| Geant4 Cross Reference |
1 //
2 // ********************************************************************
3 // * License and Disclaimer *
4 // * *
5 // * The Geant4 software is copyright of the Copyright Holders of *
6 // * the Geant4 Collaboration. It is provided under the terms and *
7 // * conditions of the Geant4 Software License, included in the file *
8 // * LICENSE and available at http://cern.ch/geant4/license . These *
9 // * include a list of copyright holders. *
10 // * *
11 // * Neither the authors of this software system, nor their employing *
12 // * institutes,nor the agencies providing financial support for this *
13 // * work make any representation or warranty, express or implied, *
14 // * regarding this software system or assume any liability for its *
15 // * use. Please see the license in the file LICENSE and URL above *
16 // * for the full disclaimer and the limitation of liability. *
17 // * *
18 // * This code implementation is the result of the scientific and *
19 // * technical work of the GEANT4 collaboration. *
20 // * By using, copying, modifying or distributing the software (or *
21 // * any work based on the software) you agree to acknowledge its *
22 // * use in resulting scientific publications, and indicate your *
23 // * acceptance of all terms of the Geant4 Software license. *
24 // ********************************************************************
25 //
26
27 #include "G4AdjointIonIonisationModel.hh"
28
29 #include "G4AdjointCSManager.hh"
30 #include "G4AdjointElectron.hh"
31 #include "G4BetheBlochModel.hh"
32 #include "G4BraggIonModel.hh"
33 #include "G4GenericIon.hh"
34 #include "G4NistManager.hh"
35 #include "G4ParticleChange.hh"
36 #include "G4PhysicalConstants.hh"
37 #include "G4SystemOfUnits.hh"
38 #include "G4TrackStatus.hh"
39
40 ////////////////////////////////////////////////////////////////////////////////
41 G4AdjointIonIonisationModel::G4AdjointIonIonisationModel()
42 : G4VEmAdjointModel("Adjoint_IonIonisation")
43 {
44 fUseMatrix = true;
45 fUseMatrixPerElement = true;
46 fApplyCutInRange = true;
47 fOneMatrixForAllElements = true;
48 fSecondPartSameType = false;
49
50 // The direct EM Model is taken as BetheBloch. It is only used for the
51 // computation of the differential cross section.
52 // The Bragg model could be used as an alternative as it offers the same
53 // differential cross section
54
55 fBetheBlochDirectEMModel = new G4BetheBlochModel(G4GenericIon::GenericIon());
56 fBraggIonDirectEMModel = new G4BraggIonModel(G4GenericIon::GenericIon());
57 fAdjEquivDirectSecondPart = G4AdjointElectron::AdjointElectron();
58 fDirectPrimaryPart = nullptr;
59 }
60
61 ////////////////////////////////////////////////////////////////////////////////
62 G4AdjointIonIonisationModel::~G4AdjointIonIonisationModel() {}
63
64 ////////////////////////////////////////////////////////////////////////////////
65 void G4AdjointIonIonisationModel::SampleSecondaries(
66 const G4Track& aTrack, G4bool isScatProjToProj,
67 G4ParticleChange* fParticleChange)
68 {
69 const G4DynamicParticle* theAdjointPrimary = aTrack.GetDynamicParticle();
70
71 // Elastic inverse scattering
72 G4double adjointPrimKinEnergy = theAdjointPrimary->GetKineticEnergy();
73 G4double adjointPrimP = theAdjointPrimary->GetTotalMomentum();
74
75 if(adjointPrimKinEnergy > GetHighEnergyLimit() * 0.999)
76 {
77 return;
78 }
79
80 // Sample secondary energy
