[824] | 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 | // $Id: G4NeutronBetaDecayChannel.cc,v 1.7 2006/06/29 19:25:38 gunter Exp $ |
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[1337] | 28 | // GEANT4 tag $Name: geant4-09-04-beta-01 $ |
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[824] | 29 | // |
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| 30 | // |
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| 31 | // ------------------------------------------------------------ |
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| 32 | // GEANT 4 class header file |
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| 33 | // |
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| 34 | // History: first implementation, based on object model of |
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| 35 | // 18 Sep 2001 H.Kurashige |
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| 36 | // |
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| 37 | // ------------------------------------------------------------ |
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| 38 | |
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| 39 | #include "G4ParticleDefinition.hh" |
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| 40 | #include "G4DecayProducts.hh" |
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| 41 | #include "G4VDecayChannel.hh" |
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| 42 | #include "G4NeutronBetaDecayChannel.hh" |
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| 43 | #include "Randomize.hh" |
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| 44 | #include "G4RotationMatrix.hh" |
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| 45 | #include "G4LorentzVector.hh" |
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| 46 | #include "G4LorentzRotation.hh" |
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| 47 | |
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| 48 | |
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| 49 | G4NeutronBetaDecayChannel::G4NeutronBetaDecayChannel( |
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| 50 | const G4String& theParentName, |
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| 51 | G4double theBR) |
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| 52 | :G4VDecayChannel("Neutron Decay"), |
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| 53 | aENuCorr(-0.102) |
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| 54 | { |
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| 55 | // set names for daughter particles |
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| 56 | if (theParentName == "neutron") { |
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| 57 | SetBR(theBR); |
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| 58 | SetParent("neutron"); |
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| 59 | SetNumberOfDaughters(3); |
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| 60 | SetDaughter(0, "e-"); |
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| 61 | SetDaughter(1, "anti_nu_e"); |
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| 62 | SetDaughter(2, "proton"); |
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| 63 | } else { |
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| 64 | #ifdef G4VERBOSE |
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| 65 | if (GetVerboseLevel()>0) { |
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| 66 | G4cout << "G4NeutronBetaDecayChannel:: constructor :"; |
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| 67 | G4cout << " parent particle is not muon but "; |
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| 68 | G4cout << theParentName << G4endl; |
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| 69 | } |
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| 70 | #endif |
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| 71 | } |
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| 72 | } |
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| 73 | |
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| 74 | G4NeutronBetaDecayChannel::~G4NeutronBetaDecayChannel() |
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| 75 | { |
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| 76 | } |
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| 77 | |
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| 78 | G4DecayProducts *G4NeutronBetaDecayChannel::DecayIt(G4double) |
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| 79 | { |
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| 80 | // This class describes free neutron beta decay kinemtics. |
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| 81 | // This version neglects neutron/electron polarization |
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| 82 | // without Coulomb effect |
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| 83 | |
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| 84 | #ifdef G4VERBOSE |
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| 85 | if (GetVerboseLevel()>1) G4cout << "G4NeutronBetaDecayChannel::DecayIt "; |
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| 86 | #endif |
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| 87 | |
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| 88 | if (parent == 0) FillParent(); |
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| 89 | if (daughters == 0) FillDaughters(); |
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| 90 | |
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| 91 | // parent mass |
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| 92 | G4double parentmass = parent->GetPDGMass(); |
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| 93 | |
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| 94 | //daughters'mass |
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| 95 | G4double daughtermass[3]; |
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| 96 | G4double sumofdaughtermass = 0.0; |
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| 97 | for (G4int index=0; index<3; index++){ |
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| 98 | daughtermass[index] = daughters[index]->GetPDGMass(); |
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| 99 | sumofdaughtermass += daughtermass[index]; |
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| 100 | } |
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| 101 | G4double xmax = parentmass-sumofdaughtermass; |
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| 102 | |
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| 103 | //create parent G4DynamicParticle at rest |
