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 | // |
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27 | // $Id: G4SynchrotronRadiation.cc,v 1.5 2006/06/29 19:56:15 gunter Exp $ |
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28 | // GEANT4 tag $Name: $ |
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29 | // |
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30 | // -------------------------------------------------------------- |
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31 | // GEANT 4 class implementation file |
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32 | // CERN Geneva Switzerland |
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33 | // |
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34 | // History: first implementation, |
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35 | // 21-5-98 V.Grichine |
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36 | // 28-05-01, V.Ivanchenko minor changes to provide ANSI -wall compilation |
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37 | // 04.03.05, V.Grichine: get local field interface |
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38 | // 18-05-06 H. Burkhardt: Energy spectrum from function rather than table |
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39 | // |
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40 | // |
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41 | // |
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42 | // |
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43 | /////////////////////////////////////////////////////////////////////////// |
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44 | |
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45 | #include "G4SynchrotronRadiation.hh" |
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46 | // #include "G4Integrator.hh" |
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47 | #include "G4UnitsTable.hh" |
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48 | |
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49 | using namespace std; |
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50 | |
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51 | /////////////////////////////////////////////////////////////////////// |
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52 | // |
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53 | // Constructor |
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54 | // |
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55 | |
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56 | G4SynchrotronRadiation::G4SynchrotronRadiation(const G4String& processName, |
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57 | G4ProcessType type):G4VDiscreteProcess (processName, type), |
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58 | theGamma (G4Gamma::Gamma() ), |
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59 | theElectron ( G4Electron::Electron() ), |
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60 | thePositron ( G4Positron::Positron() ) |
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61 | { |
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62 | G4TransportationManager* transportMgr = |
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63 | G4TransportationManager::GetTransportationManager(); |
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64 | |
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65 | fFieldPropagator = transportMgr->GetPropagatorInField(); |
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66 | |
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67 | fLambdaConst = sqrt(3.0)*electron_mass_c2/ |
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68 | (2.5*fine_structure_const*eplus*c_light) ; |
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69 | fEnergyConst = 1.5*c_light*c_light*eplus*hbar_Planck/electron_mass_c2 ; |
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70 | verboseLevel=1; |
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71 | } |
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72 | |
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73 | ///////////////////////////////////////////////////////////////////////// |
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74 | // |
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75 | // Destructor |
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76 | // |
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77 | |
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78 | G4SynchrotronRadiation::~G4SynchrotronRadiation() |
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79 | { |
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80 | ; |
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81 | } |
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82 | |
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83 | /////////////////////////////// METHODS ///////////////////////////////// |
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84 | // |
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85 | // |
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86 | // Production of synchrotron X-ray photon |
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87 | // GEANT4 internal units. |
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88 | // |
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89 | |
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90 | |
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91 | G4double |
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92 | G4SynchrotronRadiation::GetMeanFreePath( const G4Track& trackData, |
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93 | G4double, |
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94 | G4ForceCondition* condition) |
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95 | { |
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96 | // gives the MeanFreePath in GEANT4 internal units |
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97 | G4double MeanFreePath; |
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98 | |
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99 | const G4DynamicParticle* aDynamicParticle = trackData.GetDynamicParticle(); |
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100 | |
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101 | *condition = NotForced ; |
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102 | |
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103 | G4double gamma = aDynamicParticle->GetTotalEnergy()/ |
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104 | aDynamicParticle->GetMass(); |
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105 | |
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106 | G4double particleCharge = aDynamicParticle->GetDefinition()->GetPDGCharge(); |
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107 | |
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108 | if ( gamma < 1.0e3 ) MeanFreePath = DBL_MAX; |