81 G4double projectileKinEnergy =
82 SampleAdjSecEnergyFromCSMatrix(adjointPrimKinEnergy, isScatProjToProj);
83 // Caution !!!this weight correction should be always applied
84 CorrectPostStepWeight(fParticleChange, aTrack.GetWeight(),
85 adjointPrimKinEnergy, projectileKinEnergy,
86 isScatProjToProj);
87
88 // Kinematics:
89 // we consider a two body elastic scattering for the forward processes where
90 // the projectile knock on an e- at rest and gives it part of its energy
91 G4double projectileM0 = fAdjEquivDirectPrimPart->GetPDGMass();
92 G4double projectileTotalEnergy = projectileM0 + projectileKinEnergy;
93 G4double projectileP2 =
94 projectileTotalEnergy * projectileTotalEnergy - projectileM0 * projectileM0;
95
96 // Companion
97 G4double companionM0 = fAdjEquivDirectPrimPart->GetPDGMass();
98 if(isScatProjToProj)
99 {
100 companionM0 = fAdjEquivDirectSecondPart->GetPDGMass();
101 }
102 G4double companionTotalEnergy =
103 companionM0 + projectileKinEnergy - adjointPrimKinEnergy;
104 G4double companionP2 =
105 companionTotalEnergy * companionTotalEnergy - companionM0 * companionM0;
106
107 // Projectile momentum
108 G4double P_parallel =
109 (adjointPrimP * adjointPrimP + projectileP2 - companionP2) /
110 (2. * adjointPrimP);
111 G4double P_perp = std::sqrt(projectileP2 - P_parallel * P_parallel);
112 G4ThreeVector dir_parallel = theAdjointPrimary->GetMomentumDirection();
113 G4double phi = G4UniformRand() * twopi;
114 G4ThreeVector projectileMomentum =
115 G4ThreeVector(P_perp * std::cos(phi), P_perp * std::sin(phi), P_parallel);
116 projectileMomentum.rotateUz(dir_parallel);
117
118 if(!isScatProjToProj)
119 { // kill the primary and add a secondary
120 fParticleChange->ProposeTrackStatus(fStopAndKill);
121 fParticleChange->AddSecondary(
122 new G4DynamicParticle(fAdjEquivDirectPrimPart, projectileMomentum));
123 }
124 else
125 {
126 fParticleChange->ProposeEnergy(projectileKinEnergy);
127 fParticleChange->ProposeMomentumDirection(projectileMomentum.unit());
128 }
129 }
130
131 ////////////////////////////////////////////////////////////////////////////////
132 G4double G4AdjointIonIonisationModel::DiffCrossSectionPerAtomPrimToSecond(
133 G4double kinEnergyProj, G4double kinEnergyProd, G4double Z, G4double A)
134 {
135 // Probably that here the Bragg Model should be also used for
136 // kinEnergyProj/nuc<2MeV
137 G4double dSigmadEprod = 0.;
138 G4double Emax_proj = GetSecondAdjEnergyMaxForProdToProj(kinEnergyProd);
139 G4double Emin_proj = GetSecondAdjEnergyMinForProdToProj(kinEnergyProd);
140
141 G4double kinEnergyProjScaled = fMassRatio * kinEnergyProj;
142
143 // the produced particle should have a kinetic energy smaller than the
144 // projectile
145 if(kinEnergyProj > Emin_proj && kinEnergyProj <= Emax_proj)
146 {
147 G4double Tmax = kinEnergyProj;
148
149 G4double E1 = kinEnergyProd;
150 G4double E2 = kinEnergyProd * 1.000001;
151 G4double dE = (E2 - E1);
152 G4double sigma1, sigma2;
153 fDirectModel = fBraggIonDirectEMModel;
154 if(kinEnergyProjScaled > 2. * MeV && !fUseOnlyBragg)
155 fDirectModel = fBetheBlochDirectEMModel;
156 sigma1 = fDirectModel->ComputeCrossSectionPerAtom(
157 fDirectPrimaryPart, kinEnergyProj, Z, A, E1, 1.e20);
158 sigma2 = fDirectModel->ComputeCrossSectionPerAtom(
159 fDirectPrimaryPart, kinEnergyProj, Z, A, E2, 1.e20);
160
161 dSigmadEprod = (sigma1 - sigma2) / dE;
162
163 if(dSigmadEprod > 1.)
