G4NuclearStopping.cc

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//
// -----------------------------------------------------------------------------
//
// 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; 
}
 
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G4NuclearStopping::~G4NuclearStopping()
{}
 
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G4bool G4NuclearStopping::IsApplicable (const G4ParticleDefinition& p)
{
  return (p.GetPDGCharge() != 0.0);
}
 
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void G4NuclearStopping::InitialiseProcess(const G4ParticleDefinition*)
{
  if(!isInitialized) {
    isInitialized = true;
 
    if(nullptr == EmModel(0)) { 
      SetEmModel(new G4ICRU49NuclearStoppingModel());
    }
    AddEmModel(1, EmModel());
    EmModel()->SetActivationHighEnergyLimit(10*GeV);
    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::abs(part->GetPDGCharge()/eplus);
  G4double massR = proton_mass_c2/part->GetPDGMass();
 
  if(T2 > 0.0 && T2*massR < Z*Z*MeV) {
 
    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(); 
      G4double Tscaled = T*massR;
      G4VEmModel* mod = SelectModel(Tscaled, couple->GetIndex());
 
      // sample stopping
      if(mod->IsActive(Tscaled)) {
    G4double nloss = 
      length*mod->ComputeDEDXPerVolume(couple->GetMaterial(), part, T);
    nloss = std::min(nloss, T1);
    nParticleChange.SetProposedKineticEnergy(T1 - nloss);
    nParticleChange.ProposeLocalEnergyDeposit(nloss);
    nParticleChange.ProposeNonIonizingEnergyDeposit(nloss);
      }
    }
  }
  return &nParticleChange;
}
 
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void G4NuclearStopping::ProcessDescription(std::ostream& out) const
{
  out << "  Nuclear stopping";
  G4VEmProcess::ProcessDescription(out);
}
 
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