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24 | // ******************************************************************** |
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25 | // |
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26 | // $Id: G4PreCompoundTransitions.cc,v 1.20 2009/02/10 16:01:37 vnivanch Exp $ |
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27 | // GEANT4 tag $Name: geant4-09-02-ref-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: G4PreCompoundIon |
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35 | // |
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36 | // Author: V.Lara |
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37 | // |
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38 | // Modified: |
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39 | // 16.02.2008 J. M. Quesada fixed bugs |
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40 | // 06.09.2008 J. M. Quesada added external choices for: |
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41 | // - "never go back" hipothesis (useNGB=true) |
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42 | // - CEM transition probabilities (useCEMtr=true) |
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43 | |
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44 | #include "G4PreCompoundTransitions.hh" |
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45 | #include "G4HadronicException.hh" |
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46 | |
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47 | const G4PreCompoundTransitions & G4PreCompoundTransitions:: |
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48 | operator=(const G4PreCompoundTransitions &) |
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49 | { |
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50 | throw G4HadronicException(__FILE__, __LINE__, "G4PreCompoundTransitions::operator= meant to not be accessable"); |
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51 | return *this; |
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52 | } |
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53 | |
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54 | |
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55 | G4bool G4PreCompoundTransitions::operator==(const G4PreCompoundTransitions &) const |
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56 | { |
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57 | return false; |
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58 | } |
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59 | |
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60 | G4bool G4PreCompoundTransitions::operator!=(const G4PreCompoundTransitions &) const |
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61 | { |
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62 | return true; |
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63 | } |
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64 | |
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65 | |
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66 | G4double G4PreCompoundTransitions:: |
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67 | CalculateProbability(const G4Fragment & aFragment) |
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68 | { |
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69 | //G4cout<<"In G4PreCompoundTransitions.cc useNGB="<<useNGB<<G4endl; |
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70 | //G4cout<<"In G4PreCompoundTransitions.cc useCEMtr="<<useCEMtr<<G4endl; |
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71 | |
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72 | // Fermi energy |
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73 | const G4double FermiEnergy = G4PreCompoundParameters::GetAddress()->GetFermiEnergy(); |
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74 | |
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75 | // Nuclear radius |
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76 | const G4double r0 = G4PreCompoundParameters::GetAddress()->GetTransitionsr0(); |
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77 | |
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78 | // In order to calculate the level density parameter |
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79 | // G4EvaporationLevelDensityParameter theLDP; |
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80 | |
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81 | // Number of holes |
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82 | G4double H = aFragment.GetNumberOfHoles(); |
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83 | // Number of Particles |
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84 | G4double P = aFragment.GetNumberOfParticles(); |
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85 | // Number of Excitons |
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86 | G4double N = P+H; |
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87 | // Nucleus |
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88 | G4double A = aFragment.GetA(); |
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89 | G4double Z = static_cast<G4double>(aFragment.GetZ()); |
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90 | G4double U = aFragment.GetExcitationEnergy(); |
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91 | |
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92 | if(U<10*eV) return 0.0; |
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93 | |
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94 | //J. M. Quesada (Feb. 08) new physics |
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95 | // OPT=1 Transitions are calculated according to Gudima's paper (original in G4PreCompound from VL) |
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96 | // OPT=2 Transitions are calculated according to Gupta's formulae |
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97 | // |
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98 | |
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99 | |
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100 | |
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101 | if (useCEMtr){ |
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102 | |
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103 | |
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104 | // Relative Energy (T_{rel}) |
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105 | G4double RelativeEnergy = (8.0/5.0)*FermiEnergy + U/N; |
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106 | |
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107 | // Sample kind of nucleon-projectile |
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108 | G4bool ChargedNucleon(false); |
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109 | G4double chtest = 0.5; |
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110 | if (P > 0) chtest = aFragment.GetNumberOfCharged()/P; |
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111 | if (G4UniformRand() < chtest) ChargedNucleon = true; |
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112 | |
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113 | // Relative Velocity: |
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114 | // <V_{rel}>^2 |
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115 | G4double RelativeVelocitySqr(0.0); |
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116 | if (ChargedNucleon) RelativeVelocitySqr = 2.0*RelativeEnergy/proton_mass_c2; |
