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24 | // ******************************************************************** |
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25 | // |
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26 | // $Id: G4BetheBlochModel.cc,v 1.13 2007/05/22 17:34:36 vnivanch Exp $ |
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27 | // GEANT4 tag $Name: geant4-09-01-patch-02 $ |
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28 | // |
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29 | // ------------------------------------------------------------------- |
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30 | // |
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31 | // GEANT4 Class header file |
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32 | // |
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33 | // |
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34 | // File name: G4BetheBlochModel |
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35 | // |
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36 | // Author: Vladimir Ivanchenko on base of Laszlo Urban code |
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37 | // |
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38 | // Creation date: 03.01.2002 |
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39 | // |
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40 | // Modifications: |
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41 | // |
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42 | // 04-12-02 Fix problem of G4DynamicParticle constructor (V.Ivanchenko) |
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43 | // 23-12-02 Change interface in order to move to cut per region (V.Ivanchenko) |
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44 | // 27-01-03 Make models region aware (V.Ivanchenko) |
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45 | // 13-02-03 Add name (V.Ivanchenko) |
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46 | // 24-03-05 Add G4EmCorrections (V.Ivanchenko) |
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47 | // 11-04-05 Major optimisation of internal interfaces (V.Ivantchenko) |
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48 | // 11-02-06 ComputeCrossSectionPerElectron, ComputeCrossSectionPerAtom (mma) |
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49 | // 12-02-06 move G4LossTableManager::Instance()->EmCorrections() |
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50 | // in constructor (mma) |
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51 | // |
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52 | // ------------------------------------------------------------------- |
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53 | // |
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54 | |
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55 | |
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56 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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57 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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58 | |
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59 | #include "G4BetheBlochModel.hh" |
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60 | #include "Randomize.hh" |
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61 | #include "G4Electron.hh" |
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62 | #include "G4LossTableManager.hh" |
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63 | #include "G4EmCorrections.hh" |
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64 | #include "G4ParticleChangeForLoss.hh" |
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65 | |
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66 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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67 | |
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68 | using namespace std; |
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69 | |
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70 | G4BetheBlochModel::G4BetheBlochModel(const G4ParticleDefinition* p, |
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71 | const G4String& nam) |
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72 | : G4VEmModel(nam), |
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73 | particle(0), |
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74 | tlimit(DBL_MAX), |
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75 | twoln10(2.0*log(10.0)), |
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76 | bg2lim(0.0169), |
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77 | taulim(8.4146e-3), |
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78 | isIon(false) |
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79 | { |
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80 | if(p) SetParticle(p); |
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81 | theElectron = G4Electron::Electron(); |
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82 | corr = G4LossTableManager::Instance()->EmCorrections(); |
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83 | } |
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84 | |
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85 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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86 | |
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87 | G4BetheBlochModel::~G4BetheBlochModel() |
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88 | {} |
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89 | |
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90 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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91 | |
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92 | G4double G4BetheBlochModel::MinEnergyCut(const G4ParticleDefinition*, |
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93 | const G4MaterialCutsCouple* couple) |
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94 | { |
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95 | return couple->GetMaterial()->GetIonisation()->GetMeanExcitationEnergy(); |
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96 | } |
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97 | |
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98 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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99 | |
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100 | void G4BetheBlochModel::Initialise(const G4ParticleDefinition* p, |
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101 | const G4DataVector&) |
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102 | { |
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103 | if (!particle) SetParticle(p); |
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104 | G4String pname = particle->GetParticleName(); |
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105 | if (particle->GetParticleType() == "nucleus" && |
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106 | pname != "deuteron" && pname != "triton") isIon = true; |
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107 | |
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108 | if (pParticleChange) |
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109 | fParticleChange = reinterpret_cast<G4ParticleChangeForLoss*> |
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110 | (pParticleChange); |
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111 | else |
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112 | fParticleChange = new G4ParticleChangeForLoss(); |
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113 | } |
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114 | |
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115 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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116 | |
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117 | G4double G4BetheBlochModel::ComputeCrossSectionPerElectron( |
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118 | const G4ParticleDefinition* p, |
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119 | G4double kineticEnergy, |
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120 | G4double cutEnergy, |
