[819] | 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 | // 17 August 2004 P. Gumplinger, T. MacPhail |
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| 31 | // ------------------------------------------------------------ |
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| 32 | // |
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| 33 | #include "G4DecayWithSpin.hh" |
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| 34 | |
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| 35 | #include "G4Step.hh" |
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| 36 | #include "G4Track.hh" |
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| 37 | #include "G4DecayTable.hh" |
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| 38 | #include "G4MuonDecayChannelWithSpin.hh" |
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| 39 | |
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| 40 | #include "G4Vector3D.hh" |
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| 41 | |
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| 42 | #include "G4TransportationManager.hh" |
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| 43 | #include "G4PropagatorInField.hh" |
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| 44 | #include "G4FieldManager.hh" |
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| 45 | #include "G4Field.hh" |
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| 46 | |
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| 47 | #include "G4Transform3D.hh" |
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| 48 | |
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| 49 | G4DecayWithSpin::G4DecayWithSpin(const G4String& processName):G4Decay(processName){} |
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| 50 | |
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| 51 | G4DecayWithSpin::~G4DecayWithSpin(){} |
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| 52 | |
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| 53 | G4VParticleChange* G4DecayWithSpin::DecayIt(const G4Track& aTrack, const G4Step& aStep) |
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| 54 | { |
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| 55 | |
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| 56 | // get particle |
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| 57 | const G4DynamicParticle* aParticle = aTrack.GetDynamicParticle(); |
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| 58 | G4ParticleDefinition* aParticleDef = aParticle->GetDefinition(); |
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| 59 | |
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| 60 | // get parent_polarization |
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| 61 | G4ThreeVector parent_polarization = aParticle->GetPolarization(); |
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| 62 | |
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| 63 | if(parent_polarization == G4ThreeVector(0,0,0)) |
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| 64 | { |
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| 65 | // Generate random polarization direction |
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| 66 | |
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| 67 | G4double cost = 1. - 2.*G4UniformRand(); |
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| 68 | G4double sint = std::sqrt((1.-cost)*(1.+cost)); |
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| 69 | |
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| 70 | G4double phi = twopi*G4UniformRand(); |
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| 71 | G4double sinp = std::sin(phi); |
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| 72 | G4double cosp = std::cos(phi); |
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| 73 | |
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| 74 | G4double px = sint*cosp; |
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| 75 | G4double py = sint*sinp; |
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| 76 | G4double pz = cost; |
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| 77 | |
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| 78 | parent_polarization.setX(px); |
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| 79 | parent_polarization.setY(py); |
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| 80 | parent_polarization.setZ(pz); |
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| 81 | |
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| 82 | }else{ |
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| 83 | |
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| 84 | G4FieldManager* fieldMgr = aStep.GetTrack()->GetVolume()-> |
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| 85 | GetLogicalVolume()->GetFieldManager(); |
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| 86 | |
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| 87 | if (!fieldMgr) { |
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| 88 | G4TransportationManager *transportMgr = |
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| 89 | G4TransportationManager::GetTransportationManager(); |
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| 90 | G4PropagatorInField* fFieldPropagator = |
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| 91 | transportMgr->GetPropagatorInField(); |
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| 92 | if (fFieldPropagator) fieldMgr = |
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| 93 | fFieldPropagator->GetCurrentFieldManager(); |
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| 94 | } |
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| 95 | |
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| 96 | const G4Field* field = NULL; |
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| 97 | if(fieldMgr)field = fieldMgr->GetDetectorField(); |
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| 98 | |
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| 99 | if (field && !(fieldMgr->DoesFieldChangeEnergy())) { |
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| 100 | |
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| 101 | G4double point[4]; |
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| 102 | point[0] = (aStep.GetPostStepPoint()->GetPosition())[0]; |
