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// $Id: G4VEmModel.cc,v 1.8 2007/09/25 10:19:07 vnivanch Exp $
// GEANT4 tag $Name: geant4-09-01-patch-02 $
//
// -------------------------------------------------------------------
//
// GEANT4 Class file
//
//
// File name:     G4VEmModel
//
// Author:        Vladimir Ivanchenko
//
// Creation date: 25.07.2005
//
// Modifications:
// 25.10.2005 Set default highLimit=100.TeV (V.Ivanchenko)
// 06.02.2006 add method ComputeMeanFreePath() (mma)
//
//
// Class Description:
//
// Abstract interface to energy loss models

// -------------------------------------------------------------------
//

#include "G4VEmModel.hh"

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G4VEmModel::G4VEmModel(const G4String& nam):
 lowLimit(0.1*keV), highLimit(100.0*TeV), fluc(0), name(nam), pParticleChange(0)
{}

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G4VEmModel::~G4VEmModel()
{}

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G4double G4VEmModel::CrossSectionPerVolume(const G4Material* material,
					   const G4ParticleDefinition* p,
					         G4double ekin,
					         G4double emin,
                                                 G4double emax)
{
  G4double cross = 0.0;
  const G4ElementVector* theElementVector = material->GetElementVector();
  const G4double* theAtomNumDensityVector = material->GetVecNbOfAtomsPerVolume();
  size_t nelm = material->GetNumberOfElements();
  for (size_t i=0; i<nelm; i++) {
    const G4Element* elm = (*theElementVector)[i];
    cross += theAtomNumDensityVector[i]*
      ComputeCrossSectionPerAtom(p,ekin,elm->GetZ(),elm->GetN(),emin,emax);
    xsec[i] = cross;
  }
  return cross;
}

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G4double G4VEmModel::ComputeMeanFreePath(const G4ParticleDefinition* p,
					       G4double ekin,
					 const G4Material* material,     
					       G4double emin,
                                               G4double emax)
{
  G4double mfp = DBL_MAX;
  G4double cross = CrossSectionPerVolume(material,p,ekin,emin,emax);
  if (cross > DBL_MIN) mfp = 1./cross;
  return mfp;
}

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