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121 | G4double maxKinEnergy) |
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122 | { |
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123 | G4double cross = 0.0; |
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124 | G4double tmax = MaxSecondaryEnergy(p, kineticEnergy); |
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125 | G4double maxEnergy = min(tmax,maxKinEnergy); |
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126 | if(cutEnergy < maxEnergy) { |
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127 | |
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128 | G4double totEnergy = kineticEnergy + mass; |
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129 | G4double energy2 = totEnergy*totEnergy; |
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130 | G4double beta2 = kineticEnergy*(kineticEnergy + 2.0*mass)/energy2; |
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131 | |
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132 | cross = 1.0/cutEnergy - 1.0/maxEnergy - beta2*log(maxEnergy/cutEnergy)/tmax; |
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133 | |
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134 | // +term for spin=1/2 particle |
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135 | if( 0.5 == spin ) cross += 0.5*(maxEnergy - cutEnergy)/energy2; |
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136 | |
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137 | cross *= twopi_mc2_rcl2*chargeSquare/beta2; |
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138 | } |
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139 | |
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140 | // G4cout << "BB: e= " << kineticEnergy << " tmin= " << cutEnergy |
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141 | // << " tmax= " << tmax << " cross= " << cross << G4endl; |
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142 | |
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143 | return cross; |
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144 | } |
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145 | |
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146 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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147 | |
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148 | G4double G4BetheBlochModel::ComputeCrossSectionPerAtom( |
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149 | const G4ParticleDefinition* p, |
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150 | G4double kineticEnergy, |
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151 | G4double Z, G4double, |
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152 | G4double cutEnergy, |
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153 | G4double maxEnergy) |
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154 | { |
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155 | G4double cross = Z*ComputeCrossSectionPerElectron |
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156 | (p,kineticEnergy,cutEnergy,maxEnergy); |
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157 | return cross; |
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158 | } |
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159 | |
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160 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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161 | |
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162 | G4double G4BetheBlochModel::CrossSectionPerVolume( |
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163 | const G4Material* material, |
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164 | const G4ParticleDefinition* p, |
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165 | G4double kineticEnergy, |
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166 | G4double cutEnergy, |
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167 | G4double maxEnergy) |
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168 | { |
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169 | G4double eDensity = material->GetElectronDensity(); |
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170 | G4double cross = eDensity*ComputeCrossSectionPerElectron |
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171 | (p,kineticEnergy,cutEnergy,maxEnergy); |
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172 | return cross; |
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173 | } |
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174 | |
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175 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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176 | |
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177 | G4double G4BetheBlochModel::ComputeDEDXPerVolume(const G4Material* material, |
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178 | const G4ParticleDefinition* p, |
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179 | G4double kineticEnergy, |
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180 | G4double cut) |
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181 | { |
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182 | G4double tmax = MaxSecondaryEnergy(p, kineticEnergy); |
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183 | G4double cutEnergy = min(cut,tmax); |
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184 | |
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185 | G4double tau = kineticEnergy/mass; |
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186 | G4double gam = tau + 1.0; |
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187 | G4double bg2 = tau * (tau+2.0); |
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188 | G4double beta2 = bg2/(gam*gam); |
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189 | |
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190 | G4double eexc = material->GetIonisation()->GetMeanExcitationEnergy(); |
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191 | G4double eexc2 = eexc*eexc; |
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192 | G4double cden = material->GetIonisation()->GetCdensity(); |
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193 | G4double mden = material->GetIonisation()->GetMdensity(); |
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194 | G4double aden = material->GetIonisation()->GetAdensity(); |
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195 | G4double x0den = material->GetIonisation()->GetX0density(); |
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196 | G4double x1den = material->GetIonisation()->GetX1density(); |
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197 | |
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198 | G4double eDensity = material->GetElectronDensity(); |
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199 | |
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200 | G4double dedx = log(2.0*electron_mass_c2*bg2*cutEnergy/eexc2) |
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201 | - (1.0 + cutEnergy/tmax)*beta2; |
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202 | |
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203 | if(0.5 == spin) { |
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204 | G4double del = 0.5*cutEnergy/(kineticEnergy + mass); |
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205 | dedx += del*del; |
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206 | } |
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207 | |
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208 | // density correction |
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209 | G4double x = log(bg2)/twoln10; |
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210 | if ( x >= x0den ) { |
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211 | dedx -= twoln10*x - cden ; |
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212 | if ( x < x1den ) dedx -= aden*pow((x1den-x),mden) ; |
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213 | } |
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214 | |
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215 | // shell correction |
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216 | dedx -= 2.0*corr->ShellCorrection(p,material,kineticEnergy); |
