[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: G4PolarizedComptonCrossSection.cc,v 1.4 2007/11/01 17:32:34 schaelic Exp $ |
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| 27 | // GEANT4 tag $Name: $ |
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| 28 | // |
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| 29 | // GEANT4 Class file |
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| 30 | // |
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| 31 | // |
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| 32 | // File name: G4PolarizedComptonCrossSection |
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| 33 | // |
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| 34 | // Author: Andreas Schaelicke |
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| 35 | // |
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| 36 | // Creation date: 15.05.2005 |
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| 37 | // |
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| 38 | // Modifications: |
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| 39 | // |
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| 40 | // Class Description: |
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| 41 | // determine the polarization of the final state |
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| 42 | // in a Compton scattering process employing the differential |
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| 43 | // cross section by F.W.Lipps & H.A.Tolhoek |
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| 44 | // ( Physica 20 (1954) 395 ) |
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| 45 | // recalculated by P.Starovoitov |
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| 46 | // |
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| 47 | #include "G4PolarizedComptonCrossSection.hh" |
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| 48 | #include "Randomize.hh" |
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| 49 | |
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| 50 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 51 | G4PolarizedComptonCrossSection::G4PolarizedComptonCrossSection() |
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| 52 | { |
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| 53 | SetYmin(0.); |
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| 54 | |
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| 55 | // G4cout<<"G4PolarizedComptonCrossSection() init\n"; |
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| 56 | |
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| 57 | re2 = classic_electr_radius * classic_electr_radius * sqr(4*pi/hbarc); |
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| 58 | // G4double unit_conversion = hbarc_squared ; |
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| 59 | // G4cout<<" (keV)^2* m^2 ="<<unit_conversion<<"\n"; |
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| 60 | phi0 = 0.; polXS = 0.; unpXS = 0.; |
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| 61 | phi2 = G4ThreeVector(0., 0., 0.); |
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| 62 | phi3 = G4ThreeVector(0., 0., 0.); |
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| 63 | polxx = polyy = polzz = polxz = polzx = polyz = polzy = polxy = polyx = 0.; |
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| 64 | diffXSFactor = 1.; |
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| 65 | totalXSFactor = 1.; |
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| 66 | } |
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| 67 | |
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| 68 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 69 | G4PolarizedComptonCrossSection::~G4PolarizedComptonCrossSection() |
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| 70 | {} |
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| 71 | |
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| 72 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 73 | void G4PolarizedComptonCrossSection::Initialize(G4double eps, G4double X, G4double , // phi |
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| 74 | const G4StokesVector & pol0, |
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| 75 | const G4StokesVector & pol1, |
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| 76 | G4int flag) |
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| 77 | { |
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| 78 | G4double cosT = 1. - (1./eps - 1.)/X; |
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| 79 | if(cosT > 1.+1.e-8) cosT = 1.; |
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| 80 | if(cosT < -1.-1.e-8) cosT = -1.; |
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| 81 | G4double cosT2 = cosT*cosT; |
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| 82 | G4double cosT3 = cosT2*cosT; |
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| 83 | G4double sinT2 = 1. - cosT2; |
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| 84 | if(sinT2 > 1. + 1.e-8) sinT2 = 1.; |
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| 85 | if(sinT2 < 0.) sinT2 = 0.; |
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| 86 | G4double sinT = std::sqrt(sinT2); |
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| 87 | G4double cos2T = 2.*cosT2 - 1.; |
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| 88 | G4double sin2T = 2.*sinT*cosT; |
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| 89 | G4double eps2 = sqr(eps); |
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| 90 | DefineCoefficients(pol0,pol1); |
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| 91 | diffXSFactor = re2/(4.*X); |
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| 92 | |
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| 93 | // unpolarized Cross Section |
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| 94 | unpXS = (eps2 + 1. - eps*sinT2)/(2.*eps); |
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| 95 | // initial polarization dependence |
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| 96 | polXS = -sinT2*pol0.x() + (1. - eps)*sinT*polzx + ((eps2 - 1.)/eps)*cosT*polzz; |
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| 97 | polXS *= 0.5; |
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| 98 | |
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| 99 | phi0 = unpXS + polXS; |
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| 100 | |
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| 101 | if (flag == 2 ){ |
