G4AdjointAlongStepWeightCorrection.cc

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#include "G4AdjointAlongStepWeightCorrection.hh"
 
#include "G4AdjointCSManager.hh"
#include "G4ParticleChange.hh"
#include "G4ParticleDefinition.hh"
#include "G4Step.hh"
#include "G4VParticleChange.hh"
 
///////////////////////////////////////////////////////
G4AdjointAlongStepWeightCorrection::G4AdjointAlongStepWeightCorrection(
  const G4String& name, G4ProcessType type)
  : G4VContinuousProcess(name, type)
{
  fParticleChange = new G4ParticleChange();
  fCSManager      = G4AdjointCSManager::GetAdjointCSManager();
}
 
///////////////////////////////////////////////////////
G4AdjointAlongStepWeightCorrection::~G4AdjointAlongStepWeightCorrection()
{
  delete fParticleChange;
}
 
///////////////////////////////////////////////////////
void G4AdjointAlongStepWeightCorrection::ProcessDescription(
  std::ostream& out) const
{
  out <<
  "Continuous processes act on adjoint particles to continuously correct their "
  "weight during the adjoint reverse tracking. This process is needed when "
  "the adjoint cross sections are not scaled such that the total adjoint cross "
  "section matches the total forward cross section. By default the mode where "
  "the total adjoint cross section is equal to the total forward cross section "
  "is used and therefore this along step weightcorrection factor is 1. However "
  "in some cases (some energy ranges) the total forward cross section or the "
  "total adjoint cross section can be zero. In this case the along step weight "
  "correction is needed and is given by exp(-(Sigma_tot_adj-Sigma_tot_fwd).dx)"
  "\n";
}
 
///////////////////////////////////////////////////////
G4VParticleChange* G4AdjointAlongStepWeightCorrection::AlongStepDoIt(
  const G4Track& track, const G4Step& step)
{
  fParticleChange->Initialize(track);
 
  // Get the actual (true) Step length
  G4double length = step.GetStepLength();
 
  G4double Tkin = step.GetPostStepPoint()->GetKineticEnergy();
  G4ParticleDefinition* thePartDef = const_cast<G4ParticleDefinition*>(
    track.GetDynamicParticle()->GetDefinition());
  G4double weight_correction = fCSManager->GetContinuousWeightCorrection(
    thePartDef, fPreStepKinEnergy, Tkin, fCurrentCouple, length);
 
  // Caution!!!
  // It is important to select the weight of the post_step_point as the current
  // weight and not the weight of the track, as the weight of the track is
  // changed after having applied all the along_step_do_it.
  G4double new_weight =
    weight_correction * step.GetPostStepPoint()->GetWeight();
 
  // The following test check for zero weight.
  // This happens after weight correction of gamma for photo electric effect.
  // When the new weight is 0 it will be later on considered as NaN by G4.
  // Therefore we put a lower limit of 1.e-300. for new_weight
  new_weight = std::max(new_weight, 1.e-300);
 
  fParticleChange->SetParentWeightByProcess(false);
  fParticleChange->SetSecondaryWeightByProcess(false);
  fParticleChange->ProposeParentWeight(new_weight);
 
  return fParticleChange;
}
 
///////////////////////////////////////////////////////
G4double G4AdjointAlongStepWeightCorrection::GetContinuousStepLimit(
  const G4Track& track, G4double, G4double, G4double&)
{
  DefineMaterial(track.GetMaterialCutsCouple());
  fPreStepKinEnergy = track.GetKineticEnergy();
  return DBL_MAX;
}