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24 | // ******************************************************************** |
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25 | // |
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26 | // $Id: G4MuBetheBlochModel.cc,v 1.27 2009/11/09 19:18:01 vnivanch Exp $ |
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27 | // GEANT4 tag $Name: geant4-09-03-cand-01 $ |
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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: G4MuBetheBlochModel |
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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: 09.08.2002 |
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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 | // 10-02-04 Calculation of radiative corrections using R.Kokoulin model (V.I) |
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47 | // 08-04-05 Major optimisation of internal interfaces (V.Ivantchenko) |
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48 | // 12-04-05 Add usage of G4EmCorrections (V.Ivanchenko) |
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49 | // 13-02-06 ComputeCrossSectionPerElectron, ComputeCrossSectionPerAtom (mma) |
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50 | // |
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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 | |
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57 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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58 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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59 | |
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60 | #include "G4MuBetheBlochModel.hh" |
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61 | #include "Randomize.hh" |
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62 | #include "G4Electron.hh" |
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63 | #include "G4LossTableManager.hh" |
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64 | #include "G4EmCorrections.hh" |
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65 | #include "G4ParticleChangeForLoss.hh" |
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66 | |
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67 | G4double G4MuBetheBlochModel::xgi[]={ 0.0199, 0.1017, 0.2372, 0.4083, 0.5917, |
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68 | 0.7628, 0.8983, 0.9801 }; |
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69 | |
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70 | G4double G4MuBetheBlochModel::wgi[]={ 0.0506, 0.1112, 0.1569, 0.1813, 0.1813, |
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71 | 0.1569, 0.1112, 0.0506 }; |
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72 | |
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73 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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74 | |
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75 | using namespace std; |
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76 | |
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77 | G4MuBetheBlochModel::G4MuBetheBlochModel(const G4ParticleDefinition* p, |
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78 | const G4String& nam) |
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79 | : G4VEmModel(nam), |
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80 | particle(0), |
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81 | limitKinEnergy(100.*keV), |
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82 | logLimitKinEnergy(log(limitKinEnergy)), |
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83 | twoln10(2.0*log(10.0)), |
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84 | bg2lim(0.0169), |
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85 | taulim(8.4146e-3), |
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86 | alphaprime(fine_structure_const/twopi) |
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87 | { |
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88 | theElectron = G4Electron::Electron(); |
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89 | corr = G4LossTableManager::Instance()->EmCorrections(); |
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90 | fParticleChange = 0; |
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91 | |
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92 | if(p) SetParticle(p); |
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93 | } |
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94 | |
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95 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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96 | |
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97 | G4MuBetheBlochModel::~G4MuBetheBlochModel() |
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98 | {} |
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99 | |
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100 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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101 | |
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102 | G4double G4MuBetheBlochModel::MinEnergyCut(const G4ParticleDefinition*, |
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103 | const G4MaterialCutsCouple* couple) |
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104 | { |
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105 | return couple->GetMaterial()->GetIonisation()->GetMeanExcitationEnergy(); |
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106 | } |
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107 | |
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108 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo..... |
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109 | |
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110 | G4double G4MuBetheBlochModel::MaxSecondaryEnergy(const G4ParticleDefinition*, |
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111 | G4double kinEnergy) |
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112 | { |
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113 | G4double tau = kinEnergy/mass; |
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114 | G4double tmax = 2.0*electron_mass_c2*tau*(tau + 2.) / |
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115 | (1. + 2.0*(tau + 1.)*ratio + ratio*ratio); |
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116 | return tmax; |
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117 | } |
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118 | |
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119 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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120 | |
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121 | void G4MuBetheBlochModel::Initialise(const G4ParticleDefinition* p, |
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122 | const G4DataVector&) |
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123 | { |
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124 | if(p) SetParticle(p); |
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125 | if(!fParticleChange) fParticleChange = GetParticleChangeForLoss(); |
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126 | } |
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127 | |
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128 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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129 | |
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130 | G4double G4MuBetheBlochModel::ComputeCrossSectionPerElectron( |
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131 | const G4ParticleDefinition* p, |
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132 | G4double kineticEnergy, |
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133 | G4double cutEnergy, |
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134 | G4double maxKinEnergy) |
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135 | { |
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136 | G4double cross = 0.0; |
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137 | G4double tmax = MaxSecondaryEnergy(p, kineticEnergy); |
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138 | G4double maxEnergy = min(tmax,maxKinEnergy); |
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139 | if(cutEnergy < maxEnergy) { |
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140 | |
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141 | G4double totEnergy = kineticEnergy + mass; |
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142 | G4double energy2 = totEnergy*totEnergy; |
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143 | G4double beta2 = kineticEnergy*(kineticEnergy + 2.0*mass)/energy2; |
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144 | |
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145 | cross = 1.0/cutEnergy - 1.0/maxEnergy - beta2*log(maxEnergy/cutEnergy)/tmax |
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146 | + 0.5*(maxEnergy - cutEnergy)/energy2; |
