scatterFunctionData;
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| 81 | }
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| 82 |
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| 83 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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| 84 |
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| 85 | void G4LivermorePolarizedComptonModel::Initialise(const G4ParticleDefinition* particle,
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| 86 | const G4DataVector& cuts)
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| 87 | {
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| 88 | if (verboseLevel > 3)
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| 89 | G4cout << "Calling G4LivermorePolarizedComptonModel::Initialise()" << G4endl;
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| 90 |
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| 91 | if (crossSectionHandler)
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| 92 | {
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| 93 | crossSectionHandler->Clear();
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| 94 | delete crossSectionHandler;
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| 95 | }
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| 96 |
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| 97 | // Reading of data files - all materials are read
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| 98 |
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| 99 | crossSectionHandler = new G4CrossSectionHandler;
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| 100 | crossSectionHandler->Clear();
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| 101 | G4String crossSectionFile = "comp/ce-cs-";
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| 102 | crossSectionHandler->LoadData(crossSectionFile);
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| 103 |
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| 104 | meanFreePathTable = 0;
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| 105 | meanFreePathTable = crossSectionHandler->BuildMeanFreePathForMaterials();
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| 106 |
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| 107 | G4VDataSetAlgorithm* scatterInterpolation = new G4LogLogInterpolation;
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| 108 | G4String scatterFile = "comp/ce-sf-";
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| 109 | scatterFunctionData = new G4CompositeEMDataSet(scatterInterpolation, 1., 1.);
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| 110 | scatterFunctionData->LoadData(scatterFile);
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| 111 |
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| 112 | // For Doppler broadening
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| 113 | shellData.SetOccupancyData();
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| 114 | G4String file = "/doppler/shell-doppler";
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| 115 | shellData.LoadData(file);
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| 116 |
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| 117 | if (verboseLevel > 2)
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| 118 | G4cout << "Loaded cross section files for Livermore Polarized Compton model" << G4endl;
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| 119 |
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| 120 | InitialiseElementSelectors(particle,cuts);
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| 121 |
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| 122 | if( verboseLevel>0 ) {
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| 123 | G4cout << "Livermore Polarized Compton model is initialized " << G4endl
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| 124 | << "Energy range: "
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| 125 | << LowEnergyLimit() / eV << " eV - "
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| 126 | << HighEnergyLimit() / GeV << " GeV"
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| 127 | << G4endl;
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| 128 | }
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| 129 |
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| 130 | //
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| 131 |
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| 132 | if(isInitialised) return;
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| 133 | fParticleChange = GetParticleChangeForGamma();
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| 134 | isInitialised = true;
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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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| 139 | G4double G4LivermorePolarizedComptonModel::ComputeCrossSectionPerAtom(
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| 140 | const G4ParticleDefinition*,
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| 141 | G4double GammaEnergy,
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| 142 | G4double Z, G4double,
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| 143 | G4double, G4double)
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| 144 | {
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| 145 | if (verboseLevel > 3)
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| 146 | G4cout << "Calling ComputeCrossSectionPerAtom() of G4LivermorePolarizedComptonModel" << G4endl;
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| 147 |
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| 148 | if (GammaEnergy < lowEnergyLimit || GammaEnergy > highEnergyLimit) return 0.0;
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| 149 |
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| 150 | G4double cs = crossSectionHandler->FindValue(G4int(Z), GammaEnergy);
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| 151 | return cs;
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| 152 | }
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| 153 |
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| 154 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
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| 155 |
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| 156 | void G4LivermorePolarizedComptonModel::SampleSecondaries(std::vector<G4DynamicParticle*>* fvect,
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| 157 | const G4MaterialCutsCouple* couple,
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| 158 | const G4DynamicParticle* aDynamicGamma,
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| 159 | G4double,
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| 160 | G4double)
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| 161 | {
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| 162 | // The scattered gamma energy is sampled according to Klein - Nishina formula.
