| 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: G4PolarizedPairProductionCrossSection.cc,v 1.5 2007/11/01 17:32:34 schaelic Exp $ |
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| 27 | // GEANT4 tag $Name: geant4-09-02-ref-02 $ |
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| 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: G4PolarizedPairProductionCrossSection |
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| 35 | // |
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| 36 | // Author: Andreas Schaelicke on the base of Karim Laihems code |
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| 37 | // |
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| 38 | // Creation date: 16.08.2006 |
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| 39 | // |
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| 40 | |
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| 41 | #include "G4PolarizedPairProductionCrossSection.hh" |
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| 42 | // #include "G4PolarizedGammaConversionModel.hh" |
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| 43 | // #include "G4Element.hh" |
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| 44 | |
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| 45 | G4bool G4PolarizedPairProductionCrossSection::scrnInitialized=false; |
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| 46 | G4double G4PolarizedPairProductionCrossSection::SCRN [3][20]; |
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| 47 | // screening function lookup table; |
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| 48 | |
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| 49 | void G4PolarizedPairProductionCrossSection::InitializeMe() |
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| 50 | { |
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| 51 | if (!scrnInitialized) { |
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| 52 | SCRN [1][1]= 0.5 ; SCRN [2][1] = 0.0145; |
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| 53 | SCRN [1][2]= 1.0 ; SCRN [2][2] = 0.0490; |
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| 54 | SCRN [1][3]= 2.0 ; SCRN [2][3] = 0.1400; |
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| 55 | SCRN [1][4]= 4.0 ; SCRN [2][4] = 0.3312; |
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| 56 | SCRN [1][5]= 8.0 ; SCRN [2][5] = 0.6758; |
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| 57 | SCRN [1][6]= 15.0 ; SCRN [2][6] = 1.126; |
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| 58 | SCRN [1][7]= 20.0 ; SCRN [2][7] = 1.367; |
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| 59 | SCRN [1][8]= 25.0 ; SCRN [2][8] = 1.564; |
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| 60 | SCRN [1][9]= 30.0 ; SCRN [2][9] = 1.731; |
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| 61 | SCRN [1][10]= 35.0 ; SCRN [2][10]= 1.875; |
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| 62 | SCRN [1][11]= 40.0 ; SCRN [2][11]= 2.001; |
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| 63 | SCRN [1][12]= 45.0 ; SCRN [2][12]= 2.114; |
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| 64 | SCRN [1][13]= 50.0 ; SCRN [2][13]= 2.216; |
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| 65 | SCRN [1][14]= 60.0 ; SCRN [2][14]= 2.393; |
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| 66 | SCRN [1][15]= 70.0 ; SCRN [2][15]= 2.545; |
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| 67 | SCRN [1][16]= 80.0 ; SCRN [2][16]= 2.676; |
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| 68 | SCRN [1][17]= 90.0 ; SCRN [2][17]= 2.793; |
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| 69 | SCRN [1][18]= 100.0 ; SCRN [2][18]= 2.897; |
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| 70 | SCRN [1][19]= 120.0 ; SCRN [2][19]= 3.078; |
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| 71 | |
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| 72 | scrnInitialized=true; |
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| 73 | } |
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| 74 | } |
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| 75 | |
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| 76 | G4PolarizedPairProductionCrossSection::G4PolarizedPairProductionCrossSection() |
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| 77 | { |
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| 78 | InitializeMe(); |
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| 79 | } |
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| 80 | |
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| 81 | |
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| 82 | void G4PolarizedPairProductionCrossSection::Initialize(G4double aGammaE, |
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| 83 | G4double aLept0E, |
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| 84 | G4double sintheta, |
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| 85 | const G4StokesVector & beamPol, |
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| 86 | const G4StokesVector & /*p1*/, |
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| 87 | G4int /*flag*/) |
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| 88 | { |
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| 89 | G4double aLept1E = aGammaE - aLept0E; |
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| 90 | |
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| 91 | G4double Stokes_P3 = beamPol.z() ; |
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| 92 | // ************************************************************************** |
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| 93 | |
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| 94 | G4double m0_c2 = electron_mass_c2; |
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| 95 | G4double Lept0E = aLept0E/m0_c2+1., Lept0E2 = Lept0E * Lept0E ; |
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| 96 | G4double GammaE = aGammaE/m0_c2; |
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| 97 | G4double Lept1E = aLept1E/m0_c2-1., Lept1E2 = Lept1E * Lept1E ; |
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| 98 | |
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| 99 | |
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| 100 | // const G4Element* theSelectedElement = theModel->SelectedAtom(); |
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| 101 | |
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| 102 | // ******* Gamma Transvers Momentum |
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| 103 | |
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| 104 | G4double TMom = std::sqrt(Lept0E2 -1.)* sintheta, u = TMom , u2 =u * u ; |
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| 105 | G4double Xsi = 1./(1.+u2) , Xsi2 = Xsi * Xsi ; |
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| 106 | |
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| 107 | // G4double theZ = theSelectedElement->GetZ(); |
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| 108 | |
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| 109 | // G4double fCoul = theSelectedElement->GetfCoulomb(); |
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| 110 | G4double delta = 12. * std::pow(theZ, 1./3.) * Lept0E * Lept1E * Xsi / (121. * GammaE); |
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| 111 | G4double GG=0.; |
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| 112 | |
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| 113 | if(delta < 0.5) { |
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| 114 | GG = std::log(2.* Lept0E * Lept1E / GammaE) - 2. - fCoul; |
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| 115 | } |
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| 116 | else if ( delta < 120) { |
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| 117 | for (G4int j=2; j<=19; j++) { |
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| 118 | if(SCRN[1][j] >= delta) { |
