1 | // |
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2 | // ******************************************************************** |
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3 | // * License and Disclaimer * |
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4 | // * * |
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5 | // * The Geant4 software is copyright of the Copyright Holders of * |
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6 | // * the Geant4 Collaboration. It is provided under the terms and * |
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7 | // * conditions of the Geant4 Software License, included in the file * |
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8 | // * LICENSE and available at http://cern.ch/geant4/license . These * |
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9 | // * include a list of copyright holders. * |
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10 | // * * |
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11 | // * Neither the authors of this software system, nor their employing * |
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12 | // * institutes,nor the agencies providing financial support for this * |
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13 | // * work make any representation or warranty, express or implied, * |
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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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16 | // * for the full disclaimer and the limitation of liability. * |
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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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20 | // * By using, copying, modifying or distributing the software (or * |
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21 | // * any work based on the software) you agree to acknowledge its * |
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22 | // * use in resulting scientific publications, and indicate your * |
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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 | // GEANT 4 class header file |
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28 | // |
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29 | // History: |
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30 | // 01 August 2007 P.Gumplinger |
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31 | // Reference: TRIUMF PIENU Technote: |
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32 | // M. Blecher - "Inclusion of pi->enug in MC " |
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33 | // Rate is for gammas > 100keV |
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34 | // |
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35 | // ------------------------------------------------------------ |
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36 | // |
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37 | // |
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38 | // |
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39 | |
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40 | #include "G4PionRadiativeDecayChannel.hh" |
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41 | |
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42 | #include "Randomize.hh" |
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43 | #include "G4DecayProducts.hh" |
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44 | #include "G4LorentzVector.hh" |
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45 | |
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46 | G4PionRadiativeDecayChannel:: |
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47 | G4PionRadiativeDecayChannel(const G4String& theParentName, |
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48 | G4double theBR) |
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49 | : G4VDecayChannel("Radiative Pion Decay",1) |
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50 | { |
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51 | // set names for daughter particles |
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52 | if (theParentName == "pi+") { |
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53 | SetBR(theBR); |
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54 | SetParent("pi+"); |
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55 | SetNumberOfDaughters(3); |
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56 | SetDaughter(0, "e+"); |
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57 | SetDaughter(1, "gamma"); |
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58 | SetDaughter(2, "nu_e"); |
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59 | } else if (theParentName == "pi-") { |
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60 | SetBR(theBR); |
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61 | SetParent("pi-"); |
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62 | SetNumberOfDaughters(3); |
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63 | SetDaughter(0, "e-"); |
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64 | SetDaughter(1, "gamma"); |
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65 | SetDaughter(2, "anti_nu_e"); |
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66 | } else { |
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67 | #ifdef G4VERBOSE |
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68 | if (GetVerboseLevel()>0) { |
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69 | G4cout << "G4RadiativePionDecayChannel:: constructor :"; |
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70 | G4cout << " parent particle is not muon but "; |
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71 | G4cout << theParentName << G4endl; |
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72 | } |
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73 | #endif |
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74 | } |
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75 | |
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76 | beta = 3.6612e-03; |
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77 | |
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78 | cib = 1.16141e-03; |
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79 | csdp = 3.45055e-02; |
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80 | csdm = 5.14122e-03; |
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81 | cif = 4.63543e-05; |
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82 | cig = 1.78928e-05; |
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83 | |
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84 | xl = 2.*0.1*MeV/139.57*MeV; |
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85 | yl = ((1.-xl) + std::sqrt((1-xl)*(1-xl)+4*beta*beta))/2.; |
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86 | |
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87 | xu = 1. - (yl - std::sqrt(yl*yl-4.*beta*beta))/2.; |
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88 | yu = 1. + beta*beta; |
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89 | |
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90 | d2wmax = D2W(xl,yl); |
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91 | |
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92 | } |
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93 | |
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94 | G4PionRadiativeDecayChannel::~G4PionRadiativeDecayChannel() |
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95 | { |
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96 | } |
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97 | |
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98 | G4DecayProducts *G4PionRadiativeDecayChannel::DecayIt(G4double) |
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99 | { |
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100 | |
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101 | #ifdef G4VERBOSE |
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102 | if (GetVerboseLevel()>1) |
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103 | G4cout << "G4PionRadiativeDecayChannel::DecayIt "; |
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104 | #endif |
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105 | |
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106 | if (parent == 0) FillParent(); |
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107 | if (daughters == 0) FillDaughters(); |
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108 | |
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109 | // parent mass |
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110 | G4double parentmass = parent->GetPDGMass(); |
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111 | |
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112 | G4double EMPI = parentmass; |
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113 | |
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114 | //daughters'mass |