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| 163 | // The random number techniques of Butcher & Messel are used (Nuc Phys 20(1960),15).
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| 164 | // GEANT4 internal units
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| 165 | //
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| 166 | // Note : Effects due to binding of atomic electrons are negliged.
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| 167 |
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| 168 | if (verboseLevel > 3)
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| 169 | G4cout << "Calling SampleSecondaries() of G4LivermorePolarizedComptonModel" << G4endl;
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| 170 |
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| 171 | G4double gammaEnergy0 = aDynamicGamma->GetKineticEnergy();
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| 172 | G4ThreeVector gammaPolarization0 = aDynamicGamma->GetPolarization();
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| 173 |
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| 174 | // Protection: a polarisation parallel to the
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| 175 | // direction causes problems;
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| 176 | // in that case find a random polarization
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| 177 |
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| 178 | G4ThreeVector gammaDirection0 = aDynamicGamma->GetMomentumDirection();
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| 179 |
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| 180 | // Make sure that the polarization vector is perpendicular to the
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| 181 | // gamma direction. If not
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| 182 |
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| 183 | if(!(gammaPolarization0.isOrthogonal(gammaDirection0, 1e-6))||(gammaPolarization0.mag()==0))
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| 184 | { // only for testing now
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| 185 | gammaPolarization0 = GetRandomPolarization(gammaDirection0);
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| 186 | }
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| 187 | else
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| 188 | {
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| 189 | if ( gammaPolarization0.howOrthogonal(gammaDirection0) != 0)
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| 190 | {
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| 191 | gammaPolarization0 = GetPerpendicularPolarization(gammaDirection0, gammaPolarization0);
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| 192 | }
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| 193 | }
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| 194 |
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| 195 | // End of Protection
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| 196 |
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| 197 | // Within energy limit?
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| 198 |
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| 199 | if(gammaEnergy0 <= lowEnergyLimit)
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| 200 | {
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| 201 | fParticleChange->ProposeTrackStatus(fStopAndKill);
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| 202 | fParticleChange->SetProposedKineticEnergy(0.);
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| 203 | fParticleChange->ProposeLocalEnergyDeposit(gammaEnergy0);
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| 204 | return;
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| 205 | }
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| 206 |
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| 207 | G4double E0_m = gammaEnergy0 / electron_mass_c2 ;
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| 208 |
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| 209 | // Select randomly one element in the current material
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| 210 | //G4int Z = crossSectionHandler->SelectRandomAtom(couple,gammaEnergy0);
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| 211 | const G4ParticleDefinition* particle = aDynamicGamma->GetDefinition();
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| 212 | const G4Element* elm = SelectRandomAtom(couple,particle,gammaEnergy0);
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| 213 | G4int Z = (G4int)elm->GetZ();
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| 214 |
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| 215 | // Sample the energy and the polarization of the scattered photon
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| 216 |
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| 217 | G4double epsilon, epsilonSq, onecost, sinThetaSqr, greject ;
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| 218 |
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| 219 | G4double epsilon0 = 1./(1. + 2*E0_m);
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| 220 | G4double epsilon0Sq = epsilon0*epsilon0;
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| 221 | G4double alpha1 = - std::log(epsilon0);
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| 222 | G4double alpha2 = 0.5*(1.- epsilon0Sq);
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| 223 |
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| 224 | G4double wlGamma = h_Planck*c_light/gammaEnergy0;
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| 225 | G4double gammaEnergy1;
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| 226 | G4ThreeVector gammaDirection1;
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| 227 |
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| 228 | do {
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| 229 | if ( alpha1/(alpha1+alpha2) > G4UniformRand() )
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| 230 | {
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| 231 | epsilon = std::exp(-alpha1*G4UniformRand());
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| 232 | epsilonSq = epsilon*epsilon;
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| 233 | }
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| 234 | else
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| 235 | {
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| 236 | epsilonSq = epsilon0Sq + (1.- epsilon0Sq)*G4UniformRand();
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| 237 | epsilon = std::sqrt(epsilonSq);
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| 238 | }
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| 239 |
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| 240 | onecost = (1.- epsilon)/(epsilon*E0_m);
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| 241 | sinThetaSqr = onecost*(2.-onecost);
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| 242 |
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| 243 | // Protection
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| 244 | if (sinThetaSqr > 1.)
