1 | // |
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2 | // ******************************************************************** |
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3 | // * License and Disclaimer * |
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4 | // * * |
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6 | // * the Geant4 Collaboration. It is provided under the terms and * |
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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: G4UrbanMscModel93.cc,v 1.7 2010/11/04 17:30:32 vnivanch Exp $ |
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28 | // GEANT4 tag $Name: emstand-V09-03-25 $ |
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29 | // |
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30 | // ------------------------------------------------------------------- |
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31 | // |
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32 | // GEANT4 Class file |
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33 | // |
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34 | // |
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35 | // File name: G4UrbanMscModel93 |
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36 | // |
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37 | // Author: Laszlo Urban |
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38 | // |
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39 | // Creation date: 06.03.2008 |
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40 | // |
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41 | // Modifications: |
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42 | // |
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43 | // 06-03-2008 starting point : G4UrbanMscModel2 = G4UrbanMscModel 9.1 ref 02 |
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44 | // |
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45 | // 13-03-08 Bug in SampleScattering (which caused lateral asymmetry) fixed |
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46 | // (L.Urban) |
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47 | // |
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48 | // 14-03-08 Simplification of step limitation in ComputeTruePathLengthLimit, |
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49 | // + tlimitmin is the same for UseDistancetoBoundary and |
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50 | // UseSafety (L.Urban) |
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51 | // |
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52 | // 16-03-08 Reorganization of SampleCosineTheta + new method SimpleScattering |
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53 | // SimpleScattering is used if the relative energy loss is too big |
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54 | // or theta0 is too big (see data members rellossmax, theta0max) |
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55 | // (L.Urban) |
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56 | // |
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57 | // 17-03-08 tuning of the correction factor in ComputeTheta0 (L.Urban) |
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58 | // |
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59 | // 19-03-08 exponent c of the 'tail' model function is not equal to 2 any more, |
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60 | // value of c has been extracted from some e- scattering data (L.Urban) |
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61 | // |
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62 | // 24-03-08 Step limitation in ComputeTruePathLengthLimit has been |
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63 | // simplified further + some data members have been removed (L.Urban) |
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64 | // |
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65 | // 24-07-08 central part of scattering angle (theta0) has been tuned |
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66 | // tail of the scattering angle distribution has been tuned |
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67 | // using some e- and proton scattering data |
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68 | // |
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69 | // 05-08-08 bugfix in ComputeTruePathLengthLimit (L.Urban) |
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70 | // |
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71 | // 09-10-08 theta0 and tail have been retuned using some e-,mu,proton |
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72 | // scattering data (L.Urban) |
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73 | // + single scattering without path length correction for |
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74 | // small steps (t < tlimitmin, for UseDistanceToBoundary only) |
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75 | // |
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76 | // 15-10-08 Moliere-Bethe screening in the single scattering part(L.Urban) |
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77 | // |
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78 | // 17-10-08 stepping similar to that in model (9.1) for UseSafety case |
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79 | // for e+/e- in order to speed up the code for calorimeters |
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80 | // |
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81 | // 23-10-08 bugfix in the screeningparameter of the single scattering part, |
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82 | // some technical change in order to speed up the code (UpdateCache) |
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83 | // |
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84 | // 27-10-08 bugfix in ComputeTruePathLengthLimit (affects UseDistanceToBoundary |
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85 | // stepping type only) (L.Urban) |
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86 | // |
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87 | // 28-10-09 V.Ivanchenko moved G4UrbanMscModel2 to G4UrbanMscModel93, |
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88 | // now it is a frozen version of the Urban model corresponding |
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89 | // to g4 9.3 |
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90 | |
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91 | // Class Description: |
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92 | // |
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93 | // Implementation of the model of multiple scattering based on |
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94 | // H.W.Lewis Phys Rev 78 (1950) 526 and others |
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95 | |
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96 | // ------------------------------------------------------------------- |
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97 | // In its present form the model can be used for simulation |
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98 | // of the e-/e+, muon and charged hadron multiple scattering |
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99 | // |
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100 | |
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101 | |
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102 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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103 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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104 | |
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105 | #include "G4UrbanMscModel93.hh" |
