[819] | 1 | // |
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| 2 | // ******************************************************************** |
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| 3 | // * License and Disclaimer * |
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| 4 | // * * |
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| 5 | // * The Geant4 software is copyright of the Copyright Holders of * |
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| 6 | // * the Geant4 Collaboration. It is provided under the terms and * |
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| 7 | // * conditions of the Geant4 Software License, included in the file * |
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| 8 | // * LICENSE and available at http://cern.ch/geant4/license . These * |
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| 9 | // * include a list of copyright holders. * |
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| 10 | // * * |
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| 11 | // * Neither the authors of this software system, nor their employing * |
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| 12 | // * institutes,nor the agencies providing financial support for this * |
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| 13 | // * work make any representation or warranty, express or implied, * |
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| 14 | // * regarding this software system or assume any liability for its * |
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| 15 | // * use. Please see the license in the file LICENSE and URL above * |
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| 16 | // * for the full disclaimer and the limitation of liability. * |
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| 17 | // * * |
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| 18 | // * This code implementation is the result of the scientific and * |
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| 19 | // * technical work of the GEANT4 collaboration. * |
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| 20 | // * By using, copying, modifying or distributing the software (or * |
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| 21 | // * any work based on the software) you agree to acknowledge its * |
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| 22 | // * use in resulting scientific publications, and indicate your * |
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| 23 | // * acceptance of all terms of the Geant4 Software license. * |
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| 24 | // ******************************************************************** |
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| 25 | // |
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[1196] | 26 | // $Id: G4eCoulombScatteringModel.cc,v 1.78 2009/10/28 10:14:13 vnivanch Exp $ |
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[1228] | 27 | // GEANT4 tag $Name: geant4-09-03 $ |
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[819] | 28 | // |
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| 29 | // ------------------------------------------------------------------- |
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| 30 | // |
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| 31 | // GEANT4 Class file |
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| 32 | // |
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| 33 | // |
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| 34 | // File name: G4eCoulombScatteringModel |
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| 35 | // |
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| 36 | // Author: Vladimir Ivanchenko |
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| 37 | // |
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| 38 | // Creation date: 22.08.2005 |
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| 39 | // |
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| 40 | // Modifications: |
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[1196] | 41 | // |
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[819] | 42 | // 01.08.06 V.Ivanchenko extend upper limit of table to TeV and review the |
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| 43 | // logic of building - only elements from G4ElementTable |
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| 44 | // 08.08.06 V.Ivanchenko build internal table in ekin scale, introduce faclim |
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| 45 | // 19.08.06 V.Ivanchenko add inline function ScreeningParameter |
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| 46 | // 09.10.07 V.Ivanchenko reorganized methods, add cut dependence in scattering off e- |
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[961] | 47 | // 09.06.08 V.Ivanchenko add SelectIsotope and sampling of the recoil ion |
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[1196] | 48 | // 16.06.09 C.Consolandi fixed computation of effective mass |
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[819] | 49 | // |
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[1196] | 50 | // |
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[819] | 51 | // Class Description: |
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| 52 | // |
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| 53 | // ------------------------------------------------------------------- |
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| 54 | // |
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| 55 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 56 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 57 | |
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| 58 | #include "G4eCoulombScatteringModel.hh" |
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| 59 | #include "Randomize.hh" |
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| 60 | #include "G4DataVector.hh" |
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| 61 | #include "G4ElementTable.hh" |
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| 62 | #include "G4PhysicsLogVector.hh" |
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| 63 | #include "G4ParticleChangeForGamma.hh" |
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| 64 | #include "G4Electron.hh" |
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| 65 | #include "G4Positron.hh" |
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| 66 | #include "G4Proton.hh" |
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[961] | 67 | #include "G4ParticleTable.hh" |
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[1196] | 68 | #include "G4ProductionCutsTable.hh" |
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| 69 | #include "G4NucleiProperties.hh" |
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[819] | 70 | |
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| 71 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 72 | |
