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2 | // ******************************************************************** |
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15 | // * use. Please see the license in the file LICENSE and URL above * |
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24 | // ******************************************************************** |
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25 | // |
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26 | // $Id: G4PreCompoundEmission.cc,v 1.32 2010/09/01 15:11:10 vnivanch Exp $ |
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27 | // GEANT4 tag $Name: geant4-09-03-ref-09 $ |
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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: G4PreCompoundEmission |
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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 | // 15.01.2010 J.M.Quesada added protection against unphysical values of parameter an |
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40 | // 19.01.2010 V.Ivanchenko simplified computation of parameter an, sample cosTheta |
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41 | // instead of theta; protect all calls to sqrt |
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42 | // 20.08.2010 V.Ivanchenko added G4Pow and G4PreCompoundParameters pointers |
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43 | // use int Z and A and cleanup |
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44 | // |
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45 | |
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46 | #include "G4PreCompoundEmission.hh" |
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47 | #include "G4PreCompoundParameters.hh" |
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48 | #include "G4PreCompoundEmissionFactory.hh" |
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49 | #include "G4HETCEmissionFactory.hh" |
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50 | #include "G4HadronicException.hh" |
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51 | #include "G4Pow.hh" |
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52 | #include "Randomize.hh" |
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53 | |
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54 | G4PreCompoundEmission::G4PreCompoundEmission() |
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55 | { |
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56 | theFragmentsFactory = new G4PreCompoundEmissionFactory(); |
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57 | theFragmentsVector = |
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58 | new G4PreCompoundFragmentVector(theFragmentsFactory->GetFragmentVector()); |
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59 | g4pow = G4Pow::GetInstance(); |
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60 | theParameters = G4PreCompoundParameters::GetAddress(); |
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61 | } |
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62 | |
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63 | G4PreCompoundEmission::~G4PreCompoundEmission() |
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64 | { |
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65 | if (theFragmentsFactory) { delete theFragmentsFactory; } |
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66 | if (theFragmentsVector) { delete theFragmentsVector; } |
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67 | } |
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68 | |
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69 | void G4PreCompoundEmission::SetDefaultModel() |
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70 | { |
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71 | if (theFragmentsFactory) { delete theFragmentsFactory; } |
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72 | theFragmentsFactory = new G4PreCompoundEmissionFactory(); |
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73 | if (theFragmentsVector) |
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74 | { |
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75 | theFragmentsVector->SetVector(theFragmentsFactory->GetFragmentVector()); |
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76 | } |
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77 | else |
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78 | { |
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79 | theFragmentsVector = |
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80 | new G4PreCompoundFragmentVector(theFragmentsFactory->GetFragmentVector()); |
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81 | } |
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82 | return; |
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83 | } |
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84 | |
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85 | void G4PreCompoundEmission::SetHETCModel() |
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86 | { |
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87 | if (theFragmentsFactory) delete theFragmentsFactory; |
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88 | theFragmentsFactory = new G4HETCEmissionFactory(); |
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89 | if (theFragmentsVector) |
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90 | { |
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91 | theFragmentsVector->SetVector(theFragmentsFactory->GetFragmentVector()); |
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92 | } |
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93 | else |
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94 | { |
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95 | theFragmentsVector = |
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96 | new G4PreCompoundFragmentVector(theFragmentsFactory->GetFragmentVector()); |
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97 | } |
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98 | return; |
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99 | } |
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100 | |
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101 | G4ReactionProduct * G4PreCompoundEmission::PerformEmission(G4Fragment & aFragment) |
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102 | { |
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103 | // Choose a Fragment for emission |
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104 | G4VPreCompoundFragment * thePreFragment = theFragmentsVector->ChooseFragment(); |
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105 | if (thePreFragment == 0) |
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106 | { |
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107 | G4cout << "G4PreCompoundEmission::PerformEmission : I couldn't choose a fragment\n" |
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108 | << "while trying to de-excite\n" |
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109 | << aFragment << G4endl; |
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110 | throw G4HadronicException(__FILE__, __LINE__, ""); |
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111 | } |
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112 | // Kinetic Energy of emitted fragment |
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113 | G4double kinEnergyOfEmittedFragment = thePreFragment->GetKineticEnergy(aFragment); |
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114 | if(kinEnergyOfEmittedFragment < 0.0) { kinEnergyOfEmittedFragment = 0.0; } |
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115 | |
