[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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| 26 | // $Id: G4PolarizedMollerBhabhaModel.cc,v 1.4 2007/05/23 08:52:20 vnivanch Exp $ |
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[1007] | 27 | // GEANT4 tag $Name: geant4-09-02 $ |
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[819] | 28 | // ------------------------------------------------------------------- |
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| 29 | // |
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| 30 | // GEANT4 Class file |
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| 31 | // |
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| 32 | // File name: G4PolarizedMollerBhabhaModel |
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| 33 | // |
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| 34 | // Author: A.Schaelicke on base of Vladimir Ivanchenko code |
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| 35 | // |
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| 36 | // Creation date: 10.11.2005 |
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| 37 | // |
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| 38 | // Modifications: |
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| 39 | // |
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| 40 | // 20-08-05, modified interface (A.Schaelicke) |
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| 41 | // |
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| 42 | // Class Description: |
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| 43 | // |
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| 44 | // Implementation of energy loss and delta-electron production by e+/e- |
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| 45 | // (including polarization effects) |
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| 46 | // |
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| 47 | // ------------------------------------------------------------------- |
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| 48 | // |
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| 49 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 50 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 51 | |
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| 52 | #include "G4PolarizedMollerBhabhaModel.hh" |
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| 53 | #include "G4Electron.hh" |
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| 54 | #include "G4Positron.hh" |
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| 55 | #include "G4ParticleChangeForLoss.hh" |
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| 56 | #include "Randomize.hh" |
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| 57 | |
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| 58 | #include "G4PolarizationManager.hh" |
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| 59 | #include "G4PolarizationHelper.hh" |
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| 60 | #include "G4PolarizedBhabhaCrossSection.hh" |
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| 61 | #include "G4PolarizedMollerCrossSection.hh" |
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| 62 | |
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| 63 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 64 | |
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| 65 | G4PolarizedMollerBhabhaModel::G4PolarizedMollerBhabhaModel(const G4ParticleDefinition* p, |
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| 66 | const G4String& nam) |
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| 67 | : G4MollerBhabhaModel(p,nam) |
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| 68 | { |
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| 69 | |
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| 70 | // G4cout<<" particle==electron "<<(p==theElectron)<<G4endl; |
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| 71 | isElectron=(p==theElectron); // necessary due to wrong order in G4MollerBhabhaModel constructor! |
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| 72 | |
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| 73 | if (p==0) { |
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| 74 | |
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| 75 | } |
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| 76 | if (!isElectron) { |
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| 77 | G4cout<<" buildBhabha cross section "<<isElectron<<G4endl; |
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| 78 | crossSectionCalculator = new G4PolarizedBhabhaCrossSection(); |
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| 79 | } else { |
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| 80 | G4cout<<" buildMoller cross section "<<isElectron<<G4endl; |
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| 81 | crossSectionCalculator = new G4PolarizedMollerCrossSection(); |
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| 82 | } |
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| 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 | G4PolarizedMollerBhabhaModel::~G4PolarizedMollerBhabhaModel() |
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| 88 | { |
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| 89 | if (crossSectionCalculator) { |
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| 90 | delete crossSectionCalculator; |
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| 91 | } |
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| 92 | } |
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| 93 | |
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| 94 | |
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| 95 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 96 | |
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| 97 | G4double G4PolarizedMollerBhabhaModel::ComputeCrossSectionPerElectron( |
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| 98 | const G4ParticleDefinition* pd, |
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| 99 | G4double kinEnergy, |
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| 100 | G4double cut, |
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| 101 | G4double emax) |
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| 102 | { |
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| 103 | G4double xs = |
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| 104 | G4MollerBhabhaModel::ComputeCrossSectionPerElectron(pd,kinEnergy, |
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| 105 | cut,emax); |
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| 106 | // G4cout<<"calc eIoni xsec "<<xs<<G4endl; |
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| 107 | // G4cout<<" "<<kinEnergy<<" "<<cut<<" "<<emax<<G4endl; |
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| 108 | G4double factor=1.; |
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| 109 | if (xs!=0) { |
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| 110 | // G4cout<<"calc asym"<<G4endl; |
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| 111 | G4double tmax = MaxSecondaryEnergy(pd, kinEnergy); |
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| 112 | tmax = std::min(emax, tmax); |
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| 113 | |
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| 114 | if (std::fabs(cut/emax-1.)<1.e-10) return xs; |