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106 | #include "Randomize.hh" |
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107 | #include "G4Electron.hh" |
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108 | #include "G4LossTableManager.hh" |
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109 | #include "G4ParticleChangeForMSC.hh" |
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110 | |
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111 | #include "G4Poisson.hh" |
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112 | #include "globals.hh" |
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113 | |
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114 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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115 | |
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116 | using namespace std; |
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117 | |
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118 | G4UrbanMscModel93::G4UrbanMscModel93(const G4String& nam) |
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119 | : G4VMscModel(nam), |
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120 | isInitialized(false) |
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121 | { |
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122 | masslimite = 0.6*MeV; |
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123 | lambdalimit = 1.*mm; |
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124 | fr = 0.02; |
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125 | //facsafety = 0.3; |
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126 | taubig = 8.0; |
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127 | tausmall = 1.e-16; |
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128 | taulim = 1.e-6; |
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129 | currentTau = taulim; |
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130 | tlimitminfix = 1.e-6*mm; |
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131 | stepmin = tlimitminfix; |
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132 | smallstep = 1.e10; |
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133 | currentRange = 0. ; |
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134 | rangeinit = 0.; |
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135 | tlimit = 1.e10*mm; |
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136 | tlimitmin = 10.*tlimitminfix; |
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137 | tgeom = 1.e50*mm; |
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138 | geombig = 1.e50*mm; |
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139 | geommin = 1.e-3*mm; |
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140 | geomlimit = geombig; |
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141 | presafety = 0.*mm; |
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142 | |
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143 | y = 0.; |
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144 | |
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145 | Zold = 0.; |
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146 | Zeff = 1.; |
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147 | Z2 = 1.; |
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148 | Z23 = 1.; |
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149 | lnZ = 0.; |
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150 | coeffth1 = 0.; |
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151 | coeffth2 = 0.; |
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152 | coeffc1 = 0.; |
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153 | coeffc2 = 0.; |
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154 | scr1ini = fine_structure_const*fine_structure_const* |
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155 | electron_mass_c2*electron_mass_c2/(0.885*0.885*4.*pi); |
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156 | scr2ini = 3.76*fine_structure_const*fine_structure_const; |
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157 | scr1 = 0.; |
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158 | scr2 = 0.; |
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159 | |
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160 | theta0max = pi/6.; |
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161 | rellossmax = 0.50; |
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162 | third = 1./3.; |
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163 | particle = 0; |
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164 | theManager = G4LossTableManager::Instance(); |
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165 | inside = false; |
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166 | insideskin = false; |
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167 | |
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168 | skindepth = skin*stepmin; |
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169 | |
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170 | mass = proton_mass_c2; |
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171 | charge = ChargeSquare = 1.0; |
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172 | currentKinEnergy = currentRadLength = lambda0 = lambdaeff = tPathLength |
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173 | = zPathLength = par1 = par2 = par3 = 0; |
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174 | |
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175 | currentMaterialIndex = -1; |
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176 | } |
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177 | |
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178 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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179 | |
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180 | G4UrbanMscModel93::~G4UrbanMscModel93() |
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181 | {} |
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182 | |
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183 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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184 | |
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185 | void G4UrbanMscModel93::Initialise(const G4ParticleDefinition* p, |
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186 | const G4DataVector&) |
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187 | { |
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188 | skindepth = skin*stepmin; |
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189 | |
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190 | if(isInitialized) { return; } |
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191 | // set values of some data members |
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192 | SetParticle(p); |
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193 | |
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194 | fParticleChange = GetParticleChangeForMSC(); |
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195 | InitialiseSafetyHelper(); |
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196 | |
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197 | isInitialized = true; |
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198 | } |
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199 | |
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200 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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201 | |
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202 | G4double G4UrbanMscModel93::ComputeCrossSectionPerAtom( |
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203 | const G4ParticleDefinition* part, |
