1 | // |
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2 | // ******************************************************************** |
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3 | // * License and Disclaimer * |
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9 | // * include a list of copyright holders. * |
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14 | // * regarding this software system or assume any liability for its * |
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15 | // * use. Please see the license in the file LICENSE and URL above * |
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17 | // * * |
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18 | // * This code implementation is the result of the scientific and * |
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19 | // * technical work of the GEANT4 collaboration. * |
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23 | // * acceptance of all terms of the Geant4 Software license. * |
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24 | // ******************************************************************** |
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25 | // |
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26 | // |
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27 | // $Id: G4LEPionPlusInelastic.cc,v 1.15 2007/02/24 06:28:52 dennis Exp $ |
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28 | // GEANT4 tag $Name: $ |
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29 | // |
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30 | // Hadronic Process: PionPlus Inelastic Process |
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31 | // J.L. Chuma, TRIUMF, 19-Nov-1996 |
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32 | // Last modified: 27-Mar-1997 |
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33 | // Modified by J.L.Chuma 30-Apr-97: added originalTarget for CalculateMomenta |
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34 | // fixing charge exchange - HPW Sep 2002. |
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35 | |
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36 | #include "G4LEPionPlusInelastic.hh" |
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37 | #include "Randomize.hh" |
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38 | |
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39 | G4HadFinalState * |
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40 | G4LEPionPlusInelastic::ApplyYourself( const G4HadProjectile &aTrack, |
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41 | G4Nucleus &targetNucleus ) |
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42 | { |
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43 | const G4HadProjectile *originalIncident = &aTrack; |
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44 | if (originalIncident->GetKineticEnergy()<= 0.1*MeV) |
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45 | { |
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46 | theParticleChange.SetStatusChange(isAlive); |
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47 | theParticleChange.SetEnergyChange(aTrack.GetKineticEnergy()); |
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48 | theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit()); |
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49 | return &theParticleChange; |
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50 | } |
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51 | |
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52 | // create the target particle |
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53 | |
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54 | G4DynamicParticle *originalTarget = targetNucleus.ReturnTargetParticle(); |
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55 | // G4double targetMass = originalTarget->GetDefinition()->GetPDGMass(); |
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56 | G4ReactionProduct targetParticle( originalTarget->GetDefinition() ); |
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57 | |
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58 | if( verboseLevel > 1 ) |
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59 | { |
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60 | const G4Material *targetMaterial = aTrack.GetMaterial(); |
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61 | G4cout << "G4LEPionPlusInelastic::ApplyYourself called" << G4endl; |
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62 | G4cout << "kinetic energy = " << originalIncident->GetKineticEnergy() << "MeV, "; |
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63 | G4cout << "target material = " << targetMaterial->GetName() << ", "; |
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64 | G4cout << "target particle = " << originalTarget->GetDefinition()->GetParticleName() |
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65 | << G4endl; |
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66 | } |
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67 | G4ReactionProduct currentParticle( |
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68 | const_cast<G4ParticleDefinition *>(originalIncident->GetDefinition() ) ); |
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69 | currentParticle.SetMomentum( originalIncident->Get4Momentum().vect() ); |
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70 | currentParticle.SetKineticEnergy( originalIncident->GetKineticEnergy() ); |
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71 | |
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72 | // Fermi motion and evaporation |
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73 | // As of Geant3, the Fermi energy calculation had not been Done |
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74 | |
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75 | G4double ek = originalIncident->GetKineticEnergy(); |
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76 | G4double amas = originalIncident->GetDefinition()->GetPDGMass(); |
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77 | |
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78 | G4double tkin = targetNucleus.Cinema( ek ); |
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79 | ek += tkin; |
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80 | currentParticle.SetKineticEnergy( ek ); |
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81 | G4double et = ek + amas; |
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82 | G4double p = std::sqrt( std::abs((et-amas)*(et+amas)) ); |
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83 | G4double pp = currentParticle.GetMomentum().mag(); |
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84 | if( pp > 0.0 ) |
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85 | { |
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86 | G4ThreeVector momentum = currentParticle.GetMomentum(); |
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87 | currentParticle.SetMomentum( momentum * (p/pp) ); |
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88 | } |
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89 | |
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90 | // calculate black track energies |
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91 | |
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92 | tkin = targetNucleus.EvaporationEffects( ek ); |
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93 | ek -= tkin; |
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94 | currentParticle.SetKineticEnergy( ek ); |
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95 | et = ek + amas; |
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96 | p = std::sqrt( std::abs((et-amas)*(et+amas)) ); |
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97 | pp = currentParticle.GetMomentum().mag(); |
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98 | if( pp > 0.0 ) |
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99 | { |
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100 | G4ThreeVector momentum = currentParticle.GetMomentum(); |
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101 | currentParticle.SetMomentum( momentum * (p/pp) ); |
