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// $Id: G4QuasiElasticChannel.cc,v 1.4 2008/04/24 13:26:19 gunter Exp $
// GEANT4 tag $Name: geant4-09-02-ref-02 $
//

// Author : Gunter Folger March 2007
// Class Description
// Final state production model for theoretical models of hadron inelastic
// quasi elastic scattering in geant4;
// Class Description - End
//
// Modified:

#include "G4QuasiElasticChannel.hh"

#include "G4Fancy3DNucleus.hh"


#include "G4HadTmpUtil.hh"		//lrint

//#define debug_scatter

G4QuasiElasticChannel::G4QuasiElasticChannel()
{
	theQuasiElastic=G4QuasiFreeRatios::GetPointer();
}

G4QuasiElasticChannel::~G4QuasiElasticChannel()
{}

G4double G4QuasiElasticChannel::GetFraction(G4Nucleus &theNucleus,
				const G4DynamicParticle & thePrimary)
{
	std::pair<G4double,G4double> ratios;
	ratios=theQuasiElastic->GetRatios(thePrimary.GetTotalMomentum(),
			thePrimary.GetDefinition()->GetPDGEncoding(),
			G4lrint(theNucleus.GetZ()),
			G4lrint(theNucleus.GetN()-theNucleus.GetZ()));
#ifdef debug_getFraction			
	G4cout << "G4QuasiElasticChannel::ratios " << ratios.first << " x " <<ratios.second
	       << "  = " << ratios.first*ratios.second << G4endl;
#endif
	       
	return ratios.first*ratios.second;       		
}

G4KineticTrackVector * G4QuasiElasticChannel::Scatter(G4Nucleus &theNucleus,
					const G4DynamicParticle & thePrimary)
{
	
	
	G4int A=G4lrint(theNucleus.GetN());
//	G4int Z=G4lrint(theNucleus.GetZ());
//   build Nucleus and choose random nucleon to scatter with
	the3DNucleus.Init(theNucleus.GetN(),theNucleus.GetZ());
	const std::vector<G4Nucleon *> nucleons=the3DNucleus.GetNucleons();
	
        G4int index;
        do {
	   index=G4lrint((A-1)*G4UniformRand());
	   
	} while (index < 0 || index >= static_cast<G4int>(nucleons.size()));
	    
//	G4double an=G4UniformRand()*A;
	G4ParticleDefinition * pDef= nucleons[index]->GetDefinition();
	
#ifdef debug_scatter
	G4cout << " neutron - proton? A, Z, an, pdg" <<" "
	       << A <<" "<<G4lrint(theNucleus.GetZ())
	       << " "<<an <<" " << pDef->GetParticleName()<< G4endl;
#endif
//	G4LorentzVector pNucleon(G4ThreeVector(0,0,0),pDef->GetPDGMass());
	G4LorentzVector pNucleon=nucleons[index]->Get4Momentum();
	
	std::pair<G4LorentzVector,G4LorentzVector> result;
	
	result=theQuasiElastic->Scatter(pDef->GetPDGEncoding(),pNucleon,
	                       thePrimary.GetDefinition()->GetPDGEncoding(),
			        thePrimary.Get4Momentum());
				
	if (result.first.e() == 0.)
	{
	   G4cout << "Warning - G4QuasiElasticChannel::Scatter no scattering" << G4endl;
	   return 0;       //no scatter
	}

#ifdef debug_scatter
        G4LorentzVector EpConservation=pNucleon+thePrimary.Get4Momentum() 
	                                - result.first - result.second;
	if (   (EpConservation.vect().mag2() > 0.01*MeV*MeV )
	    || 	(std::abs(EpConservation.e()) > 0.1 * MeV ) ) 
	{
	    G4cout << "Warning - G4QuasiElasticChannel::Scatter E-p non conservation : "
	            << EpConservation << G4endl;
	}    
#endif

	G4KineticTrackVector * ktv;
	ktv=new G4KineticTrackVector();
	G4KineticTrack * sPrim=new G4KineticTrack(thePrimary.GetDefinition(),
			0.,G4ThreeVector(0), result.second);
	ktv->push_back(sPrim);
	G4KineticTrack * sNuc=new G4KineticTrack(pDef,
			0.,G4ThreeVector(0), result.first);
	ktv->push_back(sNuc);
	
#ifdef debug_scatter
	G4cout << " scattered Nucleon : " << result.first << " mass " <<result.first.mag() << G4endl;
	G4cout << " scattered Project : " << result.second << " mass " <<result.second.mag() << G4endl;
#endif
	return ktv;			       
}