G4NuclearStopping.cc

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// $Id: G4NuclearStopping.cc 79188 2014-02-20 09:22:48Z gcosmo $
//
// -----------------------------------------------------------------------------
//
// GEANT4 Class file
//
// File name:     G4NuclearStopping
//
// Author:        Vladimir Ivanchenko
//
// Creation date: 20 July 2009
// 
// Modified:
//
// Warning: this class should be instantiated after G4ionIonisation
//
// -----------------------------------------------------------------------------
//
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#include "G4NuclearStopping.hh"
#include "G4ICRU49NuclearStoppingModel.hh"
#include "G4SystemOfUnits.hh"
#include "G4PhysicalConstants.hh"

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using namespace std;

G4NuclearStopping::G4NuclearStopping(const G4String& processName)
  : G4VEmProcess(processName)
{
  isInitialized = false;  
  SetProcessSubType(fNuclearStopping);
  SetBuildTableFlag(false);
  enableAlongStepDoIt = true; 
  enablePostStepDoIt = false; 
  modelICRU49 = 0;
}

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G4NuclearStopping::~G4NuclearStopping()
{}

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G4bool G4NuclearStopping::IsApplicable (const G4ParticleDefinition& p)
{
  return (p.GetPDGCharge() != 0.0 && !p.IsShortLived());
}

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void G4NuclearStopping::InitialiseProcess(const G4ParticleDefinition*)
{
  if(!isInitialized) {
    isInitialized = true;

    if(!EmModel(1)) {
      modelICRU49 = new G4ICRU49NuclearStoppingModel();
      SetEmModel(modelICRU49);
    }
    AddEmModel(1, EmModel());
    EmModel()->SetParticleChange(&nParticleChange);
  }
}

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G4double 
G4NuclearStopping::AlongStepGetPhysicalInteractionLength(
     const G4Track&, G4double, G4double, G4double&, G4GPILSelection* selection)
{
  *selection = NotCandidateForSelection;
  return DBL_MAX;
}

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G4VParticleChange* G4NuclearStopping::AlongStepDoIt(const G4Track& track,
                                                    const G4Step&  step)
{
  nParticleChange.InitializeForAlongStep(track);

  // this line only valid if nuclear stopping 
  // is computed after G4ionIonisation process 
  nParticleChange.SetProposedCharge(step.GetPostStepPoint()->GetCharge());

  G4double T2 = step.GetPostStepPoint()->GetKineticEnergy();

  const G4ParticleDefinition* part = track.GetParticleDefinition();
  G4double Z = std::fabs(part->GetPDGCharge()/eplus);

  if(T2 > 0.0 && T2*proton_mass_c2 < Z*Z*MeV*part->GetPDGMass()) {

    G4double length = step.GetStepLength(); 
    if(length > 0.0) {

      // primary
      G4double T1= step.GetPreStepPoint()->GetKineticEnergy();
      G4double T = 0.5*(T1 + T2);
      const G4MaterialCutsCouple* couple = track.GetMaterialCutsCouple(); 
      G4VEmModel* mod = SelectModel(T, couple->GetIndex());

      // sample stopping
      if(modelICRU49) { modelICRU49->SetFluctuationFlag(true); }
      G4double nloss = 
        length*mod->ComputeDEDXPerVolume(couple->GetMaterial(), part, T);
      if(nloss > T1) { nloss = T1; }
      nParticleChange.SetProposedKineticEnergy(T1 - nloss);
      nParticleChange.ProposeLocalEnergyDeposit(nloss);
      nParticleChange.ProposeNonIonizingEnergyDeposit(nloss);
      if(modelICRU49) { modelICRU49->SetFluctuationFlag(false); }
    }
  }
  return &nParticleChange;
}

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void G4NuclearStopping::PrintInfo()
{}

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