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// $Id: G4NeutronRadCapture.cc,v 1.4 2009/12/16 17:51:11 gunter Exp $
// GEANT4 tag $Name: geant4-09-04-beta-01 $
//
//
// Physics model class G4NeutronRadCapture 
// Created:  31 August 2009
// Author  V.Ivanchenko
//  
// Modified:
//
//

#include "G4NeutronRadCapture.hh"
#include "G4ParticleDefinition.hh"
#include "G4Fragment.hh"
#include "G4FragmentVector.hh"
#include "G4NucleiProperties.hh"
#include "G4PhotonEvaporation.hh"
#include "G4DynamicParticle.hh"
#include "G4ParticleDefinition.hh"
#include "G4ParticleTable.hh"
#include "G4Deuteron.hh"
#include "G4Triton.hh"
#include "G4He3.hh"
#include "G4Alpha.hh"

G4NeutronRadCapture::G4NeutronRadCapture() 
  : G4HadronicInteraction("nRadCapture")
{
  lowestEnergyLimit = 0.1*eV;
  SetMinEnergy( 0.0*GeV );
  SetMaxEnergy( 100.*TeV );
  //  photonEvaporation = new G4PhotonEvaporation();
  photonEvaporation = 0;
}

G4NeutronRadCapture::~G4NeutronRadCapture()
{
  delete photonEvaporation;
}

G4HadFinalState* G4NeutronRadCapture::ApplyYourself(
		 const G4HadProjectile& aTrack, G4Nucleus& targetNucleus)
{
  theParticleChange.Clear();

  G4int Z = static_cast<G4int>(targetNucleus.GetZ()+0.5);
  G4int A = static_cast<G4int>(targetNucleus.GetN()+0.5);

  // Create initial state
  G4double m1 = G4NucleiProperties::GetNuclearMass(A, Z);
  G4LorentzVector lv0(0.0,0.0,0.0,m1);   
  G4LorentzVector lv1 = aTrack.Get4Momentum() + lv0;
  G4ThreeVector bst = lv1.boostVector();
  G4double M  = lv1.mag();

  ++A;
  G4double m2 = G4NucleiProperties::GetNuclearMass(A, Z);
  if(M - m2 <= lowestEnergyLimit) {
    return &theParticleChange;
  }

  if (verboseLevel > 1) {
    G4cout << "G4NeutronRadCapture::DoIt: Eini(MeV)=" 
	   << aTrack.GetKineticEnergy()/MeV << "  Eexc(MeV)= " 
	   << (M - m2)/MeV 
	   << "  Z= " << Z << "  A= " << A << G4endl;
  }

  G4double e1 = (M - m2)*(M + m2)/(2*M);
  G4double cost = 2.0*G4UniformRand() - 1.0;
  if(cost > 1.0) {cost = 1.0;}
  else if(cost < -1.0) {cost = -1.0;}
  G4double sint = std::sqrt((1. - cost)*(1.0 + cost));
  G4double phi  = G4UniformRand()*CLHEP::twopi;
  G4LorentzVector lv2(e1*sint*std::cos(phi),e1*sint*std::sin(phi),e1*cost,e1);   
  lv2.boost(bst);
  theParticleChange.AddSecondary(new G4DynamicParticle(G4Gamma::Gamma(), lv2));
  G4ParticleDefinition* theDef = 0;

  lv1 -= lv2; 
  if(Z > 2 || A > 4) 
    {
      theDef = G4ParticleTable::GetParticleTable()->FindIon(Z,A,0,Z);
    }
  else if (Z == 1 && A == 2) {theDef = G4Deuteron::Deuteron();}
  else if (Z == 1 && A == 3) {theDef = G4Triton::Triton();}
  else if (Z == 2 && A == 3) {theDef = G4He3::He3();}
  else if (Z == 2 && A == 4) {theDef = G4Alpha::Alpha();}

  if (verboseLevel > 1) {
    G4cout << "Gamma 4-mom: " << lv2 << "   " 
	   << theDef->GetParticleName() << "   " << lv1 << G4endl;
  }
  if(theDef) {
    theParticleChange.AddSecondary(new G4DynamicParticle(theDef, lv1));
  }
  
  /*
  // Create fragment in its rest frame
  lv1.boost(-bst);
  G4Fragment aNucleus(A+1, Z, lv1);
  if(aNucleus.GetExcitationEnergy() <= lowestEnergyLimit) {
    return &theParticleChange;
  }

  if (verboseLevel > 1) {
    G4cout << "G4NeutronRadCapture::DoIt: Eini(MeV)=" 
	   << aTrack.GetKineticEnergy()/MeV << "  Eexc(MeV)= " 
	   << lv1.e() - G4NucleiProperties::GetNuclearMass(A+1, Z) 
	   << "  Z= " << Z << "  A= " << A + 1 << G4endl;
  }

  //
  // Sample final state
  //

  G4FragmentVector* fv = photonEvaporation->BreakItUp(aNucleus);
  size_t n = fv->size();

  if (verboseLevel > 1) {
    G4cout << "G4NeutronRadCapture: " << n << " final particle" << G4endl;
  }
  for(size_t i=0; i<n; ++i) {
    G4Fragment* f = (*fv)[i];    
    G4LorentzVector lvres = f->GetMomentum();   
    lvres.boost(bst);
    G4int Z = G4int(f->GetZ() + 0.5);
    G4int A = G4int(f->GetA() + 0.5);

    G4ParticleDefinition* theDef = 0;
    if(0 == Z && 0 == A) {theDef =  f->GetParticleDefinition();}
    else if(Z > 2 || A > 4) 
      {
	theDef = G4ParticleTable::GetParticleTable()->FindIon(Z,A,0,Z);
      }
    else if (Z == 1 && A == 2) {theDef = G4Deuteron::Deuteron();}
    else if (Z == 1 && A == 3) {theDef = G4Triton::Triton();}
    else if (Z == 2 && A == 3) {theDef = G4He3::He3();}
    else if (Z == 2 && A == 4) {theDef = G4Alpha::Alpha();}

    if (verboseLevel > 1) {
      G4cout << i << ". " << theDef->GetParticleName()
	     << "   " << lvres << G4endl;
    }
    if(theDef) {
      theParticleChange.AddSecondary(new G4DynamicParticle(theDef, lvres));
    }
    delete f;
  }
  */
  return &theParticleChange;
}