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115 | G4double daughtermass[3]; |
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116 | G4double sumofdaughtermass = 0.0; |
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117 | for (G4int index=0; index<3; index++){ |
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118 | daughtermass[index] = daughters[index]->GetPDGMass(); |
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119 | sumofdaughtermass += daughtermass[index]; |
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120 | } |
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121 | |
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122 | G4double EMASS = daughtermass[0]; |
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123 | |
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124 | //create parent G4DynamicParticle at rest |
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125 | G4ThreeVector dummy; |
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126 | G4DynamicParticle * parentparticle = |
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127 | new G4DynamicParticle( parent, dummy, 0.0); |
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128 | //create G4Decayproducts |
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129 | G4DecayProducts *products = new G4DecayProducts(*parentparticle); |
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130 | delete parentparticle; |
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131 | |
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132 | G4double x, y, d2w; |
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133 | |
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134 | do { |
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135 | |
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136 | do { |
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137 | |
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138 | x = xl + G4UniformRand()*(xu-xl); |
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139 | y = yl + G4UniformRand()*(yu-yl); |
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140 | |
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141 | } while (x+y <= 1.); |
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142 | |
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143 | d2w = D2W(x,y); |
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144 | |
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145 | } while (d2w <= G4UniformRand()*d2wmax); |
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146 | |
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147 | //----------------------------------------------------------------------- |
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148 | // |
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149 | // Calculate the angle between positron and photon (cosine) |
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150 | // |
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151 | G4double cthetaGE = (y*(x-2.)+2.*(1.-x+beta*beta)) / |
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152 | (x*std::sqrt(y*y-4.*beta*beta)); |
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153 | |
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154 | // |
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155 | //----------------------------------------------------------------------- |
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156 | // |
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157 | G4double G = x * EMPI/2.; |
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158 | G4double E = y * EMPI/2.; |
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159 | // |
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160 | //----------------------------------------------------------------------- |
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161 | // |
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162 | |
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163 | if (E < EMASS) E = EMASS; |
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164 | |
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165 | // calculate daughter momentum |
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166 | G4double daughtermomentum[2]; |
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167 | |
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168 | daughtermomentum[0] = std::sqrt(E*E - EMASS*EMASS); |
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169 | |
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170 | G4double cthetaE = 2.*G4UniformRand()-1.; |
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171 | G4double sthetaE = std::sqrt(1.-cthetaE*cthetaE); |
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172 | |
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173 | G4double phiE = twopi*G4UniformRand()*rad; |
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174 | G4double cphiE = std::cos(phiE); |
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175 | G4double sphiE = std::sin(phiE); |
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176 | |
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177 | //Coordinates of the decay positron |
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178 | |
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179 | G4double px = sthetaE*cphiE; |
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180 | G4double py = sthetaE*sphiE; |
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181 | G4double pz = cthetaE; |
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182 | |
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183 | G4ThreeVector direction0(px,py,pz); |
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184 | |
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185 | G4DynamicParticle * daughterparticle0 |
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186 | = new G4DynamicParticle( daughters[0], daughtermomentum[0]*direction0); |
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187 | |
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188 | products->PushProducts(daughterparticle0); |
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189 | |
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190 | daughtermomentum[1] = G; |
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191 | |
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192 | G4double sthetaGE = std::sqrt(1.-cthetaGE*cthetaGE); |
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193 | |
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194 | G4double phiGE = twopi*G4UniformRand()*rad; |
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195 | G4double cphiGE = std::cos(phiGE); |
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196 | G4double sphiGE = std::sin(phiGE); |
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197 | |
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198 | //Coordinates of the decay gamma with respect to the decay positron |
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199 | |
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200 | px = sthetaGE*cphiGE; |
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201 | py = sthetaGE*sphiGE; |
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202 | pz = cthetaGE; |
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203 | |
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204 | G4ThreeVector direction1(px,py,pz); |
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205 | |
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206 | direction1.rotateUz(direction0); |
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207 | |
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208 | G4DynamicParticle * daughterparticle1 |
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209 | = new G4DynamicParticle( daughters[1], daughtermomentum[1]*direction1); |
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210 | |
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211 | products->PushProducts(daughterparticle1); |
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212 | |
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213 | // output message |
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214 | #ifdef G4VERBOSE |
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215 | if (GetVerboseLevel()>1) { |
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216 | G4cout << "G4PionRadiativeDecayChannel::DecayIt "; |
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217 | G4cout << " create decay products in rest frame " <<G4endl; |
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218 | products->DumpInfo(); |
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219 | } |
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220 | #endif |
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221 | |
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222 | return products; |
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223 | |
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224 | } |
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