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| 245 | {
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| 246 | G4cout
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| 247 | << " -- Warning -- G4LivermorePolarizedComptonModel::SampleSecondaries "
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| 248 | << "sin(theta)**2 = "
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| 249 | << sinThetaSqr
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| 250 | << "; set to 1"
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| 251 | << G4endl;
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| 252 | sinThetaSqr = 1.;
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| 253 | }
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| 254 | if (sinThetaSqr < 0.)
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| 255 | {
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| 256 | G4cout
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| 257 | << " -- Warning -- G4LivermorePolarizedComptonModel::SampleSecondaries "
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| 258 | << "sin(theta)**2 = "
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| 259 | << sinThetaSqr
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| 260 | << "; set to 0"
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| 261 | << G4endl;
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| 262 | sinThetaSqr = 0.;
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| 263 | }
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| 264 | // End protection
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| 265 |
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| 266 | G4double x = std::sqrt(onecost/2.) / (wlGamma/cm);;
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| 267 | G4double scatteringFunction = scatterFunctionData->FindValue(x,Z-1);
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| 268 | greject = (1. - epsilon*sinThetaSqr/(1.+ epsilonSq))*scatteringFunction;
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| 269 |
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| 270 | } while(greject < G4UniformRand()*Z);
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| 271 |
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| 272 |
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| 273 | // ****************************************************
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| 274 | // Phi determination
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| 275 | // ****************************************************
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| 276 |
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| 277 | G4double phi = SetPhi(epsilon,sinThetaSqr);
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| 278 |
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| 279 | //
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| 280 | // scattered gamma angles. ( Z - axis along the parent gamma)
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| 281 | //
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| 282 |
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| 283 | G4double cosTheta = 1. - onecost;
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| 284 |
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| 285 | // Protection
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| 286 |
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| 287 | if (cosTheta > 1.)
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| 288 | {
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| 289 | G4cout
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| 290 | << " -- Warning -- G4LivermorePolarizedComptonModel::SampleSecondaries "
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| 291 | << "cosTheta = "
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| 292 | << cosTheta
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| 293 | << "; set to 1"
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| 294 | << G4endl;
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| 295 | cosTheta = 1.;
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| 296 | }
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| 297 | if (cosTheta < -1.)
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| 298 | {
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| 299 | G4cout
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| 300 | << " -- Warning -- G4LivermorePolarizedComptonModel::SampleSecondaries "
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| 301 | << "cosTheta = "
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| 302 | << cosTheta
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| 303 | << "; set to -1"
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| 304 | << G4endl;
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| 305 | cosTheta = -1.;
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| 306 | }
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| 307 | // End protection
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| 308 |
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| 309 |
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| 310 | G4double sinTheta = std::sqrt (sinThetaSqr);
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| 311 |
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| 312 | // Protection
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| 313 | if (sinTheta > 1.)
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| 314 | {
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| 315 | G4cout
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| 316 | << " -- Warning -- G4LivermorePolarizedComptonModel::SampleSecondaries "
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| 317 | << "sinTheta = "
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| 318 | << sinTheta
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| 319 | << "; set to 1"
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| 320 | << G4endl;
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| 321 | sinTheta = 1.;
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| 322 | }
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| 323 | if (sinTheta < -1.)