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109 | else |
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110 | { |
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111 | |
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112 | G4ThreeVector FieldValue; |
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113 | const G4Field* pField = 0; |
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114 | |
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115 | G4FieldManager* fieldMgr=0; |
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116 | G4bool fieldExertsForce = false; |
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117 | |
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118 | if( (particleCharge != 0.0) ) |
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119 | { |
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120 | fieldMgr = fFieldPropagator->FindAndSetFieldManager( trackData.GetVolume() ); |
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121 | |
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122 | if ( fieldMgr != 0 ) |
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123 | { |
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124 | // If the field manager has no field, there is no field ! |
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125 | |
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126 | fieldExertsForce = ( fieldMgr->GetDetectorField() != 0 ); |
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127 | } |
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128 | } |
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129 | if ( fieldExertsForce ) |
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130 | { |
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131 | pField = fieldMgr->GetDetectorField() ; |
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132 | G4ThreeVector globPosition = trackData.GetPosition(); |
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133 | |
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134 | G4double globPosVec[3], FieldValueVec[3]; |
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135 | |
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136 | globPosVec[0] = globPosition.x(); |
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137 | globPosVec[1] = globPosition.y(); |
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138 | globPosVec[2] = globPosition.z(); |
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139 | |
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140 | pField->GetFieldValue( globPosVec, FieldValueVec ); |
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141 | |
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142 | FieldValue = G4ThreeVector( FieldValueVec[0], |
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143 | FieldValueVec[1], |
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144 | FieldValueVec[2] ); |
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145 | |
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146 | |
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147 | |
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148 | G4ThreeVector unitMomentum = aDynamicParticle->GetMomentumDirection(); |
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149 | G4ThreeVector unitMcrossB = FieldValue.cross(unitMomentum) ; |
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150 | G4double perpB = unitMcrossB.mag() ; |
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151 | |
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152 | if( perpB > 0.0 ) MeanFreePath = fLambdaConst/perpB; |
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153 | else MeanFreePath = DBL_MAX; |
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154 | |
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155 | static G4bool FirstTime=true; |
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156 | if(verboseLevel > 0 && FirstTime) |
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157 | { |
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158 | G4cout << "G4SynchrotronRadiation::GetMeanFreePath :" << '\n' << std::setprecision(4) |
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159 | << " MeanFreePath = " << G4BestUnit(MeanFreePath, "Length") |
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160 | << G4endl; |
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161 | if(verboseLevel > 1) |
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162 | { |
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163 | G4ThreeVector pvec=aDynamicParticle->GetMomentum(); |
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164 | G4double Btot=FieldValue.getR(); |
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165 | G4double ptot=pvec.getR(); |
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166 | G4double rho= ptot / (MeV * c_light * Btot ); // full bending radius |
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167 | G4double Theta=unitMomentum.theta(FieldValue); // angle between particle and field |
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168 | G4cout |
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169 | << " B = " << Btot/tesla << " Tesla" |
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170 | << " perpB = " << perpB/tesla << " Tesla" |
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171 | << " Theta = " << Theta << " sin(Theta)=" << sin(Theta) << '\n' |
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172 | << " ptot = " << G4BestUnit(ptot,"Energy") |
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173 | << " rho = " << G4BestUnit(rho,"Length") |
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174 | << G4endl; |
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175 | } |
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176 | FirstTime=false; |
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177 | } |
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178 | } |
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179 | else MeanFreePath = DBL_MAX; |
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180 | |
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181 | |
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182 | } |
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183 | |
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184 | return MeanFreePath; |
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185 | } |
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186 | |
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187 | //////////////////////////////////////////////////////////////////////////////// |
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188 | // |
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189 | // |
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190 | |
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191 | G4VParticleChange* |
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192 | G4SynchrotronRadiation::PostStepDoIt(const G4Track& trackData, |