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| 119 | GG =std::log(2 * Lept0E * Lept1E / GammaE) - 2 - fCoul |
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| 120 | -(SCRN[2][j-1]+(delta-SCRN[1][j-1])*(SCRN[2][j]-SCRN[2][j-1])/(SCRN[1][j]-SCRN[1][j-1])); |
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| 121 | break; |
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| 122 | } |
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| 123 | } |
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| 124 | } |
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| 125 | else { |
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| 126 | G4double alpha_sc = (111 * std::pow(theZ, -1./3.)) / Xsi; |
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| 127 | GG = std::log(alpha_sc)- 2 - fCoul; |
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| 128 | } |
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| 129 | |
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| 130 | if(GG<-1) GG=-1; // *KL* do we need this ?! |
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| 131 | |
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| 132 | |
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| 133 | G4double I_Lepton = (Lept0E2 + Lept1E2)*(3+2*GG) + 2 * Lept0E * Lept1E * (1 + 4 * u2 * Xsi2 * GG); |
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| 134 | |
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| 135 | // G4double D_Lepton1 = -8 * Lept0E * Lept1E * u2 * Xsi2 * GG / I_Lepton; |
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| 136 | |
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| 137 | G4double L_Lepton1 = GammaE * ((Lept0E - Lept1E) * (3. + 2. * GG)+2 * Lept1E * (1 + 4 * u2 * Xsi2 * GG))/I_Lepton; |
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| 138 | |
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| 139 | G4double T_Lepton1 = 4 * GammaE * Lept1E * Xsi * u * (1. - 2. * Xsi) * GG / I_Lepton ; |
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| 140 | |
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| 141 | |
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| 142 | G4double Stokes_S1 = (Stokes_P3 * T_Lepton1) ; |
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| 143 | G4double Stokes_S2 = 0; |
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| 144 | G4double Stokes_S3 = (Stokes_P3 * L_Lepton1) ; |
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| 145 | |
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| 146 | |
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| 147 | theFinalElectronPolarization.setX(Stokes_S1); |
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| 148 | theFinalElectronPolarization.setY(Stokes_S2); |
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| 149 | theFinalElectronPolarization.setZ(Stokes_S3); |
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| 150 | |
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| 151 | if(theFinalElectronPolarization.mag2()>1) { |
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| 152 | G4cout<<" WARNING in pol-conv theFinalElectronPolarization \n"; |
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| 153 | G4cout |
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| 154 | <<"\t"<<theFinalElectronPolarization |
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| 155 | <<"\t GG\t"<<GG |
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| 156 | <<"\t delta\t"<<delta |
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| 157 | <<G4endl; |
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| 158 | theFinalElectronPolarization.setX(0); |
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| 159 | theFinalElectronPolarization.setY(0); |
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| 160 | theFinalElectronPolarization.setZ(Stokes_S3); |
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| 161 | if(Stokes_S3>1) theFinalElectronPolarization.setZ(1); |
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| 162 | } |
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| 163 | |
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| 164 | |
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| 165 | G4double L_Lepton2 = GammaE * ((Lept1E - Lept0E) * (3. + 2. * GG)+2 * Lept0E * (1 + 4 * u2 * Xsi2 * GG))/I_Lepton; |
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| 166 | |
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| 167 | G4double T_Lepton2 = 4 * GammaE * Lept0E * Xsi * u * (1. - 2. * Xsi) * GG / I_Lepton ; |
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| 168 | |
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| 169 | G4double Stokes_SS1 = (Stokes_P3 * T_Lepton2) ; |
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| 170 | G4double Stokes_SS2 = 0; |
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| 171 | G4double Stokes_SS3 = (Stokes_P3 * L_Lepton2) ; |
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| 172 | |
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| 173 | theFinalPositronPolarization.SetPhoton(); |
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| 174 | |
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| 175 | theFinalPositronPolarization.setX(Stokes_SS1); |
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| 176 | theFinalPositronPolarization.setY(Stokes_SS2); |
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| 177 | theFinalPositronPolarization.setZ(Stokes_SS3); |
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| 178 | |
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| 179 | if(theFinalPositronPolarization.mag2()>1) { |
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| 180 | G4cout<<" WARNING in pol-conv theFinalPositronPolarization \n"; |
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| 181 | G4cout |
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| 182 | <<"\t"<<theFinalPositronPolarization |
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| 183 | <<"\t GG\t"<<GG |
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| 184 | <<"\t delta\t"<<delta |
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| 185 | <<G4endl; |
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| 186 | } |
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| 187 | } |
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| 188 | |
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| 189 | G4double G4PolarizedPairProductionCrossSection::XSection(const G4StokesVector & /*pol2*/, |
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| 190 | const G4StokesVector & /*pol3*/) |
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| 191 | { |
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| 192 | G4cout<<"ERROR dummy routine G4PolarizedPairProductionCrossSection::XSection called \n"; |
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| 193 | return 0; |
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| 194 | } |
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| 195 | |
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| 196 | // return expected mean polarisation |
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| 197 | G4StokesVector G4PolarizedPairProductionCrossSection::GetPol2() |
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| 198 | { |
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| 199 | // electron/positron |
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| 200 | return theFinalElectronPolarization; |
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| 201 | } |
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| 202 | G4StokesVector G4PolarizedPairProductionCrossSection::GetPol3() |
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| 203 | { |
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| 204 | // photon |
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| 205 | return theFinalPositronPolarization;; |
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| 206 | } |
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| 207 | |
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| 208 | |
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