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// $Id: G4PreCompoundFragment.cc,v 1.8 2009/02/10 16:01:37 vnivanch Exp $
// GEANT4 tag $Name: geant4-09-03 $
//
// J. M. Quesada (August 2008).  
// Based  on previous work by V. Lara
// JMQ (06 September 2008) Also external choice has been added for:
//                      - superimposed Coulomb barrier (if useSICB=true) 
//
#include "G4PreCompoundFragment.hh"

G4PreCompoundFragment::
G4PreCompoundFragment(const G4PreCompoundFragment &right) :
  G4VPreCompoundFragment(right)
{}


G4PreCompoundFragment::
G4PreCompoundFragment(const G4double anA,
		      const G4double aZ, 
		      G4VCoulombBarrier* aCoulombBarrier,
		      const G4String & aName):
  G4VPreCompoundFragment(anA,aZ,aCoulombBarrier,aName)
{
}



G4PreCompoundFragment::~G4PreCompoundFragment()
{
}


const G4PreCompoundFragment & G4PreCompoundFragment::
operator= (const G4PreCompoundFragment & right)
{
  if (&right != this) this->G4VPreCompoundFragment::operator=(right);
  return *this;
}

G4int G4PreCompoundFragment::operator==(const G4PreCompoundFragment & right) const
{
  return G4VPreCompoundFragment::operator==(right);
}

G4int G4PreCompoundFragment::operator!=(const G4PreCompoundFragment & right) const
{
  return G4VPreCompoundFragment::operator!=(right);
}


G4double G4PreCompoundFragment::
CalcEmissionProbability(const G4Fragment & aFragment)
{
// If  theCoulombBarrier effect is included in the emission probabilities
//if (GetMaximalKineticEnergy() <= 0.0) 
  G4double limit;
  if(OPTxs==0 ||  useSICB) limit= theCoulombBarrier;
  else limit=0.;
  if (GetMaximalKineticEnergy() <= limit) 
    {
      theEmissionProbability = 0.0;
      return 0.0;
  }    
// If  theCoulombBarrier effect is included in the emission probabilities
//  G4double LowerLimit = 0.;
// Coulomb barrier is the lower limit 
// of integration over kinetic energy
  G4double LowerLimit = limit;

// Excitation energy of nucleus after fragment emission is the upper limit of integration over kinetic energy
  G4double UpperLimit = GetMaximalKineticEnergy();
  
  theEmissionProbability = 
    IntegrateEmissionProbability(LowerLimit,UpperLimit,aFragment);
  return theEmissionProbability;
}

G4double G4PreCompoundFragment::
IntegrateEmissionProbability(const G4double & Low, const G4double & Up,
			     const G4Fragment & aFragment)
{
  static const G4int N = 10;
  // 10-Points Gauss-Legendre abcisas and weights
  static const G4double w[N] = {
    0.0666713443086881,
    0.149451349150581,
    0.219086362515982,
    0.269266719309996,
    0.295524224714753,
    0.295524224714753,
    0.269266719309996,
    0.219086362515982,
    0.149451349150581,
    0.0666713443086881
  };
  static const G4double x[N] = {
    -0.973906528517172,
    -0.865063366688985,
    -0.679409568299024,
    -0.433395394129247,
    -0.148874338981631,
    0.148874338981631,
    0.433395394129247,
    0.679409568299024,
    0.865063366688985,
    0.973906528517172
  };
  
  G4double Total = 0.0;


  for (G4int i = 0; i < N; i++) 
    {
      G4double KineticE = ((Up-Low)*x[i]+(Up+Low))/2.0;
      Total += w[i]*ProbabilityDistributionFunction(KineticE, aFragment);
    }
  Total  *= (Up-Low)/2.0;
  return Total;
}




G4double G4PreCompoundFragment::
GetKineticEnergy(const G4Fragment & aFragment) 
{

//	G4double V = this->GetCoulombBarrier();// alternative way for accessing the Coulomb barrier
//                                             //should be equivalent (in fact it is)
  G4double V;
  if(OPTxs==0 || useSICB) V= theCoulombBarrier;//let's keep this way for consistency with CalcEmissionProbability method
  else V=0.;

  G4double Tmax =  GetMaximalKineticEnergy() ;  
  G4double T(0.0);
  G4double NormalizedProbability(1.0);
  do 
    {
      T =V+ G4UniformRand()*(Tmax-V);
      NormalizedProbability = ProbabilityDistributionFunction(T,aFragment)/GetEmissionProbability();      
    }   while (G4UniformRand() > NormalizedProbability);  
  return T;
}