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217 | |
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218 | // now compute the total ionization loss |
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219 | |
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220 | if (dedx < 0.0) dedx = 0.0 ; |
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221 | |
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222 | dedx *= twopi_mc2_rcl2*chargeSquare*eDensity/beta2; |
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223 | |
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224 | //High order correction only for hadrons |
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225 | if(!isIon) dedx += corr->HighOrderCorrections(p,material,kineticEnergy); |
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226 | |
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227 | return dedx; |
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228 | } |
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229 | |
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230 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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231 | |
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232 | void G4BetheBlochModel::SampleSecondaries(vector<G4DynamicParticle*>* vdp, |
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233 | const G4MaterialCutsCouple*, |
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234 | const G4DynamicParticle* dp, |
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235 | G4double minKinEnergy, |
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236 | G4double maxEnergy) |
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237 | { |
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238 | G4double kineticEnergy = dp->GetKineticEnergy(); |
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239 | G4double tmax = MaxSecondaryEnergy(dp->GetDefinition(),kineticEnergy); |
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240 | |
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241 | G4double maxKinEnergy = min(maxEnergy,tmax); |
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242 | if(minKinEnergy >= maxKinEnergy) return; |
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243 | |
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244 | G4double totEnergy = kineticEnergy + mass; |
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245 | G4double etot2 = totEnergy*totEnergy; |
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246 | G4double beta2 = kineticEnergy*(kineticEnergy + 2.0*mass)/etot2; |
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247 | |
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248 | G4double deltaKinEnergy, f; |
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249 | |
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250 | // sampling follows ... |
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251 | do { |
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252 | G4double q = G4UniformRand(); |
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253 | deltaKinEnergy = minKinEnergy*maxKinEnergy |
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254 | /(minKinEnergy*(1.0 - q) + maxKinEnergy*q); |
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255 | |
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256 | f = 1.0 - beta2*deltaKinEnergy/tmax; |
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257 | if( 0.5 == spin ) f += 0.5*deltaKinEnergy*deltaKinEnergy/etot2; |
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258 | |
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259 | if(f > 1.0) { |
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260 | G4cout << "G4BetheBlochModel::SampleSecondary Warning! " |
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261 | << "Majorant 1.0 < " |
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262 | << f << " for Edelta= " << deltaKinEnergy |
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263 | << G4endl; |
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264 | } |
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265 | |
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266 | } while( G4UniformRand() > f ); |
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267 | |
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268 | G4double totMomentum = totEnergy*sqrt(beta2); |
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269 | G4double deltaMomentum = |
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270 | sqrt(deltaKinEnergy * (deltaKinEnergy + 2.0*electron_mass_c2)); |
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271 | G4double cost = deltaKinEnergy * (totEnergy + electron_mass_c2) / |
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272 | (deltaMomentum * totMomentum); |
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273 | if(cost > 1.0) { |
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274 | G4cout << "### G4BetheBlochModel WARNING: cost= " |
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275 | << cost << " > 1 for " |
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276 | << dp->GetDefinition()->GetParticleName() |
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277 | << " Ekin(MeV)= " << kineticEnergy |
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278 | << " p(MeV/c)= " << totMomentum |
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279 | << " delEkin(MeV)= " << deltaKinEnergy |
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280 | << " delMom(MeV/c)= " << deltaMomentum |
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281 | << " tmin(MeV)= " << minKinEnergy |
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282 | << " tmax(MeV)= " << maxKinEnergy |
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283 | << " dir= " << dp->GetMomentumDirection() |
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284 | << G4endl; |
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285 | cost = 1.0; |
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286 | } |
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287 | G4double sint = sqrt((1.0 - cost)*(1.0 + cost)); |
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288 | |
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289 | G4double phi = twopi * G4UniformRand() ; |
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290 | |
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291 | |
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292 | G4ThreeVector deltaDirection(sint*cos(phi),sint*sin(phi), cost); |
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293 | G4ThreeVector direction = dp->GetMomentumDirection(); |
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294 | deltaDirection.rotateUz(direction); |
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295 | |
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296 | // create G4DynamicParticle object for delta ray |
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297 | G4DynamicParticle* delta = new G4DynamicParticle(theElectron, |
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298 | deltaDirection,deltaKinEnergy); |
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299 | |
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300 | vdp->push_back(delta); |
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301 | |
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302 | // Change kinematics of primary particle |
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303 | kineticEnergy -= deltaKinEnergy; |
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304 | G4ThreeVector finalP = direction*totMomentum - deltaDirection*deltaMomentum; |
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305 | finalP = finalP.unit(); |
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306 | |
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307 | fParticleChange->SetProposedKineticEnergy(kineticEnergy); |
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308 | fParticleChange->SetProposedMomentumDirection(finalP); |
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309 | } |
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310 | |
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311 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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