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102 | } |
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103 | |
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104 | G4ReactionProduct modifiedOriginal = currentParticle; |
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105 | |
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106 | currentParticle.SetSide( 1 ); // incident always goes in forward hemisphere |
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107 | targetParticle.SetSide( -1 ); // target always goes in backward hemisphere |
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108 | G4bool incidentHasChanged = false; |
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109 | G4bool targetHasChanged = false; |
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110 | G4bool quasiElastic = false; |
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111 | G4FastVector<G4ReactionProduct,GHADLISTSIZE> vec; // vec will contain the secondary particles |
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112 | G4int vecLen = 0; |
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113 | vec.Initialize( 0 ); |
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114 | |
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115 | const G4double cutOff = 0.1*MeV; |
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116 | if( currentParticle.GetKineticEnergy() > cutOff ) |
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117 | Cascade( vec, vecLen, |
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118 | originalIncident, currentParticle, targetParticle, |
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119 | incidentHasChanged, targetHasChanged, quasiElastic ); |
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120 | |
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121 | CalculateMomenta( vec, vecLen, |
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122 | originalIncident, originalTarget, modifiedOriginal, |
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123 | targetNucleus, currentParticle, targetParticle, |
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124 | incidentHasChanged, targetHasChanged, quasiElastic ); |
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125 | |
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126 | SetUpChange( vec, vecLen, |
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127 | currentParticle, targetParticle, |
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128 | incidentHasChanged ); |
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129 | |
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130 | delete originalTarget; |
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131 | return &theParticleChange; |
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132 | } |
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133 | |
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134 | void |
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135 | G4LEPionPlusInelastic::Cascade( |
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136 | G4FastVector<G4ReactionProduct,GHADLISTSIZE> &vec, |
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137 | G4int& vecLen, |
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138 | const G4HadProjectile *originalIncident, |
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139 | G4ReactionProduct ¤tParticle, |
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140 | G4ReactionProduct &targetParticle, |
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141 | G4bool &incidentHasChanged, |
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142 | G4bool &targetHasChanged, |
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143 | G4bool &quasiElastic ) |
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144 | { |
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145 | // derived from original FORTRAN code CASPIP by H. Fesefeldt (18-Sep-1987) |
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146 | // |
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147 | // pi+ undergoes interaction with nucleon within nucleus. |
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148 | // Check if energetically possible to produce pions/kaons. |
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149 | // If not assume nuclear excitation occurs and input particle |
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150 | // is degraded in energy. No other particles produced. |
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151 | // If reaction is possible find correct number of pions/protons/neutrons |
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152 | // produced using an interpolation to multiplicity data. |
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153 | // Replace some pions or protons/neutrons by kaons or strange baryons |
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154 | // according to average multiplicity per inelastic reactions. |
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155 | // |
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156 | const G4double mOriginal = originalIncident->GetDefinition()->GetPDGMass(); |
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157 | const G4double etOriginal = originalIncident->GetTotalEnergy(); |
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158 | const G4double pOriginal = originalIncident->GetTotalMomentum(); |
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159 | const G4double targetMass = targetParticle.GetMass(); |
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160 | G4double centerofmassEnergy = std::sqrt( mOriginal*mOriginal + |
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161 | targetMass*targetMass + |
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162 | 2.0*targetMass*etOriginal ); |
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163 | G4double availableEnergy = centerofmassEnergy-(targetMass+mOriginal); |
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164 | static G4bool first = true; |
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165 | const G4int numMul = 1200; |
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166 | const G4int numSec = 60; |
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167 | static G4double protmul[numMul], protnorm[numSec]; // proton constants |
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168 | static G4double neutmul[numMul], neutnorm[numSec]; // neutron constants |
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169 | // np = number of pi+, nm = number of pi-, nz = number of pi0 |
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170 | G4int counter, nt=0, np=0, nm=0, nz=0; |
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171 | const G4double c = 1.25; |
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172 | const G4double b[] = { 0.70, 0.70 }; |
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173 | if( first ) { // compute normalization constants, this will only be Done once |
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174 | first = false; |
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175 | G4int i; |
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176 | for( i=0; i<numMul; ++i )protmul[i] = 0.0; |
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177 | for( i=0; i<numSec; ++i )protnorm[i] = 0.0; |
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178 | counter = -1; |
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179 | for( np=0; np<(numSec/3); ++np ) { |
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180 | for( nm=std::max(0,np-2); nm<=np; ++nm ) { |
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181 | for( nz=0; nz<numSec/3; ++nz ) { |
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182 | if( ++counter < numMul ) { |
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183 | nt = np+nm+nz; |
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184 | if( nt > 0 ) { |
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185 | protmul[counter] = Pmltpc(np,nm,nz,nt,b[0],c); |
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186 | protnorm[nt-1] += protmul[counter]; |
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187 | } |