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[1055] | 73 | G4double G4eCoulombScatteringModel::ScreenRSquare[] = {0.0}; |
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| 74 | G4double G4eCoulombScatteringModel::FormFactor[] = {0.0}; |
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| 75 | |
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[819] | 76 | using namespace std; |
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| 77 | |
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[961] | 78 | G4eCoulombScatteringModel::G4eCoulombScatteringModel(const G4String& nam) |
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[819] | 79 | : G4VEmModel(nam), |
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[961] | 80 | cosThetaMin(1.0), |
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| 81 | cosThetaMax(-1.0), |
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| 82 | q2Limit(TeV*TeV), |
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[819] | 83 | alpha2(fine_structure_const*fine_structure_const), |
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| 84 | faclim(100.0), |
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| 85 | isInitialised(false) |
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| 86 | { |
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| 87 | fNistManager = G4NistManager::Instance(); |
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[961] | 88 | theParticleTable = G4ParticleTable::GetParticleTable(); |
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[819] | 89 | theElectron = G4Electron::Electron(); |
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| 90 | thePositron = G4Positron::Positron(); |
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| 91 | theProton = G4Proton::Proton(); |
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[961] | 92 | currentMaterial = 0; |
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| 93 | currentElement = 0; |
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[1196] | 94 | lowEnergyLimit = 0.1*keV; |
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[819] | 95 | G4double p0 = electron_mass_c2*classic_electr_radius; |
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| 96 | coeff = twopi*p0*p0; |
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[961] | 97 | tkin = targetZ = mom2 = DBL_MIN; |
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[819] | 98 | elecXSection = nucXSection = 0.0; |
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[1196] | 99 | recoilThreshold = 0.*keV; |
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[819] | 100 | ecut = DBL_MAX; |
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| 101 | particle = 0; |
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[961] | 102 | currentCouple = 0; |
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[1055] | 103 | |
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| 104 | // Thomas-Fermi screening radii |
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| 105 | // Formfactors from A.V. Butkevich et al., NIM A 488 (2002) 282 |
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| 106 | |
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| 107 | if(0.0 == ScreenRSquare[0]) { |
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| 108 | G4double a0 = electron_mass_c2/0.88534; |
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| 109 | G4double constn = 6.937e-6/(MeV*MeV); |
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| 110 | |
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| 111 | ScreenRSquare[0] = alpha2*a0*a0; |
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| 112 | for(G4int j=1; j<100; j++) { |
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| 113 | G4double x = a0*fNistManager->GetZ13(j); |
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| 114 | ScreenRSquare[j] = alpha2*x*x; |
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| 115 | x = fNistManager->GetA27(j); |
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| 116 | FormFactor[j] = constn*x*x; |
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| 117 | } |
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| 118 | } |
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[819] | 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 | G4eCoulombScatteringModel::~G4eCoulombScatteringModel() |
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[961] | 124 | {} |
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[819] | 125 | |
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| 126 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 127 | |
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| 128 | void G4eCoulombScatteringModel::Initialise(const G4ParticleDefinition* p, |
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[961] | 129 | const G4DataVector& cuts) |
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[819] | 130 | { |
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[961] | 131 | SetupParticle(p); |
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| 132 | currentCouple = 0; |
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| 133 | elecXSection = nucXSection = 0.0; |
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| 134 | tkin = targetZ = mom2 = DBL_MIN; |
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| 135 | ecut = etag = DBL_MAX; |
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| 136 | cosThetaMin = cos(PolarAngleLimit()); |
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[1196] | 137 | pCuts = G4ProductionCutsTable::GetProductionCutsTable()->GetEnergyCutsVector(3); |
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[961] | 138 | //G4cout << "!!! G4eCoulombScatteringModel::Initialise for " |
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| 139 | // << p->GetParticleName() << " cos(TetMin)= " << cosThetaMin |
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| 140 | // << " cos(TetMax)= " << cosThetaMax <<G4endl; |
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[1196] | 141 | // G4cout << "cut0= " << cuts[0] << " cut1= " << cuts[1] << G4endl; |
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[819] | 142 | if(!isInitialised) { |
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| 143 | isInitialised = true; |
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[1055] | 144 | fParticleChange = GetParticleChangeForGamma(); |
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[819] | 145 | } |
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[961] | 146 | if(mass < GeV && particle->GetParticleType() != "nucleus") { |
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| 147 | InitialiseElementSelectors(p,cuts); |
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| 148 | } |
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| 149 | } |
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[819] | 150 | |
