[968] | 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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[1196] | 26 | // $Id: G4eeTo3PiModel.cc,v 1.3 2009/11/11 17:13:47 vnivanch Exp $ |
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| 27 | // GEANT4 tag $Name: geant4-09-03-cand-01 $ |
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[968] | 28 | // |
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| 29 | // ------------------------------------------------------------------- |
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| 30 | // |
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| 31 | // GEANT4 Class header file |
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| 32 | // |
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| 33 | // |
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| 34 | // File name: G4eeTo3PiModel |
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| 35 | // |
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| 36 | // Author: Vladimir Ivanchenko |
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| 37 | // |
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| 38 | // Creation date: 25.10.2003 |
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| 39 | // |
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| 40 | // Modifications: |
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| 41 | // |
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| 42 | // |
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| 43 | // ------------------------------------------------------------------- |
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| 44 | // |
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| 45 | |
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| 46 | |
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| 47 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 48 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 49 | |
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| 50 | #include "G4eeTo3PiModel.hh" |
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| 51 | #include "Randomize.hh" |
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| 52 | #include "G4PionPlus.hh" |
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| 53 | #include "G4PionMinus.hh" |
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| 54 | #include "G4PionZero.hh" |
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| 55 | #include "G4DynamicParticle.hh" |
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| 56 | #include "G4PhysicsVector.hh" |
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| 57 | #include "G4PhysicsLinearVector.hh" |
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| 58 | #include "G4eeCrossSections.hh" |
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| 59 | #include "G4RandomDirection.hh" |
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| 60 | #include <complex> |
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| 61 | |
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| 62 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 63 | |
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| 64 | using namespace std; |
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| 65 | |
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| 66 | G4eeTo3PiModel::G4eeTo3PiModel(G4eeCrossSections* cr): |
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| 67 | cross(cr) |
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| 68 | { |
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| 69 | massPi = G4PionPlus::PionPlus()->GetPDGMass(); |
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| 70 | massPi0 = G4PionZero::PionZero()->GetPDGMass(); |
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| 71 | massOm = 782.62*MeV; |
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| 72 | massPhi = 1019.46*MeV; |
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| 73 | gcash = 0.0; |
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| 74 | gmax = 1.0; |
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| 75 | } |
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| 76 | |
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| 77 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 78 | |
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| 79 | G4eeTo3PiModel::~G4eeTo3PiModel() |
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| 80 | { |
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| 81 | G4cout << "### G4eeTo3PiModel::~G4eeTo3PiModel: gmax= " |
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| 82 | << gmax << " gcash= " << gcash << G4endl; |
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| 83 | } |
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| 84 | |
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| 85 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 86 | |
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[1055] | 87 | G4double G4eeTo3PiModel::ThresholdEnergy() const |
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| 88 | { |
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| 89 | return std::max(LowEnergy(),2.0*massPi + massPi0); |
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| 90 | } |
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| 91 | |
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| 92 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 93 | |
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| 94 | G4double G4eeTo3PiModel::PeakEnergy() const |
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| 95 | { |
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| 96 | G4double e = massOm; |
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| 97 | if(HighEnergy() > massPhi) e = massPhi; |
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| 98 | return e; |
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| 99 | } |
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| 100 | |
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| 101 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 102 | |
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| 103 | G4double G4eeTo3PiModel::ComputeCrossSection(G4double e) const |
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| 104 | { |
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| 105 | G4double ee = std::min(HighEnergy(),e); |
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| 106 | return cross->CrossSection3pi(ee); |
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| 107 | } |
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| 108 | |
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| 109 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 110 | |
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[968] | 111 | G4PhysicsVector* G4eeTo3PiModel::PhysicsVector(G4double emin, |
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| 112 | G4double emax) const |
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| 113 | { |
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| 114 | G4double tmin = std::max(emin, ThresholdEnergy()); |
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| 115 | G4double tmax = std::max(tmin, emax); |
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| 116 | G4int nbins = (G4int)((tmax - tmin)/(1.*MeV)); |