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116 | // Calculate the fragment momentum (three vector) |
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117 | AngularDistribution(thePreFragment,aFragment,kinEnergyOfEmittedFragment); |
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118 | |
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119 | // Mass of emittef fragment |
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120 | G4double EmittedMass = thePreFragment->GetNuclearMass(); |
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121 | |
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122 | // Now we can calculate the four momentum |
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123 | // both options are valid and give the same result but 2nd one is faster |
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124 | G4LorentzVector Emitted4Momentum(theFinalMomentum, |
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125 | EmittedMass + kinEnergyOfEmittedFragment); |
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126 | |
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127 | // Perform Lorentz boost |
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128 | G4LorentzVector Rest4Momentum = aFragment.GetMomentum(); |
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129 | Emitted4Momentum.boost(Rest4Momentum.boostVector()); |
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130 | |
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131 | // Set emitted fragment momentum |
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132 | thePreFragment->SetMomentum(Emitted4Momentum); |
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133 | |
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134 | // NOW THE RESIDUAL NUCLEUS |
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135 | // ------------------------ |
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136 | |
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137 | Rest4Momentum -= Emitted4Momentum; |
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138 | |
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139 | // Update nucleus parameters: |
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140 | // -------------------------- |
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141 | |
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142 | // Number of excitons |
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143 | aFragment.SetNumberOfParticles(aFragment.GetNumberOfParticles()- |
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144 | thePreFragment->GetA()); |
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145 | // Number of charges |
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146 | aFragment.SetNumberOfCharged(aFragment.GetNumberOfCharged()- |
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147 | thePreFragment->GetZ()); |
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148 | |
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149 | // Z and A |
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150 | aFragment.SetZandA_asInt(thePreFragment->GetRestZ(), |
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151 | thePreFragment->GetRestA()); |
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152 | |
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153 | // Update nucleus momentum |
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154 | // A check on consistence of Z, A, and mass will be performed |
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155 | aFragment.SetMomentum(Rest4Momentum); |
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156 | |
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157 | // Create a G4ReactionProduct |
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158 | G4ReactionProduct * MyRP = thePreFragment->GetReactionProduct(); |
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159 | |
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160 | //G4cout << "G4PreCompoundEmission::Fragment emitted" << G4endl; |
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161 | //G4cout << thePreFragment << G4endl; |
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162 | |
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163 | return MyRP; |
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164 | } |
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165 | |
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166 | void |
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167 | G4PreCompoundEmission::AngularDistribution(G4VPreCompoundFragment* thePreFragment, |
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168 | const G4Fragment& aFragment, |
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169 | G4double ekin) |
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170 | { |
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171 | G4int p = aFragment.GetNumberOfParticles(); |
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172 | G4int h = aFragment.GetNumberOfHoles(); |
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173 | G4double U = aFragment.GetExcitationEnergy(); |
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174 | |
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175 | // Emission particle separation energy |
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176 | G4double Bemission = thePreFragment->GetBindingEnergy(); |
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177 | |
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178 | // Fermi energy |
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179 | G4double Ef = theParameters->GetFermiEnergy(); |
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180 | |
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181 | // |
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182 | // G4EvaporationLevelDensityParameter theLDP; |
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183 | // G4double g = (6.0/pi2)*aFragment.GetA()* |
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184 | |
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185 | G4double g = (6.0/pi2)*aFragment.GetA_asInt()*theParameters->GetLevelDensity(); |
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186 | |
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187 | // Average exciton energy relative to bottom of nuclear well |
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188 | G4double Eav = 2*p*(p+1)/((p+h)*g); |
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189 | |
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190 | // Excitation energy relative to the Fermi Level |
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191 | G4double Uf = std::max(U - (p - h)*Ef , 0.0); |
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192 | // G4double Uf = U - KineticEnergyOfEmittedFragment - Bemission; |
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193 | |
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194 | G4double w_num = rho(p+1, h, g, Uf, Ef); |
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195 | G4double w_den = rho(p, h, g, Uf, Ef); |
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196 | if (w_num > 0.0 && w_den > 0.0) |
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197 | { |
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198 | Eav *= (w_num/w_den); |
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199 | Eav += - Uf/(p+h) + Ef; |
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200 | } |
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201 | else |
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202 | { |
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203 | Eav = Ef; |
