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// $Id: G4RPGProtonInelastic.cc,v 1.4 2008/05/05 21:21:55 dennis Exp $
// GEANT4 tag $Name: geant4-09-04-beta-01 $
//
 
#include "G4RPGProtonInelastic.hh"
#include "Randomize.hh"
 
G4HadFinalState*
G4RPGProtonInelastic::ApplyYourself(const G4HadProjectile& aTrack,
                                    G4Nucleus& targetNucleus )
{
  theParticleChange.Clear();
  const G4HadProjectile *originalIncident = &aTrack;
  if (originalIncident->GetKineticEnergy()<= 0.1) 
  {
    theParticleChange.SetStatusChange(isAlive);
    theParticleChange.SetEnergyChange(aTrack.GetKineticEnergy());
    theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit()); 
    return &theParticleChange;      
  }

  //
  // create the target particle
  //
  G4DynamicParticle *originalTarget = targetNucleus.ReturnTargetParticle();

  if (originalIncident->GetKineticEnergy()/GeV < 0.01+2.*G4UniformRand()/9. )
  {
    SlowProton( originalIncident, targetNucleus );
    delete originalTarget;
    return &theParticleChange;
  }

  // Fermi motion and evaporation
  // As of Geant3, the Fermi energy calculation had not been Done

  G4double ek = originalIncident->GetKineticEnergy();
  G4double amas = originalIncident->GetDefinition()->GetPDGMass();
  G4ReactionProduct modifiedOriginal;
  modifiedOriginal = *originalIncident;
    
  G4double tkin = targetNucleus.Cinema( ek );
  ek += tkin;
  modifiedOriginal.SetKineticEnergy(ek);
  G4double et = ek + amas;
  G4double p = std::sqrt( std::abs((et-amas)*(et+amas)) );
  G4double pp = modifiedOriginal.GetMomentum().mag();
  if (pp > 0.0) {
    G4ThreeVector momentum = modifiedOriginal.GetMomentum();
    modifiedOriginal.SetMomentum( momentum * (p/pp) );
  }
  //
  // calculate black track energies
  //
  tkin = targetNucleus.EvaporationEffects(ek);
  ek -= tkin;
  modifiedOriginal.SetKineticEnergy(ek);
  et = ek + amas;
  p = std::sqrt( std::abs((et-amas)*(et+amas)) );
  pp = modifiedOriginal.GetMomentum().mag();
  if (pp > 0.0) {
    G4ThreeVector momentum = modifiedOriginal.GetMomentum();
    modifiedOriginal.SetMomentum( momentum * (p/pp) );
  }
  const G4double cutOff = 0.1;
  if (modifiedOriginal.GetKineticEnergy() < cutOff) {
    SlowProton( originalIncident, targetNucleus );
    delete originalTarget;
    return &theParticleChange;
  }

  G4ReactionProduct currentParticle = modifiedOriginal;
  G4ReactionProduct targetParticle;
  targetParticle = *originalTarget;
  currentParticle.SetSide( 1 ); // incident always goes in forward hemisphere
  targetParticle.SetSide( -1 );  // target always goes in backward hemisphere
  G4bool incidentHasChanged = false;
  G4bool targetHasChanged = false;
  G4bool quasiElastic = false;
  G4FastVector<G4ReactionProduct,256> vec;  // vec will contain the sec. particles
  G4int vecLen = 0;
  vec.Initialize( 0 );

  InitialCollision(vec, vecLen, currentParticle, targetParticle,
                   incidentHasChanged, targetHasChanged);

  CalculateMomenta(vec, vecLen,
                   originalIncident, originalTarget, modifiedOriginal,
                   targetNucleus, currentParticle, targetParticle,
                   incidentHasChanged, targetHasChanged, quasiElastic);

  SetUpChange( vec, vecLen,
               currentParticle, targetParticle,
               incidentHasChanged );

  delete originalTarget;
  return &theParticleChange;
}


void
G4RPGProtonInelastic::SlowProton(const G4HadProjectile *originalIncident,
                                 G4Nucleus &targetNucleus )
{
  const G4double A = targetNucleus.GetN();    // atomic weight
  const G4double Z = targetNucleus.GetZ();    // atomic number
//  G4double currentKinetic = originalIncident->GetKineticEnergy();
  //
  // calculate Q-value of reactions
  //
  G4double theAtomicMass = targetNucleus.AtomicMass( A, Z );
  G4double massVec[9];
  massVec[0] = targetNucleus.AtomicMass( A+1.0, Z+1.0 );
  massVec[1] = 0.;
  if (A > Z+1.0)
     massVec[1] = targetNucleus.AtomicMass( A    , Z+1.0 );
  massVec[2] = theAtomicMass;
  massVec[3] = 0.;
  if (A > 1.0 && A-1.0 > Z) 
     massVec[3] = targetNucleus.AtomicMass( A-1.0, Z );
  massVec[4] = 0.;
  if (A > 2.0 && A-2.0 > Z) 
     massVec[4] = targetNucleus.AtomicMass( A-2.0, Z     );
  massVec[5] = 0.;
  if (A > 3.0 && Z > 1.0 && A-3.0 > Z-1.0) 
     massVec[5] = targetNucleus.AtomicMass( A-3.0, Z-1.0 );
  massVec[6] = 0.;
  if (A > 1.0 && A-1.0 > Z+1.0) 
     massVec[6] = targetNucleus.AtomicMass( A-1.0, Z+1.0 );
  massVec[7] = massVec[3];
  massVec[8] = 0.;
  if (A > 1.0 && Z > 1.0) 
     massVec[8] = targetNucleus.AtomicMass( A-1.0, Z-1.0 );
    