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| 117 | G4PhysicsVector* v = new G4PhysicsLinearVector(emin,emax,nbins); |
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| 118 | v->SetSpline(true); |
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| 119 | return v; |
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| 120 | } |
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| 121 | |
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| 122 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 123 | |
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| 124 | void G4eeTo3PiModel::SampleSecondaries(std::vector<G4DynamicParticle*>* newp, |
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| 125 | G4double e, const G4ThreeVector& direction) |
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| 126 | { |
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| 127 | if(e < ThresholdEnergy()) return; |
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| 128 | |
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| 129 | G4double x0 = massPi0/e; |
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| 130 | G4double x1 = massPi/e; |
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| 131 | |
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| 132 | G4LorentzVector w0, w1, w2; |
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[1196] | 133 | G4ThreeVector dir0, dir1; |
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[968] | 134 | G4double e0, p0, e2, p, g, m01, m02, m12; |
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| 135 | |
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| 136 | // max pi0 energy |
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| 137 | G4double edel = 0.5*e*(1.0 + x0*x0 - 4.0*x1*x1) - massPi0; |
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| 138 | |
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| 139 | do { |
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| 140 | // pi0 sample |
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| 141 | e0 = edel*G4UniformRand() + massPi0; |
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| 142 | p0 = sqrt(e0 - massPi0*massPi0); |
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| 143 | dir0 = G4RandomDirection(); |
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| 144 | w0 = G4LorentzVector(p0*dir0.x(),p0*dir0.y(),p0*dir0.z(),e0); |
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| 145 | |
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| 146 | // pi+pi- pair |
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| 147 | w1 = G4LorentzVector(-p0*dir0.x(),-p0*dir0.y(),-p0*dir0.z(),e-e0); |
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| 148 | G4ThreeVector bst = w1.boostVector(); |
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| 149 | e2 = 0.25*w1.m2(); |
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| 150 | |
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| 151 | // pi+ |
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| 152 | p = sqrt(e2 - massPi*massPi); |
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| 153 | dir1 = G4RandomDirection(); |
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| 154 | w2 = G4LorentzVector(p*dir1.x(),p*dir1.y(),p*dir1.z(),sqrt(e2)); |
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| 155 | w2.boost(bst); |
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[1196] | 156 | G4double px2 = w2.x(); |
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| 157 | G4double py2 = w2.y(); |
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| 158 | G4double pz2 = w2.z(); |
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[968] | 159 | |
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| 160 | // pi- |
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| 161 | w1 -= w2; |
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[1196] | 162 | G4double px1 = w1.x(); |
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| 163 | G4double py1 = w1.y(); |
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| 164 | G4double pz1 = w1.z(); |
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[968] | 165 | |
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| 166 | m01 = w0*w1; |
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| 167 | m02 = w0*w2; |
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| 168 | m12 = w1*w2; |
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| 169 | |
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[1196] | 170 | G4double px = py1*pz2 - py2*pz1; |
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| 171 | G4double py = pz1*px2 - pz2*px1; |
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| 172 | G4double pz = px1*py2 - px2*py1; |
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| 173 | |
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| 174 | g = (px*px + py*py + pz*pz)* |
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| 175 | norm( 1.0/cross->DpRho(m01) + 1.0/cross->DpRho(m02) |
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| 176 | + 1.0/cross->DpRho(m12) ); |
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[968] | 177 | if(g > gmax) { |
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| 178 | G4cout << "G4eeTo3PiModel::SampleSecondaries WARNING matrix element g= " |
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| 179 | << g << " > " << gmax << " (majoranta)" << G4endl; |
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| 180 | } |
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| 181 | if(g > gcash) gcash = g; |
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| 182 | |
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| 183 | } while( gmax*G4UniformRand() > g ); |
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| 184 | |
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| 185 | w0.rotateUz(direction); |
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| 186 | w1.rotateUz(direction); |
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| 187 | w2.rotateUz(direction); |
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| 188 | |
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| 189 | // create G4DynamicParticle objects |
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| 190 | G4DynamicParticle* dp0 = |
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| 191 | new G4DynamicParticle(G4PionZero::PionZero(), w0); |
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| 192 | G4DynamicParticle* dp1 = |
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| 193 | new G4DynamicParticle(G4PionPlus::PionPlus(), w1); |
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| 194 | G4DynamicParticle* dp2 = |
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| 195 | new G4DynamicParticle(G4PionMinus::PionMinus(), w2); |
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| 196 | newp->push_back(dp0); |
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| 197 | newp->push_back(dp1); |
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| 198 | newp->push_back(dp2); |
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| 199 | } |
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| 200 | |
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| 201 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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| 202 | |
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