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| 324 | {
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| 325 | G4cout
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| 326 | << " -- Warning -- G4LivermorePolarizedComptonModel::SampleSecondaries "
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| 327 | << "sinTheta = "
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| 328 | << sinTheta
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| 329 | << "; set to -1"
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| 330 | << G4endl;
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| 331 | sinTheta = -1.;
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| 332 | }
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| 333 | // End protection
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| 334 |
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| 335 |
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| 336 | G4double dirx = sinTheta*std::cos(phi);
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| 337 | G4double diry = sinTheta*std::sin(phi);
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| 338 | G4double dirz = cosTheta ;
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| 339 |
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| 340 |
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| 341 | // oneCosT , eom
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| 342 |
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| 343 | // Doppler broadening - Method based on:
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| 344 | // Y. Namito, S. Ban and H. Hirayama,
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| 345 | // "Implementation of the Doppler Broadening of a Compton-Scattered Photon Into the EGS4 Code"
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| 346 | // NIM A 349, pp. 489-494, 1994
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| 347 |
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| 348 | // Maximum number of sampling iterations
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| 349 |
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| 350 | G4int maxDopplerIterations = 1000;
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| 351 | G4double bindingE = 0.;
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| 352 | G4double photonEoriginal = epsilon * gammaEnergy0;
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| 353 | G4double photonE = -1.;
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| 354 | G4int iteration = 0;
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| 355 | G4double eMax = gammaEnergy0;
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| 356 |
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| 357 | do
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| 358 | {
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| 359 | iteration++;
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| 360 | // Select shell based on shell occupancy
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| 361 | G4int shell = shellData.SelectRandomShell(Z);
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| 362 | bindingE = shellData.BindingEnergy(Z,shell);
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| 363 |
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| 364 | eMax = gammaEnergy0 - bindingE;
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| 365 |
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| 366 | // Randomly sample bound electron momentum (memento: the data set is in Atomic Units)
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| 367 | G4double pSample = profileData.RandomSelectMomentum(Z,shell);
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| 368 | // Rescale from atomic units
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| 369 | G4double pDoppler = pSample * fine_structure_const;
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| 370 | G4double pDoppler2 = pDoppler * pDoppler;
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| 371 | G4double var2 = 1. + onecost * E0_m;
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| 372 | G4double var3 = var2*var2 - pDoppler2;
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| 373 | G4double var4 = var2 - pDoppler2 * cosTheta;
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| 374 | G4double var = var4*var4 - var3 + pDoppler2 * var3;
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| 375 | if (var > 0.)
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| 376 | {
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| 377 | G4double varSqrt = std::sqrt(var);
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| 378 | G4double scale = gammaEnergy0 / var3;
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| 379 | // Random select either root
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| 380 | if (G4UniformRand() < 0.5) photonE = (var4 - varSqrt) * scale;
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| 381 | else photonE = (var4 + varSqrt) * scale;
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| 382 | }
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| 383 | else
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| 384 | {
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| 385 | photonE = -1.;
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| 386 | }
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| 387 | } while ( iteration <= maxDopplerIterations &&
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| 388 | (photonE < 0. || photonE > eMax || photonE < eMax*G4UniformRand()) );
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| 389 |
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| 390 | // End of recalculation of photon energy with Doppler broadening
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| 391 | // Revert to original if maximum number of iterations threshold has been reached
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| 392 | if (iteration >= maxDopplerIterations)
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| 393 | {
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| 394 | photonE = photonEoriginal;
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| 395 | bindingE = 0.;
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| 396 | }
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| 397 |
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| 398 | gammaEnergy1 = photonE;
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| 399 |
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| 400 | //
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| 401 | // update G4VParticleChange for the scattered photon
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| 402 | //
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| 403 |
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| 404 | // gammaEnergy1 = epsilon*gammaEnergy0;
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| 405 |
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| 406 |
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| 407 | // New polarization
|
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| 408 |
|
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| 409 | G4ThreeVector gammaPolarization1 = SetNewPolarization(epsilon,
|
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| 410 | sinThetaSqr,
|
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| 411 | phi,
|
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| 412 | cosTheta);
|
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| 413 |
|
|---|
| 414 | // Set new direction
|
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| 415 | G4ThreeVector tmpDirection1( dirx,diry,dirz );
|
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| 416 | gammaDirection1 = tmpDirection1;
|
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| 417 |
|
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| 418 | // Change reference frame.