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193 | const G4Step& stepData ) |
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194 | |
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195 | { |
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196 | aParticleChange.Initialize(trackData); |
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197 | |
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198 | const G4DynamicParticle* aDynamicParticle=trackData.GetDynamicParticle(); |
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199 | |
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200 | G4double gamma = aDynamicParticle->GetTotalEnergy()/ |
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201 | (aDynamicParticle->GetMass() ); |
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202 | |
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203 | if(gamma <= 1.0e3 ) |
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204 | { |
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205 | return G4VDiscreteProcess::PostStepDoIt(trackData,stepData); |
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206 | } |
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207 | G4double particleCharge = aDynamicParticle->GetDefinition()->GetPDGCharge(); |
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208 | |
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209 | G4ThreeVector FieldValue; |
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210 | const G4Field* pField = 0 ; |
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211 | |
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212 | G4FieldManager* fieldMgr=0; |
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213 | G4bool fieldExertsForce = false; |
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214 | |
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215 | if( (particleCharge != 0.0) ) |
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216 | { |
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217 | fieldMgr = fFieldPropagator->FindAndSetFieldManager( trackData.GetVolume() ); |
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218 | if ( fieldMgr != 0 ) |
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219 | { |
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220 | // If the field manager has no field, there is no field ! |
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221 | |
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222 | fieldExertsForce = ( fieldMgr->GetDetectorField() != 0 ); |
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223 | } |
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224 | } |
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225 | if ( fieldExertsForce ) |
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226 | { |
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227 | pField = fieldMgr->GetDetectorField() ; |
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228 | G4ThreeVector globPosition = trackData.GetPosition() ; |
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229 | G4double globPosVec[3], FieldValueVec[3] ; |
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230 | globPosVec[0] = globPosition.x() ; |
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231 | globPosVec[1] = globPosition.y() ; |
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232 | globPosVec[2] = globPosition.z() ; |
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233 | |
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234 | pField->GetFieldValue( globPosVec, FieldValueVec ) ; |
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235 | FieldValue = G4ThreeVector( FieldValueVec[0], |
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236 | FieldValueVec[1], |
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237 | FieldValueVec[2] ); |
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238 | |
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239 | G4ThreeVector unitMomentum = aDynamicParticle->GetMomentumDirection(); |
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240 | G4ThreeVector unitMcrossB = FieldValue.cross(unitMomentum); |
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241 | G4double perpB = unitMcrossB.mag() ; |
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242 | if(perpB > 0.0) |
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243 | { |
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244 | // M-C of synchrotron photon energy |
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245 | |
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246 | G4double energyOfSR = GetRandomEnergySR(gamma,perpB); |
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247 | |
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248 | // check against insufficient energy |
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249 | |
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250 | if( energyOfSR <= 0.0 ) |
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251 | { |
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252 | return G4VDiscreteProcess::PostStepDoIt(trackData,stepData); |
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253 | } |
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254 | G4double kineticEnergy = aDynamicParticle->GetKineticEnergy(); |
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255 | G4ParticleMomentum |
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256 | particleDirection = aDynamicParticle->GetMomentumDirection(); |
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257 | |
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258 | // M-C of its direction |
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259 | |
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260 | G4double Teta = G4UniformRand()/gamma ; // Very roughly |
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261 | |
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262 | G4double Phi = twopi * G4UniformRand() ; |
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263 | |
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264 | G4double dirx = sin(Teta)*cos(Phi) , |
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265 | diry = sin(Teta)*sin(Phi) , |
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266 | dirz = cos(Teta) ; |
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267 | |
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268 | G4ThreeVector gammaDirection ( dirx, diry, dirz); |
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269 | gammaDirection.rotateUz(particleDirection); |
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270 | |
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271 | // polarization of new gamma |
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272 | |
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273 | // G4double sx = cos(Teta)*cos(Phi); |
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274 | // G4double sy = cos(Teta)*sin(Phi); |