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204 | G4double KineticEnergy, |
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205 | G4double AtomicNumber,G4double, |
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206 | G4double, G4double) |
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207 | { |
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208 | const G4double sigmafactor = twopi*classic_electr_radius*classic_electr_radius; |
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209 | const G4double epsfactor = 2.*electron_mass_c2*electron_mass_c2* |
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210 | Bohr_radius*Bohr_radius/(hbarc*hbarc); |
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211 | const G4double epsmin = 1.e-4 , epsmax = 1.e10; |
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212 | |
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213 | const G4double Zdat[15] = { 4., 6., 13., 20., 26., 29., 32., 38., 47., |
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214 | 50., 56., 64., 74., 79., 82. }; |
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215 | |
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216 | const G4double Tdat[22] = { 100*eV, 200*eV, 400*eV, 700*eV, |
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217 | 1*keV, 2*keV, 4*keV, 7*keV, |
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218 | 10*keV, 20*keV, 40*keV, 70*keV, |
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219 | 100*keV, 200*keV, 400*keV, 700*keV, |
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220 | 1*MeV, 2*MeV, 4*MeV, 7*MeV, |
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221 | 10*MeV, 20*MeV}; |
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222 | |
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223 | // corr. factors for e-/e+ lambda for T <= Tlim |
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224 | G4double celectron[15][22] = |
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225 | {{1.125,1.072,1.051,1.047,1.047,1.050,1.052,1.054, |
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226 | 1.054,1.057,1.062,1.069,1.075,1.090,1.105,1.111, |
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227 | 1.112,1.108,1.100,1.093,1.089,1.087 }, |
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228 | {1.408,1.246,1.143,1.096,1.077,1.059,1.053,1.051, |
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229 | 1.052,1.053,1.058,1.065,1.072,1.087,1.101,1.108, |
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230 | 1.109,1.105,1.097,1.090,1.086,1.082 }, |
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231 | {2.833,2.268,1.861,1.612,1.486,1.309,1.204,1.156, |
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232 | 1.136,1.114,1.106,1.106,1.109,1.119,1.129,1.132, |
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233 | 1.131,1.124,1.113,1.104,1.099,1.098 }, |
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234 | {3.879,3.016,2.380,2.007,1.818,1.535,1.340,1.236, |
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235 | 1.190,1.133,1.107,1.099,1.098,1.103,1.110,1.113, |
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236 | 1.112,1.105,1.096,1.089,1.085,1.098 }, |
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237 | {6.937,4.330,2.886,2.256,1.987,1.628,1.395,1.265, |
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238 | 1.203,1.122,1.080,1.065,1.061,1.063,1.070,1.073, |
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239 | 1.073,1.070,1.064,1.059,1.056,1.056 }, |
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240 | {9.616,5.708,3.424,2.551,2.204,1.762,1.485,1.330, |
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241 | 1.256,1.155,1.099,1.077,1.070,1.068,1.072,1.074, |
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242 | 1.074,1.070,1.063,1.059,1.056,1.052 }, |
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243 | {11.72,6.364,3.811,2.806,2.401,1.884,1.564,1.386, |
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244 | 1.300,1.180,1.112,1.082,1.073,1.066,1.068,1.069, |
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245 | 1.068,1.064,1.059,1.054,1.051,1.050 }, |
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246 | {18.08,8.601,4.569,3.183,2.662,2.025,1.646,1.439, |
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247 | 1.339,1.195,1.108,1.068,1.053,1.040,1.039,1.039, |
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248 | 1.039,1.037,1.034,1.031,1.030,1.036 }, |
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249 | {18.22,10.48,5.333,3.713,3.115,2.367,1.898,1.631, |
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250 | 1.498,1.301,1.171,1.105,1.077,1.048,1.036,1.033, |
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251 | 1.031,1.028,1.024,1.022,1.021,1.024 }, |
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252 | {14.14,10.65,5.710,3.929,3.266,2.453,1.951,1.669, |
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253 | 1.528,1.319,1.178,1.106,1.075,1.040,1.027,1.022, |
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254 | 1.020,1.017,1.015,1.013,1.013,1.020 }, |
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255 | {14.11,11.73,6.312,4.240,3.478,2.566,2.022,1.720, |
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256 | 1.569,1.342,1.186,1.102,1.065,1.022,1.003,0.997, |
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257 | 0.995,0.993,0.993,0.993,0.993,1.011 }, |
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258 | {22.76,20.01,8.835,5.287,4.144,2.901,2.219,1.855, |
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259 | 1.677,1.410,1.224,1.121,1.073,1.014,0.986,0.976, |
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260 | 0.974,0.972,0.973,0.974,0.975,0.987 }, |
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261 | {50.77,40.85,14.13,7.184,5.284,3.435,2.520,2.059, |
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262 | 1.837,1.512,1.283,1.153,1.091,1.010,0.969,0.954, |
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263 | 0.950,0.947,0.949,0.952,0.954,0.963 }, |
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264 | {65.87,59.06,15.87,7.570,5.567,3.650,2.682,2.182, |
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265 | 1.939,1.579,1.325,1.178,1.108,1.014,0.965,0.947, |
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266 | 0.941,0.938,0.940,0.944,0.946,0.954 }, |
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267 | {55.60,47.34,15.92,7.810,5.755,3.767,2.760,2.239, |
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268 | 1.985,1.609,1.343,1.188,1.113,1.013,0.960,0.939, |
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269 | 0.933,0.930,0.933,0.936,0.939,0.949 }}; |
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270 | |
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271 | G4double cpositron[15][22] = { |
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272 | {2.589,2.044,1.658,1.446,1.347,1.217,1.144,1.110, |
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273 | 1.097,1.083,1.080,1.086,1.092,1.108,1.123,1.131, |
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274 | 1.131,1.126,1.117,1.108,1.103,1.100 }, |
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275 | {3.904,2.794,2.079,1.710,1.543,1.325,1.202,1.145, |
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276 | 1.122,1.096,1.089,1.092,1.098,1.114,1.130,1.137, |
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277 | 1.138,1.132,1.122,1.113,1.108,1.102 }, |
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278 | {7.970,6.080,4.442,3.398,2.872,2.127,1.672,1.451, |
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279 | 1.357,1.246,1.194,1.179,1.178,1.188,1.201,1.205, |
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280 | 1.203,1.190,1.173,1.159,1.151,1.145 }, |
