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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: G4PreCompoundTransitions.cc,v 1.27 2010/10/20 00:47:46 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: 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 | // 30.10.2009 J.M.Quesada: CEM transition probabilities have been renormalized |
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44 | // (IAEA benchmark) |
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45 | // 20.08.2010 V.Ivanchenko move constructor and destructor to the source and |
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46 | // optimise the code |
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47 | // |
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48 | |
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49 | #include "G4PreCompoundTransitions.hh" |
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50 | #include "G4HadronicException.hh" |
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51 | #include "G4PreCompoundParameters.hh" |
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52 | #include "G4Proton.hh" |
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53 | #include "Randomize.hh" |
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54 | #include "G4Pow.hh" |
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55 | |
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56 | G4PreCompoundTransitions::G4PreCompoundTransitions() |
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57 | { |
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58 | proton = G4Proton::Proton(); |
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59 | FermiEnergy = G4PreCompoundParameters::GetAddress()->GetFermiEnergy(); |
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60 | r0 = G4PreCompoundParameters::GetAddress()->GetTransitionsr0(); |
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61 | aLDP = G4PreCompoundParameters::GetAddress()->GetLevelDensity(); |
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62 | g4pow = G4Pow::GetInstance(); |
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63 | } |
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64 | |
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65 | G4PreCompoundTransitions::~G4PreCompoundTransitions() |
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66 | {} |
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67 | |
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68 | // Calculates transition probabilities with |
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69 | // DeltaN = +2 (Trans1) -2 (Trans2) and 0 (Trans3) |
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70 | G4double G4PreCompoundTransitions:: |
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71 | CalculateProbability(const G4Fragment & aFragment) |
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72 | { |
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73 | // Number of holes |
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74 | G4int H = aFragment.GetNumberOfHoles(); |
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75 | // Number of Particles |
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76 | G4int P = aFragment.GetNumberOfParticles(); |
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77 | // Number of Excitons |
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78 | G4int N = P+H; |
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79 | // Nucleus |
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80 | G4int A = aFragment.GetA_asInt(); |
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81 | G4int Z = aFragment.GetZ_asInt(); |
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82 | G4double U = aFragment.GetExcitationEnergy(); |
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83 | |
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84 | //G4cout << aFragment << G4endl; |
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85 | |
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86 | if(U < 10*eV) { return 0.0; } |
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87 | |
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88 | //J. M. Quesada (Feb. 08) new physics |
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89 | // OPT=1 Transitions are calculated according to Gudima's paper |
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90 | // (original in G4PreCompound from VL) |
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91 | // OPT=2 Transitions are calculated according to Gupta's formulae |
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92 | // |
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93 | if (useCEMtr){ |
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94 | |
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95 | // Relative Energy (T_{rel}) |
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96 | G4double RelativeEnergy = 1.6*FermiEnergy + U/G4double(N); |
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97 | |
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98 | // Sample kind of nucleon-projectile |
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99 | G4bool ChargedNucleon(false); |
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100 | G4double chtest = 0.5; |
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101 | if (P > 0) { |
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102 | chtest = G4double(aFragment.GetNumberOfCharged())/G4double(P); |
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103 | } |
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104 | if (G4UniformRand() < chtest) { ChargedNucleon = true; } |
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105 | |
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106 | // Relative Velocity: |
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107 | // <V_{rel}>^2 |
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108 | G4double RelativeVelocitySqr(0.0); |
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109 | if (ChargedNucleon) { |
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110 | RelativeVelocitySqr = 2.0*RelativeEnergy/CLHEP::proton_mass_c2; |
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111 | } else { |
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112 | RelativeVelocitySqr = 2.0*RelativeEnergy/CLHEP::neutron_mass_c2; |
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113 | } |
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114 | |
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115 | // <V_{rel}> |
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116 | G4double RelativeVelocity = std::sqrt(RelativeVelocitySqr); |
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117 | |
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118 | // Proton-Proton Cross Section |
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119 | G4double ppXSection = |
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120 | (10.63/RelativeVelocitySqr - 29.92/RelativeVelocity + 42.9) |
