1 | // |
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2 | // ******************************************************************** |
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3 | // * License and Disclaimer * |
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4 | // * * |
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11 | // * Neither the authors of this software system, nor their employing * |
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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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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 | // * * |
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21 | // * Parts of this code which have been developed by QinetiQ Ltd * |
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22 | // * under contract to the European Space Agency (ESA) are the * |
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23 | // * intellectual property of ESA. Rights to use, copy, modify and * |
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24 | // * redistribute this software for general public use are granted * |
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25 | // * in compliance with any licensing, distribution and development * |
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26 | // * policy adopted by the Geant4 Collaboration. This code has been * |
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27 | // * written by QinetiQ Ltd for the European Space Agency, under ESA * |
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28 | // * contract 17191/03/NL/LvH (Aurora Programme). * |
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29 | // * * |
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30 | // * By using, copying, modifying or distributing the software (or * |
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31 | // * any work based on the software) you agree to acknowledge its * |
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32 | // * use in resulting scientific publications, and indicate your * |
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33 | // * acceptance of all terms of the Geant4 Software license. * |
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34 | // ******************************************************************** |
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35 | // |
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36 | // %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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37 | // |
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38 | // MODULE: G4EMDissociationCrossSection.cc |
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39 | // |
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40 | // Version: B.1 |
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41 | // Date: 15/04/04 |
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42 | // Author: P R Truscott |
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43 | // Organisation: QinetiQ Ltd, UK |
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44 | // Customer: ESA/ESTEC, NOORDWIJK |
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45 | // Contract: 17191/03/NL/LvH |
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46 | // |
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47 | // %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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48 | // |
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49 | // CHANGE HISTORY |
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50 | // -------------- |
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51 | // |
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52 | // 17 October 2003, P R Truscott, QinetiQ Ltd, UK |
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53 | // Created. |
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54 | // |
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55 | // 15 March 2004, P R Truscott, QinetiQ Ltd, UK |
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56 | // Beta release |
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57 | // |
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58 | // 30. May 2005, J.P. Wellisch removed a compilation warning on gcc 3.4 for gant4 7.1. |
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59 | // |
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60 | // %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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61 | //////////////////////////////////////////////////////////////////////////////// |
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62 | // |
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63 | #include "G4EMDissociationCrossSection.hh" |
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64 | #include "G4PhysicsFreeVector.hh" |
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65 | #include "G4ParticleTable.hh" |
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66 | #include "G4IonTable.hh" |
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67 | #include "globals.hh" |
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68 | //////////////////////////////////////////////////////////////////////////////// |
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69 | // |
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70 | G4EMDissociationCrossSection::G4EMDissociationCrossSection () |
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71 | { |
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72 | // |
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73 | // |
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74 | // This function makes use of the class which can sample the virtual photon |
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75 | // spectrum, G4EMDissociationSpectrum. |
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76 | // |
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77 | thePhotonSpectrum = new G4EMDissociationSpectrum(); |
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78 | // |
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79 | // |
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80 | // Define other constants. |
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81 | // |
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82 | r0 = 1.18 * fermi; |
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83 | J = 36.8 * MeV; |
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84 | Qprime = 17.0 * MeV; |
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85 | epsilon = 0.0768; |
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86 | xd = 0.25; |
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87 | } |
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88 | //////////////////////////////////////////////////////////////////////////////// |
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89 | // |
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90 | G4EMDissociationCrossSection::~G4EMDissociationCrossSection() |
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91 | { |
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92 | delete thePhotonSpectrum; |
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93 | } |
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94 | /////////////////////////////////////////////////////////////////////////////// |
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95 | // |
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96 | G4bool G4EMDissociationCrossSection::IsZAApplicable |
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97 | (const G4DynamicParticle* theDynamicParticle, G4double /*ZZ*/, G4double AA) |
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98 | { |
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99 | // |
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100 | // The condition for the applicability of this class is that the projectile |
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101 | // must be an ion and the target must have more than one nucleon. In reality |
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102 | // the value of A for either the projectile or target could be much higher, |