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204 | } |
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205 | |
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206 | // VI + JMQ 19/01/2010 update computation of the parameter an |
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207 | // |
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208 | G4double an = 0.0; |
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209 | G4double Eeff = ekin + Bemission + Ef; |
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210 | if(ekin > DBL_MIN && Eeff > DBL_MIN) { |
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211 | |
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212 | G4double zeta = std::max(1.0,9.3/std::sqrt(ekin/MeV)); |
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213 | |
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214 | // This should be the projectile energy. If I would know which is |
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215 | // the projectile (proton, neutron) I could remove the binding energy. |
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216 | // But, what happens if INC precedes precompound? This approximation |
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217 | // seems to work well enough |
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218 | G4double ProjEnergy = aFragment.GetExcitationEnergy(); |
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219 | |
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220 | an = 3*std::sqrt((ProjEnergy+Ef)*Eeff)/(zeta*Eav); |
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221 | |
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222 | G4int ne = aFragment.GetNumberOfExcitons() - 1; |
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223 | if ( ne > 1 ) { an /= (G4double)ne; } |
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224 | |
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225 | // protection of exponent |
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226 | if ( an > 10. ) { an = 10.; } |
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227 | } |
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228 | |
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229 | // sample cosine of theta and not theta as in old versions |
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230 | G4double random = G4UniformRand(); |
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231 | G4double cost; |
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232 | |
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233 | if(an < 0.1) { cost = 1. - 2*random; } |
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234 | else { |
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235 | G4double exp2an = std::exp(-2*an); |
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236 | cost = 1. + std::log(1-random*(1-exp2an))/an; |
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237 | if(cost > 1.) { cost = 1.; } |
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238 | else if(cost < -1.) {cost = -1.; } |
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239 | } |
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240 | |
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241 | G4double phi = CLHEP::twopi*G4UniformRand(); |
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242 | |
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243 | // Calculate the momentum magnitude of emitted fragment |
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244 | G4double pmag = std::sqrt(ekin*(ekin + 2.0*thePreFragment->GetNuclearMass())); |
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245 | |
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246 | G4double sint = std::sqrt((1.0-cost)*(1.0+cost)); |
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247 | |
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248 | theFinalMomentum.set(pmag*std::cos(phi)*sint,pmag*std::sin(phi)*sint,pmag*cost); |
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249 | |
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250 | // theta is the angle wrt the incident direction |
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251 | G4ThreeVector theIncidentDirection = aFragment.GetMomentum().vect().unit(); |
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252 | theFinalMomentum.rotateUz(theIncidentDirection); |
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253 | } |
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254 | |
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255 | G4double G4PreCompoundEmission::rho(G4int p, G4int h, G4double g, |
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256 | G4double E, G4double Ef) const |
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257 | { |
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258 | // 25.02.2010 V.Ivanchenko added more protections |
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259 | G4double Aph = (p*p + h*h + p - 3.0*h)/(4.0*g); |
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260 | // G4double alpha = (p*p + h*h)/(2.0*g); |
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261 | |
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262 | if ( E - Aph < 0.0) { return 0.0; } |
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263 | |
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264 | G4double logConst = (p+h)*std::log(g) |
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265 | - g4pow->logfactorial(p+h-1) - g4pow->logfactorial(p) - g4pow->logfactorial(h); |
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266 | |
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267 | // initialise values using j=0 |
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268 | |
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269 | G4double t1=1; |
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270 | G4double t2=1; |
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271 | G4double logt3 = (p+h-1) * std::log(E-Aph) + logConst; |
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272 | const G4double logmax = 200.; |
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273 | if(logt3 > logmax) { logt3 = logmax; } |
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274 | G4double tot = std::exp( logt3 ); |
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275 | |
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276 | // and now sum rest of terms |
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277 | // 25.02.2010 V.Ivanchenko change while to for loop and cleanup |
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278 | G4double Eeff = E - Aph; |
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279 | for(G4int j=1; j<=h; ++j) |
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280 | { |
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281 | Eeff -= Ef; |
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282 | if(Eeff < 0.0) { break; } |
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283 | t1 *= -1.; |
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284 | t2 *= (G4double)(h+1-j)/(G4double)j; |
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285 | logt3 = (p+h-1) * std::log( Eeff) + logConst; |
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286 | if(logt3 > logmax) { logt3 = logmax; } |
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287 | tot += t1*t2*std::exp(logt3); |
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288 | } |
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289 | |
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290 | return tot; |
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291 | } |
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