source: trunk/source/processes/electromagnetic/lowenergy/src/G4CrossSectionChargeIncrease.cc @ 846

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// $Id: G4CrossSectionChargeIncrease.cc,v 1.3 2007/12/10 16:31:21 gunter Exp $
// GEANT4 tag $Name:  $
// 
// Contact Author: Maria Grazia Pia (Maria.Grazia.Pia@cern.ch)
//
// Reference: TNS Geant4-DNA paper
// Reference for implementation model: NIM. 155, pp. 145-156, 1978

// History:
// -----------
// Date         Name              Modification
// 28 Apr 2007  M.G. Pia          Created in compliance with design described in TNS paper
//
// -------------------------------------------------------------------

// Class description:
// Geant4-DNA Cross total cross section for electron elastic scattering in water
// Reference: TNS Geant4-DNA paper
// S. Chauvie et al., Geant4 physics processes for microdosimetry simulation:
// design foundation and implementation of the first set of models,
// IEEE Trans. Nucl. Sci., vol. 54, no. 6, Dec. 2007.
// Further documentation available from http://www.ge.infn.it/geant4/dna

// -------------------------------------------------------------------


#include "G4CrossSectionChargeIncrease.hh"
#include "G4Track.hh"
#include "G4DynamicParticle.hh"
#include "G4ParticleDefinition.hh"
#include "G4DNAGenericIonsManager.hh"

G4CrossSectionChargeIncrease::G4CrossSectionChargeIncrease()
{
  // Default energy limits (defined for protection against anomalous behaviour only)
  name = "ChargeIncrease";
  lowEnergyLimitDefault = 1 * keV;
  highEnergyLimitDefault = 10 * MeV;

  G4DNAGenericIonsManager *instance;
  instance = G4DNAGenericIonsManager::Instance();
  G4ParticleDefinition* hydrogenDef = instance->GetIon("hydrogen");
  G4ParticleDefinition* alphaPlusDef = instance->GetIon("alpha+");
  G4ParticleDefinition* heliumDef = instance->GetIon("helium");

  G4String hydrogen;
  G4String alphaPlus;
  G4String helium;

  if (hydrogenDef != 0)
    {
      hydrogen = hydrogenDef->GetParticleName();
      lowEnergyLimit[hydrogen] = 1. * keV;
      highEnergyLimit[hydrogen] = 10. * MeV;
    }
  else
    {
      G4Exception("G4CrossSectionChargeIncrease Constructor: hydrogen is not defined");
    }

  if (alphaPlusDef != 0)
    {
      alphaPlus = alphaPlusDef->GetParticleName();
      lowEnergyLimit[alphaPlus] = 1. * keV;
      highEnergyLimit[alphaPlus] = 10. * MeV;
    }
  else
    {
      G4Exception("G4CrossSectionChargeIncrease Constructor: alphaPlus is not defined");
    }

  if (heliumDef != 0)
    {
      helium = heliumDef->GetParticleName();
      lowEnergyLimit[helium] = 1. * keV;
      highEnergyLimit[helium] = 10. * MeV;
    }
  else
    {
      G4Exception("G4CrossSectionChargeIncrease Constructor: helium is not defined");
    }

}


G4CrossSectionChargeIncrease::~G4CrossSectionChargeIncrease()
{}
 

G4double G4CrossSectionChargeIncrease::CrossSection(const G4Track& track)
{
  G4double lowLim = lowEnergyLimitDefault;
  G4double highLim = highEnergyLimitDefault;

  const G4DynamicParticle* particle = track.GetDynamicParticle();
  G4double k = particle->GetKineticEnergy();

  const G4String& particleName = particle->GetDefinition()->GetParticleName();

  G4DNAGenericIonsManager *instance;
  instance = G4DNAGenericIonsManager::Instance();
  
  const G4ParticleDefinition* particleDefinition = track.GetDefinition();

  if (
      particleDefinition != instance->GetIon("hydrogen")
      &&
      particleDefinition != instance->GetIon("alpha+")
      &&
      particleDefinition != instance->GetIon("helium")
      )
            
    G4Exception("G4CrossSectionChargeIncrease: attempting to calculate cross section for wrong particle");


  // Retrieve energy limits for the current particle type

  std::map< G4String,G4double,std::less<G4String> >::iterator pos1;
  pos1 = lowEnergyLimit.find(particleName);

  // Lower limit
  if (pos1 != lowEnergyLimit.end())
    {
      lowLim = pos1->second;
    }

  // Upper limit
  std::map< G4String,G4double,std::less<G4String> >::iterator pos2;
  pos2 = highEnergyLimit.find(particleName);

  if (pos2 != highEnergyLimit.end())
    {
      highLim = pos2->second;
    }

  G4double totalCrossSection = 0.;

  if (k >= lowLim && k <= highLim)
    {
      //HYDROGEN
      if (particleDefinition == instance->GetIon("hydrogen"))
        {
          const  G4double aa = 2.835;
          const  G4double bb = 0.310;
          const  G4double cc = 2.100;
          const  G4double dd = 0.760;
          const  G4double fac = 1.0e-18;
          const  G4double rr = 13.606 * eV;  
          
          G4double t = k / (proton_mass_c2/electron_mass_c2); 
          G4double x = t / rr; 
          G4double temp = 4.0 * pi * Bohr_radius/nm * Bohr_radius/nm * fac;
          G4double sigmal =  temp * cc * (std::pow(x,dd));
          G4double sigmah = temp * (aa * std::log(1.0 + x) + bb) / x;
          totalCrossSection = 1.0/(1.0/sigmal + 1.0/sigmah) *m*m;
        }
      else
        {
          totalCrossSection = partialCrossSection.Sum(k,particleDefinition);
        }
    }
  
  return totalCrossSection;
}