|
|---|
| 419 |
|
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| 420 | SystemOfRefChange(gammaDirection0,gammaDirection1,
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| 421 | gammaPolarization0,gammaPolarization1);
|
|---|
| 422 |
|
|---|
| 423 | if (gammaEnergy1 > 0.)
|
|---|
| 424 | {
|
|---|
| 425 | fParticleChange->SetProposedKineticEnergy( gammaEnergy1 ) ;
|
|---|
| 426 | fParticleChange->ProposeMomentumDirection( gammaDirection1 );
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|---|
| 427 | fParticleChange->ProposePolarization( gammaPolarization1 );
|
|---|
| 428 | }
|
|---|
| 429 | else
|
|---|
| 430 | {
|
|---|
| 431 | gammaEnergy1 = 0.;
|
|---|
| 432 | fParticleChange->SetProposedKineticEnergy(0.) ;
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| 433 | fParticleChange->ProposeTrackStatus(fStopAndKill);
|
|---|
| 434 | }
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|---|
| 435 |
|
|---|
| 436 | //
|
|---|
| 437 | // kinematic of the scattered electron
|
|---|
| 438 | //
|
|---|
| 439 |
|
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| 440 | G4double ElecKineEnergy = gammaEnergy0 - gammaEnergy1 -bindingE;
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| 441 |
|
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| 442 | // SI -protection against negative final energy: no e- is created
|
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| 443 | // like in G4LivermoreComptonModel.cc
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| 444 | if(ElecKineEnergy < 0.0) {
|
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| 445 | fParticleChange->ProposeLocalEnergyDeposit(gammaEnergy0 - gammaEnergy1);
|
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| 446 | return;
|
|---|
| 447 | }
|
|---|
| 448 |
|
|---|
| 449 | // SI - Removed range test
|
|---|
| 450 |
|
|---|
| 451 | G4double ElecMomentum = std::sqrt(ElecKineEnergy*(ElecKineEnergy+2.*electron_mass_c2));
|
|---|
| 452 |
|
|---|
| 453 | G4ThreeVector ElecDirection((gammaEnergy0 * gammaDirection0 -
|
|---|
| 454 | gammaEnergy1 * gammaDirection1) * (1./ElecMomentum));
|
|---|
| 455 |
|
|---|
| 456 | fParticleChange->ProposeLocalEnergyDeposit(bindingE);
|
|---|
| 457 |
|
|---|
| 458 | G4DynamicParticle* dp = new G4DynamicParticle (G4Electron::Electron(),ElecDirection.unit(),ElecKineEnergy) ;
|
|---|
| 459 | fvect->push_back(dp);
|
|---|
| 460 |
|
|---|
| 461 | }
|
|---|
| 462 |
|
|---|
| 463 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
|
|---|
| 464 |
|
|---|
| 465 | G4double G4LivermorePolarizedComptonModel::SetPhi(G4double energyRate,
|
|---|
| 466 | G4double sinSqrTh)
|
|---|
| 467 | {
|
|---|
| 468 | G4double rand1;
|
|---|
| 469 | G4double rand2;
|
|---|
| 470 | G4double phiProbability;
|
|---|
| 471 | G4double phi;
|
|---|
| 472 | G4double a, b;
|
|---|
| 473 |
|
|---|
| 474 | do
|
|---|
| 475 | {
|
|---|
| 476 | rand1 = G4UniformRand();
|
|---|
| 477 | rand2 = G4UniformRand();
|
|---|
| 478 | phiProbability=0.;
