G4GEMCoulombBarrier.cc

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// J. M. Quesada (July 2009):  New class based on G4GEMCoulombBarrierHE
// Coded strictly according to Furihata's GEM paper 
// NEW:effective decrease  of barrier with E* (Barashenkov) has been added
//
#include "G4GEMCoulombBarrier.hh"
#include "G4HadronicException.hh"
#include "G4Pow.hh"
#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"

G4GEMCoulombBarrier::G4GEMCoulombBarrier(G4int anA, G4int aZ) :
  G4VCoulombBarrier(anA,aZ) 
{}

G4GEMCoulombBarrier::~G4GEMCoulombBarrier() 
{}

G4double G4GEMCoulombBarrier::GetCoulombBarrier(G4int ARes, G4int ZRes, G4double U) const 
// Calculation of Coulomb potential energy (barrier) for outgoing fragment
{
  G4double Barrier = 0.0;
  if (ZRes > ARes || ARes < 1) {
    G4cout << "G4GEMCoulombBarrier::GetCoulombBarrier: "
           << "Wrong values for "
           << "residual nucleus A = " << ARes << " "
           << "and residual nucleus Z = " << ZRes << G4endl;
    throw G4HadronicException(__FILE__, __LINE__,"FATAL error");
  }
  if (GetZ() == 0) {
    Barrier = 0.0;   // If there is no charge there is neither barrier

  } else {
    G4double CompoundRadius = CalcCompoundRadius(ARes);
    Barrier = ( elm_coupling * GetZ() * ZRes)/CompoundRadius;
      
    // Barrier penetration coeficient
    if(GetA() <= 4) { Barrier *= BarrierPenetrationFactor(G4double(ZRes)); }
  
    //JMQ 200709 effective decrease  of barrier with E* (Barashenkov)
    // (not inclued in original Furihata's formulation)
    Barrier /= (1.0 + std::sqrt(U/(static_cast<G4double>(2*ARes))));
  }
  return Barrier;
}

G4double G4GEMCoulombBarrier::CalcCompoundRadius(G4int ARes) const
{      
  G4Pow* g4pow = G4Pow::GetInstance();
  G4double AresOneThird = g4pow->Z13(ARes);
  G4int A = GetA();
  G4double AejectOneThird = g4pow->Z13(A);

  G4double Result = 0.0;
  if(A == 1){
    Result = 1.7* AresOneThird;

  } else if (A <= 4){
    Result = 1.7* AresOneThird + 1.2;

  } else {
    Result = 1.12*(AresOneThird + AejectOneThird) - 
      0.86*(AresOneThird+AejectOneThird)/(AresOneThird*AejectOneThird)+3.75;
  }
  return Result*fermi;
}

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