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| 102 | // polarization of outgoing photon |
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| 103 | G4double PHI21 = -sinT2 + 0.5*(cos2T + 3.)*pol0.x() - ((1. - eps)/eps)*sinT*polzx; |
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| 104 | PHI21 *= 0.5; |
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| 105 | G4double PHI22 = cosT*pol0.y() + ((1. - eps)/(2.*eps))*sinT*polzy; |
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| 106 | G4double PHI23 = ((eps2 + 1.)/eps)*cosT*pol0.z() - ((1. - eps)/eps)*(eps*cosT2 + 1.)*pol1.z(); |
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| 107 | PHI23 += 0.5*(1. - eps)*sin2T*pol1.x(); |
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| 108 | PHI23 += (eps - 1.)*(-sinT2*polxz + sinT*polyy - 0.5*sin2T*polxx); |
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| 109 | PHI23 *= 0.5; |
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| 110 | phi2 = G4ThreeVector(PHI21, PHI22, PHI23); |
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| 111 | |
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| 112 | // polarization of outgoing electron |
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| 113 | G4double PHI32 = -sinT2*polxy + ((1. - eps)/eps)*sinT*polyz + 0.5*(cos2T + 3.)*pol1.y(); |
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| 114 | PHI32 *= 0.5; |
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| 115 | |
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| 116 | G4double PHI31 = 0., PHI31add = 0., PHI33 = 0., PHI33add = 0.; |
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| 117 | |
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| 118 | if ((1. - eps) > 1.e-12){ |
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| 119 | G4double helpVar = std::sqrt(eps2 - 2.*cosT*eps + 1.); |
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| 120 | |
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| 121 | PHI31 = (1. - eps)*(1. + cosT)*sinT*pol0.z(); |
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| 122 | PHI31 += (-eps*cosT3 + eps*cosT2 + (eps - 2.)*cosT + eps)*pol1.x(); |
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| 123 | PHI31 += -(eps*cosT2 - eps*cosT + cosT + 1.)*sinT*pol1.z(); |
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| 124 | PHI31 /= 2.*helpVar; |
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| 125 | |
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| 126 | PHI31add = -eps*sqr(1. - cosT)*(1. + cosT)*polxx; |
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| 127 | PHI31add += (1. - eps)*sinT2*polyy; |
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| 128 | PHI31add += -(-eps2 + cosT*(cosT*eps - eps + 1.)*eps + eps - 1.)*sinT*polxz/eps; |
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| 129 | PHI31add /= 2.*helpVar; |
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| 130 | |
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| 131 | PHI33 = ((1. - eps)/eps)*(-eps*cosT2 + eps*(eps + 1.)*cosT - 1.)*pol0.z(); |
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| 132 | PHI33 += -(eps*cosT2 + (1. - eps)*eps*cosT + 1.)*sinT*pol1.x(); |
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| 133 | PHI33 += -(-eps2*cosT3 + eps*(eps2 - eps + 1.)*cosT2 - cosT + eps2)*pol1.z()/eps; |
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| 134 | PHI33 /= -2.*helpVar; |
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| 135 | |
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| 136 | PHI33add = (eps*(eps - cosT - 1.)*cosT + 1.)*sinT*polxx; |
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| 137 | PHI33add += -(-eps2 + cosT*eps + eps - 1.)*sinT2*polxz; |
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| 138 | PHI33add += (eps - 1.)*(cosT - eps)*sinT*polyy; |
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| 139 | PHI33add /= -2.*helpVar; |
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| 140 | }else{ |
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| 141 | PHI31 = -pol1.z() - (X - 1.)*std::sqrt(1. - eps)*pol1.x()/std::sqrt(2.*X); |
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| 142 | PHI31add = -(-X*X*pol1.z() - 2.*X*(2.*pol0.z() - pol1.z()) - (4.*pol0.x() + 5.)*pol1.z())*(1. - eps)/(4.*X); |
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| 143 | |
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| 144 | PHI33 = pol1.x() - (X - 1.)*std::sqrt(1. - eps)*pol1.z()/std::sqrt(2.*X); |
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| 145 | PHI33add = -(X*X - 2.*X + 4.*pol0.x() + 5.)*(1. - eps)*pol1.x()/(4.*X); |
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| 146 | } |
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| 147 | phi3 = G4ThreeVector(PHI31 + PHI31add, PHI32, PHI33 + PHI33add); |
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| 148 | |
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| 149 | } |
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| 150 | unpXS *= diffXSFactor; |
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| 151 | polXS *= diffXSFactor; |
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| 152 | phi0 *= diffXSFactor; |
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| 153 | phi2 *= diffXSFactor; |
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| 154 | phi3 *= diffXSFactor; |
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| 155 | |
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| 156 | } |
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| 157 | |
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| 158 | G4double G4PolarizedComptonCrossSection::XSection(const G4StokesVector & pol2,const G4StokesVector & pol3) |
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| 159 | { |
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| 160 | gammaPol2 = !(pol2==G4StokesVector::ZERO); |
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| 161 | electronPol3 = !(pol3==G4StokesVector::ZERO); |
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| 162 | |
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| 163 | G4double phi = 0.; |
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| 164 | // polarization independent part |
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| 165 | phi += phi0; |
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| 166 | |
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| 167 | |
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| 168 | if (gammaPol2) { |
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| 169 | // part depending on the polarization of the final photon |
