| Geant4 Cross Reference |
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25 //
26
27 #include "G4AdjointAlongStepWeightCorrection.hh"
28
29 #include "G4AdjointCSManager.hh"
30 #include "G4ParticleChange.hh"
31 #include "G4ParticleDefinition.hh"
32 #include "G4Step.hh"
33 #include "G4VParticleChange.hh"
34
35 ///////////////////////////////////////////////////////
36 G4AdjointAlongStepWeightCorrection::G4AdjointAlongStepWeightCorrection(
37 const G4String& name, G4ProcessType type)
38 : G4VContinuousProcess(name, type)
39 {
40 fParticleChange = new G4ParticleChange();
41 fCSManager = G4AdjointCSManager::GetAdjointCSManager();
42 }
43
44 ///////////////////////////////////////////////////////
45 G4AdjointAlongStepWeightCorrection::~G4AdjointAlongStepWeightCorrection()
46 {
47 delete fParticleChange;
48 }
49
50 ///////////////////////////////////////////////////////
51 void G4AdjointAlongStepWeightCorrection::ProcessDescription(
52 std::ostream& out) const
53 {
54 out <<
55 "Continuous processes act on adjoint particles to continuously correct their "
56 "weight during the adjoint reverse tracking. This process is needed when "
57 "the adjoint cross sections are not scaled such that the total adjoint cross "
58 "section matches the total forward cross section. By default the mode where "
59 "the total adjoint cross section is equal to the total forward cross section "
60 "is used and therefore this along step weightcorrection factor is 1. However "
61 "in some cases (some energy ranges) the total forward cross section or the "
62 "total adjoint cross section can be zero. In this case the along step weight "
63 "correction is needed and is given by exp(-(Sigma_tot_adj-Sigma_tot_fwd).dx)"
64 "\n";
65 }
66
67 ///////////////////////////////////////////////////////
68 G4VParticleChange* G4AdjointAlongStepWeightCorrection::AlongStepDoIt(
69 const G4Track& track, const G4Step& step)
70 {
71 fParticleChange->Initialize(track);
72
73 // Get the actual (true) Step length
74 G4double length = step.GetStepLength();
75
76 G4double Tkin = step.GetPostStepPoint()->GetKineticEnergy();
77 G4ParticleDefinition* thePartDef = const_cast<G4ParticleDefinition*>(
78 track.GetDynamicParticle()->GetDefinition());
79 G4double weight_correction = fCSManager->GetContinuousWeightCorrection(
80 thePartDef, fPreStepKinEnergy, Tkin, fCurrentCouple, length);
81
82 // Caution!!!
83 // It is important to select the weight of the post_step_point as the current
84 // weight and not the weight of the track, as the weight of the track is
85 // changed after having applied all the along_step_do_it.
86 G4double new_weight =
87 weight_correction * step.GetPostStepPoint()->GetWeight();
88
89 // The following test check for zero weight.
90 // This happens after weight correction of gamma for photo electric effect.
91 // When the new weight is 0 it will be later on considered as NaN by G4.
92 // Therefore we put a lower limit of 1.e-300. for new_weight
93 if(new_weight == 0. || (new_weight <= 0. && new_weight > 0.))
94 {
95 new_weight = 1.e-300;
96 }
97
98 fParticleChange->SetParentWeightByProcess(false);
99 fParticleChange->SetSecondaryWeightByProcess(false);
100 fParticleChange->ProposeParentWeight(new_weight);
101
102 return fParticleChange;
103 }
104
105 ///////////////////////////////////////////////////////
106 G4double G4AdjointAlongStepWeightCorrection::GetContinuousStepLimit(
107 const G4Track& track, G4double, G4double, G4double&)
108 {
109 DefineMaterial(track.GetMaterialCutsCouple());
110 fPreStepKinEnergy = track.GetKineticEnergy();
111 return DBL_MAX;
112 }
113