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281 | {9.714,7.607,5.747,4.493,3.815,2.777,2.079,1.715, |
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282 | 1.553,1.353,1.253,1.219,1.211,1.214,1.225,1.228, |
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283 | 1.225,1.210,1.191,1.175,1.166,1.174 }, |
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284 | {17.97,12.95,8.628,6.065,4.849,3.222,2.275,1.820, |
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285 | 1.624,1.382,1.259,1.214,1.202,1.202,1.214,1.219, |
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286 | 1.217,1.203,1.184,1.169,1.160,1.151 }, |
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287 | {24.83,17.06,10.84,7.355,5.767,3.707,2.546,1.996, |
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288 | 1.759,1.465,1.311,1.252,1.234,1.228,1.238,1.241, |
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289 | 1.237,1.222,1.201,1.184,1.174,1.159 }, |
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290 | {23.26,17.15,11.52,8.049,6.375,4.114,2.792,2.155, |
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291 | 1.880,1.535,1.353,1.281,1.258,1.247,1.254,1.256, |
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292 | 1.252,1.234,1.212,1.194,1.183,1.170 }, |
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293 | {22.33,18.01,12.86,9.212,7.336,4.702,3.117,2.348, |
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294 | 2.015,1.602,1.385,1.297,1.268,1.251,1.256,1.258, |
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295 | 1.254,1.237,1.214,1.195,1.185,1.179 }, |
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296 | {33.91,24.13,15.71,10.80,8.507,5.467,3.692,2.808, |
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297 | 2.407,1.873,1.564,1.425,1.374,1.330,1.324,1.320, |
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298 | 1.312,1.288,1.258,1.235,1.221,1.205 }, |
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299 | {32.14,24.11,16.30,11.40,9.015,5.782,3.868,2.917, |
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300 | 2.490,1.925,1.596,1.447,1.391,1.342,1.332,1.327, |
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301 | 1.320,1.294,1.264,1.240,1.226,1.214 }, |
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302 | {29.51,24.07,17.19,12.28,9.766,6.238,4.112,3.066, |
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303 | 2.602,1.995,1.641,1.477,1.414,1.356,1.342,1.336, |
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304 | 1.328,1.302,1.270,1.245,1.231,1.233 }, |
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305 | {38.19,30.85,21.76,15.35,12.07,7.521,4.812,3.498, |
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306 | 2.926,2.188,1.763,1.563,1.484,1.405,1.382,1.371, |
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307 | 1.361,1.330,1.294,1.267,1.251,1.239 }, |
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308 | {49.71,39.80,27.96,19.63,15.36,9.407,5.863,4.155, |
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309 | 3.417,2.478,1.944,1.692,1.589,1.480,1.441,1.423, |
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310 | 1.409,1.372,1.330,1.298,1.280,1.258 }, |
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311 | {59.25,45.08,30.36,20.83,16.15,9.834,6.166,4.407, |
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312 | 3.641,2.648,2.064,1.779,1.661,1.531,1.482,1.459, |
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313 | 1.442,1.400,1.354,1.319,1.299,1.272 }, |
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314 | {56.38,44.29,30.50,21.18,16.51,10.11,6.354,4.542, |
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315 | 3.752,2.724,2.116,1.817,1.692,1.554,1.499,1.474, |
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316 | 1.456,1.412,1.364,1.328,1.307,1.282 }}; |
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317 | |
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318 | //data/corrections for T > Tlim |
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319 | G4double Tlim = 10.*MeV; |
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320 | G4double beta2lim = Tlim*(Tlim+2.*electron_mass_c2)/ |
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321 | ((Tlim+electron_mass_c2)*(Tlim+electron_mass_c2)); |
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322 | G4double bg2lim = Tlim*(Tlim+2.*electron_mass_c2)/ |
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323 | (electron_mass_c2*electron_mass_c2); |
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324 | |
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325 | G4double sig0[15] = {0.2672*barn, 0.5922*barn, 2.653*barn, 6.235*barn, |
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326 | 11.69*barn , 13.24*barn , 16.12*barn, 23.00*barn , |
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327 | 35.13*barn , 39.95*barn , 50.85*barn, 67.19*barn , |
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328 | 91.15*barn , 104.4*barn , 113.1*barn}; |
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329 | |
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330 | G4double hecorr[15] = {120.70, 117.50, 105.00, 92.92, 79.23, 74.510, 68.29, |
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331 | 57.39, 41.97, 36.14, 24.53, 10.21, -7.855, -16.84, |
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332 | -22.30}; |
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333 | |
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334 | G4double sigma; |
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335 | SetParticle(part); |
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336 | |
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337 | G4double Z23 = 2.*log(AtomicNumber)/3.; Z23 = exp(Z23); |
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338 | |
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339 | // correction if particle .ne. e-/e+ |
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340 | // compute equivalent kinetic energy |
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341 | // lambda depends on p*beta .... |
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342 | |
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343 | G4double eKineticEnergy = KineticEnergy; |
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344 | |
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345 | if(mass > electron_mass_c2) |
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346 | { |
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347 | G4double TAU = KineticEnergy/mass ; |
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348 | G4double c = mass*TAU*(TAU+2.)/(electron_mass_c2*(TAU+1.)) ; |
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349 | G4double w = c-2. ; |
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350 | G4double tau = 0.5*(w+sqrt(w*w+4.*c)) ; |
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351 | eKineticEnergy = electron_mass_c2*tau ; |
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352 | } |
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353 | |
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354 | G4double eTotalEnergy = eKineticEnergy + electron_mass_c2 ; |
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355 | G4double beta2 = eKineticEnergy*(eTotalEnergy+electron_mass_c2) |
---|
356 | /(eTotalEnergy*eTotalEnergy); |
---|
357 | G4double bg2 = eKineticEnergy*(eTotalEnergy+electron_mass_c2) |
---|
358 | /(electron_mass_c2*electron_mass_c2); |
---|
359 | |
---|
360 | G4double eps = epsfactor*bg2/Z23; |
---|
361 | |
---|
362 | if (eps<epsmin) sigma = 2.*eps*eps; |
---|
363 | else if(eps<epsmax) sigma = log(1.+2.*eps)-2.*eps/(1.+2.*eps); |
---|
364 | else sigma = log(2.*eps)-1.+1./eps; |
---|
365 | |
---|
366 | sigma *= ChargeSquare*AtomicNumber*AtomicNumber/(beta2*bg2); |
---|
367 | |
---|
368 | // interpolate in AtomicNumber and beta2 |
---|
