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24 | // ******************************************************************** |
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25 | // |
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26 | // $Id: G4ionEffectiveCharge.cc,v 1.17.2.1 2008/04/22 15:28:13 vnivanch Exp $ |
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27 | // GEANT4 tag $Name: geant4-09-01-patch-02 $ |
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28 | // |
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29 | // ------------------------------------------------------------------- |
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30 | // |
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31 | // GEANT4 Class 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 "G4ParticleDefinition.hh" |
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57 | #include "G4Material.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 = 10.0*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 = 0.1; |
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69 | } |
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70 | |
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71 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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72 | |
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73 | G4ionEffectiveCharge::~G4ionEffectiveCharge() |
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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 | G4double G4ionEffectiveCharge::EffectiveCharge(const G4ParticleDefinition* p, |
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79 | const G4Material* material, |
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80 | G4double kineticEnergy) |
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81 | { |
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82 | G4double mass = p->GetPDGMass(); |
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83 | G4double charge = p->GetPDGCharge(); |
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84 | G4double Zi = charge/eplus; |
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85 | |
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86 | chargeCorrection = 1.0; |
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87 | |
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88 | // The aproximation of ion effective charge from: |
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89 | // J.F.Ziegler, J.P. Biersack, U. Littmark |
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90 | // The Stopping and Range of Ions in Matter, |
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91 | // Vol.1, Pergamon Press, 1985 |
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92 | // Fast ions or hadrons |
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93 | G4double reducedEnergy = kineticEnergy * proton_mass_c2/mass ; |
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94 | if( reducedEnergy > Zi*energyHighLimit || Zi < 1.5 || !material) return charge; |
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95 | |
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96 | static G4double c[6] = {0.2865, 0.1266, -0.001429, |
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97 | 0.02402,-0.01135, 0.001475} ; |
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98 | |
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99 | G4double z = material->GetIonisation()->GetZeffective(); |
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100 | reducedEnergy = std::max(reducedEnergy,energyLowLimit); |
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101 | G4double q; |
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102 | |
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103 | // Helium ion case |
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104 | if( Zi < 2.5 ) { |
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105 | |
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106 | G4double Q = std::max(0.0,std::log(reducedEnergy*massFactor)); |
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107 | G4double x = c[0]; |
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108 | G4double y = 1.0; |
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109 | for (G4int i=1; i<6; i++) { |
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110 | y *= Q; |
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111 | x += y * c[i] ; |
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112 | } |
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113 | G4double ex; |
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114 | if(x < 0.2) ex = x * (1 - 0.5*x); |
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115 | else ex = 1. - std::exp(-x); |
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116 | |
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117 | G4double tq = 7.6 - Q; |
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118 | G4double tq2= tq*tq; |
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119 | G4double tt = ( 0.007 + 0.00005 * z ); |
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120 | if(tq2 < 0.2) tt *= (1.0 - tq2 + 0.5*tq2*tq2); |
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121 | else tt *= std::exp(-tq2); |
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122 | q = (1.0 + tt) * std::sqrt(ex); |
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123 | |
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124 | // Heavy ion case |
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125 | } else { |
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126 | |
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127 | G4double z23 = std::pow(z, 0.666666); |
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128 | G4double zi13 = std::pow(Zi, 0.333333); |
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129 | G4double zi23 = zi13*zi13; |
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130 | G4double e = std::max(reducedEnergy,energyBohr/z23); |
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131 | |
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132 | // v1 is ion velocity in vF unit |
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133 | G4double eF = material->GetIonisation()->GetFermiEnergy(); |
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134 | G4double v1sq = e/eF; |
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135 | G4double vFsq = eF/energyBohr; |
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136 | G4double vF = std::sqrt(vFsq); |
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137 | |
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138 | G4double y ; |
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139 | |
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140 | // Faster than Fermi velocity |
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141 | if ( v1sq > 1.0 ) { |
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142 | y = vF * std::sqrt(v1sq) * ( 1.0 + 0.2/v1sq ) / zi23 ; |
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143 | |
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144 | // Slower than Fermi velocity |
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145 | } else { |
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146 | y = 0.692308 * vF * (1.0 + 0.666666*v1sq + v1sq*v1sq/15.0) / zi23 ; |
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147 | } |
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148 | |
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149 | G4double y3 = std::pow(y, 0.3) ; |
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150 | // G4cout << "y= " << y << " y3= " << y3 << " v1= " << v1 << " vF= " << vF << G4endl; |
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151 | q = 1.0 - std::exp( 0.803*y3 - 1.3167*y3*y3 - 0.38157*y - 0.008983*y*y ) ; |
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152 | |
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153 | // q = 1.0 - std::exp(-0.95*std::sqrt(reducedEnergy/energyBohr)/zi23); |
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154 | |
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155 | G4double qmin = minCharge/Zi; |
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156 | |
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157 | if(q < qmin) q = qmin; |
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158 | |
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159 | G4double tq = 7.6 - std::log(reducedEnergy/keV); |
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160 | G4double tq2= tq*tq; |
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161 | G4double sq = ( 0.18 + 0.0015 * z ) / (Zi*Zi); |
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162 | if(tq2 < 0.2) sq *= (1.0 - tq2 + 0.5*tq2*tq2); |
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163 | else sq *= std::exp(-tq2); |
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164 | sq += 1.0; |
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165 | // G4cout << "sq= " << sq << G4endl; |
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166 | |
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167 | // Screen length according to |
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168 | // J.F.Ziegler and J.M.Manoyan, The stopping of ions in compaunds, |
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169 | // Nucl. Inst. & Meth. in Phys. Res. B35 (1988) 215-228. |
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170 | |
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171 | G4double lambda = 10.0 * vF / (zi13 * (6.0 + q)); |
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172 | if(q < 0.2) lambda *= (1.0 - 0.666666*q - q*q/9.0); |
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173 | else lambda *= std::pow(1.0-q, 0.666666); |
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174 | |
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175 | G4double lambda2 = lambda*lambda; |
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176 | |
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177 | G4double xx = (0.5/q - 0.5)/vFsq; |
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178 | if(lambda2 < 0.2) xx *= lambda2*(1.0 - 0.5*lambda2); |
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179 | else xx *= std::log(1.0 + lambda2); |
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180 | |
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181 | chargeCorrection = sq * (1.0 + xx); |
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182 | } |
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183 | // G4cout << "G4ionEffectiveCharge: charge= " << charge << " q= " << q |
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184 | // << " chargeCor= " << chargeCorrection |
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185 | // << " e(MeV)= " << kineticEnergy/MeV << G4endl; |
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186 | return q*charge; |
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187 | } |
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188 | |
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189 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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190 | |
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191 | |
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