164 {
165 G4cout << "sigma1 " << kinEnergyProj / MeV << '\t' << kinEnergyProd / MeV
166 << '\t' << sigma1 << G4endl;
167 G4cout << "sigma2 " << kinEnergyProj / MeV << '\t' << kinEnergyProd / MeV
168 << '\t' << sigma2 << G4endl;
169 G4cout << "dsigma " << kinEnergyProj / MeV << '\t' << kinEnergyProd / MeV
170 << '\t' << dSigmadEprod << G4endl;
171 }
172
173 if(fDirectModel == fBetheBlochDirectEMModel)
174 {
175 // correction of differential cross section at high energy to correct for
176 // the suppression of particle at secondary at high energy used in the
177 // Bethe Bloch Model. This correction consist to multiply by g the
178 // probability function used to test the rejection of a secondary Source
179 // code taken from G4BetheBlochModel::SampleSecondaries
180
181 G4double deltaKinEnergy = kinEnergyProd;
182
183 G4double x = fFormFact * deltaKinEnergy;
184 if(x > 1.e-6)
185 {
186 G4double totEnergy = kinEnergyProj + fMass;
187 G4double etot2 = totEnergy * totEnergy;
188 G4double beta2 = kinEnergyProj * (kinEnergyProj + 2.0 * fMass) / etot2;
189 G4double f1 = 0.0;
190 G4double f = 1.0 - beta2 * deltaKinEnergy / Tmax;
191 if(0.5 == fSpin)
192 {
193 f1 = 0.5 * deltaKinEnergy * deltaKinEnergy / etot2;
194 f += f1;
195 }
196 G4double x1 = 1.0 + x;
197 G4double gg = 1.0 / (x1 * x1);
198 if(0.5 == fSpin)
199 {
200 G4double x2 =
201 0.5 * electron_mass_c2 * deltaKinEnergy / (fMass * fMass);
202 gg *= (1.0 + fMagMoment2 * (x2 - f1 / f) / (1.0 + x2));
203 }
204 if(gg > 1.0)
205 {
206 G4cout << "### G4BetheBlochModel in Adjoint Sim WARNING: gg= " << gg
207 << G4endl;
208 gg = 1.;
209 }
210 dSigmadEprod *= gg;
211 }
212 }
213 }
214 return dSigmadEprod;
215 }
216
217 ////////////////////////////////////////////////////////////////////////////////
218 void G4AdjointIonIonisationModel::SetIon(G4ParticleDefinition* adj_ion,
219 G4ParticleDefinition* fwd_ion)
220 {
221 fDirectPrimaryPart = fwd_ion;
222 fAdjEquivDirectPrimPart = adj_ion;
223
224 DefineProjectileProperty();
225 }
226
227 ////////////////////////////////////////////////////////////////////////////////
228 void G4AdjointIonIonisationModel::CorrectPostStepWeight(
229 G4ParticleChange* fParticleChange, G4double old_weight,
230 G4double adjointPrimKinEnergy, G4double projectileKinEnergy, G4bool)
231 {
232 // It is needed because the direct cross section used to compute the
233 // differential cross section is not the one used in
234 // the direct model where the GenericIon stuff is considered with correction
235 // of effective charge. In the direct model the samnepl of secondaries does
236 // not reflect the integral cross section. The integral fwd cross section that
237 // we used to compute the differential CS match the sample of secondaries in
238 // the forward case despite the fact that its is not the same total CS than in
239 // the FWD case. For this reason an extra weight correction is needed at the
240 // end.
241
242 G4double new_weight = old_weight;
243
244 // the correction of CS due to the problem explained above
245 G4double kinEnergyProjScaled = fMassRatio * projectileKinEnergy;
246 fDirectModel = fBraggIonDirectEMModel;
247 if(kinEnergyProjScaled > 2. * MeV && !fUseOnlyBragg)
248 fDirectModel = fBetheBlochDirectEMModel;
249 G4double UsedFwdCS = fDirectModel->ComputeCrossSectionPerAtom(
250 fDirectPrimaryPart, projectileKinEnergy, 1, 1, fTcutSecond, 1.e20);
251 G4double chargeSqRatio = 1.;
252 if(fChargeSquare > 1.)
