[819] | 1 | // |
---|
| 2 | // ******************************************************************** |
---|
| 3 | // * License and Disclaimer * |
---|
| 4 | // * * |
---|
| 5 | // * The Geant4 software is copyright of the Copyright Holders of * |
---|
| 6 | // * the Geant4 Collaboration. It is provided under the terms and * |
---|
| 7 | // * conditions of the Geant4 Software License, included in the file * |
---|
| 8 | // * LICENSE and available at http://cern.ch/geant4/license . These * |
---|
| 9 | // * include a list of copyright holders. * |
---|
| 10 | // * * |
---|
| 11 | // * Neither the authors of this software system, nor their employing * |
---|
| 12 | // * institutes,nor the agencies providing financial support for this * |
---|
| 13 | // * work make any representation or warranty, express or implied, * |
---|
| 14 | // * regarding this software system or assume any liability for its * |
---|
| 15 | // * use. Please see the license in the file LICENSE and URL above * |
---|
| 16 | // * for the full disclaimer and the limitation of liability. * |
---|
| 17 | // * * |
---|
| 18 | // * This code implementation is the result of the scientific and * |
---|
| 19 | // * technical work of the GEANT4 collaboration. * |
---|
| 20 | // * By using, copying, modifying or distributing the software (or * |
---|
| 21 | // * any work based on the software) you agree to acknowledge its * |
---|
| 22 | // * use in resulting scientific publications, and indicate your * |
---|
| 23 | // * acceptance of all terms of the Geant4 Software license. * |
---|
| 24 | // ******************************************************************** |
---|
| 25 | // |
---|
| 26 | // |
---|
| 27 | // |
---|
| 28 | // CERN Geneva Switzerland |
---|
| 29 | // |
---|
| 30 | // ------------ G4ReactionDynamics::TwoBody ------ |
---|
| 31 | // new method TwoBodyScattering |
---|
| 32 | // by Christian V"olcker (CERN-Munich), September 1997 |
---|
| 33 | // E-mail: Christian.Volcker@cern.ch |
---|
| 34 | // ************************************************************ |
---|
| 35 | //----------------------------------------------------------------------------- |
---|
| 36 | |
---|
| 37 | #include "G4ReactionKinematics.hh" |
---|
| 38 | |
---|
| 39 | // ************************************************************ |
---|
| 40 | void G4ReactionKinematics::TwoBodyScattering( |
---|
| 41 | const G4DynamicParticle* pIn1, const G4DynamicParticle* pIn2, |
---|
| 42 | G4DynamicParticle* pOut1, G4DynamicParticle* pOut2) |
---|
| 43 | // ************************************************************ |
---|
| 44 | { |
---|
| 45 | // initial particles: |
---|
| 46 | |
---|
| 47 | // - total invariant mass |
---|
| 48 | G4LorentzVector sumIn(pIn1->Get4Momentum()+pIn2->Get4Momentum()); |
---|
| 49 | G4double invariantMass=sumIn.mag(); |
---|
| 50 | |
---|
| 51 | // - beta of center-of-mass system |
---|
| 52 | G4ThreeVector betaCMS=sumIn.boostVector(); |
---|
| 53 | |
---|
| 54 | // final particles: |
---|
| 55 | |
---|
| 56 | // - get final particle masses |
---|
| 57 | G4double massOut1=pOut1->GetMass(); |
---|
| 58 | G4double massOut2=pOut2->GetMass(); |
---|
| 59 | |
---|
| 60 | // - calculate breakup momentum: |
---|
| 61 | G4double breakupMomentum=BreakupMomentum(invariantMass, massOut1, massOut2); |
---|
| 62 | |
---|
| 63 | // - isotropic decay angle |
---|
| 64 | G4double costheta = 2.0*G4UniformRand() - 1.0; |
---|
| 65 | G4double sintheta = std::sqrt(1.0 - costheta*costheta); |
---|
| 66 | G4double phi = 2.0*pi*G4UniformRand(); |
---|
| 67 | |
---|
| 68 | // - setup LorentzVectors |
---|
| 69 | G4double pz=costheta*breakupMomentum; |
---|
| 70 | G4double px=sintheta*std::cos(phi)*breakupMomentum; |
---|
| 71 | G4double py=sintheta*std::sin(phi)*breakupMomentum; |
---|
| 72 | |
---|
| 73 | G4double breakupMomentumSquared=breakupMomentum*breakupMomentum; |
---|
| 74 | G4double energy1=std::sqrt(breakupMomentumSquared+massOut1*massOut1); |
---|
| 75 | G4double energy2=std::sqrt(breakupMomentumSquared+massOut2*massOut2); |
---|
| 76 | |
---|
| 77 | G4LorentzVector lorentz1(px, py, pz, energy1); |
---|
| 78 | G4LorentzVector lorentz2(px, py, pz, energy2); |
---|
| 79 | |
---|
| 80 | // - back into lab system |
---|
| 81 | |
---|
| 82 | lorentz1.boost(betaCMS); |
---|
| 83 | lorentz2.boost(betaCMS); |
---|
| 84 | |
---|
| 85 | // fill in new particles: |
---|
| 86 | |
---|
| 87 | pOut1->Set4Momentum(lorentz1); |
---|
| 88 | pOut2->Set4Momentum(lorentz2); |
---|
| 89 | |
---|
| 90 | return; |
---|
| 91 | } |
---|