  G4FastVector<G4ReactionProduct,4> vec;  // vec will contain the secondary particles
  G4int vecLen = 0;
  vec.Initialize( 0 );
    
  twoBody.NuclearReaction( vec, vecLen, originalIncident,
                           targetNucleus, theAtomicMass, massVec );
    
  theParticleChange.SetStatusChange( stopAndKill );
  theParticleChange.SetEnergyChange( 0.0 );
    
  G4DynamicParticle *pd;
  for( G4int i=0; i<vecLen; ++i )
  {
    pd = new G4DynamicParticle();
    pd->SetDefinition( vec[i]->GetDefinition() );
    pd->SetMomentum( vec[i]->GetMomentum() );
    theParticleChange.AddSecondary( pd );
    delete vec[i];
  }
}


// Initial Collision
//   selects the particle types arising from the initial collision of
//   the proton and target nucleon.  Secondaries are assigned to forward 
//   and backward reaction hemispheres, but final state energies and 
//   momenta are not calculated here.

void 
G4RPGProtonInelastic::InitialCollision(G4FastVector<G4ReactionProduct,256>& vec,
                                  G4int& vecLen,
                                  G4ReactionProduct& currentParticle,
                                  G4ReactionProduct& targetParticle,
                                  G4bool& incidentHasChanged,
                                  G4bool& targetHasChanged)
{
  G4double KE = currentParticle.GetKineticEnergy()/GeV;

  G4int mult;
  G4int partType;
  std::vector<G4int> fsTypes;
  G4int part1; 
  G4int part2;

  G4double testCharge;
  G4double testBaryon;
  G4double testStrange;
 
  // Get particle types according to incident and target types
 
  if (targetParticle.GetDefinition() == particleDef[pro]) {
    mult = GetMultiplicityT1(KE);
    fsTypes = GetFSPartTypesForPP(mult, KE);

    part1 = fsTypes[0];
    part2 = fsTypes[1];
    currentParticle.SetDefinition(particleDef[part1]);
    targetParticle.SetDefinition(particleDef[part2]);
    if (part1 == pro) {
      if (part2 == neu) {
        if (G4UniformRand() > 0.5) {
          incidentHasChanged = true;
          targetParticle.SetDefinition(particleDef[part1]);
          currentParticle.SetDefinition(particleDef[part2]);
	} else {
          targetHasChanged = true;
	}
      } else if (part2 > neu && part2 < xi0) {
        targetHasChanged = true;
      }

    } else {  // neutron
      targetHasChanged = true;
      incidentHasChanged = true;
    }

    testCharge = 2.0;
    testBaryon = 2.0;
    testStrange = 0.0;
 
  } else {   // target was a neutron
    mult = GetMultiplicityT0(KE);
    fsTypes = GetFSPartTypesForPN(mult, KE);

    part1 = fsTypes[0];
    part2 = fsTypes[1];
    currentParticle.SetDefinition(particleDef[part1]);
    targetParticle.SetDefinition(particleDef[part2]);
    if (part1 == pro) {
      if (part2 == pro) {
        targetHasChanged = true;
      } else if (part2 == neu) {
        if (G4UniformRand() > 0.5) {
          incidentHasChanged = true;
          targetHasChanged = true;
          targetParticle.SetDefinition(particleDef[part1]);
          currentParticle.SetDefinition(particleDef[part2]);
	}
      } else {  // hyperon 
        targetHasChanged = true;
      }

    } else {  // neutron
      incidentHasChanged = true;
      if (part2 > neu && part2 < xi0) targetHasChanged = true;
    }

    testCharge = 1.0;
    testBaryon = 2.0;
    testStrange = 0.0;
  }

  // Remove incident and target from fsTypes
 
  fsTypes.erase(fsTypes.begin());
  fsTypes.erase(fsTypes.begin());

  // Remaining particles are secondaries.  Put them into vec.
 
  G4ReactionProduct* rp(0);
  for(G4int i=0; i < mult-2; ++i ) {
    partType = fsTypes[i];
    rp = new G4ReactionProduct();
    rp->SetDefinition(particleDef[partType]);
    (G4UniformRand() < 0.5) ? rp->SetSide(-1) : rp->SetSide(1);
    vec.SetElement(vecLen++, rp);
  }

  // Check conservation of charge, strangeness, baryon number
 
  CheckQnums(vec, vecLen, currentParticle, targetParticle,
             testCharge, testBaryon, testStrange);
 
  return;
}