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147 | |
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148 | // radiative corrections of R. Kokoulin |
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149 | if (maxEnergy > limitKinEnergy) { |
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150 | |
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151 | G4double logtmax = log(maxEnergy); |
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152 | G4double logtmin = log(max(cutEnergy,limitKinEnergy)); |
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153 | G4double logstep = logtmax - logtmin; |
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154 | G4double dcross = 0.0; |
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155 | |
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156 | for (G4int ll=0; ll<8; ll++) |
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157 | { |
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158 | G4double ep = exp(logtmin + xgi[ll]*logstep); |
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159 | G4double a1 = log(1.0 + 2.0*ep/electron_mass_c2); |
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160 | G4double a3 = log(4.0*totEnergy*(totEnergy - ep)/massSquare); |
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161 | dcross += wgi[ll]*(1.0/ep - beta2/tmax + 0.5*ep/energy2)*a1*(a3 - a1); |
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162 | } |
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163 | |
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164 | cross += dcross*logstep*alphaprime; |
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165 | } |
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166 | |
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167 | cross *= twopi_mc2_rcl2/beta2; |
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168 | |
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169 | } |
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170 | |
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171 | // G4cout << "tmin= " << cutEnergy << " tmax= " << tmax |
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172 | // << " cross= " << cross << G4endl; |
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173 | |
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174 | return cross; |
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175 | } |
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176 | |
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177 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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178 | |
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179 | G4double G4MuBetheBlochModel::ComputeCrossSectionPerAtom( |
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180 | const G4ParticleDefinition* p, |
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181 | G4double kineticEnergy, |
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182 | G4double Z, G4double, |
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183 | G4double cutEnergy, |
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184 | G4double maxEnergy) |
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185 | { |
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186 | G4double cross = Z*ComputeCrossSectionPerElectron |
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187 | (p,kineticEnergy,cutEnergy,maxEnergy); |
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188 | return cross; |
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189 | } |
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190 | |
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191 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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192 | |
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193 | G4double G4MuBetheBlochModel::CrossSectionPerVolume( |
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194 | const G4Material* material, |
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195 | const G4ParticleDefinition* p, |
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196 | G4double kineticEnergy, |
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197 | G4double cutEnergy, |
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198 | G4double maxEnergy) |
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199 | { |
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200 | G4double eDensity = material->GetElectronDensity(); |
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201 | G4double cross = eDensity*ComputeCrossSectionPerElectron |
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202 | (p,kineticEnergy,cutEnergy,maxEnergy); |
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203 | return cross; |
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204 | } |
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205 | |
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206 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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207 | |
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208 | G4double G4MuBetheBlochModel::ComputeDEDXPerVolume(const G4Material* material, |
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209 | const G4ParticleDefinition* p, |
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210 | G4double kineticEnergy, |
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211 | G4double cut) |
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212 | { |
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213 | G4double tmax = MaxSecondaryEnergy(p, kineticEnergy); |
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214 | G4double tau = kineticEnergy/mass; |
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215 | G4double cutEnergy = min(cut,tmax); |
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216 | G4double gam = tau + 1.0; |
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217 | G4double bg2 = tau * (tau+2.0); |
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218 | G4double beta2 = bg2/(gam*gam); |
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219 | |
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220 | G4double eexc = material->GetIonisation()->GetMeanExcitationEnergy(); |
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221 | G4double eexc2 = eexc*eexc; |
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222 | //G4double cden = material->GetIonisation()->GetCdensity(); |
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223 | //G4double mden = material->GetIonisation()->GetMdensity(); |
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224 | //G4double aden = material->GetIonisation()->GetAdensity(); |
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225 | //G4double x0den = material->GetIonisation()->GetX0density(); |
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226 | //G4double x1den = material->GetIonisation()->GetX1density(); |
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227 | |
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228 | G4double eDensity = material->GetElectronDensity(); |
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229 | |
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230 | G4double dedx = log(2.0*electron_mass_c2*bg2*cutEnergy/eexc2) |
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231 | -(1.0 + cutEnergy/tmax)*beta2; |
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232 | |
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233 | G4double totEnergy = kineticEnergy + mass; |
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234 | G4double del = 0.5*cutEnergy/totEnergy; |
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235 | dedx += del*del; |
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236 | |
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237 | // density correction |
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238 | G4double x = log(bg2)/twoln10; |
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239 | //if ( x >= x0den ) { |
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240 | // dedx -= twoln10*x - cden ; |
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241 | // if ( x < x1den ) dedx -= aden*pow((x1den-x),mden) ; |
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242 | //} |
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243 | dedx -= material->GetIonisation()->DensityCorrection(x); |
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244 | |
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245 | // shell correction |
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246 | dedx -= 2.0*corr->ShellCorrection(p,material,kineticEnergy); |
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247 | |
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248 | // now compute the total ionization loss |
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249 | |
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250 | if (dedx < 0.0) dedx = 0.0 ; |
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251 | |
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252 | // radiative corrections of R. Kokoulin |
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253 | if (cutEnergy > limitKinEnergy) { |
