G4alphaIonisation.cc

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// -------------------------------------------------------------------
//
// GEANT4 Class file
//
//
// File name:     G4alphaIonisation
//
// Author:        Vladimir Ivanchenko
//
// Creation date: 28.10.2009 created from G4ionIonisation
//
// Modifications:
//
//
//
// -------------------------------------------------------------------
//
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#include "G4alphaIonisation.hh"

#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"
#include "G4Electron.hh"
#include "G4Alpha.hh"
#include "G4BraggIonModel.hh"
#include "G4BetheBlochModel.hh"
#include "G4UnitsTable.hh"
#include "G4LossTableManager.hh"
#include "G4IonFluctuations.hh"
#include "G4UniversalFluctuation.hh"
#include "G4EmParameters.hh"

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using namespace std;

G4alphaIonisation::G4alphaIonisation(const G4String& name)
  : G4VEnergyLossProcess(name),
    theParticle(nullptr),
    isInitialised(false)
{
  G4Exception("G4alphaIonisation::G4alphaIonisation","em0007",JustWarning,
        " The process is not ready for use - incorrect results are expected");
  SetLinearLossLimit(0.02);
  SetProcessSubType(fIonisation);
  mass = 0.0;
  ratio = 0.0;
  eth = 8*MeV;
}

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G4alphaIonisation::~G4alphaIonisation()
{}

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G4bool G4alphaIonisation::IsApplicable(const G4ParticleDefinition& p)
{
  return (!p.IsShortLived() &&
    std::abs(p.GetPDGCharge()/CLHEP::eplus - 2) < 0.01);
}

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G4double G4alphaIonisation::MinPrimaryEnergy(const G4ParticleDefinition*, 
               const G4Material*, 
               G4double cut)
{
  G4double x = 0.5*cut/electron_mass_c2;
  G4double gam = x*ratio + std::sqrt((1. + x)*(1. + x*ratio*ratio));
  return mass*(gam - 1.0);
}

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void G4alphaIonisation::InitialiseEnergyLossProcess(
          const G4ParticleDefinition* part,
          const G4ParticleDefinition* bpart)
{
  if(!isInitialised) {

    theParticle = part;
    G4String pname = part->GetParticleName();

    // define base particle
    const G4ParticleDefinition* theBaseParticle = nullptr;
    if(bpart == 0) { 
      if(pname != "alpha") { theBaseParticle = G4Alpha::Alpha(); }
    } else { theBaseParticle = bpart; }

    mass  = part->GetPDGMass();
    ratio = mass/electron_mass_c2/mass;

    SetBaseParticle(theBaseParticle);
    SetSecondaryParticle(G4Electron::Electron());

    if (!EmModel(0)) { SetEmModel(new G4BraggIonModel()); }

    G4EmParameters* param = G4EmParameters::Instance();
    G4double emin = param->MinKinEnergy();
    EmModel(0)->SetLowEnergyLimit(emin);

    // model limit defined for alpha
    eth = (EmModel(0)->HighEnergyLimit())*ratio;
    EmModel(0)->SetHighEnergyLimit(eth);
    AddEmModel(1, EmModel(0), new G4IonFluctuations());

    if (!FluctModel()) { SetFluctModel(new G4UniversalFluctuation()); }

    if (!EmModel(1)) { SetEmModel(new G4BetheBlochModel()); }  
    EmModel(1)->SetLowEnergyLimit(eth);
    EmModel(1)->SetHighEnergyLimit(param->MaxKinEnergy());
    AddEmModel(2, EmModel(1), FluctModel());    

    isInitialised = true;
  }
}

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void G4alphaIonisation::PrintInfo()
{}

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void G4alphaIonisation::ProcessDescription(std::ostream& out) const
{
  out << "  Alpha ionisation";
  G4VEnergyLossProcess::ProcessDescription(out);
}

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