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[961] | 151 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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[819] | 152 | |
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[961] | 153 | void G4eCoulombScatteringModel::ComputeMaxElectronScattering(G4double cutEnergy) |
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| 154 | { |
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| 155 | ecut = cutEnergy; |
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| 156 | G4double tmax = tkin; |
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| 157 | cosTetMaxElec = 1.0; |
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| 158 | if(mass > MeV) { |
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| 159 | G4double ratio = electron_mass_c2/mass; |
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| 160 | G4double tau = tkin/mass; |
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| 161 | tmax = 2.0*electron_mass_c2*tau*(tau + 2.)/ |
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| 162 | (1.0 + 2.0*ratio*(tau + 1.0) + ratio*ratio); |
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| 163 | cosTetMaxElec = 1.0 - std::min(cutEnergy, tmax)*electron_mass_c2/mom2; |
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| 164 | } else { |
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| 165 | |
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| 166 | if(particle == theElectron) tmax *= 0.5; |
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| 167 | G4double t = std::min(cutEnergy, tmax); |
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| 168 | G4double mom21 = t*(t + 2.0*electron_mass_c2); |
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| 169 | G4double t1 = tkin - t; |
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| 170 | //G4cout << "tkin= " << tkin << " t= " << t << " t1= " << t1 << G4endl; |
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| 171 | if(t1 > 0.0) { |
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| 172 | G4double mom22 = t1*(t1 + 2.0*mass); |
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| 173 | G4double ctm = (mom2 + mom22 - mom21)*0.5/sqrt(mom2*mom22); |
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| 174 | //G4cout << "ctm= " << ctm << G4endl; |
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[1055] | 175 | if(ctm < 1.0) cosTetMaxElec = ctm; |
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| 176 | if(ctm < -1.0) cosTetMaxElec = -1.0; |
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[961] | 177 | } |
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| 178 | } |
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[819] | 179 | } |
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| 180 | |
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| 181 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 182 | |
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| 183 | G4double G4eCoulombScatteringModel::ComputeCrossSectionPerAtom( |
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| 184 | const G4ParticleDefinition* p, |
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| 185 | G4double kinEnergy, |
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[961] | 186 | G4double Z, G4double, |
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[819] | 187 | G4double cutEnergy, G4double) |
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| 188 | { |
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| 189 | //G4cout << "### G4eCoulombScatteringModel::ComputeCrossSectionPerAtom for " |
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[961] | 190 | // << p->GetParticleName()<<" Z= "<<Z<<" e(MeV)= "<< kinEnergy/MeV << G4endl; |
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| 191 | G4double xsec = 0.0; |
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| 192 | SetupParticle(p); |
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[1196] | 193 | if(kinEnergy < lowEnergyLimit) return xsec; |
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| 194 | SetupKinematic(kinEnergy, cutEnergy); |
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[961] | 195 | if(cosTetMaxNuc < cosTetMinNuc) { |
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[1196] | 196 | SetupTarget(Z, kinEnergy); |
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[961] | 197 | xsec = CrossSectionPerAtom(); |
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| 198 | } |
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| 199 | /* |
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| 200 | G4cout << "e(MeV)= " << ekin/MeV << "cosTetMinNuc= " << cosTetMinNuc |
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| 201 | << " cosTetMaxNuc= " << cosTetMaxNuc |
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| 202 | << " cosTetMaxElec= " << cosTetMaxElec |
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| 203 | << " screenZ= " << screenZ |
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[1196] | 204 | << " formfactA= " << formfactA << G4endl; |
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[961] | 205 | */ |
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| 206 | return xsec; |
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[819] | 207 | } |
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| 208 | |
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| 209 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 210 | |
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[961] | 211 | G4double G4eCoulombScatteringModel::CrossSectionPerAtom() |
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[819] | 212 | { |
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[961] | 213 | // This method needs initialisation before be called |
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[1196] | 214 | //G4double fac = coeff*targetZ*chargeSquare*invbeta2/mom2; |
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| 215 | |
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| 216 | G4double meff = targetMass/(mass+targetMass); |
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| 217 | G4double fac = coeff*targetZ*chargeSquare*invbeta2/(mom2*meff*meff); |
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| 218 | |
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[819] | 219 | elecXSection = 0.0; |
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[961] | 220 | nucXSection = 0.0; |
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[819] | 221 | |
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[961] | 222 | G4double x = 1.0 - cosTetMinNuc; |
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| 223 | G4double x1 = x + screenZ; |
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[819] | 224 | |
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[961] | 225 | if(cosTetMaxElec2 < cosTetMinNuc) { |
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| 226 | elecXSection = fac*(cosTetMinNuc - cosTetMaxElec2)/ |