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117 | else RelativeVelocitySqr = 2.0*RelativeEnergy/neutron_mass_c2; |
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118 | |
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119 | // <V_{rel}> |
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120 | G4double RelativeVelocity = std::sqrt(RelativeVelocitySqr); |
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121 | |
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122 | // Proton-Proton Cross Section |
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123 | G4double ppXSection = (10.63/RelativeVelocitySqr - 29.92/RelativeVelocity + 42.9)*millibarn; |
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124 | // Proton-Neutron Cross Section |
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125 | G4double npXSection = (34.10/RelativeVelocitySqr - 82.20/RelativeVelocity + 82.2)*millibarn; |
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126 | |
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127 | // Averaged Cross Section: \sigma(V_{rel}) |
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128 | // G4double AveragedXSection = (ppXSection+npXSection)/2.0; |
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129 | G4double AveragedXSection(0.0); |
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130 | if (ChargedNucleon) |
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131 | { |
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132 | //JMQ: small bug fixed |
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133 | // AveragedXSection = ((Z-1.0) * ppXSection + (A-Z-1.0) * npXSection) / (A-1.0); |
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134 | AveragedXSection = ((Z-1.0) * ppXSection + (A-Z) * npXSection) / (A-1.0); |
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135 | } |
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136 | else |
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137 | { |
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138 | AveragedXSection = ((A-Z-1.0) * ppXSection + Z * npXSection) / (A-1.0); |
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139 | } |
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140 | |
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141 | // Fermi relative energy ratio |
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142 | G4double FermiRelRatio = FermiEnergy/RelativeEnergy; |
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143 | |
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144 | // This factor is introduced to take into account the Pauli principle |
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145 | G4double PauliFactor = 1.0 - (7.0/5.0)*FermiRelRatio; |
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146 | if (FermiRelRatio > 0.5) PauliFactor += (2.0/5.0)*FermiRelRatio*std::pow(2.0 - (1.0/FermiRelRatio), 5.0/2.0); |
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147 | |
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148 | // Interaction volume |
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149 | // G4double Vint = (4.0/3.0)*pi*std::pow(2.0*r0 + hbarc/(proton_mass_c2*RelativeVelocity) , 3.0); |
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150 | G4double xx=2.0*r0 + hbarc/(proton_mass_c2*RelativeVelocity); |
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151 | G4double Vint = (4.0/3.0)*pi*xx*xx*xx; |
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152 | |
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153 | // Transition probability for \Delta n = +2 |
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154 | |
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155 | TransitionProb1 = AveragedXSection*PauliFactor*std::sqrt(2.0*RelativeEnergy/proton_mass_c2)/Vint; |
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156 | if (TransitionProb1 < 0.0) TransitionProb1 = 0.0; |
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157 | |
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158 | G4double a = G4PreCompoundParameters::GetAddress()->GetLevelDensity(); |
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159 | // GE = g*E where E is Excitation Energy |
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160 | G4double GE = (6.0/pi2)*a*A*U; |
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161 | |
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162 | G4double Fph = ((P*P+H*H+P-H)/4.0 - H/2.0); |
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163 | |
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164 | //G4bool NeverGoBack(false); |
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165 | G4bool NeverGoBack; |
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166 | if(useNGB) NeverGoBack=true; |
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167 | else NeverGoBack=false; |
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168 | |
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169 | |
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170 | //JMQ/AH bug fixed: if (U-Fph < 0.0) NeverGoBack = true; |
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171 | if (GE-Fph < 0.0) NeverGoBack = true; |
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172 | |
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173 | // F(p+1,h+1) |
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174 | G4double Fph1 = Fph + N/2.0; |
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175 | |
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176 | G4double ProbFactor = std::pow((GE-Fph)/(GE-Fph1),N+1.0); |
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177 | |
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178 | |
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179 | if (NeverGoBack) |
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180 | { |
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181 | TransitionProb2 = 0.0; |
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182 | TransitionProb3 = 0.0; |
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183 | } |
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184 | else |
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185 | { |
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186 | // Transition probability for \Delta n = -2 (at F(p,h) = 0) |
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187 | TransitionProb2 = TransitionProb1 * ProbFactor * (P*H*(N+1.0)*(N-2.0))/((GE-Fph)*(GE-Fph)); |
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188 | if (TransitionProb2 < 0.0) TransitionProb2 = 0.0; |
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189 | |
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190 | // Transition probability for \Delta n = 0 (at F(p,h) = 0) |
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191 | TransitionProb3 = TransitionProb1* ((N+1.0)/N) * ProbFactor * (P*(P-1.0) + 4.0*P*H + H*(H-1.0))/(GE-Fph); |
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192 | if (TransitionProb3 < 0.0) TransitionProb3 = 0.0; |
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193 | } |
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194 | |
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195 | // G4cout<<"U = "<<U<<G4endl; |
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196 | // G4cout<<"N="<<N<<" P="<<P<<" H="<<H<<G4endl; |
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197 | // G4cout<<"l+ ="<<TransitionProb1<<" l- ="<< TransitionProb2<<" l0 ="<< TransitionProb3<<G4endl; |
