G4GammaConversion.cc

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// $Id$
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// 
//------------------ G4GammaConversion physics process -------------------------
//                   by Michel Maire, 24 May 1996
//
// 11-06-96 Added SelectRandomAtom() method, M.Maire
// 21-06-96 SetCuts implementation, M.Maire
// 24-06-96 simplification in ComputeCrossSectionPerAtom, M.Maire
// 24-06-96 in DoIt : change the particleType stuff, M.Maire
// 25-06-96 modification in the generation of the teta angle, M.Maire
// 16-09-96 minors optimisations in DoIt. Thanks to P.Urban
//          dynamical array PartialSumSigma
// 13-12-96 fast sampling of epsil below 2 MeV, L.Urban
// 14-01-97 crossection table + meanfreepath table.
//          PartialSumSigma removed, M.Maire
// 14-01-97 in DoIt the positron is always created, even with Ekine=0,
//          for further annihilation, M.Maire
// 14-03-97 new Physics scheme for geant4alpha, M.Maire
// 28-03-97 protection in BuildPhysicsTable, M.Maire
// 19-06-97 correction in ComputeCrossSectionPerAtom, L.Urban
// 04-06-98 in DoIt, secondary production condition:
//            range>std::min(threshold,safety)
// 13-08-98 new methods SetBining() PrintInfo()
// 28-05-01 V.Ivanchenko minor changes to provide ANSI -wall compilation
// 11-07-01 PostStepDoIt - sampling epsil: power(rndm,0.333333)
// 13-07-01 DoIt: suppression of production cut for the (e-,e+) (mma)
// 06-08-01 new methods Store/Retrieve PhysicsTable (mma)
// 06-08-01 BuildThePhysicsTable() called from constructor (mma)
// 17-09-01 migration of Materials to pure STL (mma)
// 20-09-01 DoIt: fminimalEnergy = 1*eV (mma)
// 01-10-01 come back to BuildPhysicsTable(const G4ParticleDefinition&)
// 11-01-02 ComputeCrossSection: correction of extrapolation below EnergyLimit
// 21-03-02 DoIt: correction of the e+e- angular distribution (bug 363) mma
// 08-11-04 Remove of Store/Retrieve tables (V.Ivantchenko)
// 19-04-05 Migrate to model interface and inherit 
//          from G4VEmProcess (V.Ivanchenko) 
// 04-05-05, Make class to be default (V.Ivanchenko)
// 09-08-06, add SetModel(G4VEmModel*) (mma)
// 12-09-06, move SetModel(G4VEmModel*) in G4VEmProcess (mma)
// -----------------------------------------------------------------------------

#include "G4GammaConversion.hh"
#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"
#include "G4BetheHeitlerModel.hh"
#include "G4PairProductionRelModel.hh"
#include "G4Electron.hh"

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using namespace std;

G4GammaConversion::G4GammaConversion(const G4String& processName,
  G4ProcessType type):G4VEmProcess (processName, type),
    isInitialised(false)
{
  SetMinKinEnergy(2.0*electron_mass_c2);
  SetProcessSubType(fGammaConversion);
  SetStartFromNullFlag(true);
  SetBuildTableFlag(true);
  SetSecondaryParticle(G4Electron::Electron());
}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
 
G4GammaConversion::~G4GammaConversion()
{}

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G4bool G4GammaConversion::IsApplicable(const G4ParticleDefinition& p)
{
  return (&p == G4Gamma::Gamma());
}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....

void G4GammaConversion::InitialiseProcess(const G4ParticleDefinition*)
{
  if(!isInitialised) {
    isInitialised = true;
    const G4double limit = 80*GeV;
    G4double emin = std::max(MinKinEnergy(), 2*electron_mass_c2);
    G4double emax = MaxKinEnergy();
    SetMinKinEnergy(emin);

    if(!EmModel(1)) { SetEmModel(new G4BetheHeitlerModel(), 1); }
    EmModel(1)->SetLowEnergyLimit(emin);
    G4double ehigh = std::min(emax,limit);
    ehigh = std::min(ehigh,EmModel(1)->HighEnergyLimit());
    EmModel(1)->SetHighEnergyLimit(ehigh);
    AddEmModel(1, EmModel(1));

    if(emax > ehigh) {
      if(!EmModel(2)) { SetEmModel(new G4PairProductionRelModel(), 2); }
      EmModel(2)->SetLowEnergyLimit(ehigh);
      EmModel(2)->SetHighEnergyLimit(emax);
      AddEmModel(2, EmModel(2));
    }
  } 
}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....

G4double G4GammaConversion::MinPrimaryEnergy(const G4ParticleDefinition*,
                         const G4Material*)
{
  return 2*electron_mass_c2;
}

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void G4GammaConversion::PrintInfo()
{}         

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