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| 227 | (x1*(1.0 - cosTetMaxElec2 + screenZ)); |
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| 228 | nucXSection = elecXSection; |
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[819] | 229 | } |
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| 230 | |
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[961] | 231 | //G4cout << "XS tkin(MeV)= " << tkin<<" xs= " <<nucXSection |
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| 232 | // << " costmax= " << cosTetMaxNuc2 |
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| 233 | // << " costmin= " << cosTetMinNuc << " Z= " << targetZ <<G4endl; |
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| 234 | if(cosTetMaxNuc2 < cosTetMinNuc) { |
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| 235 | G4double s = screenZ*formfactA; |
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| 236 | G4double z1 = 1.0 - cosTetMaxNuc2 + screenZ; |
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[1055] | 237 | G4double s1 = 1.0 - s; |
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| 238 | G4double d = s1/formfactA; |
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[961] | 239 | //G4cout <<"x1= "<<x1<<" z1= " <<z1<<" s= "<<s << " d= " <<d <<G4endl; |
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| 240 | if(d < 0.2*x1) { |
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| 241 | G4double x2 = x1*x1; |
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| 242 | G4double z2 = z1*z1; |
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| 243 | x = (1.0/(x1*x2) - 1.0/(z1*z2) - d*1.5*(1.0/(x2*x2) - 1.0/(z2*z2)))/ |
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| 244 | (3.0*formfactA*formfactA); |
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| 245 | } else { |
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| 246 | G4double x2 = x1 + d; |
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| 247 | G4double z2 = z1 + d; |
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[1055] | 248 | x = (1.0/x1 - 1.0/z1 + 1.0/x2 - 1.0/z2 - 2.0*log(z1*x2/(z2*x1))/d)/(s1*s1); |
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[961] | 249 | } |
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| 250 | nucXSection += fac*targetZ*x; |
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[819] | 251 | } |
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[961] | 252 | //G4cout<<" cross(bn)= "<<nucXSection/barn<<" xsElec(bn)= "<<elecXSection/barn |
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| 253 | // << " Asc= " << screenZ << G4endl; |
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[819] | 254 | |
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[961] | 255 | return nucXSection; |
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[819] | 256 | } |
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| 257 | |
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| 258 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 259 | |
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| 260 | void G4eCoulombScatteringModel::SampleSecondaries( |
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[961] | 261 | std::vector<G4DynamicParticle*>* fvect, |
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[819] | 262 | const G4MaterialCutsCouple* couple, |
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| 263 | const G4DynamicParticle* dp, |
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| 264 | G4double cutEnergy, |
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[961] | 265 | G4double) |
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[819] | 266 | { |
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| 267 | G4double kinEnergy = dp->GetKineticEnergy(); |
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[1196] | 268 | if(kinEnergy < lowEnergyLimit) return; |
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[961] | 269 | DefineMaterial(couple); |
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| 270 | SetupParticle(dp->GetDefinition()); |
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[1196] | 271 | |
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| 272 | SetupKinematic(kinEnergy, cutEnergy); |
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[961] | 273 | //G4cout << "G4eCoulombScatteringModel::SampleSecondaries e(MeV)= " |
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[1196] | 274 | // << kinEnergy << " " << particle->GetParticleName() |
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| 275 | // << " cut= " << cutEnergy<< G4endl; |
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[961] | 276 | |
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| 277 | // Choose nucleus |
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[1196] | 278 | currentElement = SelectRandomAtom(couple,particle, |
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| 279 | kinEnergy,cutEnergy,kinEnergy); |
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[819] | 280 | |
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[1196] | 281 | SetupTarget(currentElement->GetZ(),kinEnergy); |
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| 282 | |
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| 283 | G4int ia = SelectIsotopeNumber(currentElement); |
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| 284 | targetMass = G4NucleiProperties::GetNuclearMass(ia, iz); |
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[961] | 285 | |
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| 286 | G4double cost = SampleCosineTheta(); |
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| 287 | G4double z1 = 1.0 - cost; |
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| 288 | if(z1 < 0.0) return; |
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[819] | 289 | |
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[961] | 290 | G4double sint = sqrt(z1*(1.0 + cost)); |
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| 291 | |
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[1196] | 292 | //G4cout<<"## Sampled sint= " << sint << " Z= " << targetZ << " A= " << ia |
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[961] | 293 | // << " screenZ= " << screenZ << " cn= " << formfactA << G4endl; |
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| 294 | |
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| 295 | G4double phi = twopi * G4UniformRand(); |
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[819] | 296 | |
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[961] | 297 | G4ThreeVector direction = dp->GetMomentumDirection(); |
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| 298 | G4ThreeVector newDirection(cos(phi)*sint,sin(phi)*sint,cost); |
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| 299 | newDirection.rotateUz(direction); |
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| 300 | |
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| 301 | fParticleChange->ProposeMomentumDirection(newDirection); |