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| 103 | point[1] = (aStep.GetPostStepPoint()->GetPosition())[1]; |
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| 104 | point[2] = (aStep.GetPostStepPoint()->GetPosition())[2]; |
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| 105 | point[3] = aTrack.GetGlobalTime(); |
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| 106 | |
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| 107 | G4double fieldValue[3]; |
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| 108 | field -> GetFieldValue(point,fieldValue); |
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| 109 | |
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| 110 | G4ThreeVector B(fieldValue[0],fieldValue[1],fieldValue[2]); |
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| 111 | |
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| 112 | parent_polarization = Spin_Precession(aStep,B,fRemainderLifeTime); |
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| 113 | |
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| 114 | } |
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| 115 | } |
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| 116 | |
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| 117 | // decay table |
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| 118 | G4DecayTable *decaytable = aParticleDef->GetDecayTable(); |
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| 119 | |
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| 120 | if (decaytable) { |
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| 121 | G4MuonDecayChannelWithSpin *decaychannel; |
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| 122 | decaychannel = (G4MuonDecayChannelWithSpin*)decaytable->SelectADecayChannel(); |
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| 123 | if (decaychannel) decaychannel->SetPolarization(parent_polarization); |
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| 124 | } |
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| 125 | |
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| 126 | G4ParticleChangeForDecay* pParticleChangeForDecay; |
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| 127 | |
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| 128 | pParticleChangeForDecay = (G4ParticleChangeForDecay*)G4Decay::DecayIt(aTrack,aStep); |
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| 129 | |
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| 130 | pParticleChangeForDecay->ProposePolarization(parent_polarization); |
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| 131 | |
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| 132 | return pParticleChangeForDecay; |
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| 133 | |
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| 134 | } |
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| 135 | |
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| 136 | G4ThreeVector G4DecayWithSpin::Spin_Precession( const G4Step& aStep, |
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| 137 | G4ThreeVector B, G4double deltatime ) |
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| 138 | { |
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| 139 | G4double Bnorm = std::sqrt(sqr(B[0]) + sqr(B[1]) +sqr(B[2]) ); |
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| 140 | |
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| 141 | G4double q = aStep.GetTrack()->GetDefinition()->GetPDGCharge(); |
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| 142 | G4double a = 1.165922e-3; |
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| 143 | G4double s_omega = 8.5062e+7*rad/(s*kilogauss); |
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| 144 | |
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| 145 | G4double omega = -(q*s_omega)*(1.+a) * Bnorm; |
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| 146 | |
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| 147 | G4double rotationangle = deltatime * omega; |
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| 148 | |
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| 149 | G4Transform3D SpinRotation = G4Rotate3D(rotationangle,B.unit()); |
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| 150 | |
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| 151 | G4Vector3D Spin = aStep.GetTrack() -> GetPolarization(); |
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| 152 | |
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| 153 | G4Vector3D newSpin = SpinRotation * Spin; |
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| 154 | |
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| 155 | #ifdef G4VERBOSE |
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| 156 | if (GetVerboseLevel()>2) { |
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| 157 | G4double normspin = std::sqrt(Spin*Spin); |
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| 158 | G4double normnewspin = std::sqrt(newSpin*newSpin); |
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| 159 | //G4double cosalpha = Spin*newSpin/normspin/normnewspin; |
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| 160 | //G4double alpha = std::acos(cosalpha); |
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| 161 | |
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| 162 | G4cout << "AT REST::: PARAMETERS " << G4endl; |
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| 163 | G4cout << "Initial spin : " << Spin << G4endl; |
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| 164 | G4cout << "Delta time : " << deltatime << G4endl; |
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| 165 | G4cout << "Rotation angle: " << rotationangle/rad << G4endl; |
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| 166 | G4cout << "New spin : " << newSpin << G4endl; |
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| 167 | G4cout << "Checked norms : " << normspin <<" " << normnewspin << G4endl; |
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| 168 | } |
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| 169 | #endif |
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| 170 | |
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| 171 | return newSpin; |
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| 172 | |
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| 173 | } |
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