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24 | // ******************************************************************** |
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25 | // |
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26 | // $Id: G4ionEffectiveCharge.cc,v 1.25 2009/10/29 16:57:39 vnivanch Exp $ |
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27 | // GEANT4 tag $Name: geant4-09-04-beta-01 $ |
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28 | // |
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29 | // ------------------------------------------------------------------- |
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30 | // |
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31 | // GEANT4 Class file |
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32 | // |
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33 | // |
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34 | // File name: G4ionEffectiveCharge |
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35 | // |
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36 | // Author: Vladimir Ivanchenko |
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37 | // |
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38 | // Creation date: 07.05.2002 |
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39 | // |
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40 | // Modifications: |
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41 | // 12.09.2004 Set low energy limit to 1 keV (V.Ivanchenko) |
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42 | // 25.01.2005 Add protection - min Charge 0.1 eplus (V.Ivanchenko) |
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43 | // 28.04.2006 Set upper energy limit to 50 MeV (V.Ivanchenko) |
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44 | // 23.05.2006 Set upper energy limit to Z*10 MeV (V.Ivanchenko) |
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45 | // 15.08.2006 Add protection for not defined material (V.Ivanchenko) |
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46 | // 27-09-2007 Use Fermi energy from material, optimazed formulas (V.Ivanchenko) |
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47 | // |
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48 | |
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49 | // ------------------------------------------------------------------- |
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50 | // |
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51 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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52 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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53 | |
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54 | #include "G4ionEffectiveCharge.hh" |
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55 | #include "G4UnitsTable.hh" |
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56 | #include "G4Material.hh" |
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57 | #include "G4NistManager.hh" |
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58 | |
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59 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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60 | |
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61 | G4ionEffectiveCharge::G4ionEffectiveCharge() |
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62 | { |
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63 | chargeCorrection = 1.0; |
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64 | energyHighLimit = 20.0*MeV; |
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65 | energyLowLimit = 1.0*keV; |
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66 | energyBohr = 25.*keV; |
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67 | massFactor = amu_c2/(proton_mass_c2*keV); |
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68 | minCharge = 1.0; |
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69 | lastPart = 0; |
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70 | lastMat = 0; |
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71 | lastKinEnergy = 0.0; |
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72 | effCharge = eplus; |
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73 | nist = G4NistManager::Instance(); |
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74 | } |
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75 | |
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76 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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77 | |
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78 | G4ionEffectiveCharge::~G4ionEffectiveCharge() |
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79 | {} |
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80 | |
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81 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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82 | |
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83 | G4double G4ionEffectiveCharge::EffectiveCharge(const G4ParticleDefinition* p, |
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84 | const G4Material* material, |
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85 | G4double kineticEnergy) |
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86 | { |
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87 | if(p == lastPart && material == lastMat && kineticEnergy == lastKinEnergy) |
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88 | return effCharge; |
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89 | |
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90 | lastPart = p; |
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91 | lastMat = material; |
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92 | lastKinEnergy = kineticEnergy; |
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93 | |
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94 | G4double mass = p->GetPDGMass(); |
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95 | G4double charge = p->GetPDGCharge(); |
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96 | G4double Zi = charge/eplus; |
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97 | |
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98 | chargeCorrection = 1.0; |
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99 | effCharge = charge; |
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100 | |
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101 | // The aproximation of ion effective charge from: |
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102 | // J.F.Ziegler, J.P. Biersack, U. Littmark |
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103 | // The Stopping and Range of Ions in Matter, |
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104 | // Vol.1, Pergamon Press, 1985 |
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105 | // Fast ions or hadrons |
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106 | G4double reducedEnergy = kineticEnergy * proton_mass_c2/mass ; |
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107 | |
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108 | //G4cout << "e= " << reducedEnergy << " Zi= " << Zi << " " << material->GetName() << G4endl; |
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109 | |
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110 | if( reducedEnergy > Zi*energyHighLimit || Zi < 1.5 || !material) return charge; |
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111 | |
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112 | G4double z = material->GetIonisation()->GetZeffective(); |
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113 | reducedEnergy = std::max(reducedEnergy,energyLowLimit); |
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114 | |
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115 | // Helium ion case |
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116 | if( Zi < 2.5 ) { |
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117 | |
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118 | static G4double c[6] = {0.2865, 0.1266, -0.001429, |
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119 | 0.02402,-0.01135, 0.001475} ; |
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120 | |
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121 | G4double Q = std::max(0.0,std::log(reducedEnergy*massFactor)); |
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122 | G4double x = c[0]; |
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123 | G4double y = 1.0; |