|
|---|
| 479 | phi = twopi*rand1;
|
|---|
| 480 |
|
|---|
| 481 | a = 2*sinSqrTh;
|
|---|
| 482 | b = energyRate + 1/energyRate;
|
|---|
| 483 |
|
|---|
| 484 | phiProbability = 1 - (a/b)*(std::cos(phi)*std::cos(phi));
|
|---|
| 485 |
|
|---|
| 486 |
|
|---|
| 487 |
|
|---|
| 488 | }
|
|---|
| 489 | while ( rand2 > phiProbability );
|
|---|
| 490 | return phi;
|
|---|
| 491 | }
|
|---|
| 492 |
|
|---|
| 493 |
|
|---|
| 494 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
|
|---|
| 495 |
|
|---|
| 496 | G4ThreeVector G4LivermorePolarizedComptonModel::SetPerpendicularVector(G4ThreeVector& a)
|
|---|
| 497 | {
|
|---|
| 498 | G4double dx = a.x();
|
|---|
| 499 | G4double dy = a.y();
|
|---|
| 500 | G4double dz = a.z();
|
|---|
| 501 | G4double x = dx < 0.0 ? -dx : dx;
|
|---|
| 502 | G4double y = dy < 0.0 ? -dy : dy;
|
|---|
| 503 | G4double z = dz < 0.0 ? -dz : dz;
|
|---|
| 504 | if (x < y) {
|
|---|
| 505 | return x < z ? G4ThreeVector(-dy,dx,0) : G4ThreeVector(0,-dz,dy);
|
|---|
| 506 | }else{
|
|---|
| 507 | return y < z ? G4ThreeVector(dz,0,-dx) : G4ThreeVector(-dy,dx,0);
|
|---|
| 508 | }
|
|---|
| 509 | }
|
|---|
| 510 |
|
|---|
| 511 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
|
|---|
| 512 |
|
|---|
| 513 | G4ThreeVector G4LivermorePolarizedComptonModel::GetRandomPolarization(G4ThreeVector& direction0)
|
|---|
| 514 | {
|
|---|
| 515 | G4ThreeVector d0 = direction0.unit();
|
|---|
| 516 | G4ThreeVector a1 = SetPerpendicularVector(d0); //different orthogonal
|
|---|
| 517 | G4ThreeVector a0 = a1.unit(); // unit vector
|
|---|
| 518 |
|
|---|
| 519 | G4double rand1 = G4UniformRand();
|
|---|
| 520 |
|
|---|
| 521 | G4double angle = twopi*rand1; // random polar angle
|
|---|
| 522 | G4ThreeVector b0 = d0.cross(a0); // cross product
|
|---|
| 523 |
|
|---|
| 524 | G4ThreeVector c;
|
|---|
| 525 |
|
|---|
| 526 | c.setX(std::cos(angle)*(a0.x())+std::sin(angle)*b0.x());
|
|---|
| 527 | c.setY(std::cos(angle)*(a0.y())+std::sin(angle)*b0.y());
|
|---|
| 528 | c.setZ(std::cos(angle)*(a0.z())+std::sin(angle)*b0.z());
|
|---|
| 529 |
|
|---|
| 530 | G4ThreeVector c0 = c.unit();
|
|---|
| 531 |
|
|---|
| 532 | return c0;
|
|---|
| 533 |
|
|---|
| 534 | }
|
|---|
| 535 |
|
|---|
| 536 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
|
|---|
| 537 |
|
|---|
| 538 | G4ThreeVector G4LivermorePolarizedComptonModel::GetPerpendicularPolarization
|
|---|
| 539 | (const G4ThreeVector& gammaDirection, const G4ThreeVector& gammaPolarization) const
|
|---|
| 540 | {
|
|---|
| 541 |
|
|---|
| 542 | //
|
|---|
| 543 | // The polarization of a photon is always perpendicular to its momentum direction.
|
|---|
| 544 | // Therefore this function removes those vector component of gammaPolarization, which
|
|---|
| 545 | // points in direction of gammaDirection
|
|---|
| 546 | //
|
|---|
| 547 | // Mathematically we search the projection of the vector a on the plane E, where n is the
|
|---|
| 548 | // plains normal vector.