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275 | // G4double sz = -sin(Teta); |
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276 | |
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277 | G4ThreeVector gammaPolarization = FieldValue.cross(gammaDirection); |
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278 | gammaPolarization = gammaPolarization.unit(); |
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279 | |
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280 | // (sx, sy, sz); |
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281 | // gammaPolarization.rotateUz(particleDirection); |
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282 | |
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283 | // create G4DynamicParticle object for the SR photon |
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284 | |
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285 | G4DynamicParticle* aGamma= new G4DynamicParticle ( theGamma, |
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286 | gammaDirection, |
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287 | energyOfSR ); |
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288 | aGamma->SetPolarization( gammaPolarization.x(), |
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289 | gammaPolarization.y(), |
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290 | gammaPolarization.z() ); |
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291 | |
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292 | |
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293 | aParticleChange.SetNumberOfSecondaries(1); |
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294 | aParticleChange.AddSecondary(aGamma); |
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295 | |
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296 | // Update the incident particle |
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297 | |
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298 | G4double newKinEnergy = kineticEnergy - energyOfSR ; |
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299 | aParticleChange.ProposeLocalEnergyDeposit (0.); |
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300 | |
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301 | if (newKinEnergy > 0.) |
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302 | { |
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303 | aParticleChange.ProposeMomentumDirection( particleDirection ); |
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304 | aParticleChange.ProposeEnergy( newKinEnergy ); |
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305 | } |
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306 | else |
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307 | { |
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308 | aParticleChange.ProposeEnergy( 0. ); |
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309 | } |
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310 | } |
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311 | } |
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312 | return G4VDiscreteProcess::PostStepDoIt(trackData,stepData); |
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313 | } |
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314 | |
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315 | |
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316 | ///////////////////////////////////////////////////////////////////////////////// |
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317 | // |
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318 | // |
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319 | |
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320 | G4double G4SynchrotronRadiation::InvSynFracInt(G4double x) |
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321 | // direct generation |
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322 | { |
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323 | // from 0 to 0.7 |
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324 | const G4double aa1=0 ,aa2=0.7; |
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325 | const G4int ncheb1=27; |
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326 | static const G4double cheb1[] = |
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327 | { 1.22371665676046468821,0.108956475422163837267,0.0383328524358594396134,0.00759138369340257753721, |
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328 | 0.00205712048644963340914,0.000497810783280019308661,0.000130743691810302187818,0.0000338168760220395409734, |
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329 | 8.97049680900520817728e-6,2.38685472794452241466e-6,6.41923109149104165049e-7,1.73549898982749277843e-7, |
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330 | 4.72145949240790029153e-8,1.29039866111999149636e-8,3.5422080787089834182e-9,9.7594757336403784905e-10, |
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331 | 2.6979510184976065731e-10,7.480422622550977077e-11,2.079598176402699913e-11,5.79533622220841193e-12, |
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332 | 1.61856011449276096e-12,4.529450993473807e-13,1.2698603951096606e-13,3.566117394511206e-14,1.00301587494091e-14, |
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333 | 2.82515346447219e-15,7.9680747949792e-16}; |
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334 | // from 0.7 to 0.9132260271183847 |
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335 | const G4double aa3=0.9132260271183847; |
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336 | const G4int ncheb2=27; |
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337 | static const G4double cheb2[] = |
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338 | { 1.1139496701107756,0.3523967429328067,0.0713849171926623,0.01475818043595387,0.003381255637322462, |
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339 | 0.0008228057599452224,0.00020785506681254216,0.00005390169253706556,0.000014250571923902464,3.823880733161044e-6, |
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340 | 1.0381966089136036e-6,2.8457557457837253e-7,7.86223332179956e-8,2.1866609342508474e-8,6.116186259857143e-9, |
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341 | 1.7191233618437565e-9,4.852755117740807e-10,1.3749966961763457e-10,3.908961987062447e-11,1.1146253766895824e-11, |
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342 | 3.1868887323415814e-12,9.134319791300977e-13,2.6211077371181566e-13,7.588643377757906e-14,2.1528376972619e-14, |
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343 | 6.030906040404772e-15,1.9549163926819867e-15}; |
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344 | // Chebyshev with exp/log scale |
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345 | // a = -Log[1 - SynFracInt[1]]; b = -Log[1 - SynFracInt[7]]; |
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346 | const G4double aa4=2.4444485538746025480,aa5=9.3830728608909477079; |