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188 | } |
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189 | } |
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190 | } |
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191 | } |
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192 | for( i=0; i<numMul; ++i )neutmul[i] = 0.0; |
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193 | for( i=0; i<numSec; ++i )neutnorm[i] = 0.0; |
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194 | counter = -1; |
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195 | for( np=0; np<numSec/3; ++np ) { |
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196 | for( nm=std::max(0,np-1); nm<=(np+1); ++nm ) { |
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197 | for( nz=0; nz<numSec/3; ++nz ) { |
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198 | if( ++counter < numMul ) { |
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199 | nt = np+nm+nz; |
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200 | if( (nt>0) && (nt<=numSec) ) { |
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201 | neutmul[counter] = Pmltpc(np,nm,nz,nt,b[1],c); |
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202 | neutnorm[nt-1] += neutmul[counter]; |
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203 | } |
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204 | } |
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205 | } |
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206 | } |
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207 | } |
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208 | for( i=0; i<numSec; ++i ) { |
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209 | if( protnorm[i] > 0.0 )protnorm[i] = 1.0/protnorm[i]; |
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210 | if( neutnorm[i] > 0.0 )neutnorm[i] = 1.0/neutnorm[i]; |
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211 | } |
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212 | } // end of initialization |
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213 | |
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214 | const G4double expxu = 82.; // upper bound for arg. of exp |
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215 | const G4double expxl = -expxu; // lower bound for arg. of exp |
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216 | G4ParticleDefinition *aNeutron = G4Neutron::Neutron(); |
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217 | G4ParticleDefinition *aProton = G4Proton::Proton(); |
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218 | G4ParticleDefinition *aPiZero = G4PionZero::PionZero(); |
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219 | G4int ieab = static_cast<G4int>(availableEnergy*5.0/GeV); |
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220 | const G4double supp[] = {0.,0.2,0.45,0.55,0.65,0.75,0.85,0.90,0.94,0.98}; |
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221 | G4double test, w0, wp, wt, wm; |
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222 | if( (availableEnergy < 2.0*GeV) && (G4UniformRand() >= supp[ieab]) ) |
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223 | { |
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224 | // suppress high multiplicity events at low momentum |
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225 | // only one pion will be produced |
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226 | // charge exchange reaction is included in inelastic cross section |
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227 | |
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228 | const G4double cech[] = {1.,0.95,0.79,0.32,0.19,0.16,0.14,0.12,0.10,0.08}; |
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229 | G4int iplab = G4int(std::min( 9.0, pOriginal/GeV*5.0 )); |
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230 | if( G4UniformRand() <= cech[iplab] ) |
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231 | { |
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232 | if( targetParticle.GetDefinition() == aNeutron ) |
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233 | { |
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234 | currentParticle.SetDefinitionAndUpdateE( aPiZero ); // charge exchange |
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235 | targetParticle.SetDefinitionAndUpdateE( aProton ); |
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236 | incidentHasChanged = true; |
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237 | targetHasChanged = true; |
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238 | } |
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239 | } |
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240 | |
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241 | if( availableEnergy <= G4PionMinus::PionMinus()->GetPDGMass() ) |
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242 | { |
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243 | quasiElastic = true; |
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244 | return; |
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245 | } |
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246 | |
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247 | nm = np = nz = 0; |
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248 | if( targetParticle.GetDefinition() == aProton ) { |
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249 | test = std::exp( std::min( expxu, std::max( expxl, -sqr(1.0+b[0])/(2.0*c*c) ) ) ); |
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250 | w0 = test; |
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251 | wp = test; |
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252 | if( G4UniformRand() < w0/(w0+wp) ) |
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253 | nz =1; |
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254 | else |
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255 | np = 1; |
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256 | } else { // target is a neutron |
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257 | test = std::exp( std::min( expxu, std::max( expxl, -sqr(1.0+b[1])/(2.0*c*c) ) ) ); |
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258 | w0 = test; |
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259 | wp = test; |
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260 | test = std::exp( std::min( expxu, std::max( expxl, -sqr(-1.0+b[1])/(2.0*c*c) ) ) ); |
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261 | wm = test; |
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262 | wt = w0+wp+wm; |
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263 | wp = w0+wp; |
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264 | G4double ran = G4UniformRand(); |
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265 | if( ran < w0/wt ) |
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266 | nz = 1; |
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267 | else if( ran < wp/wt ) |
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268 | np = 1; |
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269 | else |
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270 | nm = 1; |
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271 | } |
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272 | } else { |
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273 | if( availableEnergy <= G4PionMinus::PionMinus()->GetPDGMass() ) |
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274 | { |
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275 | quasiElastic = true; |
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276 | return; |
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277 | } |
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278 | G4double n, anpn; |
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279 | GetNormalizationConstant( availableEnergy, n, anpn ); |
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280 | G4double ran = G4UniformRand(); |
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281 | G4double dum, excs = 0.0; |
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282 | if( targetParticle.GetDefinition() == aProton ) { |