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254 | |
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255 | G4double logtmax = log(cutEnergy); |
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256 | G4double logstep = logtmax - logLimitKinEnergy; |
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257 | G4double dloss = 0.0; |
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258 | G4double ftot2= 0.5/(totEnergy*totEnergy); |
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259 | |
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260 | for (G4int ll=0; ll<8; ll++) |
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261 | { |
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262 | G4double ep = exp(logLimitKinEnergy + xgi[ll]*logstep); |
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263 | G4double a1 = log(1.0 + 2.0*ep/electron_mass_c2); |
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264 | G4double a3 = log(4.0*totEnergy*(totEnergy - ep)/massSquare); |
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265 | dloss += wgi[ll]*(1.0 - beta2*ep/tmax + ep*ep*ftot2)*a1*(a3 - a1); |
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266 | } |
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267 | dedx += dloss*logstep*alphaprime; |
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268 | } |
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269 | |
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270 | dedx *= twopi_mc2_rcl2*eDensity/beta2; |
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271 | |
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272 | //High order corrections |
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273 | dedx += corr->HighOrderCorrections(p,material,kineticEnergy,cutEnergy); |
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274 | |
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275 | return dedx; |
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276 | } |
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277 | |
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278 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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279 | |
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280 | void G4MuBetheBlochModel::SampleSecondaries(vector<G4DynamicParticle*>* vdp, |
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281 | const G4MaterialCutsCouple*, |
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282 | const G4DynamicParticle* dp, |
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283 | G4double minKinEnergy, |
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284 | G4double maxEnergy) |
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285 | { |
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286 | G4double tmax = MaxSecondaryKinEnergy(dp); |
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287 | G4double maxKinEnergy = min(maxEnergy,tmax); |
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288 | if(minKinEnergy >= maxKinEnergy) return; |
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289 | |
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290 | G4double kineticEnergy = dp->GetKineticEnergy(); |
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291 | G4double totEnergy = kineticEnergy + mass; |
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292 | G4double etot2 = totEnergy*totEnergy; |
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293 | G4double beta2 = kineticEnergy*(kineticEnergy + 2.0*mass)/etot2; |
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294 | |
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295 | G4double grej = 1.; |
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296 | if(tmax > limitKinEnergy) { |
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297 | G4double a0 = log(2.*totEnergy/mass); |
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298 | grej += alphaprime*a0*a0; |
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299 | } |
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300 | |
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301 | G4double deltaKinEnergy, f; |
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302 | |
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303 | // sampling follows ... |
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304 | do { |
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305 | G4double q = G4UniformRand(); |
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306 | deltaKinEnergy = minKinEnergy*maxKinEnergy |
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307 | /(minKinEnergy*(1.0 - q) + maxKinEnergy*q); |
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308 | |
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309 | |
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310 | f = 1.0 - beta2*deltaKinEnergy/tmax |
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311 | + 0.5*deltaKinEnergy*deltaKinEnergy/etot2; |
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312 | |
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313 | if(deltaKinEnergy > limitKinEnergy) { |
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314 | G4double a1 = log(1.0 + 2.0*deltaKinEnergy/electron_mass_c2); |
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315 | G4double a3 = log(4.0*totEnergy*(totEnergy - deltaKinEnergy)/massSquare); |
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316 | f *= (1. + alphaprime*a1*(a3 - a1)); |
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317 | } |
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318 | |
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319 | if(f > grej) { |
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320 | G4cout << "G4MuBetheBlochModel::SampleSecondary Warning! " |
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321 | << "Majorant " << grej << " < " |
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322 | << f << " for edelta= " << deltaKinEnergy |
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323 | << " tmin= " << minKinEnergy << " max= " << maxKinEnergy |
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324 | << G4endl; |
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325 | } |
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326 | |
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327 | |
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328 | } while( grej*G4UniformRand() > f ); |
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329 | |
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330 | G4double deltaMomentum = |
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331 | sqrt(deltaKinEnergy * (deltaKinEnergy + 2.0*electron_mass_c2)); |
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332 | G4double totalMomentum = totEnergy*sqrt(beta2); |
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333 | G4double cost = deltaKinEnergy * (totEnergy + electron_mass_c2) / |
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334 | (deltaMomentum * totalMomentum); |
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335 | |
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336 | G4double sint = sqrt(1.0 - cost*cost); |
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337 | |
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338 | G4double phi = twopi * G4UniformRand() ; |
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339 | |
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340 | G4ThreeVector deltaDirection(sint*cos(phi),sint*sin(phi), cost) ; |
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341 | G4ThreeVector direction = dp->GetMomentumDirection(); |
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342 | deltaDirection.rotateUz(direction); |
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343 | |
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344 | // primary change |
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345 | kineticEnergy -= deltaKinEnergy; |
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346 | G4ThreeVector dir = totalMomentum*direction - deltaMomentum*deltaDirection; |
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347 | direction = dir.unit(); |
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348 | fParticleChange->SetProposedKineticEnergy(kineticEnergy); |
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349 | fParticleChange->SetProposedMomentumDirection(direction); |
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350 | |
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351 | // create G4DynamicParticle object for delta ray |
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352 | G4DynamicParticle* delta = new G4DynamicParticle(theElectron, |
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353 | deltaDirection,deltaKinEnergy); |
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354 | vdp->push_back(delta); |
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355 | } |
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356 | |
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357 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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