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// $Id: G4RToEConvForProton.cc,v 1.6 2009/09/14 07:27:46 kurasige Exp $
// GEANT4 tag $Name: geant4-09-03 $
//
//
// --------------------------------------------------------------
//      GEANT 4 class implementation file/  History:
//    5 Oct. 2002, H.Kuirashige : Structure created based on object model
// --------------------------------------------------------------

#include "G4RToEConvForProton.hh"
#include "G4ParticleTable.hh"
#include "G4Material.hh"
#include "G4PhysicsLogVector.hh"

#include "G4ios.hh"

G4RToEConvForProton::G4RToEConvForProton() : G4VRangeToEnergyConverter()
{    
  theParticle =  G4ParticleTable::GetParticleTable()->FindParticle("proton");
  if (theParticle ==0) {
#ifdef G4VERBOSE
    if (GetVerboseLevel()>0) {
      G4cout << " G4RToEConvForProton::G4RToEConvForProton() ";
      G4cout << " proton is not defined !!" << G4endl;
    }
#endif
  } 
}

G4RToEConvForProton::~G4RToEConvForProton()
{ 
}


G4double G4RToEConvForProton::Convert(G4double rangeCut, const G4Material* )
{
  // Simple formula
  //   range = Ekin/(100*keV)*(1*mm);
  return (rangeCut/(1.0*mm)) * (100.0*keV); 
}


// **********************************************************************
// ************************* ComputeLoss ********************************
// **********************************************************************
G4double G4RToEConvForProton::ComputeLoss(G4double AtomicNumber,
                                                G4double KineticEnergy) const
{
  //  calculate dE/dx

  static G4double Z;  
  static G4double ionpot, tau0, taum, taul, ca, cba, cc;

  G4double  z2Particle = theParticle->GetPDGCharge()/eplus;
  z2Particle *=  z2Particle;
  if (z2Particle < 0.1) return 0.0;

  if( std::fabs(AtomicNumber-Z)>0.1 ){
    // recalculate constants
    Z = AtomicNumber;
    G4double Z13 = std::exp(std::log(Z)/3.);
    tau0 = 0.1*Z13*MeV/proton_mass_c2;
    taum = 0.035*Z13*MeV/proton_mass_c2;
    taul = 2.*MeV/proton_mass_c2;
    ionpot = 1.6e-5*MeV*std::exp(0.9*std::log(Z));
   cc = (taul+1.)*(taul+1.)*std::log(2.*electron_mass_c2*taul*(taul+2.)/ionpot)/(taul*(taul+2.))-1.;
    cc = 2.*twopi_mc2_rcl2*Z*cc*std::sqrt(taul);
    ca = cc/((1.-0.5*std::sqrt(tau0/taum))*tau0);
    cba = -0.5/std::sqrt(taum);
  }

  G4double tau = KineticEnergy/theParticle->GetPDGMass();
  G4double dEdx;
  if ( tau <= tau0 ) {
    dEdx = ca*(std::sqrt(tau)+cba*tau);
  } else {
    if( tau <= taul ) {
      dEdx = cc/std::sqrt(tau);
    } else {
      dEdx = (tau+1.)*(tau+1.)*
             std::log(2.*electron_mass_c2*tau*(tau+2.)/ionpot)/(tau*(tau+2.))-1.;
      dEdx = 2.*twopi_mc2_rcl2*Z*dEdx;
    }
  }
  return dEdx*z2Particle ;
}


// **********************************************************************
// ************************* Reset       ********************************
// **********************************************************************
void G4RToEConvForProton::Reset()
{
  // do nothing because loss tables and range vectors are not used 
  return;
}