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283 | counter = -1; |
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284 | for( np=0; (np<numSec/3) && (ran>=excs); ++np ) { |
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285 | for( nm=std::max(0,np-2); (nm<=np) && (ran>=excs); ++nm ) { |
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286 | for( nz=0; (nz<numSec/3) && (ran>=excs); ++nz ) { |
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287 | if( ++counter < numMul ) { |
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288 | nt = np+nm+nz; |
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289 | if( nt > 0 ) { |
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290 | test = std::exp( std::min( expxu, std::max( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) ); |
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291 | dum = (pi/anpn)*nt*protmul[counter]*protnorm[nt-1]/(2.0*n*n); |
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292 | if( std::fabs(dum) < 1.0 ) { |
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293 | if( test >= 1.0e-10 )excs += dum*test; |
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294 | } else { |
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295 | excs += dum*test; |
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296 | } |
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297 | } |
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298 | } |
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299 | } |
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300 | } |
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301 | } |
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302 | if( ran >= excs ) |
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303 | { |
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304 | quasiElastic = true; |
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305 | return; // 3 previous loops continued to the end |
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306 | } |
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307 | np--; nm--; nz--; |
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308 | } else { // target must be a neutron |
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309 | counter = -1; |
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310 | for( np=0; (np<numSec/3) && (ran>=excs); ++np ) { |
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311 | for( nm=std::max(0,np-1); (nm<=(np+1)) && (ran>=excs); ++nm ) { |
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312 | for( nz=0; (nz<numSec/3) && (ran>=excs); ++nz ) { |
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313 | if( ++counter < numMul ) { |
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314 | nt = np+nm+nz; |
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315 | if( (nt>=1) && (nt<=numSec) ) { |
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316 | test = std::exp( std::min( expxu, std::max( expxl, -(pi/4.0)*(nt*nt)/(n*n) ) ) ); |
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317 | dum = (pi/anpn)*nt*neutmul[counter]*neutnorm[nt-1]/(2.0*n*n); |
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318 | if( std::fabs(dum) < 1.0 ) { |
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319 | if( test >= 1.0e-10 )excs += dum*test; |
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320 | } else { |
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321 | excs += dum*test; |
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322 | } |
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323 | } |
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324 | } |
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325 | } |
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326 | } |
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327 | } |
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328 | if( ran >= excs ) // 3 previous loops continued to the end |
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329 | { |
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330 | quasiElastic = true; |
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331 | return; // 3 previous loops continued to the end |
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332 | } |
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333 | np--; nm--; nz--; |
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334 | } |
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335 | } |
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336 | if( targetParticle.GetDefinition() == aProton ) { |
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337 | switch( np-nm ) { |
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338 | case 1: |
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339 | if( G4UniformRand() < 0.5 ) { |
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340 | currentParticle.SetDefinitionAndUpdateE( aPiZero ); |
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341 | incidentHasChanged = true; |
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342 | } else { |
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343 | targetParticle.SetDefinitionAndUpdateE( aNeutron ); |
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344 | targetHasChanged = true; |
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345 | } |
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346 | break; |
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347 | case 2: |
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348 | currentParticle.SetDefinitionAndUpdateE( aPiZero ); |
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349 | targetParticle.SetDefinitionAndUpdateE( aNeutron ); |
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350 | incidentHasChanged = true; |
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351 | targetHasChanged = true; |
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352 | break; |
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353 | default: |
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354 | break; |
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355 | } |
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356 | } else { |
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357 | switch( np-nm ) { |
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358 | case 0: |
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359 | if( G4UniformRand() < 0.25 ) { |
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360 | currentParticle.SetDefinitionAndUpdateE( aPiZero ); |
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361 | targetParticle.SetDefinitionAndUpdateE( aProton ); |
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362 | incidentHasChanged = true; |
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363 | targetHasChanged = true; |
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364 | } |
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365 | break; |
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366 | case 1: |
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367 | currentParticle.SetDefinitionAndUpdateE( aPiZero ); |
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368 | incidentHasChanged = true; |
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369 | break; |
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370 | default: |
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371 | targetParticle.SetDefinitionAndUpdateE( aProton ); |
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372 | targetHasChanged = true; |
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373 | break; |
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374 | } |
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375 | } |
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376 | SetUpPions( np, nm, nz, vec, vecLen ); |
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377 | return; |
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378 | } |
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379 | |
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380 | /* end of file */ |
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381 | |
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