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198 | return TransitionProb1 + TransitionProb2 + TransitionProb3; |
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199 | } |
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200 | |
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201 | else { |
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202 | //JMQ: Transition probabilities from Gupta's work |
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203 | |
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204 | G4double a = G4PreCompoundParameters::GetAddress()->GetLevelDensity(); |
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205 | // GE = g*E where E is Excitation Energy |
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206 | G4double GE = (6.0/pi2)*a*A*U; |
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207 | |
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208 | G4double Kmfp=2.; |
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209 | |
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210 | |
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211 | TransitionProb1=1./Kmfp*3./8.*1./c_light*1.0e-9*(1.4e+21*U-2./(N+1)*6.0e+18*U*U); |
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212 | if (TransitionProb1 < 0.0) TransitionProb1 = 0.0; |
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213 | |
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214 | if (useNGB){ |
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215 | TransitionProb2=0.; |
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216 | TransitionProb3=0.; |
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217 | } |
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218 | else{ |
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219 | if (N<=1) TransitionProb2=0. ; |
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220 | else TransitionProb2=1./Kmfp*3./8.*1./c_light*1.0e-9*(N-1.)*(N-2.)*P*H/(GE*GE)*(1.4e+21*U - 2./(N-1)*6.0e+18*U*U); |
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221 | if (TransitionProb2 < 0.0) TransitionProb2 = 0.0; |
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222 | TransitionProb3=0.; |
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223 | } |
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224 | |
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225 | // G4cout<<"U = "<<U<<G4endl; |
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226 | // G4cout<<"N="<<N<<" P="<<P<<" H="<<H<<G4endl; |
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227 | // G4cout<<"l+ ="<<TransitionProb1<<" l- ="<< TransitionProb2<<" l0 ="<< TransitionProb3<<G4endl; |
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228 | return TransitionProb1 + TransitionProb2 + TransitionProb3; |
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229 | } |
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230 | } |
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231 | |
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232 | |
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233 | G4Fragment G4PreCompoundTransitions::PerformTransition(const G4Fragment & aFragment) |
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234 | { |
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235 | G4Fragment result(aFragment); |
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236 | G4double ChosenTransition = G4UniformRand()*(TransitionProb1 + TransitionProb2 + TransitionProb3); |
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237 | G4int deltaN = 0; |
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238 | G4int Nexcitons = result.GetNumberOfExcitons(); |
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239 | if (ChosenTransition <= TransitionProb1) |
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240 | { |
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241 | // Number of excitons is increased on \Delta n = +2 |
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242 | deltaN = 2; |
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243 | } |
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244 | else if (ChosenTransition <= TransitionProb1+TransitionProb2) |
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245 | { |
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246 | // Number of excitons is increased on \Delta n = -2 |
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247 | deltaN = -2; |
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248 | } |
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249 | |
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250 | // AH/JMQ: Randomly decrease the number of charges if deltaN is -2 and in proportion |
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251 | // to the number charges w.r.t. number of particles, PROVIDED that there are charged particles |
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252 | if(deltaN < 0 && G4UniformRand() <= |
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253 | static_cast<G4double>(result.GetNumberOfCharged())/static_cast<G4double>(result.GetNumberOfParticles()) |
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254 | && (result.GetNumberOfCharged() >= 1)) { |
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255 | result.SetNumberOfCharged(result.GetNumberOfCharged()+deltaN/2); // deltaN is negative! |
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256 | } |
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257 | |
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258 | // JMQ the following lines have to be before SetNumberOfCharged, otherwise the check on |
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259 | // number of charged vs. number of particles fails |
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260 | result.SetNumberOfParticles(result.GetNumberOfParticles()+deltaN/2); |
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261 | result.SetNumberOfHoles(result.GetNumberOfHoles()+deltaN/2); |
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262 | |
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263 | // With weight Z/A, number of charged particles is increased with +1 |
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264 | if ( ( deltaN > 0 ) && |
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265 | (G4UniformRand() <= static_cast<G4double>(result.GetZ()-result.GetNumberOfCharged())/ |
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266 | std::max(static_cast<G4double>(result.GetA()-Nexcitons),1.))) |
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267 | { |
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268 | result.SetNumberOfCharged(result.GetNumberOfCharged()+deltaN/2); |
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269 | } |
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270 | |
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271 | // Number of charged can not be greater that number of particles |
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272 | if ( result.GetNumberOfParticles() < result.GetNumberOfCharged() ) |
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273 | { |
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274 | result.SetNumberOfCharged(result.GetNumberOfParticles()); |
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275 | } |
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276 | |
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277 | return result; |
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278 | } |
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279 | |
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