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124 | for (G4int i=1; i<6; i++) { |
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125 | y *= Q; |
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126 | x += y * c[i] ; |
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127 | } |
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128 | G4double ex; |
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129 | if(x < 0.2) ex = x * (1 - 0.5*x); |
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130 | else ex = 1. - std::exp(-x); |
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131 | |
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132 | G4double tq = 7.6 - Q; |
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133 | G4double tq2= tq*tq; |
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134 | G4double tt = ( 0.007 + 0.00005 * z ); |
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135 | if(tq2 < 0.2) tt *= (1.0 - tq2 + 0.5*tq2*tq2); |
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136 | else tt *= std::exp(-tq2); |
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137 | |
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138 | effCharge = charge*(1.0 + tt) * std::sqrt(ex); |
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139 | |
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140 | // Heavy ion case |
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141 | } else { |
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142 | |
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143 | G4double y; |
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144 | // = nist->GetZ13(z); |
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145 | //G4double z23 = y*y; |
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146 | G4double zi13 = nist->GetZ13(Zi); |
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147 | G4double zi23 = zi13*zi13; |
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148 | // G4double e = std::max(reducedEnergy,energyBohr/z23); |
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149 | //G4double e = reducedEnergy; |
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150 | |
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151 | // v1 is ion velocity in vF unit |
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152 | G4double eF = material->GetIonisation()->GetFermiEnergy(); |
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153 | G4double v1sq = reducedEnergy/eF; |
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154 | G4double vFsq = eF/energyBohr; |
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155 | G4double vF = std::sqrt(eF/energyBohr); |
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156 | |
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157 | // Faster than Fermi velocity |
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158 | if ( v1sq > 1.0 ) { |
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159 | y = vF * std::sqrt(v1sq) * ( 1.0 + 0.2/v1sq ) / zi23 ; |
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160 | |
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161 | // Slower than Fermi velocity |
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162 | } else { |
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163 | y = 0.692308 * vF * (1.0 + 0.666666*v1sq + v1sq*v1sq/15.0) / zi23 ; |
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164 | } |
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165 | |
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166 | G4double q; |
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167 | G4double y3 = std::pow(y, 0.3) ; |
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168 | // G4cout<<"y= "<<y<<" y3= "<<y3<<" v1= "<<v1<<" vF= "<<vF<<G4endl; |
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169 | q = 1.0 - std::exp( 0.803*y3 - 1.3167*y3*y3 - 0.38157*y - 0.008983*y*y ) ; |
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170 | |
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171 | //y *= 0.77; |
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172 | //y *= (0.75 + 0.52/Zi); |
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173 | |
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174 | //if( y < 0.2 ) q = y*(1.0 - 0.5*y); |
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175 | //else q = 1.0 - std::exp(-y); |
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176 | |
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177 | G4double qmin = minCharge/Zi; |
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178 | if(q < qmin) q = qmin; |
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179 | |
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180 | effCharge = q*charge; |
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181 | |
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182 | /* |
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183 | G4double x1 = 1.0*effCharge*(1.0 - 0.132*std::log(y))/(y*std::sqrt(z)); |
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184 | G4double x2 = 0.1*effCharge*effCharge*energyBohr/reducedEnergy; |
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185 | |
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186 | chargeCorrection = 1.0 + x1 - x2; |
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187 | |
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188 | G4cout << "x1= "<<x1<<" x2= "<< x2<<" corr= "<<chargeCorrection<<G4endl; |
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189 | */ |
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190 | |
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191 | G4double tq = 7.6 - std::log(reducedEnergy/keV); |
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192 | G4double tq2= tq*tq; |
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193 | G4double sq = ( 0.18 + 0.0015 * z ) / (Zi*Zi); |
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194 | if(tq2 < 0.2) sq *= (1.0 - tq2 + 0.5*tq2*tq2); |
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195 | else sq *= std::exp(-tq2); |
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196 | sq += 1.0; |
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197 | // G4cout << "sq= " << sq << G4endl; |
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198 | |
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199 | // Screen length according to |
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200 | // J.F.Ziegler and J.M.Manoyan, The stopping of ions in compaunds, |
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201 | // Nucl. Inst. & Meth. in Phys. Res. B35 (1988) 215-228. |
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202 | |
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203 | G4double lambda = 10.0 * vF / (zi13 * (6.0 + q)); |
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204 | if(q < 0.2) lambda *= (1.0 - 0.66666667*q - q*q/9.0); |
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205 | else lambda *= std::pow(1.0-q, 0.666666); |
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206 | |
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207 | G4double lambda2 = lambda*lambda; |
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208 | |
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209 | G4double xx = (0.5/q - 0.5)/vFsq; |
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210 | if(lambda2 < 0.2) xx *= lambda2*(1.0 - 0.5*lambda2); |
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211 | else xx *= std::log(1.0 + lambda2); |
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212 | |
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213 | chargeCorrection = sq * (1.0 + xx); |
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214 | |
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215 | } |
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216 | // G4cout << "G4ionEffectiveCharge: charge= " << charge << " q= " << q |
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217 | // << " chargeCor= " << chargeCorrection |
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218 | // << " e(MeV)= " << kineticEnergy/MeV << G4endl; |
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219 | return effCharge; |
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220 | } |
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221 | |
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222 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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223 | |
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224 | |
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