|
|---|
| 549 | // The basic equation can be found in each geometry book (e.g. Bronstein):
|
|---|
| 550 | // p = a - (a o n)/(n o n)*n
|
|---|
| 551 |
|
|---|
| 552 | return gammaPolarization - gammaPolarization.dot(gammaDirection)/gammaDirection.dot(gammaDirection) * gammaDirection;
|
|---|
| 553 | }
|
|---|
| 554 |
|
|---|
| 555 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
|
|---|
| 556 |
|
|---|
| 557 | G4ThreeVector G4LivermorePolarizedComptonModel::SetNewPolarization(G4double epsilon,
|
|---|
| 558 | G4double sinSqrTh,
|
|---|
| 559 | G4double phi,
|
|---|
| 560 | G4double costheta)
|
|---|
| 561 | {
|
|---|
| 562 | G4double rand1;
|
|---|
| 563 | G4double rand2;
|
|---|
| 564 | G4double cosPhi = std::cos(phi);
|
|---|
| 565 | G4double sinPhi = std::sin(phi);
|
|---|
| 566 | G4double sinTheta = std::sqrt(sinSqrTh);
|
|---|
| 567 | G4double cosSqrPhi = cosPhi*cosPhi;
|
|---|
| 568 | // G4double cossqrth = 1.-sinSqrTh;
|
|---|
| 569 | // G4double sinsqrphi = sinPhi*sinPhi;
|
|---|
| 570 | G4double normalisation = std::sqrt(1. - cosSqrPhi*sinSqrTh);
|
|---|
| 571 |
|
|---|
| 572 |
|
|---|
| 573 | // Determination of Theta
|
|---|
| 574 |
|
|---|
| 575 | // ---- MGP ---- Commented out the following 3 lines to avoid compilation
|
|---|
| 576 | // warnings (unused variables)
|
|---|
| 577 | // G4double thetaProbability;
|
|---|
| 578 | G4double theta;
|
|---|
| 579 | // G4double a, b;
|
|---|
| 580 | // G4double cosTheta;
|
|---|
| 581 |
|
|---|
| 582 | /*
|
|---|
| 583 |
|
|---|
| 584 | depaola method
|
|---|
| 585 |
|
|---|
| 586 | do
|
|---|
| 587 | {
|
|---|
| 588 | rand1 = G4UniformRand();
|
|---|
| 589 | rand2 = G4UniformRand();
|
|---|
| 590 | thetaProbability=0.;
|
|---|
| 591 | theta = twopi*rand1;
|
|---|
| 592 | a = 4*normalisation*normalisation;
|
|---|
| 593 | b = (epsilon + 1/epsilon) - 2;
|
|---|
| 594 | thetaProbability = (b + a*std::cos(theta)*std::cos(theta))/(a+b);
|
|---|
| 595 | cosTheta = std::cos(theta);
|
|---|
| 596 | }
|
|---|
| 597 | while ( rand2 > thetaProbability );
|
|---|
| 598 |
|
|---|
| 599 | G4double cosBeta = cosTheta;
|
|---|
| 600 |
|
|---|
| 601 | */
|
|---|
| 602 |
|
|---|
| 603 |
|
|---|
| 604 | // Dan Xu method (IEEE TNS, 52, 1160 (2005))
|
|---|
| 605 |
|
|---|
| 606 | rand1 = G4UniformRand();
|
|---|
| 607 | rand2 = G4UniformRand();
|
|---|
| 608 |
|
|---|
| 609 | if (rand1<(epsilon+1.0/epsilon-2)/(2.0*(epsilon+1.0/epsilon)-4.0*sinSqrTh*cosSqrPhi))
|
|---|
| 610 | {
|
|---|
| 611 | if (rand2<0.5)
|
|---|
| 612 | theta = pi/2.0;
|
|---|
| 613 | else
|
|---|
| 614 | theta = 3.0*pi/2.0;
|
|---|
| 615 | }
|
|---|
| 616 | else
|
|---|
| 617 | {
|
|---|
| 618 | if (rand2<0.5)
|
|---|