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121 | * CLHEP::millibarn; |
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122 | // Proton-Neutron Cross Section |
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123 | G4double npXSection = |
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124 | (34.10/RelativeVelocitySqr - 82.20/RelativeVelocity + 82.2) |
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125 | * CLHEP::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)*ppXSection + (A-Z)*npXSection)/G4double(A-1); |
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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)*ppXSection + Z*npXSection)/G4double(A-1); |
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139 | //AveragedXSection = ((A-Z-1)*npXSection + Z*ppXSection)/G4double(A-1); |
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140 | } |
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141 | |
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142 | // Fermi relative energy ratio |
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143 | G4double FermiRelRatio = FermiEnergy/RelativeEnergy; |
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144 | |
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145 | // This factor is introduced to take into account the Pauli principle |
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146 | G4double PauliFactor = 1.0 - 1.4*FermiRelRatio; |
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147 | if (FermiRelRatio > 0.5) { |
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148 | G4double x = 2.0 - 1.0/FermiRelRatio; |
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149 | PauliFactor += 0.4*FermiRelRatio*x*x*std::sqrt(x); |
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150 | //PauliFactor += |
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151 | //(2.0/5.0)*FermiRelRatio*std::pow(2.0 - (1.0/FermiRelRatio), 5.0/2.0); |
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152 | } |
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153 | // Interaction volume |
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154 | // G4double Vint = (4.0/3.0) |
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155 | //*pi*std::pow(2.0*r0 + hbarc/(proton_mass_c2*RelativeVelocity) , 3.0); |
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156 | G4double xx = 2.0*r0 + hbarc/(CLHEP::proton_mass_c2*RelativeVelocity); |
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157 | // G4double Vint = (4.0/3.0)*CLHEP::pi*xx*xx*xx; |
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158 | G4double Vint = CLHEP::pi*xx*xx*xx/0.75; |
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159 | |
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160 | // Transition probability for \Delta n = +2 |
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161 | |
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162 | TransitionProb1 = AveragedXSection*PauliFactor |
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163 | *std::sqrt(2.0*RelativeEnergy/CLHEP::proton_mass_c2)/Vint; |
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164 | |
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165 | //JMQ 281009 phenomenological factor in order to increase |
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166 | // equilibrium contribution |
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167 | // G4double factor=5.0; |
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168 | // TransitionProb1 *= factor; |
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169 | // |
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170 | if (TransitionProb1 < 0.0) { TransitionProb1 = 0.0; } |
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171 | |
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172 | // GE = g*E where E is Excitation Energy |
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173 | G4double GE = (6.0/pi2)*aLDP*A*U; |
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174 | |
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175 | //G4double Fph = ((P*P+H*H+P-H)/4.0 - H/2.0); |
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176 | G4double Fph = G4double(P*P+H*H+P-3*H)/4.0; |
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177 | |
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178 | G4bool NeverGoBack(false); |
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179 | if(useNGB) { NeverGoBack=true; } |
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180 | |
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181 | //JMQ/AH bug fixed: if (U-Fph < 0.0) NeverGoBack = true; |
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182 | if (GE-Fph < 0.0) { NeverGoBack = true; } |
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183 | |
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184 | // F(p+1,h+1) |
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185 | G4double Fph1 = Fph + N/2.0; |
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186 | |
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187 | G4double ProbFactor = g4pow->powN((GE-Fph)/(GE-Fph1),N+1); |
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188 | |
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189 | if (NeverGoBack) |
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190 | { |
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191 | TransitionProb2 = 0.0; |
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192 | TransitionProb3 = 0.0; |
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193 | } |
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194 | else |
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195 | { |
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196 | // Transition probability for \Delta n = -2 (at F(p,h) = 0) |
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197 | TransitionProb2 = |
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198 | TransitionProb1 * ProbFactor * (P*H*(N+1)*(N-2))/((GE-Fph)*(GE-Fph)); |
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199 | if (TransitionProb2 < 0.0) { TransitionProb2 = 0.0; } |
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200 | |
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201 | // Transition probability for \Delta n = 0 (at F(p,h) = 0) |
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202 | TransitionProb3 = TransitionProb1*(N+1)* ProbFactor |
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203 | * (P*(P-1) + 4.0*P*H + H*(H-1))/(N*(GE-Fph)); |
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204 | if (TransitionProb3 < 0.0) { TransitionProb3 = 0.0; } |
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205 | } |
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206 | } else { |
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207 | //JMQ: Transition probabilities from Gupta's work |
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208 | // GE = g*E where E is Excitation Energy |
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209 | G4double GE = (6.0/pi2)*aLDP*A*U; |
