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// $Id: G4PreCompoundNucleon.cc,v 1.14 2010/08/28 15:16:55 vnivanch Exp $
// GEANT4 tag $Name: geant4-09-03-ref-09 $
//
// -------------------------------------------------------------------
//
// GEANT4 Class file
//
//
// File name:     G4PreCompoundNucleon
//
// Author:         V.Lara
//
// Modified:  
// 10.02.2009 J. M. Quesada cleanup
// 20.08.2010 V.Ivanchenko added G4Pow and G4PreCompoundParameters pointers
//                         use int Z and A and cleanup
//

#include "G4PreCompoundNucleon.hh"

G4PreCompoundNucleon::
G4PreCompoundNucleon(const G4ParticleDefinition* part,
		      G4VCoulombBarrier* aCoulombBarrier)
  : G4PreCompoundFragment(part,aCoulombBarrier)
{
  fact = 2*CLHEP::millibarn/(CLHEP::pi2*CLHEP::hbarc*CLHEP::hbarc*CLHEP::hbarc);
}

G4PreCompoundNucleon::~G4PreCompoundNucleon()
{}

G4double G4PreCompoundNucleon::
ProbabilityDistributionFunction(G4double eKin, 
				const G4Fragment& aFragment)
{
  if ( !IsItPossible(aFragment) ) { return 0.0; }

  G4double U = aFragment.GetExcitationEnergy();
  G4int P = aFragment.GetNumberOfParticles();
  G4int H = aFragment.GetNumberOfHoles();
  G4int N = P + H;

  G4double g0 = (6.0/pi2)*aFragment.GetA_asInt()*theParameters->GetLevelDensity();
  G4double g1 = (6.0/pi2)*GetRestA()*theParameters->GetLevelDensity();
  
  G4double A0 = G4double(P*P+H*H+P-3*H)/(4.0*g0);
  G4double A1 = (A0 - 0.5*P)/g1;  

  G4double E0 = U - A0;
  if (E0 <= 0.0) { return 0.0; }

  G4double E1 = U - eKin - GetBindingEnergy() - A1;
  if (E1 <= 0.0) { return 0.0; }

  G4double rj = GetRj(P, aFragment.GetNumberOfCharged());
  G4double xs = CrossSection(eKin);

  if (rj <0.0 || xs < 0.0) {  
    std::ostringstream errOs;
    G4cout<<"WARNING:  NEGATIVE VALUES "<<G4endl;     
    errOs << "Rj=" << rj <<"  xsec("
	  <<eKin/MeV<<" MeV)= "<< xs <<"  A= "<<GetA()<<"  Z= "<<GetZ()
	  <<G4endl;
    throw G4HadronicException(__FILE__, __LINE__, errOs.str());
  }

  G4double Probability = fact * GetReducedMass() * rj * xs * eKin * P * (N-1) 
    * g4pow->powN(g1*E1/(g0*E0),N-2) * g1 / (E0*g0*g0);
  
  /*
  G4double Probability = 1.0/pi2*2.0/(hbarc*hbarc*hbarc) * GetReducedMass()
    * GetRj(aFragment.GetNumberOfParticles(), aFragment.GetNumberOfCharged())  
    * eKin*CrossSection(eKin)*millibarn * P*(N-1.0) * 
   std::pow(g1*E1/(g0*E0),N-2.0)/E0 * g1/(g0*g0);
  */

  return Probability;
}