| 619 | theta = 0;
|
|---|
| 620 | else
|
|---|
| 621 | theta = pi;
|
|---|
| 622 | }
|
|---|
| 623 | G4double cosBeta = std::cos(theta);
|
|---|
| 624 | G4double sinBeta = std::sqrt(1-cosBeta*cosBeta);
|
|---|
| 625 |
|
|---|
| 626 | G4ThreeVector gammaPolarization1;
|
|---|
| 627 |
|
|---|
| 628 | G4double xParallel = normalisation*cosBeta;
|
|---|
| 629 | G4double yParallel = -(sinSqrTh*cosPhi*sinPhi)*cosBeta/normalisation;
|
|---|
| 630 | G4double zParallel = -(costheta*sinTheta*cosPhi)*cosBeta/normalisation;
|
|---|
| 631 | G4double xPerpendicular = 0.;
|
|---|
| 632 | G4double yPerpendicular = (costheta)*sinBeta/normalisation;
|
|---|
| 633 | G4double zPerpendicular = -(sinTheta*sinPhi)*sinBeta/normalisation;
|
|---|
| 634 |
|
|---|
| 635 | G4double xTotal = (xParallel + xPerpendicular);
|
|---|
| 636 | G4double yTotal = (yParallel + yPerpendicular);
|
|---|
| 637 | G4double zTotal = (zParallel + zPerpendicular);
|
|---|
| 638 |
|
|---|
| 639 | gammaPolarization1.setX(xTotal);
|
|---|
| 640 | gammaPolarization1.setY(yTotal);
|
|---|
| 641 | gammaPolarization1.setZ(zTotal);
|
|---|
| 642 |
|
|---|
| 643 | return gammaPolarization1;
|
|---|
| 644 |
|
|---|
| 645 | }
|
|---|
| 646 |
|
|---|
| 647 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
|
|---|
| 648 |
|
|---|
| 649 | void G4LivermorePolarizedComptonModel::SystemOfRefChange(G4ThreeVector& direction0,
|
|---|
| 650 | G4ThreeVector& direction1,
|
|---|
| 651 | G4ThreeVector& polarization0,
|
|---|
| 652 | G4ThreeVector& polarization1)
|
|---|
| 653 | {
|
|---|
| 654 | // direction0 is the original photon direction ---> z
|
|---|
| 655 | // polarization0 is the original photon polarization ---> x
|
|---|
| 656 | // need to specify y axis in the real reference frame ---> y
|
|---|
| 657 | G4ThreeVector Axis_Z0 = direction0.unit();
|
|---|
| 658 | G4ThreeVector Axis_X0 = polarization0.unit();
|
|---|
| 659 | G4ThreeVector Axis_Y0 = (Axis_Z0.cross(Axis_X0)).unit(); // to be confirmed;
|
|---|
| 660 |
|
|---|
| 661 | G4double direction_x = direction1.getX();
|
|---|
| 662 | G4double direction_y = direction1.getY();
|
|---|
| 663 | G4double direction_z = direction1.getZ();
|
|---|
| 664 |
|
|---|
| 665 | direction1 = (direction_x*Axis_X0 + direction_y*Axis_Y0 + direction_z*Axis_Z0).unit();
|
|---|
| 666 | G4double polarization_x = polarization1.getX();
|
|---|
| 667 | G4double polarization_y = polarization1.getY();
|
|---|
| 668 | G4double polarization_z = polarization1.getZ();
|
|---|
| 669 |
|
|---|
| 670 | polarization1 = (polarization_x*Axis_X0 + polarization_y*Axis_Y0 + polarization_z*Axis_Z0).unit();
|
|---|
| 671 |
|
|---|
| 672 | }
|
|---|
| 673 |
|
|---|
| 674 |
|
|---|