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210 | |
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211 | G4double Kmfp=2.; |
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212 | |
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213 | //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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214 | TransitionProb1 = 3.0e-9*(1.4e+21*U - 1.2e+19*U*U/G4double(N+1)) |
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215 | /(8*Kmfp*CLHEP::c_light); |
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216 | if (TransitionProb1 < 0.0) { TransitionProb1 = 0.0; } |
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217 | |
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218 | TransitionProb2=0.; |
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219 | TransitionProb3=0.; |
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220 | |
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221 | if (!useNGB && N > 1) { |
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222 | // 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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223 | TransitionProb2 = |
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224 | 3.0e-9*(N-2)*P*H*(1.4e+21*U*(N-1) - 1.2e+19*U*U)/(8*Kmfp*c_light*GE*GE); |
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225 | if (TransitionProb2 < 0.0) TransitionProb2 = 0.0; |
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226 | } |
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227 | } |
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228 | // G4cout<<"U = "<<U<<G4endl; |
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229 | // G4cout<<"N="<<N<<" P="<<P<<" H="<<H<<G4endl; |
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230 | // G4cout<<"l+ ="<<TransitionProb1<<" l- ="<< TransitionProb2 |
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231 | // <<" l0 ="<< TransitionProb3<<G4endl; |
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232 | return TransitionProb1 + TransitionProb2 + TransitionProb3; |
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233 | } |
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234 | |
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235 | void G4PreCompoundTransitions::PerformTransition(G4Fragment & result) |
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236 | { |
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237 | G4double ChosenTransition = |
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238 | G4UniformRand()*(TransitionProb1 + TransitionProb2 + TransitionProb3); |
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239 | G4int deltaN = 0; |
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240 | // G4int Nexcitons = result.GetNumberOfExcitons(); |
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241 | G4int Npart = result.GetNumberOfParticles(); |
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242 | G4int Ncharged = result.GetNumberOfCharged(); |
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243 | G4int Nholes = result.GetNumberOfHoles(); |
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244 | if (ChosenTransition <= TransitionProb1) |
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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 | else if (ChosenTransition <= TransitionProb1+TransitionProb2) |
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250 | { |
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251 | // Number of excitons is increased on \Delta n = -2 |
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252 | deltaN = -2; |
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253 | } |
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254 | |
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255 | // AH/JMQ: Randomly decrease the number of charges if deltaN is -2 and |
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256 | // in proportion to the number charges w.r.t. number of particles, |
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257 | // PROVIDED that there are charged particles |
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258 | deltaN /= 2; |
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259 | |
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260 | //G4cout << "deltaN= " << deltaN << G4endl; |
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261 | |
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262 | // JMQ the following lines have to be before SetNumberOfCharged, otherwise the check on |
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263 | // number of charged vs. number of particles fails |
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264 | result.SetNumberOfParticles(Npart+deltaN); |
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265 | result.SetNumberOfHoles(Nholes+deltaN); |
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266 | |
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267 | if(deltaN < 0) { |
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268 | if( Ncharged >= 1 && G4int(Npart*G4UniformRand()) <= Ncharged) |
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269 | { |
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270 | result.SetNumberOfCharged(Ncharged+deltaN); // deltaN is negative! |
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271 | } |
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272 | |
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273 | } else if ( deltaN > 0 ) { |
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274 | // With weight Z/A, number of charged particles is increased with +1 |
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275 | G4int A = result.GetA_asInt(); |
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276 | G4int Z = result.GetZ_asInt(); |
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277 | if( G4int(std::max(1, A - Npart)*G4UniformRand()) <= Z) |
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278 | { |
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279 | result.SetNumberOfCharged(Ncharged+deltaN); |
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280 | } |
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281 | } |
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282 | |
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283 | // Number of charged can not be greater that number of particles |
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284 | if ( Npart < Ncharged ) |
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285 | { |
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286 | result.SetNumberOfCharged(Npart); |
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287 | } |
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288 | //G4cout << "### After transition" << G4endl; |
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289 | //G4cout << result << G4endl; |
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290 | } |
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291 | |
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