G4INCLNNbarCEXChannel.cc

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//
// INCL++ intra-nuclear cascade model
// Alain Boudard, CEA-Saclay, France
// Joseph Cugnon, University of Liege, Belgium
// Jean-Christophe David, CEA-Saclay, France
// Pekka Kaitaniemi, CEA-Saclay, France, and Helsinki Institute of Physics, Finland
// Sylvie Leray, CEA-Saclay, France
// Davide Mancusi, CEA-Saclay, France
//
#define INCLXX_IN_GEANT4_MODE 1
 
#include "globals.hh"
 
#include "G4INCLNNbarCEXChannel.hh"
#include "G4INCLKinematicsUtils.hh"
#include "G4INCLBinaryCollisionAvatar.hh"
#include "G4INCLRandom.hh"
#include "G4INCLGlobals.hh"
#include "G4INCLLogger.hh"
#include <algorithm>
#include "G4INCLPhaseSpaceGenerator.hh"
 
namespace G4INCL {
    
    NNbarCEXChannel::NNbarCEXChannel(Particle *p1, Particle *p2)
        : particle1(p1), particle2(p2)
        {}
    
    NNbarCEXChannel::~NNbarCEXChannel(){}
    
    void NNbarCEXChannel::fillFinalState(FinalState *fs) {
 
        //brief ppbar
        // p pbar -> n nbar (BFMM 204)
        //
        //brief nnbar
        // n nbar -> p pbar (same as BFMM 204, but no threshold)
        //
 
        Particle *nucleon;
        Particle *antinucleon;
        
        if(particle1->isNucleon()){
            nucleon = particle1;
            antinucleon = particle2;
        }
        else{
            nucleon = particle2;
            antinucleon = particle1;
        }
        
        const G4double sqrtS = KinematicsUtils::totalEnergyInCM(nucleon, antinucleon);
 
        //setting types of new particles
        if(nucleon->getType()==Proton){
            if(antinucleon->getType()==antiProton){ //ppbar case
                nucleon->setType(Neutron);
                antinucleon->setType(antiNeutron);
            }
            else{ //pnbar case
                //no CEX for pnbar
                INCL_ERROR("We should not be in this channel " << '\n');
            }
        }
        else{ // neutron
            if(antinucleon->getType()==antiNeutron){ //nnbar case
                nucleon->setType(Proton);
                antinucleon->setType(antiProton);
            }
            else{ //npbar case
                //no CEX for npbar
                INCL_ERROR("We should not be in this channel " << '\n');
            }
        }
        
        G4double mn=nucleon->getMass();
        G4double my=antinucleon->getMass();
        
        G4double ey=(sqrtS*sqrtS+my*my-mn*mn)/(2*sqrtS);
        G4double en=std::sqrt(ey*ey-my*my+mn*mn);
        nucleon->setEnergy(en);
        antinucleon->setEnergy(ey);
        G4double py=std::sqrt(ey*ey-my*my);
        
        
        ThreeVector mom_antinucleon = Random::normVector(py);
 
        antinucleon->setMomentum(mom_antinucleon);
        nucleon->setMomentum(-mom_antinucleon);
        
        fs->addModifiedParticle(nucleon);
        fs->addModifiedParticle(antinucleon);
                
    }
}