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103 | // since for cases where both he projectile and target are medium to small |
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104 | // Z, the probability of the EMD process is, I think, VERY small. |
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105 | // |
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106 | if (G4ParticleTable::GetParticleTable()->GetIonTable()-> |
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107 | IsIon(theDynamicParticle->GetDefinition()) && AA > 1.0) |
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108 | return true; |
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109 | else |
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110 | return false; |
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111 | } |
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112 | |
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113 | G4bool G4EMDissociationCrossSection::IsApplicable |
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114 | (const G4DynamicParticle* theDynamicParticle, const G4Element* theElement) |
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115 | { |
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116 | return IsZAApplicable(theDynamicParticle, 0., theElement->GetN()); |
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117 | } |
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118 | |
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119 | ////////////////////////////////////////////////////////////////////////////// |
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120 | // |
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121 | G4double G4EMDissociationCrossSection::GetCrossSection |
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122 | (const G4DynamicParticle* theDynamicParticle, const G4Element* theElement, |
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123 | G4double temperature) |
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124 | { |
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125 | G4int nIso = theElement->GetNumberOfIsotopes(); |
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126 | G4double crossSection = 0; |
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127 | |
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128 | if (nIso) { |
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129 | G4double sig; |
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130 | G4IsotopeVector* isoVector = theElement->GetIsotopeVector(); |
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131 | G4double* abundVector = theElement->GetRelativeAbundanceVector(); |
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132 | G4double ZZ; |
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133 | G4double AA; |
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134 | |
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135 | for (G4int i = 0; i < nIso; i++) { |
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136 | ZZ = G4double( (*isoVector)[i]->GetZ() ); |
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137 | AA = G4double( (*isoVector)[i]->GetN() ); |
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138 | sig = GetIsoZACrossSection(theDynamicParticle, ZZ, AA, temperature); |
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139 | crossSection += sig*abundVector[i]; |
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140 | } |
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141 | |
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142 | } else { |
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143 | crossSection = |
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144 | GetIsoZACrossSection(theDynamicParticle, theElement->GetZ(), |
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145 | theElement->GetN(), temperature); |
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146 | } |
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147 | |
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148 | return crossSection; |
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149 | } |
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150 | |
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151 | |
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152 | G4double G4EMDissociationCrossSection::GetIsoZACrossSection |
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153 | (const G4DynamicParticle *theDynamicParticle, G4double ZZ, G4double AA, |
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154 | G4double /*temperature*/) |
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155 | { |
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156 | // |
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157 | // |
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158 | // Get relevant information about the projectile and target (A, Z) and |
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159 | // velocity of the projectile. |
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160 | // |
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161 | G4ParticleDefinition *definitionP = theDynamicParticle->GetDefinition(); |
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162 | G4double AP = definitionP->GetBaryonNumber(); |
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163 | G4double ZP = definitionP->GetPDGCharge(); |
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164 | G4double b = theDynamicParticle->Get4Momentum().beta(); |
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165 | // G4double bsq = b * b; |
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166 | |
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167 | G4double AT = AA; |
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168 | G4double ZT = ZZ; |
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169 | G4double bmin = thePhotonSpectrum->GetClosestApproach(AP, ZP, AT, ZT, b); |
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170 | // |
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171 | // |
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172 | // Calculate the cross-section for the projectile and then the target. The |
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173 | // information is returned in a G4PhysicsFreeVector, which separates out the |
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174 | // cross-sections for the E1 and E2 moments of the virtual photon field, and |
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175 | // the energies (GDR and GQR). |
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176 | // |
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177 | G4PhysicsFreeVector *theProjectileCrossSections = |
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178 | GetCrossSectionForProjectile (AP, ZP, AT, ZT, b, bmin); |
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179 | G4double crossSection = |
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180 | (*theProjectileCrossSections)[0]+(*theProjectileCrossSections)[1]; |
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181 | delete theProjectileCrossSections; |
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182 | G4PhysicsFreeVector *theTargetCrossSections = |
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183 | GetCrossSectionForTarget (AP, ZP, AT, ZT, b, bmin); |
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184 | crossSection += |
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185 | (*theTargetCrossSections)[0]+(*theTargetCrossSections)[1]; |
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186 | delete theTargetCrossSections; |
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187 | |
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188 | return crossSection; |
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189 | } |
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190 | //////////////////////////////////////////////////////////////////////////////// |
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191 | // |
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192 | G4PhysicsFreeVector * |
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193 | G4EMDissociationCrossSection::GetCrossSectionForProjectile (G4double AP, |