369 | G4double c1,c2,cc1,cc2,corr; |
---|
370 | |
---|
371 | // get bin number in Z |
---|
372 | G4int iZ = 14; |
---|
373 | while ((iZ>=0)&&(Zdat[iZ]>=AtomicNumber)) iZ -= 1; |
---|
374 | if (iZ==14) iZ = 13; |
---|
375 | if (iZ==-1) iZ = 0 ; |
---|
376 | |
---|
377 | G4double Z1 = Zdat[iZ]; |
---|
378 | G4double Z2 = Zdat[iZ+1]; |
---|
379 | G4double ratZ = (AtomicNumber-Z1)*(AtomicNumber+Z1)/ |
---|
380 | ((Z2-Z1)*(Z2+Z1)); |
---|
381 | |
---|
382 | if(eKineticEnergy <= Tlim) |
---|
383 | { |
---|
384 | // get bin number in T (beta2) |
---|
385 | G4int iT = 21; |
---|
386 | while ((iT>=0)&&(Tdat[iT]>=eKineticEnergy)) iT -= 1; |
---|
387 | if(iT==21) iT = 20; |
---|
388 | if(iT==-1) iT = 0 ; |
---|
389 | |
---|
390 | // calculate betasquare values |
---|
391 | G4double T = Tdat[iT], E = T + electron_mass_c2; |
---|
392 | G4double b2small = T*(E+electron_mass_c2)/(E*E); |
---|
393 | |
---|
394 | T = Tdat[iT+1]; E = T + electron_mass_c2; |
---|
395 | G4double b2big = T*(E+electron_mass_c2)/(E*E); |
---|
396 | G4double ratb2 = (beta2-b2small)/(b2big-b2small); |
---|
397 | |
---|
398 | if (charge < 0.) |
---|
399 | { |
---|
400 | c1 = celectron[iZ][iT]; |
---|
401 | c2 = celectron[iZ+1][iT]; |
---|
402 | cc1 = c1+ratZ*(c2-c1); |
---|
403 | |
---|
404 | c1 = celectron[iZ][iT+1]; |
---|
405 | c2 = celectron[iZ+1][iT+1]; |
---|
406 | cc2 = c1+ratZ*(c2-c1); |
---|
407 | |
---|
408 | corr = cc1+ratb2*(cc2-cc1); |
---|
409 | |
---|
410 | sigma *= sigmafactor/corr; |
---|
411 | } |
---|
412 | else |
---|
413 | { |
---|
414 | c1 = cpositron[iZ][iT]; |
---|
415 | c2 = cpositron[iZ+1][iT]; |
---|
416 | cc1 = c1+ratZ*(c2-c1); |
---|
417 | |
---|
418 | c1 = cpositron[iZ][iT+1]; |
---|
419 | c2 = cpositron[iZ+1][iT+1]; |
---|
420 | cc2 = c1+ratZ*(c2-c1); |
---|
421 | |
---|
422 | corr = cc1+ratb2*(cc2-cc1); |
---|
423 | |
---|
424 | sigma *= sigmafactor/corr; |
---|
425 | } |
---|
426 | } |
---|
427 | else |
---|
428 | { |
---|
429 | c1 = bg2lim*sig0[iZ]*(1.+hecorr[iZ]*(beta2-beta2lim))/bg2; |
---|
430 | c2 = bg2lim*sig0[iZ+1]*(1.+hecorr[iZ+1]*(beta2-beta2lim))/bg2; |
---|
431 | if((AtomicNumber >= Z1) && (AtomicNumber <= Z2)) |
---|
432 | sigma = c1+ratZ*(c2-c1) ; |
---|
433 | else if(AtomicNumber < Z1) |
---|
434 | sigma = AtomicNumber*AtomicNumber*c1/(Z1*Z1); |
---|
435 | else if(AtomicNumber > Z2) |
---|
436 | sigma = AtomicNumber*AtomicNumber*c2/(Z2*Z2); |
---|
437 | } |
---|
438 | return sigma; |
---|
439 | |
---|
440 | } |
---|
441 | |
---|
442 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
---|
443 | |
---|
444 | G4double G4UrbanMscModel93::ComputeTruePathLengthLimit( |
---|
445 | const G4Track& track, |
---|
446 | G4PhysicsTable* theTable, |
---|
447 | G4double currentMinimalStep) |
---|
448 | { |
---|
449 | tPathLength = currentMinimalStep; |
---|
450 | G4StepPoint* sp = track.GetStep()->GetPreStepPoint(); |
---|
451 | G4StepStatus stepStatus = sp->GetStepStatus(); |
---|
452 | |
---|
453 | const G4DynamicParticle* dp = track.GetDynamicParticle(); |
---|
454 | |
---|
455 | if(stepStatus == fUndefined) { |
---|
456 | inside = false; |
---|
457 | insideskin = false; |
---|
458 | tlimit = geombig; |
---|
459 | SetParticle( dp->GetDefinition() ); |
---|
460 | } |
---|
461 | |
---|
462 | theLambdaTable = theTable; |
---|
463 | couple = track.GetMaterialCutsCouple(); |
---|
464 | currentMaterialIndex = couple->GetIndex(); |
---|
465 | currentKinEnergy = dp->GetKineticEnergy(); |
---|
466 | currentRange = |
---|
467 | theManager->GetRangeFromRestricteDEDX(particle,currentKinEnergy,couple); |
---|
468 | lambda0 = GetLambda(currentKinEnergy); |
---|
469 | |
---|
470 | // stop here if small range particle |
---|
471 | if(inside) { return tPathLength; } |
---|
472 | |
---|
473 | if(tPathLength > currentRange) { tPathLength = currentRange; } |
---|
474 | |
---|
475 | presafety = sp->GetSafety(); |
---|
476 | |
---|
477 | // G4cout << "G4Urban2::StepLimit tPathLength= " |
---|
478 | // <<tPathLength<<" safety= " << presafety |
---|
479 | // << " range= " <<currentRange<< " lambda= "<<lambda0 |
---|
480 | // << " Alg: " << steppingAlgorithm <<G4endl; |
---|
481 | |
---|
482 | // far from geometry boundary |
---|
483 | if(currentRange < presafety) |
---|
484 | { |
---|
485 | inside = true; |
---|
486 | return tPathLength; |
---|
487 | } |
---|
488 | |
---|
489 | // standard version |
---|
490 | // |
---|
491 | if (steppingAlgorithm == fUseDistanceToBoundary) |
---|
492 | { |
---|
493 | //compute geomlimit and presafety |
---|
494 | G4double geomlimit = ComputeGeomLimit(track, presafety, currentRange); |
---|
495 | |
---|
496 | // is it far from boundary ? |
---|
497 | if(currentRange < presafety) |
---|
498 | { |
---|
499 | inside = true; |
---|
500 | return tPathLength; |
---|
501 | } |
---|
502 | |
---|
503 | smallstep += 1.; |
---|
504 | insideskin = false; |
---|
505 | |
---|
506 | if((stepStatus == fGeomBoundary) || (stepStatus == fUndefined)) |
---|
507 | { |
---|
508 | rangeinit = currentRange; |
---|
509 | if(stepStatus == fUndefined) smallstep = 1.e10; |
---|
510 | else smallstep = 1.; |
---|
511 | |
---|
512 | //define stepmin here (it depends on lambda!) |
---|
513 | //rough estimation of lambda_elastic/lambda_transport |
---|
514 | G4double rat = currentKinEnergy/MeV ; |
---|
515 | rat = 1.e-3/(rat*(10.+rat)) ; |
---|
516 | //stepmin ~ lambda_elastic |
---|
517 | stepmin = rat*lambda0; |
---|
518 | skindepth = skin*stepmin; |
---|
519 | //define tlimitmin |
---|
520 | tlimitmin = 10.*stepmin; |
---|
521 | if(tlimitmin < tlimitminfix) tlimitmin = tlimitminfix; |
---|
522 | //G4cout << "rangeinit= " << rangeinit << " stepmin= " << stepmin |
---|
523 | // << " tlimitmin= " << tlimitmin << " geomlimit= " << geomlimit <<G4endl; |
---|
524 | // constraint from the geometry |
---|
525 | if((geomlimit < geombig) && (geomlimit > geommin)) |
---|
526 | { |
---|
527 | // geomlimit is a geometrical step length |
---|
528 | // transform it to true path length (estimation) |
---|
529 | if((1.-geomlimit/lambda0) > 0.) |
---|
530 | geomlimit = -lambda0*log(1.-geomlimit/lambda0)+tlimitmin ; |
---|
531 | |
---|
532 | if(stepStatus == fGeomBoundary) |
---|
533 | tgeom = geomlimit/facgeom; |
---|
534 | else |
---|
535 | tgeom = 2.*geomlimit/facgeom; |
---|
536 | } |
---|
537 | else |
---|
538 | tgeom = geombig; |
---|
539 | } |
---|
540 | |
---|
541 | |
---|
542 | //step limit |
---|
543 | tlimit = facrange*rangeinit; |
---|
544 | if(tlimit < facsafety*presafety) |
---|
545 | tlimit = facsafety*presafety; |
---|
546 | |
---|
547 | //lower limit for tlimit |
---|
548 | if(tlimit < tlimitmin) tlimit = tlimitmin; |
---|
549 | |
---|
550 | if(tlimit > tgeom) tlimit = tgeom; |
---|
551 | |
---|
552 | //G4cout << "tgeom= " << tgeom << " geomlimit= " << geomlimit |
---|
553 | // << " tlimit= " << tlimit << " presafety= " << presafety << G4endl; |
---|
554 | |
---|
555 | // shortcut |
---|
556 | if((tPathLength < tlimit) && (tPathLength < presafety) && |
---|
557 | (smallstep >= skin) && (tPathLength < geomlimit-0.999*skindepth)) |
---|
558 | return tPathLength; |
---|
559 | |
---|
560 | // step reduction near to boundary |
---|
561 | if(smallstep < skin) |
---|
562 | { |
---|
563 | tlimit = stepmin; |
---|
564 | insideskin = true; |
---|
565 | } |
---|
566 | else if(geomlimit < geombig) |
---|
567 | { |
---|
568 | if(geomlimit > skindepth) |
---|
569 | { |
---|
570 | if(tlimit > geomlimit-0.999*skindepth) |
---|
571 | tlimit = geomlimit-0.999*skindepth; |
---|
572 | } |
---|
573 | else |
---|
574 | { |
---|
575 | insideskin = true; |
---|
576 | if(tlimit > stepmin) tlimit = stepmin; |
---|
577 | } |
---|
578 | } |
---|
579 | |
---|
580 | if(tlimit < stepmin) tlimit = stepmin; |
---|
581 | |
---|
582 | // randomize 1st step or 1st 'normal' step in volume |
---|
583 | if((stepStatus == fUndefined) || |
---|
584 | ((smallstep == skin) && !insideskin)) |
---|
585 | { |
---|
586 | G4double temptlimit = tlimit; |
---|
587 | if(temptlimit > tlimitmin) |
---|
