G4ProtonField.cc

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// -------------------------------------------------------------------
//      GEANT 4 class implementation file 
//
//      CERN, Geneva, Switzerland
//
//      File name:     G4ProtonField.cc
//
//      Author:        Alessandro Brunengo (Alessandro.Brunengo@ge.infn.it)
// 
//      Creation date: 5 June 2000
// -------------------------------------------------------------------

#include "G4ProtonField.hh"
#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"
#include "G4VNuclearDensity.hh"
#include "G4FermiMomentum.hh"
#include "G4V3DNucleus.hh"

G4ProtonField::G4ProtonField(G4V3DNucleus * aNucleus) : 
   G4VNuclearField(aNucleus), theDensity(theNucleus->GetNuclearDensity())
{ 
  theA = theNucleus->GetMassNumber();
  theZ = theNucleus->GetCharge();
  theBarrier = GetBarrier();
  theRadius = 2.*theNucleus->GetOuterRadius();
  theFermi.Init(theA, theZ);
  G4double aR=0;
  while(aR<theRadius)
  {
    G4ThreeVector aPosition(0,0,aR);
    G4double density = GetDensity(aPosition);
    G4double fermiMom = GetFermiMomentum(density);
    theFermiMomBuffer.push_back(fermiMom);
    aR+=0.3*fermi;
  }
  {
  G4ThreeVector aPosition(0,0,theRadius);
  G4double density = GetDensity(aPosition);
  G4double fermiMom = GetFermiMomentum(density);
  theFermiMomBuffer.push_back(fermiMom);  
  }
  {
  G4ThreeVector aPosition(0,0,theRadius+0.001*fermi);
  theFermiMomBuffer.push_back(0);  
  }
  {
  G4ThreeVector aPosition(0,0,1.*m);
  theFermiMomBuffer.push_back(0);  
  }
}


G4ProtonField::~G4ProtonField()
{ }

G4double G4ProtonField::GetField(const G4ThreeVector & aPosition)
{
//G4cout << " Fermi Potential " << (fermiMom*fermiMom)/(2*proton_mass_c2) <<G4endl;
  G4double x = aPosition.mag();
  unsigned int index = static_cast<unsigned int>(x/(0.3*fermi));
  if((index+2) > theFermiMomBuffer.size()) return theFermiMomBuffer.back();
  G4double y1 = theFermiMomBuffer[index];
  G4double y2 = theFermiMomBuffer[index+1];
  G4double x1 = (0.3*fermi)*index;
  G4double x2 = (0.3*fermi)*(index+1);
  G4double fermiMom = y1 + (x-x1)*(y2-y1)/(x2-x1);
  G4double y = -1*(fermiMom*fermiMom)/(2*proton_mass_c2)+theBarrier;
//  G4cout <<" Protonfield test "<<index<<" "<< x1<<" "<<y1<<" "<<x2<<" "<<y2<<" "<<x<<" "<<y<<" "<<theBarrier<<G4endl;
  return y;
}

G4double G4ProtonField::GetBarrier()
{
  G4double coulombBarrier = (1.44/1.14) * MeV * theZ / (1.0 + std::pow(theA,1./3.));
//GF   G4double bindingEnergy = G4NucleiPropertiesTable::GetBindingEnergy(Z, A);
  G4double bindingEnergy =0;
/*
 *   G4cout << " coulombBarrier/bindingEnergy : " 
 *       << coulombBarrier << " /" << bindingEnergy << G4endl;
 */
  return bindingEnergy/theA+coulombBarrier;
}