text: //
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  // -------------------------------------------------------------------
  //      GEANT 4 class implementation file 
  //
  //      CERN, Geneva, Switzerland
  //
  //      File name:     G4KaonPlusField.cc
  //
  //      Author:        Alessandro Brunengo (Alessandro.Brunengo@ge.infn.it)
  // 
  //      Creation date: 5 June 2000
  // -------------------------------------------------------------------
  
  #include "G4KaonPlusField.hh"
  #include "G4PhysicalConstants.hh"
  #include "G4SystemOfUnits.hh"
  #include "G4NucleiProperties.hh"
  #include "G4VNuclearDensity.hh"
  #include "G4FermiMomentum.hh"
  #include "G4KaonPlus.hh"
  #include "G4HadTmpUtil.hh"
  #include "G4Pow.hh"
  
  G4KaonPlusField::G4KaonPlusField(G4V3DNucleus * nucleus, G4double coeff)
    : G4VNuclearField(nucleus)
  {
    theCoeff = coeff;
  }
  
  
  G4KaonPlusField::~G4KaonPlusField()
  { }
  
  G4double G4KaonPlusField::GetField(const G4ThreeVector & aPosition)
  {
  // Field is 0 out of the nucleus!
    if(aPosition.mag() >= radius) return 0.0;
  
    G4double kaonMass = G4KaonPlus::KaonPlus()->GetPDGMass();
  
    G4int A = theNucleus->GetMassNumber();
    G4int Z = theNucleus->GetCharge();
    G4double bindingEnergy = G4NucleiProperties::GetBindingEnergy(A, Z);
    G4double nucleusMass = Z*proton_mass_c2+(A-Z)*neutron_mass_c2+bindingEnergy;
    G4double reducedMass = kaonMass*nucleusMass/(kaonMass+nucleusMass);
  
    G4double density = theNucleus->GetNuclearDensity()->GetDensity(aPosition);
  
    return -2.*pi*hbarc*hbarc/reducedMass*(2.0)*theCoeff*density+GetBarrier();
  }
  
  G4double G4KaonPlusField::GetBarrier()
  {
    G4int A = theNucleus->GetMassNumber();
    G4int Z = theNucleus->GetCharge();
    G4double coulombBarrier = (1.44/1.14) * MeV * Z / (1.0 + G4Pow::GetInstance()->Z13(A));
    return coulombBarrier;
  }
  
  
  