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| 115 | |
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| 116 | if(cut < tmax) { |
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| 117 | |
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| 118 | G4double xmin = cut/kinEnergy; |
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| 119 | G4double xmax = tmax/kinEnergy; |
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| 120 | // G4cout<<"calc asym "<<xmin<<","<<xmax<<G4endl; |
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| 121 | G4double gam = kinEnergy/electron_mass_c2 + 1.0; |
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| 122 | |
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| 123 | G4double crossPol=crossSectionCalculator-> |
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| 124 | TotalXSection(xmin,xmax,gam, |
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| 125 | theBeamPolarization, |
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| 126 | theTargetPolarization); |
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| 127 | G4double crossUnpol=crossSectionCalculator-> |
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| 128 | TotalXSection(xmin,xmax,gam, |
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| 129 | G4StokesVector::ZERO, |
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| 130 | G4StokesVector::ZERO); |
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| 131 | if (crossUnpol>0.) factor=crossPol/crossUnpol; |
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| 132 | // G4cout<<" factor="<<factor<<G4endl; |
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| 133 | } |
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| 134 | } |
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| 135 | return xs*factor; |
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| 136 | } |
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| 137 | |
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| 138 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 139 | |
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| 140 | void G4PolarizedMollerBhabhaModel::SampleSecondaries(std::vector<G4DynamicParticle*>* vdp, |
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| 141 | const G4MaterialCutsCouple* , |
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| 142 | const G4DynamicParticle* dp, |
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| 143 | G4double tmin, |
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| 144 | G4double maxEnergy) |
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| 145 | { |
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| 146 | // *** obtain and save target and beam polarization *** |
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| 147 | G4PolarizationManager * polarizationManger = G4PolarizationManager::GetInstance(); |
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| 148 | |
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| 149 | const G4Track * aTrack = fParticleChange->GetCurrentTrack(); |
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| 150 | |
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| 151 | // obtain polarization of the beam |
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| 152 | theBeamPolarization = dp->GetPolarization(); |
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| 153 | |
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| 154 | // obtain polarization of the media |
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| 155 | G4VPhysicalVolume* aPVolume = aTrack->GetVolume(); |
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| 156 | G4LogicalVolume* aLVolume = aPVolume->GetLogicalVolume(); |
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| 157 | const G4bool targetIsPolarized = polarizationManger->IsPolarized(aLVolume); |
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| 158 | theTargetPolarization = polarizationManger->GetVolumePolarization(aLVolume); |
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| 159 | |
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| 160 | // transfer target polarization in interaction frame |
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| 161 | if (targetIsPolarized) |
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| 162 | theTargetPolarization.rotateUz(dp->GetMomentumDirection()); |
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| 163 | |
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| 164 | |
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| 165 | |
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| 166 | |
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| 167 | G4double tmax = std::min(maxEnergy, MaxSecondaryKinEnergy(dp)); |
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| 168 | if(tmin >= tmax) return; |
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| 169 | // if(tmin > tmax) tmin = tmax; |
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| 170 | |
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| 171 | G4double polL = theBeamPolarization.z()*theTargetPolarization.z(); |
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| 172 | polL=std::fabs(polL); |
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| 173 | G4double polT = theBeamPolarization.x()*theTargetPolarization.x() + |
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| 174 | theBeamPolarization.y()*theTargetPolarization.y(); |
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| 175 | polT=std::fabs(polT); |
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| 176 | |
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| 177 | G4double kineticEnergy = dp->GetKineticEnergy(); |
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| 178 | G4double energy = kineticEnergy + electron_mass_c2; |
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| 179 | G4double totalMomentum = std::sqrt(kineticEnergy*(energy + electron_mass_c2)); |
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| 180 | G4double xmin = tmin/kineticEnergy; |
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| 181 | G4double xmax = tmax/kineticEnergy; |
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| 182 | G4double gam = energy/electron_mass_c2; |
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| 183 | G4double gamma2 = gam*gam; |
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| 184 | G4double gmo = gam - 1.; |
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| 185 | G4double gmo2 = gmo*gmo; |
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| 186 | G4double gmo3 = gmo2*gmo; |
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| 187 | G4double gpo = gam + 1.; |
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| 188 | G4double gpo2 = gpo*gpo; |
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| 189 | G4double gpo3 = gpo2*gpo; |
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| 190 | G4double x, y, q, grej, grej2; |
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| 191 | G4double z = 0.; |
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| 192 | G4double xs = 0., phi =0.; |
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| 193 | G4ThreeVector direction = dp->GetMomentumDirection(); |
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| 194 | |
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| 195 | //(Polarized) Moller (e-e-) scattering |