588 | { |
---|
589 | do { |
---|
590 | temptlimit = G4RandGauss::shoot(tlimit,0.3*tlimit); |
---|
591 | } while ((temptlimit < tlimitmin) || |
---|
592 | (temptlimit > 2.*tlimit-tlimitmin)); |
---|
593 | } |
---|
594 | else |
---|
595 | temptlimit = tlimitmin; |
---|
596 | if(tPathLength > temptlimit) tPathLength = temptlimit; |
---|
597 | } |
---|
598 | else |
---|
599 | { |
---|
600 | if(tPathLength > tlimit) tPathLength = tlimit ; |
---|
601 | } |
---|
602 | |
---|
603 | } |
---|
604 | // for 'normal' simulation with or without magnetic field |
---|
605 | // there no small step/single scattering at boundaries |
---|
606 | else if(steppingAlgorithm == fUseSafety) |
---|
607 | { |
---|
608 | // compute presafety again if presafety <= 0 and no boundary |
---|
609 | // i.e. when it is needed for optimization purposes |
---|
610 | if((stepStatus != fGeomBoundary) && (presafety < tlimitminfix)) |
---|
611 | presafety = ComputeSafety(sp->GetPosition(),tPathLength); |
---|
612 | |
---|
613 | // is far from boundary |
---|
614 | if(currentRange < presafety) |
---|
615 | { |
---|
616 | inside = true; |
---|
617 | return tPathLength; |
---|
618 | } |
---|
619 | |
---|
620 | if((stepStatus == fGeomBoundary) || (stepStatus == fUndefined)) |
---|
621 | { |
---|
622 | rangeinit = currentRange; |
---|
623 | fr = facrange; |
---|
624 | // 9.1 like stepping for e+/e- only (not for muons,hadrons) |
---|
625 | if(mass < masslimite) |
---|
626 | { |
---|
627 | if(lambda0 > currentRange) |
---|
628 | rangeinit = lambda0; |
---|
629 | if(lambda0 > lambdalimit) |
---|
630 | fr *= 0.75+0.25*lambda0/lambdalimit; |
---|
631 | } |
---|
632 | |
---|
633 | //lower limit for tlimit |
---|
634 | G4double rat = currentKinEnergy/MeV ; |
---|
635 | rat = 1.e-3/(rat*(10.+rat)) ; |
---|
636 | tlimitmin = 10.*lambda0*rat; |
---|
637 | if(tlimitmin < tlimitminfix) tlimitmin = tlimitminfix; |
---|
638 | } |
---|
639 | //step limit |
---|
640 | tlimit = fr*rangeinit; |
---|
641 | |
---|
642 | if(tlimit < facsafety*presafety) |
---|
643 | tlimit = facsafety*presafety; |
---|
644 | |
---|
645 | //lower limit for tlimit |
---|
646 | if(tlimit < tlimitmin) tlimit = tlimitmin; |
---|
647 | |
---|
648 | if(tPathLength > tlimit) tPathLength = tlimit; |
---|
649 | |
---|
650 | } |
---|
651 | |
---|
652 | // version similar to 7.1 (needed for some experiments) |
---|
653 | else |
---|
654 | { |
---|
655 | if (stepStatus == fGeomBoundary) |
---|
656 | { |
---|
657 | if (currentRange > lambda0) tlimit = facrange*currentRange; |
---|
658 | else tlimit = facrange*lambda0; |
---|
659 | |
---|
660 | if(tlimit < tlimitmin) tlimit = tlimitmin; |
---|
661 | if(tPathLength > tlimit) tPathLength = tlimit; |
---|
662 | } |
---|
663 | } |
---|
664 | //G4cout << "tPathLength= " << tPathLength |
---|
665 | // << " currentMinimalStep= " << currentMinimalStep << G4endl; |
---|
666 | return tPathLength ; |
---|
667 | } |
---|
668 | |
---|
669 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
---|
670 | |
---|
671 | G4double G4UrbanMscModel93::ComputeGeomPathLength(G4double) |
---|
672 | { |
---|
673 | lambdaeff = lambda0; |
---|
674 | par1 = -1. ; |
---|
675 | par2 = par3 = 0. ; |
---|
676 | |
---|
677 | // do the true -> geom transformation |
---|
678 | zPathLength = tPathLength; |
---|
679 | |
---|
680 | // z = t for very small tPathLength |
---|
681 | if(tPathLength < tlimitminfix) return zPathLength; |
---|
682 | |
---|
683 | // this correction needed to run MSC with eIoni and eBrem inactivated |
---|
684 | // and makes no harm for a normal run |
---|
685 | if(tPathLength > currentRange) |
---|
686 | tPathLength = currentRange ; |
---|
687 | |
---|
688 | G4double tau = tPathLength/lambda0 ; |
---|
689 | |
---|
690 | if ((tau <= tausmall) || insideskin) { |
---|
691 | zPathLength = tPathLength; |
---|
692 | if(zPathLength > lambda0) zPathLength = lambda0; |
---|
693 | return zPathLength; |
---|
694 | } |
---|
695 | |
---|
696 | G4double zmean = tPathLength; |
---|
697 | if (tPathLength < currentRange*dtrl) { |
---|
698 | if(tau < taulim) zmean = tPathLength*(1.-0.5*tau) ; |
---|
699 | else zmean = lambda0*(1.-exp(-tau)); |
---|
700 | } else if(currentKinEnergy < mass) { |
---|
701 | par1 = 1./currentRange ; |
---|
702 | par2 = 1./(par1*lambda0) ; |
---|
703 | par3 = 1.+par2 ; |
---|
704 | if(tPathLength < currentRange) |
---|
705 | zmean = (1.-exp(par3*log(1.-tPathLength/currentRange)))/(par1*par3) ; |
---|
706 | else |
---|
707 | zmean = 1./(par1*par3) ; |
---|
708 | } else { |
---|
709 | G4double T1 = theManager->GetEnergy(particle,currentRange-tPathLength,couple); |
---|
710 | G4double lambda1 = GetLambda(T1); |
---|
711 | |
---|
712 | par1 = (lambda0-lambda1)/(lambda0*tPathLength) ; |
---|
713 | par2 = 1./(par1*lambda0) ; |
---|
714 | par3 = 1.+par2 ; |
---|
715 | zmean = (1.-exp(par3*log(lambda1/lambda0)))/(par1*par3) ; |
---|
716 | } |
---|
717 | |
---|
718 | zPathLength = zmean ; |
---|
719 | |
---|
720 | // sample z |
---|
721 | if(samplez) |
---|
722 | { |
---|
723 | const G4double ztmax = 0.99 ; |
---|
724 | G4double zt = zmean/tPathLength ; |
---|
725 | |
---|
726 | if (tPathLength > stepmin && zt < ztmax) |
---|
727 | { |
---|
728 | G4double u,cz1; |
---|
729 | if(zt >= third) |
---|
730 | { |
---|
731 | G4double cz = 0.5*(3.*zt-1.)/(1.-zt) ; |
---|
732 | cz1 = 1.+cz ; |
---|
733 | G4double u0 = cz/cz1 ; |
---|
734 | G4double grej ; |
---|
735 | do { |
---|
736 | u = exp(log(G4UniformRand())/cz1) ; |
---|
737 | grej = exp(cz*log(u/u0))*(1.-u)/(1.-u0) ; |
---|
738 | } while (grej < G4UniformRand()) ; |
---|
739 | } |
---|
740 | else |
---|
741 | { |
---|
742 | cz1 = 1./zt-1.; |
---|
743 | u = 1.-exp(log(G4UniformRand())/cz1) ; |
---|
744 | } |
---|
745 | zPathLength = tPathLength*u ; |
---|
746 | } |
---|
747 | } |
---|
748 | |
---|
749 | if(zPathLength > lambda0) zPathLength = lambda0; |
---|
750 | //G4cout << "zPathLength= " << zPathLength << " lambda1= " << lambda0 << G4endl; |
---|
751 | return zPathLength; |
---|
752 | } |
---|
753 | |
---|
754 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
---|
755 | |
---|
756 | G4double G4UrbanMscModel93::ComputeTrueStepLength(G4double geomStepLength) |
---|
757 | { |
---|
758 | // step defined other than transportation |
---|
759 | if(geomStepLength == zPathLength && tPathLength <= currentRange) |
---|
760 | return tPathLength; |
---|
761 | |
---|
762 | // t = z for very small step |
---|
763 | zPathLength = geomStepLength; |
---|
764 | tPathLength = geomStepLength; |
---|
765 | if(geomStepLength < tlimitminfix) return tPathLength; |
---|
766 | |
---|
767 | // recalculation |
---|
768 | if((geomStepLength > lambda0*tausmall) && !insideskin) |
---|
769 | { |
---|
770 | if(par1 < 0.) |
---|
771 | tPathLength = -lambda0*log(1.-geomStepLength/lambda0) ; |
---|
772 | else |
---|
773 | { |
---|
774 | if(par1*par3*geomStepLength < 1.) |
---|
775 | tPathLength = (1.-exp(log(1.-par1*par3*geomStepLength)/par3))/par1 ; |
---|
776 | else |
---|
777 | tPathLength = currentRange; |
---|
778 | } |
---|
779 | } |
---|
780 | if(tPathLength < geomStepLength) tPathLength = geomStepLength; |
---|
781 | //G4cout << "tPathLength= " << tPathLength << " step= " << geomStepLength << G4endl; |
---|
782 | |
---|
783 | return tPathLength; |
---|
784 | } |
---|
785 | |
---|
786 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
---|
787 | |
---|
788 | G4double G4UrbanMscModel93::ComputeTheta0(G4double trueStepLength, |
---|
789 | G4double KineticEnergy) |
---|
790 | { |
---|
791 | // for all particles take the width of the central part |
---|
792 | // from a parametrization similar to the Highland formula |
---|
793 | // ( Highland formula: Particle Physics Booklet, July 2002, eq. 26.10) |
---|
794 | const G4double c_highland = 13.6*MeV ; |
---|
795 | G4double betacp = sqrt(currentKinEnergy*(currentKinEnergy+2.*mass)* |
---|
796 | KineticEnergy*(KineticEnergy+2.*mass)/ |
---|
797 | ((currentKinEnergy+mass)*(KineticEnergy+mass))); |
---|