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| 104 | G4ThreeVector dummy; |
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| 105 | G4DynamicParticle * parentparticle = new G4DynamicParticle( parent, dummy, 0.0); |
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| 106 | |
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| 107 | //create G4Decayproducts |
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| 108 | G4DecayProducts *products = new G4DecayProducts(*parentparticle); |
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| 109 | delete parentparticle; |
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| 110 | |
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| 111 | // calculate daughter momentum |
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| 112 | G4double daughtermomentum[3]; |
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| 113 | |
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| 114 | // calcurate electron energy |
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| 115 | G4double x; // Ee |
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| 116 | G4double p; // Pe |
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| 117 | G4double m = daughtermass[0]; //Me |
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| 118 | G4double w; // cosine of e-nu angle |
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| 119 | G4double r; |
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| 120 | G4double r0; |
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| 121 | do { |
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| 122 | x = xmax*G4UniformRand(); |
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| 123 | p = std::sqrt(x*(x+2.0*m)); |
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| 124 | w = 1.0-2.0*G4UniformRand(); |
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| 125 | r = p*(x+m)*(xmax-x)*(xmax-x)*(1.0+aENuCorr*p/(x+m)*w); |
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| 126 | r0 = G4UniformRand()*(xmax+m)*(xmax+m)*xmax*xmax*(1.0+aENuCorr); |
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| 127 | } while (r < r0); |
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| 128 | |
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| 129 | //create daughter G4DynamicParticle |
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| 130 | // rotation materix to lab frame |
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| 131 | G4double costheta = 2.*G4UniformRand()-1.0; |
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| 132 | G4double theta = std::acos(costheta)*rad; |
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| 133 | G4double phi = twopi*G4UniformRand()*rad; |
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| 134 | G4RotationMatrix rm; |
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| 135 | rm.rotateY(theta); |
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| 136 | rm.rotateZ(phi); |
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| 137 | |
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| 138 | // daughter 0 (electron) in Z direction |
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| 139 | daughtermomentum[0] = p; |
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| 140 | G4ThreeVector direction0(0.0, 0.0, 1.0); |
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| 141 | direction0 = rm * direction0; |
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| 142 | G4DynamicParticle * daughterparticle0 |
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| 143 | = new G4DynamicParticle( daughters[0], direction0*daughtermomentum[0]); |
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| 144 | products->PushProducts(daughterparticle0); |
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| 145 | |
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| 146 | // daughter 1 (nutrino) in XZ plane |
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| 147 | G4double eNu = xmax-x; |
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| 148 | G4double cosn = w; |
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| 149 | G4double sinn = std::sqrt((1.0-cosn)*(1.0+cosn)); |
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| 150 | |
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| 151 | G4ThreeVector direction1(sinn, 0.0, cosn); |
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| 152 | direction1 = rm * direction1; |
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| 153 | G4DynamicParticle * daughterparticle1 |
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| 154 | = new G4DynamicParticle( daughters[1], direction1*eNu); |
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| 155 | products->PushProducts(daughterparticle1); |
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| 156 | |
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| 157 | // daughter 2 (proton) at REST |
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| 158 | G4ThreeVector direction2(0.0, 0.0, 0.0); |
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| 159 | G4DynamicParticle * daughterparticle2 |
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| 160 | = new G4DynamicParticle( daughters[2], direction2); |
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| 161 | products->PushProducts(daughterparticle2); |
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| 162 | |
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| 163 | |
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| 164 | // output message |
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| 165 | #ifdef G4VERBOSE |
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| 166 | if (GetVerboseLevel()>1) { |
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| 167 | G4cout << "G4NeutronBetaDecayChannel::DecayIt "; |
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| 168 | G4cout << " create decay products in rest frame " <<G4endl; |
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| 169 | products->DumpInfo(); |
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| 170 | } |
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| 171 | #endif |
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| 172 | return products; |
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| 173 | } |
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| 174 | |
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| 175 | |
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| 176 | |
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| 177 | |
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| 178 | |
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| 179 | |
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