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| 196 | if (isElectron) { |
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| 197 | // *** dice according to polarized cross section |
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| 198 | G4double G = ((2.0*gam - 1.0)/gamma2)*(1. - polT - polL*gam); |
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| 199 | G4double H = (sqr(gam - 1.0)/gamma2)*(1. + polT + polL*((gam + 3.)/(gam - 1.))); |
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| 200 | |
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| 201 | y = 1.0 - xmax; |
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| 202 | grej = 1.0 - G*xmax + xmax*xmax*(H + (1.0 - G*y)/(y*y)); |
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| 203 | grej2 = 1.0 - G*xmin + xmin*xmin*(H + (1.0 - G*y)/(y*y)); |
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| 204 | if (grej2 > grej) grej = grej2; |
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| 205 | G4double prefM = gamma2*classic_electr_radius*classic_electr_radius/(gmo2*(gam + 1.0)); |
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| 206 | grej *= prefM; |
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| 207 | do { |
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| 208 | q = G4UniformRand(); |
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| 209 | x = xmin*xmax/(xmin*(1.0 - q) + xmax*q); |
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| 210 | if (crossSectionCalculator) { |
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| 211 | crossSectionCalculator->Initialize(x,gam,phi,theBeamPolarization, |
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| 212 | theTargetPolarization,1); |
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| 213 | xs=crossSectionCalculator->XSection(G4StokesVector::ZERO, |
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| 214 | G4StokesVector::ZERO); |
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| 215 | z=xs*sqr(x)*4.; |
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| 216 | if (grej < z) { |
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| 217 | G4cout<<"WARNING : error in Moller rejection routine! \n" |
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| 218 | <<" z = "<<z<<" grej="<<grej<<"\n"; |
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| 219 | } |
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| 220 | } else { |
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| 221 | G4cout<<"No calculator in Moller scattering"<<G4endl; |
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| 222 | } |
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| 223 | } while(grej * G4UniformRand() > z); |
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| 224 | //Bhabha (e+e-) scattering |
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| 225 | } else { |
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| 226 | // *** dice according to polarized cross section |
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| 227 | y = xmax*xmax; |
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| 228 | grej = 0.; |
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| 229 | grej += y*y*gmo3*(1. + (polL + polT)*(gam + 3.)/gmo); |
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| 230 | grej += -2.*xmin*xmin*xmin*gam*gmo2*(1. - (polL + polT)*(gam + 3.)/gmo); |
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| 231 | grej += y*y*gmo*(3.*gamma2 + 6.*gam + 4.)*(1. + (polL*(3.*gam + 1.)*(gamma2 + gam + 1.) + polT*((gam + 2.)*gamma2 + 1.))/(gmo*(3.*gam*(gam + 2.) + 4.))); |
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| 232 | grej /= gpo3; |
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| 233 | grej += -xmin*(2.*gamma2 + 4.*gam + 1.)*(1. - gam*(polL*(2.*gam + 1.) + polT)/(2.*gam*(gam + 2.) + 1.))/gpo2; |
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| 234 | grej += gamma2/(gamma2 - 1.); |
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| 235 | G4double prefB = classic_electr_radius*classic_electr_radius/(gam - 1.0); |
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| 236 | grej *= prefB; |
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| 237 | |
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| 238 | do { |
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| 239 | q = G4UniformRand(); |
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| 240 | x = xmin*xmax/(xmin*(1.0 - q) + xmax*q); |
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| 241 | if (crossSectionCalculator) { |
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| 242 | crossSectionCalculator->Initialize(x,gam,phi,theBeamPolarization, |
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| 243 | theTargetPolarization,1); |
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| 244 | xs=crossSectionCalculator->XSection(G4StokesVector::ZERO, |
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| 245 | G4StokesVector::ZERO); |
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| 246 | z=xs*sqr(x)*4.; |
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| 247 | } else { |
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| 248 | G4cout<<"No calculator in Bhabha scattering"<<G4endl; |
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| 249 | } |
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| 250 | |
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| 251 | if(z > grej) { |
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| 252 | G4cout<<"&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&"<<G4endl; |
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| 253 | G4cout << "G4PolarizedMollerBhabhaModel::SampleSecondaries Warning! "<<G4endl |
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| 254 | << "Majorant " << grej << " < " |
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| 255 | << z << " for x= " << x<<G4endl |
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| 256 | << " e+e- (Bhabha) scattering"<<" at KinEnergy "<<kineticEnergy<<G4endl; |
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| 257 | G4cout<<"&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&"<<G4endl; |
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| 258 | } |
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| 259 | } while(grej * G4UniformRand() > z); |
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| 260 | } |
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| 261 | // |
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| 262 | // |
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| 263 | // polar asymmetries (due to transverse polarizations) |
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| 264 | // |
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| 265 | // |
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| 266 | if (crossSectionCalculator) { |
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| 267 | // grej*=1./(sqr(x)*sqr(gamma2-1))*sqr(gam*(1+gam)); |
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| 268 | grej=xs*2.; |
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| 269 | do { |
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| 270 | phi = twopi * G4UniformRand() ; |
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| 271 | crossSectionCalculator->Initialize(x,gam,phi,theBeamPolarization, |
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| 272 | theTargetPolarization,1); |