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347 | const G4int ncheb3=28; |
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348 | static const G4double cheb3[] = |
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349 | { 1.2292683840435586977,0.160353449247864455879,-0.0353559911947559448721,0.00776901561223573936985, |
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350 | -0.00165886451971685133259,0.000335719118906954279467,-0.0000617184951079161143187,9.23534039743246708256e-6, |
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351 | -6.06747198795168022842e-7,-3.07934045961999778094e-7,1.98818772614682367781e-7,-8.13909971567720135413e-8, |
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352 | 2.84298174969641838618e-8,-9.12829766621316063548e-9,2.77713868004820551077e-9,-8.13032767247834023165e-10, |
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353 | 2.31128525568385247392e-10,-6.41796873254200220876e-11,1.74815310473323361543e-11,-4.68653536933392363045e-12, |
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354 | 1.24016595805520752748e-12,-3.24839432979935522159e-13,8.44601465226513952994e-14,-2.18647276044246803998e-14, |
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355 | 5.65407548745690689978e-15,-1.46553625917463067508e-15,3.82059606377570462276e-16,-1.00457896653436912508e-16}; |
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356 | const G4double aa6=33.122936966163038145; |
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357 | const G4int ncheb4=27; |
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358 | static const G4double cheb4[] = |
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359 | {1.69342658227676741765,0.0742766400841232319225,-0.019337880608635717358,0.00516065527473364110491, |
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360 | -0.00139342012990307729473,0.000378549864052022522193,-0.000103167085583785340215,0.0000281543441271412178337, |
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361 | -7.68409742018258198651e-6,2.09543221890204537392e-6,-5.70493140367526282946e-7,1.54961164548564906446e-7, |
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362 | -4.19665599629607704794e-8,1.13239680054166507038e-8,-3.04223563379021441863e-9,8.13073745977562957997e-10, |
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363 | -2.15969415476814981374e-10,5.69472105972525594811e-11,-1.48844799572430829499e-11,3.84901514438304484973e-12, |
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364 | -9.82222575944247161834e-13,2.46468329208292208183e-13,-6.04953826265982691612e-14,1.44055805710671611984e-14, |
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365 | -3.28200813577388740722e-15,6.96566359173765367675e-16,-1.294122794852896275e-16}; |
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366 | |
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367 | if(x<aa2) return x*x*x*Chebyshev(aa1,aa2,cheb1,ncheb1,x); |
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368 | else if(x<aa3) return Chebyshev(aa2,aa3,cheb2,ncheb2,x); |
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369 | else if(x<1-0.0000841363) |
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370 | { G4double y=-log(1-x); |
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371 | return y*Chebyshev(aa4,aa5,cheb3,ncheb3,y); |
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372 | } |
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373 | else |
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374 | { G4double y=-log(1-x); |
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375 | return y*Chebyshev(aa5,aa6,cheb4,ncheb4,y); |
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376 | } |
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377 | } |
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378 | |
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379 | G4double G4SynchrotronRadiation::GetRandomEnergySR(G4double gamma, G4double perpB) |
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380 | { |
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381 | |
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382 | G4double Ecr=fEnergyConst*gamma*gamma*perpB; |
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383 | |
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384 | static G4bool FirstTime=true; |
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385 | if(verboseLevel > 0 && FirstTime) |
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386 | { G4double Emean=8./(15.*sqrt(3.))*Ecr; // mean photon energy |
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387 | G4double E_rms=sqrt(211./675.)*Ecr; // rms of photon energy distribution |
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388 | G4cout << "G4SynchrotronRadiation::GetRandomEnergySR :" << '\n' << std::setprecision(4) |
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389 | << " Ecr = " << G4BestUnit(Ecr,"Energy") << '\n' |
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390 | << " Emean = " << G4BestUnit(Emean,"Energy") << '\n' |
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391 | << " E_rms = " << G4BestUnit(E_rms,"Energy") << G4endl; |
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392 | FirstTime=false; |
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393 | } |
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394 | |
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395 | G4double energySR=Ecr*InvSynFracInt(G4UniformRand()); |
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396 | return energySR; |
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397 | } |
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398 | |
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399 | |
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400 | void G4SynchrotronRadiation::BuildPhysicsTable(const G4ParticleDefinition& part) |
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401 | { |
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402 | if(0 < verboseLevel && &part==theElectron ) PrintInfoDefinition(); |
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403 | } |
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404 | |
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405 | void G4SynchrotronRadiation::PrintInfoDefinition() // not yet called, usually called from BuildPhysicsTable |
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406 | { |
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407 | G4String comments ="Incoherent Synchrotron Radiation\n"; |
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408 | G4cout << G4endl << GetProcessName() << ": " << comments |
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409 | << " good description for long magnets at all energies" << G4endl; |
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410 | } |
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411 | |
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412 | ///////////////////// end of G4SynchrotronRadiation.cc |
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