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//
// 18-Sep-2003 First version is written by T. Koi
// 23-Dec-2006 Isotope dependence added by D. Wright
//

#include "G4IonsSihverCrossSection.hh"
#include "G4ParticleTable.hh"
#include "G4IonTable.hh"

G4double G4IonsSihverCrossSection::
GetIsoZACrossSection(const G4DynamicParticle* aParticle, G4double /*ZZ*/, 
                G4double AA, G4double /*aTemperature*/)
{
   G4double xsection = 0.0;

   G4int At = G4int(AA);
   //G4int Zt = G4int(ZZ);  // not used 

   G4int Ap = aParticle->GetDefinition()->GetBaryonNumber();
   //Zp = aParticle->GetDefinition()->GetPDGCharge();   // not used  
 
   G4double one_third = 1.0 / 3.0;

   G4double cubicrAt = std::pow ( G4double(At) , G4double(one_third) ); 
   G4double cubicrAp = std::pow ( G4double(Ap) , G4double(one_third) );  

   G4double b0 = 1.581 - 0.876 * ( 1.0 / cubicrAp + 1.0 / cubicrAt );

   xsection = pi * square_r0 
            * std::pow ( G4double(cubicrAp + cubicrAt - b0 * (  1.0 / cubicrAp + 1.0 / cubicrAt ) ), G4double(2) );
  
   return xsection; 
}


G4double G4IonsSihverCrossSection::
GetCrossSection(const G4DynamicParticle* aParticle, 
                const G4Element* anElement, G4double temperature)
{
  G4int nIso = anElement->GetNumberOfIsotopes();
  G4double xsection = 0;
    
  if (nIso) {
    G4double sig;
    G4IsotopeVector* isoVector = anElement->GetIsotopeVector();
    G4double* abundVector = anElement->GetRelativeAbundanceVector();
    G4double ZZ;
    G4double AA;
    
    for (G4int i = 0; i < nIso; i++) {
      ZZ = G4double( (*isoVector)[i]->GetZ() );
      AA = G4double( (*isoVector)[i]->GetN() );
      sig = GetIsoZACrossSection(aParticle, ZZ, AA, temperature);
      xsection += sig*abundVector[i];
    }
  
  } else {
    xsection =
      GetIsoZACrossSection(aParticle, anElement->GetZ(), anElement->GetN(),
                           temperature);
  }
   
  return xsection;
}