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| 170 | phi += phi2*pol2; |
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| 171 | } |
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| 172 | |
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| 173 | if (electronPol3) { |
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| 174 | // part depending on the polarization of the final electron |
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| 175 | phi += phi3*pol3; |
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| 176 | } |
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| 177 | |
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| 178 | // return cross section. |
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| 179 | return phi; |
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| 180 | } |
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| 181 | |
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| 182 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 183 | |
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| 184 | |
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| 185 | G4double G4PolarizedComptonCrossSection::TotalXSection(G4double /*xmin*/, G4double /*xmax*/, G4double k0, |
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| 186 | const G4StokesVector & pol0, |
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| 187 | const G4StokesVector & pol1) |
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| 188 | { |
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| 189 | |
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| 190 | // G4double k0 = gammaEnergy / electron_mass_c2 ; |
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| 191 | G4double k1 = 1 + 2*k0 ; |
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| 192 | |
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| 193 | // // pi*re^2 |
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| 194 | // G4double re=2.81794e-15; //m |
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| 195 | // G4double barn=1.e-28; //m^2 |
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| 196 | G4double Z=theZ; |
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| 197 | |
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| 198 | G4double unit = Z*pi*classic_electr_radius |
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| 199 | * classic_electr_radius ; // *1./barn; |
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| 200 | |
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| 201 | G4double pre = unit/(sqr(k0)*sqr(1.+2.*k0)); |
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| 202 | |
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| 203 | G4double xs_0 = ((k0 - 2.)*k0 -2.)*sqr(k1)*std::log(k1) + 2.*k0*(k0*(k0 + 1.)*(k0 + 8.) + 2.); |
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| 204 | G4double xs_pol = (k0 + 1.)*sqr(k1)*std::log(k1) - 2.*k0*(5.*sqr(k0) + 4.*k0 + 1.); |
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| 205 | |
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| 206 | return pre*(xs_0/k0 + pol0.p3()*pol1.z()*xs_pol); |
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| 207 | } |
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| 208 | |
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| 209 | |
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| 210 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 211 | |
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| 212 | |
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| 213 | G4StokesVector G4PolarizedComptonCrossSection::GetPol2() |
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| 214 | { |
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| 215 | // Note, mean polarization can not contain correlation |
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| 216 | // effects. |
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| 217 | return 1./phi0 * phi2; |
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| 218 | } |
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| 219 | |
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| 220 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 221 | |
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| 222 | G4StokesVector G4PolarizedComptonCrossSection::GetPol3() |
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| 223 | { |
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| 224 | // Note, mean polarization can not contain correlation |
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| 225 | // effects. |
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| 226 | return 1./phi0 * phi3; |
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| 227 | } |
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| 228 | |
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| 229 | |
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| 230 | |
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| 231 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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| 232 | void G4PolarizedComptonCrossSection::DefineCoefficients(const G4StokesVector & pol0, |
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| 233 | const G4StokesVector & pol1) |
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| 234 | { |
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| 235 | polxx=pol0.x()*pol1.x(); |
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| 236 | polyy=pol0.y()*pol1.y(); |
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| 237 | polzz=pol0.z()*pol1.z(); |
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| 238 | |
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| 239 | polxz=pol0.x()*pol1.z(); |
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| 240 | polzx=pol0.z()*pol1.x(); |
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| 241 | |
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| 242 | polyz=pol0.y()*pol1.z(); |
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| 243 | polzy=pol0.z()*pol1.y(); |
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| 244 | |
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| 245 | polxy=pol0.x()*pol1.y(); |
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| 246 | polyx=pol0.y()*pol1.x(); |
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| 247 | } |
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| 248 | |
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| 249 | |
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| 250 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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