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194 | G4double ZP, G4double /* AT */, G4double ZT, G4double b, G4double bmin) |
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195 | { |
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196 | // |
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197 | // |
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198 | // Use Wilson et al's approach to calculate the cross-sections due to the E1 |
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199 | // and E2 moments of the field at the giant dipole and quadrupole resonances |
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200 | // respectively, Note that the algorithm is traditionally applied to the |
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201 | // EMD break-up of the projectile in the field of the target, as is implemented |
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202 | // here. |
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203 | // |
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204 | // Initialise variables and calculate the energies for the GDR and GQR. |
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205 | // |
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206 | G4double AProot3 = std::pow(AP,1.0/3.0); |
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207 | G4double u = 3.0 * J / Qprime / AProot3; |
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208 | G4double R0 = r0 * AProot3; |
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209 | G4double E_GDR = hbarc / std::sqrt(0.7*amu_c2*R0*R0/8.0/J* |
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210 | (1.0 + u - (1.0 + epsilon + 3.0*u)/(1.0 + epsilon + u)*epsilon)); |
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211 | G4double E_GQR = 63.0 * MeV / AProot3; |
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212 | // |
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213 | // |
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214 | // Determine the virtual photon spectra at these energies. |
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215 | // |
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216 | G4double ZTsq = ZT * ZT; |
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217 | G4double nE1 = ZTsq * |
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218 | thePhotonSpectrum->GetGeneralE1Spectrum(E_GDR, b, bmin); |
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219 | G4double nE2 = ZTsq * |
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220 | thePhotonSpectrum->GetGeneralE2Spectrum(E_GQR, b, bmin); |
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221 | // |
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222 | // |
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223 | // Now calculate the cross-section of the projectile for interaction with the |
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224 | // E1 and E2 fields. |
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225 | // |
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226 | G4double sE1 = 60.0 * millibarn * MeV * (AP-ZP)*ZP/AP; |
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227 | G4double sE2 = 0.22 * microbarn / MeV * ZP * AProot3 * AProot3; |
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228 | if (AP > 100.0) sE2 *= 0.9; |
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229 | else if (AP > 40.0) sE2 *= 0.6; |
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230 | else sE2 *= 0.3; |
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231 | // |
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232 | // |
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233 | // ... and multiply with the intensity of the virtual photon spectra to get |
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234 | // the probability of interaction. |
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235 | // |
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236 | G4PhysicsFreeVector *theCrossSectionVector = new G4PhysicsFreeVector(2); |
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237 | theCrossSectionVector->PutValue(0, E_GDR, sE1*nE1); |
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238 | theCrossSectionVector->PutValue(1, E_GQR, sE2*nE2*E_GQR*E_GQR); |
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239 | |
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240 | return theCrossSectionVector; |
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241 | } |
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242 | //////////////////////////////////////////////////////////////////////////////// |
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243 | // |
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244 | G4PhysicsFreeVector * |
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245 | G4EMDissociationCrossSection::GetCrossSectionForTarget (G4double AP, |
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246 | G4double ZP, G4double AT, G4double ZT, G4double b, G4double bmin) |
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247 | { |
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248 | // |
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249 | // |
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250 | // This is a cheaky little member function to calculate the probability of |
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251 | // EMD for the target in the field of the projectile ... just by reversing the |
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252 | // A and Z's for the participants. |
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253 | // |
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254 | return GetCrossSectionForProjectile (AT, ZT, AP, ZP, b, bmin); |
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255 | } |
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256 | //////////////////////////////////////////////////////////////////////////////// |
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257 | // |
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258 | G4double |
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259 | G4EMDissociationCrossSection::GetWilsonProbabilityForProtonDissociation |
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260 | (G4double A, G4double Z) |
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261 | { |
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262 | // |
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263 | // |
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264 | // This is a simple algorithm to choose whether a proton or neutron is ejected |
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265 | // from the nucleus in the EMD interaction. |
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266 | // |
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267 | G4double p = 0.0; |
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268 | if (Z < 6.0) |
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269 | p = 0.5; |
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270 | else if (Z < 8.0) |
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271 | p = 0.6; |
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272 | else if (Z < 14.0) |
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273 | p = 0.7; |
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274 | else |
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275 | { |
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276 | G4double p1 = (G4double) Z / (G4double) A; |
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277 | G4double p2 = 1.95*std::exp(-0.075*Z); |
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278 | if (p1 < p2) p = p1; |
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279 | else p = p2; |
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280 | } |
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281 | |
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282 | return p; |
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283 | } |
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284 | //////////////////////////////////////////////////////////////////////////////// |
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285 | // |
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