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| 273 | xs=crossSectionCalculator->XSection(G4StokesVector::ZERO, |
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| 274 | G4StokesVector::ZERO); |
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| 275 | if(xs > grej) { |
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| 276 | if (isElectron){ |
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| 277 | G4cout << "G4PolarizedMollerBhabhaModel::SampleSecondaries Warning! "<<G4endl |
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| 278 | << "Majorant " << grej << " < " |
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| 279 | << xs << " for phi= " << phi<<G4endl |
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| 280 | << " e-e- (Moller) scattering"<< G4endl |
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| 281 | <<"PHI DICING"<<G4endl; |
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| 282 | } else { |
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| 283 | G4cout << "G4PolarizedMollerBhabhaModel::SampleSecondaries Warning! "<<G4endl |
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| 284 | << "Majorant " << grej << " < " |
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| 285 | << xs << " for phi= " << phi<<G4endl |
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| 286 | << " e+e- (Bhabha) scattering"<< G4endl |
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| 287 | <<"PHI DICING"<<G4endl; |
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| 288 | } |
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| 289 | } |
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| 290 | } while(grej * G4UniformRand() > xs); |
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| 291 | } |
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| 292 | |
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| 293 | // fix kinematics of delta electron |
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| 294 | G4double deltaKinEnergy = x * kineticEnergy; |
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| 295 | G4double deltaMomentum = |
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| 296 | std::sqrt(deltaKinEnergy * (deltaKinEnergy + 2.0*electron_mass_c2)); |
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| 297 | G4double cost = deltaKinEnergy * (energy + electron_mass_c2) / |
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| 298 | (deltaMomentum * totalMomentum); |
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| 299 | G4double sint = 1.0 - cost*cost; |
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| 300 | if(sint > 0.0) sint = std::sqrt(sint); |
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| 301 | |
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| 302 | |
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| 303 | G4ThreeVector deltaDirection(-sint*std::cos(phi),-sint*std::sin(phi), cost) ; |
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| 304 | deltaDirection.rotateUz(direction); |
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| 305 | |
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| 306 | // primary change |
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| 307 | kineticEnergy -= deltaKinEnergy; |
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| 308 | fParticleChange->SetProposedKineticEnergy(kineticEnergy); |
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| 309 | |
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| 310 | if(kineticEnergy > DBL_MIN) { |
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| 311 | G4ThreeVector dir = totalMomentum*direction - deltaMomentum*deltaDirection; |
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| 312 | direction = dir.unit(); |
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| 313 | fParticleChange->SetProposedMomentumDirection(direction); |
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| 314 | } |
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| 315 | |
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| 316 | // create G4DynamicParticle object for delta ray |
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| 317 | G4DynamicParticle* delta = new G4DynamicParticle(theElectron,deltaDirection,deltaKinEnergy); |
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| 318 | vdp->push_back(delta); |
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| 319 | |
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| 320 | // get interaction frame |
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| 321 | G4ThreeVector nInteractionFrame = |
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| 322 | G4PolarizationHelper::GetFrame(direction,deltaDirection); |
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| 323 | |
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| 324 | if (crossSectionCalculator) { |
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| 325 | // calculate mean final state polarizations |
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| 326 | |
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| 327 | theBeamPolarization.InvRotateAz(nInteractionFrame,direction); |
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| 328 | theTargetPolarization.InvRotateAz(nInteractionFrame,direction); |
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| 329 | crossSectionCalculator->Initialize(x,gam,phi,theBeamPolarization, |
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| 330 | theTargetPolarization,2); |
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| 331 | |
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| 332 | // electron/positron |
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| 333 | fPositronPolarization=crossSectionCalculator->GetPol2(); |
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| 334 | fPositronPolarization.RotateAz(nInteractionFrame,direction); |
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| 335 | |
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| 336 | fParticleChange->ProposePolarization(fPositronPolarization); |
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| 337 | |
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| 338 | // electron |
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| 339 | fElectronPolarization=crossSectionCalculator->GetPol3(); |
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| 340 | fElectronPolarization.RotateAz(nInteractionFrame,deltaDirection); |
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| 341 | delta->SetPolarization(fElectronPolarization.x(), |
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| 342 | fElectronPolarization.y(), |
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| 343 | fElectronPolarization.z()); |
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| 344 | } |
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| 345 | else { |
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| 346 | fPositronPolarization=G4ThreeVector(); |
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| 347 | fElectronPolarization=G4ThreeVector(); |
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| 348 | } |
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| 349 | } |
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| 350 | |
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| 351 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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