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| 302 | |
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| 303 | // recoil sampling assuming a small recoil |
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| 304 | // and first order correction to primary 4-momentum |
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[1196] | 305 | G4double q2 = 2*z1*mom2; |
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| 306 | G4double trec = q2/(sqrt(targetMass*targetMass + q2) + targetMass); |
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| 307 | G4double finalT = kinEnergy - trec; |
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| 308 | //G4cout<<"G4eCoulombScatteringModel: finalT= "<<finalT<<" Trec= "<<trec<<G4endl; |
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| 309 | if(finalT <= lowEnergyLimit) { |
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| 310 | trec = kinEnergy; |
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| 311 | finalT = 0.0; |
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| 312 | } |
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[961] | 313 | |
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[1196] | 314 | fParticleChange->SetProposedKineticEnergy(finalT); |
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| 315 | G4double tcut = recoilThreshold; |
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| 316 | if(pCuts) { tcut= std::max(tcut,(*pCuts)[currentMaterialIndex]); } |
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| 317 | |
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| 318 | if(trec > tcut) { |
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| 319 | G4ParticleDefinition* ion = theParticleTable->FindIon(iz, ia, 0, iz); |
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| 320 | G4ThreeVector dir = (direction*sqrt(mom2) - |
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| 321 | newDirection*sqrt(finalT*(2*mass + finalT))).unit(); |
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| 322 | G4DynamicParticle* newdp = new G4DynamicParticle(ion, dir, trec); |
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| 323 | fvect->push_back(newdp); |
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| 324 | } else { |
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| 325 | fParticleChange->ProposeLocalEnergyDeposit(trec); |
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| 326 | fParticleChange->ProposeNonIonizingEnergyDeposit(trec); |
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[961] | 327 | } |
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| 328 | |
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| 329 | return; |
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| 330 | } |
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| 331 | |
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| 332 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 333 | |
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| 334 | G4double G4eCoulombScatteringModel::SampleCosineTheta() |
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| 335 | { |
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| 336 | G4double costm = cosTetMaxNuc2; |
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[819] | 337 | G4double formf = formfactA; |
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[961] | 338 | G4double prob = 0.0; |
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| 339 | G4double xs = CrossSectionPerAtom(); |
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| 340 | if(xs > 0.0) prob = elecXSection/xs; |
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| 341 | |
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| 342 | // scattering off e or A? |
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| 343 | if(G4UniformRand() < prob) { |
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| 344 | costm = cosTetMaxElec2; |
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[819] | 345 | formf = 0.0; |
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| 346 | } |
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[961] | 347 | |
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[1196] | 348 | /* |
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[961] | 349 | G4cout << "SampleCost: e(MeV)= " << tkin |
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[1196] | 350 | << " 1-ctmaxN= " << 1. - cosTetMinNuc |
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| 351 | << " 1-ctmax= " << 1. - costm |
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| 352 | << " Z= " << targetZ |
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[819] | 353 | << G4endl; |
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| 354 | */ |
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[1196] | 355 | |
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[961] | 356 | if(costm >= cosTetMinNuc) return 2.0; |
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[819] | 357 | |
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[961] | 358 | G4double x1 = 1. - cosTetMinNuc + screenZ; |
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| 359 | G4double x2 = 1. - costm + screenZ; |
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| 360 | G4double x3 = cosTetMinNuc - costm; |
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| 361 | G4double grej, z1; |
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[819] | 362 | do { |
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[961] | 363 | z1 = x1*x2/(x1 + G4UniformRand()*x3) - screenZ; |
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[819] | 364 | grej = 1.0/(1.0 + formf*z1); |
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| 365 | } while ( G4UniformRand() > grej*grej ); |
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| 366 | |
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[1196] | 367 | if(mass > MeV) { |
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| 368 | if(G4UniformRand() > (1. - z1*0.5)/(1.0 + z1*sqrt(mom2)/targetMass)) { |
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| 369 | return 2.0; |
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| 370 | } |
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| 371 | } |
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| 372 | //G4cout << "z1= " << z1 << " cross= " << nucXSection/barn |
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| 373 | // << " crossE= " << elecXSection/barn << G4endl; |
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[819] | 374 | |
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[961] | 375 | return 1.0 - z1; |
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[819] | 376 | } |
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| 377 | |
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| 378 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 379 | |
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| 380 | |
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