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25 //
26
27 #include "G4AdjointeIonisationModel.hh"
28
29 #include "G4AdjointElectron.hh"
30 #include "G4Electron.hh"
31 #include "G4ParticleChange.hh"
32 #include "G4PhysicalConstants.hh"
33 #include "G4TrackStatus.hh"
34
35 ////////////////////////////////////////////////////////////////////////////////
36 G4AdjointeIonisationModel::G4AdjointeIonisationModel()
37 : G4VEmAdjointModel("Inv_eIon_model")
38
39 {
40 fUseMatrix = true;
41 fUseMatrixPerElement = true;
42 fApplyCutInRange = true;
43 fOneMatrixForAllElements = true;
44
45 fAdjEquivDirectPrimPart = G4AdjointElectron::AdjointElectron();
46 fAdjEquivDirectSecondPart = G4AdjointElectron::AdjointElectron();
47 fDirectPrimaryPart = G4Electron::Electron();
48 fSecondPartSameType = true;
49 }
50
51 ////////////////////////////////////////////////////////////////////////////////
52 G4AdjointeIonisationModel::~G4AdjointeIonisationModel() {}
53
54 ////////////////////////////////////////////////////////////////////////////////
55 void G4AdjointeIonisationModel::SampleSecondaries(
56 const G4Track& aTrack, G4bool IsScatProjToProj,
57 G4ParticleChange* fParticleChange)
58 {
59 const G4DynamicParticle* theAdjointPrimary = aTrack.GetDynamicParticle();
60
61 // Elastic inverse scattering
62 G4double adjointPrimKinEnergy = theAdjointPrimary->GetKineticEnergy();
63 G4double adjointPrimP = theAdjointPrimary->GetTotalMomentum();
64
65 if(adjointPrimKinEnergy > GetHighEnergyLimit() * 0.999)
66 {
67 return;
68 }
69
70 // Sample secondary energy
71 G4double projectileKinEnergy;
72 if(!fWithRapidSampling)
73 { // used by default
74 projectileKinEnergy =
75 SampleAdjSecEnergyFromCSMatrix(adjointPrimKinEnergy, IsScatProjToProj);
76
77 // Caution!!! this weight correction should be always applied
78 CorrectPostStepWeight(fParticleChange, aTrack.GetWeight(),
79 adjointPrimKinEnergy, projectileKinEnergy,
80 IsScatProjToProj);
81 }
82 else
83 { // only for testing
84 G4double Emin, Emax;
85 if(IsScatProjToProj)
86 {
87 Emin = GetSecondAdjEnergyMinForScatProjToProj(adjointPrimKinEnergy,
88 fTcutSecond);
89 Emax = GetSecondAdjEnergyMaxForScatProjToProj(adjointPrimKinEnergy);
90 }
91 else
92 {
93 Emin = GetSecondAdjEnergyMinForProdToProj(adjointPrimKinEnergy);
94 Emax = GetSecondAdjEnergyMaxForProdToProj(adjointPrimKinEnergy);
95 }
96 projectileKinEnergy = Emin * std::pow(Emax / Emin, G4UniformRand());
97
98 fLastCS = fLastAdjointCSForScatProjToProj;
99 if(!IsScatProjToProj)
100 fLastCS = fLastAdjointCSForProdToProj;
101
102 G4double new_weight = aTrack.GetWeight();
103 G4double used_diffCS =
104 fLastCS * std::log(Emax / Emin) / projectileKinEnergy;
105 G4double needed_diffCS = adjointPrimKinEnergy / projectileKinEnergy;
106 if(!IsScatProjToProj)
107 needed_diffCS *= DiffCrossSectionPerVolumePrimToSecond(
108 fCurrentMaterial, projectileKinEnergy, adjointPrimKinEnergy);
109 else
110 needed_diffCS *= DiffCrossSectionPerVolumePrimToScatPrim(
111 fCurrentMaterial, projectileKinEnergy, adjointPrimKinEnergy);
112 new_weight *= needed_diffCS / used_diffCS;
113 fParticleChange->SetParentWeightByProcess(false);
114 fParticleChange->SetSecondaryWeightByProcess(false);
115 fParticleChange->ProposeParentWeight(new_weight);
116 }
117
118 // Kinematic:
119 // we consider a two body elastic scattering for the forward processes where
120 // the projectile knock on an e- at rest and gives it part of its energy
121 G4double projectileM0 = fAdjEquivDirectPrimPart->GetPDGMass();
122 G4double projectileTotalEnergy = projectileM0 + projectileKinEnergy;
123 G4double projectileP2 =
124 projectileTotalEnergy * projectileTotalEnergy - projectileM0 * projectileM0;
125
126 // Companion
127 G4double companionM0 = fAdjEquivDirectPrimPart->GetPDGMass();
128 if(IsScatProjToProj)
129 {
130 companionM0 = fAdjEquivDirectSecondPart->GetPDGMass();
131 }
132 G4double companionTotalEnergy =
133 companionM0 + projectileKinEnergy - adjointPrimKinEnergy;
134 G4double companionP2 =
135 companionTotalEnergy * companionTotalEnergy - companionM0 * companionM0;
136
137 // Projectile momentum
138 G4double P_parallel =
139 (adjointPrimP * adjointPrimP + projectileP2 - companionP2) /
140 (2. * adjointPrimP);
141 G4double P_perp = std::sqrt(projectileP2 - P_parallel * P_parallel);
142 G4ThreeVector dir_parallel = theAdjointPrimary->GetMomentumDirection();
143 G4double phi = G4UniformRand() * twopi;
144 G4ThreeVector projectileMomentum =
145 G4ThreeVector(P_perp * std::cos(phi), P_perp * std::sin(phi), P_parallel);
146 projectileMomentum.rotateUz(dir_parallel);
147
148 if(!IsScatProjToProj)
149 { // kill the primary and add a secondary
150 fParticleChange->ProposeTrackStatus(fStopAndKill);
151 fParticleChange->AddSecondary(
152 new G4DynamicParticle(fAdjEquivDirectPrimPart, projectileMomentum));
153 }
154 else
155 {
156 fParticleChange->ProposeEnergy(projectileKinEnergy);
157 fParticleChange->ProposeMomentumDirection(projectileMomentum.unit());
158 }
159 }
160
161 ////////////////////////////////////////////////////////////////////////////////
162 // The implementation here is correct for energy loss process, for the
163 // photoelectric and compton scattering the method should be redefined
164 G4double G4AdjointeIonisationModel::DiffCrossSectionPerAtomPrimToSecond(
165 G4double kinEnergyProj, G4double kinEnergyProd, G4double Z, G4double)
166 {
167 G4double dSigmadEprod = 0.;
168 G4double Emax_proj = GetSecondAdjEnergyMaxForProdToProj(kinEnergyProd);
169 G4double Emin_proj = GetSecondAdjEnergyMinForProdToProj(kinEnergyProd);
170
171 // the produced particle should have a kinetic energy smaller than the
172 // projectile
173 if(kinEnergyProj > Emin_proj && kinEnergyProj <= Emax_proj)
174 {
175 dSigmadEprod = Z * DiffCrossSectionMoller(kinEnergyProj, kinEnergyProd);
176 }
177 return dSigmadEprod;
178 }
179
180 //////////////////////////////////////////////////////////////////////////////
181 G4double G4AdjointeIonisationModel::DiffCrossSectionMoller(
182 G4double kinEnergyProj, G4double kinEnergyProd)
183 {
184 // G4double energy = kinEnergyProj + electron_mass_c2;
185 G4double x = kinEnergyProd / kinEnergyProj;
186 G4double gam = (kinEnergyProj + electron_mass_c2) / electron_mass_c2;
187 G4double gamma2 = gam * gam;
188 G4double beta2 = 1.0 - 1.0 / gamma2;
189
190 G4double gg = (2.0 * gam - 1.0) / gamma2;
191 G4double y = 1.0 - x;
192 G4double fac = twopi_mc2_rcl2 / electron_mass_c2;
193 G4double dCS =
194 fac * (1. - gg + ((1.0 - gg * x) / (x * x)) + ((1.0 - gg * y) / (y * y))) /
195 (beta2 * (gam - 1.));
196 return dCS / kinEnergyProj;
197 }
198