798 | y = trueStepLength/currentRadLength; |
---|
799 | G4double theta0 = c_highland*std::abs(charge)*sqrt(y)/betacp; |
---|
800 | y = log(y); |
---|
801 | // correction factor from e- scattering data |
---|
802 | G4double corr = coeffth1+coeffth2*y; |
---|
803 | |
---|
804 | theta0 *= corr ; |
---|
805 | |
---|
806 | return theta0; |
---|
807 | } |
---|
808 | |
---|
809 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
---|
810 | |
---|
811 | void G4UrbanMscModel93::SampleScattering(const G4DynamicParticle* dynParticle, |
---|
812 | G4double safety) |
---|
813 | { |
---|
814 | G4double kineticEnergy = dynParticle->GetKineticEnergy(); |
---|
815 | |
---|
816 | if((kineticEnergy <= 0.0) || (tPathLength <= tlimitminfix) || |
---|
817 | (tPathLength/tausmall < lambda0)) return; |
---|
818 | |
---|
819 | G4double cth = SampleCosineTheta(tPathLength,kineticEnergy); |
---|
820 | |
---|
821 | // protection against 'bad' cth values |
---|
822 | if(std::abs(cth) > 1.) return; |
---|
823 | |
---|
824 | G4double sth = sqrt((1.0 - cth)*(1.0 + cth)); |
---|
825 | G4double phi = twopi*G4UniformRand(); |
---|
826 | G4double dirx = sth*cos(phi); |
---|
827 | G4double diry = sth*sin(phi); |
---|
828 | |
---|
829 | G4ThreeVector oldDirection = dynParticle->GetMomentumDirection(); |
---|
830 | G4ThreeVector newDirection(dirx,diry,cth); |
---|
831 | newDirection.rotateUz(oldDirection); |
---|
832 | fParticleChange->ProposeMomentumDirection(newDirection); |
---|
833 | |
---|
834 | if (latDisplasment && safety > tlimitminfix) { |
---|
835 | |
---|
836 | G4double r = SampleDisplacement(); |
---|
837 | /* |
---|
838 | G4cout << "G4UrbanMscModel93::SampleSecondaries: e(MeV)= " << kineticEnergy |
---|
839 | << " sinTheta= " << sth << " r(mm)= " << r |
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840 | << " trueStep(mm)= " << tPathLength |
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841 | << " geomStep(mm)= " << zPathLength |
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842 | << G4endl; |
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843 | */ |
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844 | if(r > 0.) |
---|
845 | { |
---|
846 | G4double latcorr = LatCorrelation(); |
---|
847 | if(latcorr > r) latcorr = r; |
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848 | |
---|
849 | // sample direction of lateral displacement |
---|
850 | // compute it from the lateral correlation |
---|
851 | G4double Phi = 0.; |
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852 | if(std::abs(r*sth) < latcorr) |
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853 | Phi = twopi*G4UniformRand(); |
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854 | else |
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855 | { |
---|
856 | G4double psi = std::acos(latcorr/(r*sth)); |
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857 | if(G4UniformRand() < 0.5) |
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858 | Phi = phi+psi; |
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859 | else |
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860 | Phi = phi-psi; |
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861 | } |
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862 | |
---|
863 | dirx = std::cos(Phi); |
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864 | diry = std::sin(Phi); |
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865 | |
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866 | G4ThreeVector latDirection(dirx,diry,0.0); |
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867 | latDirection.rotateUz(oldDirection); |
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868 | |
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869 | ComputeDisplacement(fParticleChange, latDirection, r, safety); |
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870 | } |
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871 | } |
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872 | } |
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873 | |
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874 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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875 | |
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876 | G4double G4UrbanMscModel93::SampleCosineTheta(G4double trueStepLength, |
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877 | G4double KineticEnergy) |
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878 | { |
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879 | G4double cth = 1. ; |
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880 | G4double tau = trueStepLength/lambda0 ; |
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881 | |
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882 | Zeff = couple->GetMaterial()->GetTotNbOfElectPerVolume()/ |
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883 | couple->GetMaterial()->GetTotNbOfAtomsPerVolume() ; |
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884 | |
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885 | if(Zold != Zeff) |
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886 | UpdateCache(); |
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887 | |
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888 | if(insideskin) |
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889 | { |
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890 | //no scattering, single or plural scattering |
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891 | G4double mean = trueStepLength/stepmin ; |
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892 | |
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893 | G4int n = G4Poisson(mean); |
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894 | if(n > 0) |
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895 | { |
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896 | //screening (Moliere-Bethe) |
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897 | G4double mom2 = KineticEnergy*(2.*mass+KineticEnergy); |
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898 | G4double beta2 = mom2/((KineticEnergy+mass)*(KineticEnergy+mass)); |
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899 | G4double ascr = scr1/mom2; |
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900 | ascr *= 1.13+scr2/beta2; |
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901 | G4double ascr1 = 1.+2.*ascr; |
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902 | G4double bp1=ascr1+1.; |
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903 | G4double bm1=ascr1-1.; |
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904 | |
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905 | // single scattering from screened Rutherford x-section |
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906 | G4double ct,st,phi; |
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907 | G4double sx=0.,sy=0.,sz=0.; |
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908 | for(G4int i=1; i<=n; i++) |
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909 | { |
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910 | ct = ascr1-bp1*bm1/(2.*G4UniformRand()+bm1); |
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911 | if(ct < -1.) ct = -1.; |
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912 | if(ct > 1.) ct = 1.; |
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913 | st = sqrt(1.-ct*ct); |
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914 | phi = twopi*G4UniformRand(); |
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915 | sx += st*cos(phi); |
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916 | sy += st*sin(phi); |
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917 | sz += ct; |
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918 | } |
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919 | cth = sz/sqrt(sx*sx+sy*sy+sz*sz); |
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920 | } |
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921 | } |
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922 | else |
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923 | { |
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924 | if(trueStepLength >= currentRange*dtrl) |
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925 | { |
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926 | if(par1*trueStepLength < 1.) |
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927 | tau = -par2*log(1.-par1*trueStepLength) ; |
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928 | // for the case if ioni/brems are inactivated |
---|
929 | // see the corresponding condition in ComputeGeomPathLength |
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930 | else if(1.-KineticEnergy/currentKinEnergy > taulim) |
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931 | tau = taubig ; |
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932 | } |
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933 | currentTau = tau ; |
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934 | lambdaeff = trueStepLength/currentTau; |
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935 | currentRadLength = couple->GetMaterial()->GetRadlen(); |
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936 | |
---|
937 | if (tau >= taubig) cth = -1.+2.*G4UniformRand(); |
---|
938 | else if (tau >= tausmall) |
---|
939 | { |
---|
940 | G4double xsi = 3.; |
---|
941 | G4double x0 = 1.; |
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942 | G4double a = 1., ea = 0., eaa = 1.; |
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943 | G4double b=2.,b1=3.,bx=1.,eb1=3.,ebx=1.; |
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944 | G4double prob = 1. , qprob = 1. ; |
---|
945 | G4double xmean1 = 1., xmean2 = 0.; |
---|
946 | G4double xmeanth = exp(-tau); |
---|
947 | G4double x2meanth = (1.+2.*exp(-2.5*tau))/3.; |
---|
948 | |
---|
949 | G4double relloss = 1.-KineticEnergy/currentKinEnergy; |
---|
950 | if(relloss > rellossmax) |
---|
951 | return SimpleScattering(xmeanth,x2meanth); |
---|
952 | |
---|
953 | G4double theta0 = ComputeTheta0(trueStepLength,KineticEnergy); |
---|
954 | |
---|
955 | // protection for very small angles |
---|
956 | if(theta0 < tausmall) return cth; |
---|
957 | |
---|
958 | if(theta0 > theta0max) |
---|
959 | return SimpleScattering(xmeanth,x2meanth); |
---|
960 | G4double sth = sin(0.5*theta0); |
---|
961 | a = 0.25/(sth*sth); |
---|
962 | |
---|
963 | ea = exp(-xsi); |
---|
964 | eaa = 1.-ea ; |
---|
965 | xmean1 = 1.-(1.-(1.+xsi)*ea)/(a*eaa); |
---|
966 | x0 = 1.-xsi/a; |
---|
967 | |
---|
968 | if(xmean1 <= 0.999*xmeanth) |
---|
969 | return SimpleScattering(xmeanth,x2meanth); |
---|
970 | |
---|
971 | // from e- and muon scattering data |
---|
972 | G4double c = coeffc1+coeffc2*y; ; |
---|
973 | |
---|
974 | if(abs(c-3.) < 0.001) c = 3.001; |
---|
975 | if(abs(c-2.) < 0.001) c = 2.001; |
---|
976 | if(abs(c-1.) < 0.001) c = 1.001; |
---|
977 | |
---|
978 | G4double c1 = c-1.; |
---|
979 | |
---|
980 | //from continuity of derivatives |
---|
981 | b = 1.+(c-xsi)/a; |
---|
982 | |
---|
983 | b1 = b+1.; |
---|
984 | bx = c/a; |
---|
985 | eb1 = exp(c1*log(b1)); |
---|
986 | ebx = exp(c1*log(bx)); |
---|
987 | |
---|
988 | xmean2 = (x0*eb1+ebx-(eb1*bx-b1*ebx)/(c-2.))/(eb1-ebx); |
---|
989 | |
---|
990 | G4double f1x0 = a*ea/eaa; |
---|
991 | G4double f2x0 = c1*eb1/(bx*(eb1-ebx)); |
---|
992 | prob = f2x0/(f1x0+f2x0); |
---|
993 | |
---|
994 | qprob = xmeanth/(prob*xmean1+(1.-prob)*xmean2); |
---|
995 | |
---|
996 | // sampling of costheta |
---|
997 | if(G4UniformRand() < qprob) |
---|
998 | { |
---|
999 | if(G4UniformRand() < prob) |
---|
1000 | cth = 1.+log(ea+G4UniformRand()*eaa)/a ; |
---|
1001 | else |
---|
1002 | cth = b-b1*bx/exp(log(ebx+(eb1-ebx)*G4UniformRand())/c1) ; |
---|
1003 | } |
---|
1004 | else |
---|
1005 | cth = -1.+2.*G4UniformRand(); |
---|
1006 | } |
---|
1007 | } |
---|
1008 | return cth ; |
---|
1009 | } |
---|
1010 | |
---|
1011 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
---|
1012 | |
---|
1013 | G4double G4UrbanMscModel93::SimpleScattering(G4double xmeanth,G4double x2meanth) |
---|
1014 | { |
---|
1015 | // 'large angle scattering' |
---|
1016 | // 2 model functions with correct xmean and x2mean |
---|
1017 | G4double a = (2.*xmeanth+9.*x2meanth-3.)/(2.*xmeanth-3.*x2meanth+1.); |
---|
1018 | G4double prob = (a+2.)*xmeanth/a; |
---|
1019 | |
---|
1020 | // sampling |
---|
1021 | G4double cth = 1.; |
---|
1022 | if(G4UniformRand() < prob) |
---|
1023 | cth = -1.+2.*exp(log(G4UniformRand())/(a+1.)); |
---|
1024 | else |
---|
1025 | cth = -1.+2.*G4UniformRand(); |
---|
1026 | return cth; |
---|
1027 | } |
---|
1028 | |
---|
1029 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
---|
1030 | |
---|
1031 | G4double G4UrbanMscModel93::SampleDisplacement() |
---|
1032 | { |
---|
1033 | // compute rmean = sqrt(<r**2>) from theory |
---|
1034 | const G4double kappa = 2.5; |
---|
1035 | const G4double kappapl1 = kappa+1.; |
---|
1036 | const G4double kappami1 = kappa-1.; |
---|
1037 | // Compute rmean = sqrt(<r**2>) from theory |
---|
1038 | G4double rmean = 0.0; |
---|
1039 | if ((currentTau >= tausmall) && !insideskin) { |
---|
1040 | if (currentTau < taulim) { |
---|
1041 | rmean = kappa*currentTau*currentTau*currentTau* |
---|
1042 | (1.-kappapl1*currentTau*0.25)/6. ; |
---|
1043 | |
---|
1044 | } else { |
---|
1045 | G4double etau = 0.0; |
---|
1046 | if (currentTau<taubig) etau = exp(-currentTau); |
---|
1047 | rmean = -kappa*currentTau; |
---|
1048 | rmean = -exp(rmean)/(kappa*kappami1); |
---|
1049 | rmean += currentTau-kappapl1/kappa+kappa*etau/kappami1; |
---|
1050 | } |
---|
1051 | if (rmean>0.) rmean = 2.*lambdaeff*sqrt(rmean/3.0); |
---|
1052 | else rmean = 0.; |
---|
1053 | } |
---|
1054 | |
---|
1055 | if(rmean == 0.) return rmean; |
---|
1056 | |
---|
1057 | // protection against z > t ........................... |
---|
1058 | G4double rmax = (tPathLength-zPathLength)*(tPathLength+zPathLength); |
---|
1059 | if(rmax <= 0.) |
---|
1060 | rmax = 0.; |
---|
1061 | else |
---|
1062 | rmax = sqrt(rmax); |
---|
1063 | |
---|
1064 | if(rmean >= rmax) return rmax; |
---|
1065 | |
---|
1066 | return rmean; |
---|
1067 | // VI comment out for the time being |
---|
1068 | /* |
---|
1069 | //sample r (Gaussian distribution with a mean of rmean ) |
---|
1070 | G4double r = 0.; |
---|
1071 | G4double sigma = min(rmean,rmax-rmean); |
---|
1072 | sigma /= 3.; |
---|
1073 | G4double rlow = rmean-3.*sigma; |
---|
1074 | G4double rhigh = rmean+3.*sigma; |
---|
1075 | do { |
---|
1076 | r = G4RandGauss::shoot(rmean,sigma); |
---|
1077 | } while ((r < rlow) || (r > rhigh)); |
---|
1078 | |
---|
1079 | return r; |
---|
1080 | */ |
---|
1081 | } |
---|
1082 | |
---|
1083 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
---|
1084 | |
---|
1085 | G4double G4UrbanMscModel93::LatCorrelation() |
---|
1086 | { |
---|
1087 | const G4double kappa = 2.5; |
---|
1088 | const G4double kappami1 = kappa-1.; |
---|
1089 | |
---|
1090 | G4double latcorr = 0.; |
---|
1091 | if((currentTau >= tausmall) && !insideskin) |
---|
1092 | { |
---|
1093 | if(currentTau < taulim) |
---|
1094 | latcorr = lambdaeff*kappa*currentTau*currentTau* |
---|
1095 | (1.-(kappa+1.)*currentTau/3.)/3.; |
---|
1096 | else |
---|
1097 | { |
---|
1098 | G4double etau = 0.; |
---|
1099 | if(currentTau < taubig) etau = exp(-currentTau); |
---|
1100 | latcorr = -kappa*currentTau; |
---|
1101 | latcorr = exp(latcorr)/kappami1; |
---|
1102 | latcorr += 1.-kappa*etau/kappami1 ; |
---|
1103 | latcorr *= 2.*lambdaeff/3. ; |
---|
1104 | } |
---|
1105 | } |
---|
1106 | |
---|
1107 | return latcorr; |
---|
1108 | } |
---|
1109 | |
---|
1110 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
---|