253 chargeSqRatio = fDirectModel->GetChargeSquareRatio(
254 fDirectPrimaryPart, fCurrentMaterial, projectileKinEnergy);
255 G4double CorrectFwdCS =
256 chargeSqRatio * fDirectModel->ComputeCrossSectionPerAtom(
257 G4GenericIon::GenericIon(), kinEnergyProjScaled, 1, 1,
258 fTcutSecond, 1.e20);
259 // May be some check is needed if UsedFwdCS ==0 probably that then we should
260 // avoid a secondary to be produced,
261 if(UsedFwdCS > 0.)
262 new_weight *= CorrectFwdCS / UsedFwdCS;
263
264 // additional CS correction needed for cross section biasing in general.
265 // May be wrong for ions. Most of the time not used.
266 new_weight *=
267 G4AdjointCSManager::GetAdjointCSManager()->GetPostStepWeightCorrection() /
268 fCsBiasingFactor;
269
270 new_weight *= projectileKinEnergy / adjointPrimKinEnergy;
271
272 fParticleChange->SetParentWeightByProcess(false);
273 fParticleChange->SetSecondaryWeightByProcess(false);
274 fParticleChange->ProposeParentWeight(new_weight);
275 }
276
277 ////////////////////////////////////////////////////////////////////////////////
278 void G4AdjointIonIonisationModel::DefineProjectileProperty()
279 {
280 // Slightly modified code taken from G4BetheBlochModel::SetParticle
281 G4String pname = fDirectPrimaryPart->GetParticleName();
282
283 fMass = fDirectPrimaryPart->GetPDGMass();
284 fMassRatio = G4GenericIon::GenericIon()->GetPDGMass() / fMass;
285 fSpin = fDirectPrimaryPart->GetPDGSpin();
286 G4double q = fDirectPrimaryPart->GetPDGCharge() / eplus;
287 fChargeSquare = q * q;
288 fRatio = electron_mass_c2 / fMass;
289 fOnePlusRatio2 = (1. + fRatio) * (1. + fRatio);
290 fOneMinusRatio2 = (1. - fRatio) * (1. - fRatio);
291 G4double magmom = fDirectPrimaryPart->GetPDGMagneticMoment() * fMass /
292 (0.5 * eplus * hbar_Planck * c_squared);
293 fMagMoment2 = magmom * magmom - 1.0;
294 if(fDirectPrimaryPart->GetLeptonNumber() == 0)
295 {
296 G4double x = 0.8426 * GeV;
297 if(fSpin == 0.0 && fMass < GeV)
298 {
299 x = 0.736 * GeV;
300 }
301 else if(fMass > GeV)
302 {
303 x /= G4NistManager::Instance()->GetZ13(fMass / proton_mass_c2);
304 }
305 fFormFact = 2.0 * electron_mass_c2 / (x * x);
306 }
307 }
308
309 //////////////////////////////////////////////////////////////////////////////
310 G4double G4AdjointIonIonisationModel::GetSecondAdjEnergyMaxForScatProjToProj(
311 G4double primAdjEnergy)
312 {
313 return primAdjEnergy * fOnePlusRatio2 /
314 (fOneMinusRatio2 - 2. * fRatio * primAdjEnergy / fMass);
315 }
316
317 //////////////////////////////////////////////////////////////////////////////
318 G4double G4AdjointIonIonisationModel::GetSecondAdjEnergyMinForScatProjToProj(
319 G4double primAdjEnergy, G4double tcut)
320 {
321 return primAdjEnergy + tcut;
322 }
323
324 //////////////////////////////////////////////////////////////////////////////
325 G4double G4AdjointIonIonisationModel::GetSecondAdjEnergyMaxForProdToProj(
326 G4double)
327 {
328 return GetHighEnergyLimit();
329 }
330
331 //////////////////////////////////////////////////////////////////////////////
332 G4double G4AdjointIonIonisationModel::GetSecondAdjEnergyMinForProdToProj(
333 G4double primAdjEnergy)
334 {
335 return (2. * primAdjEnergy - 4. * fMass +
336 std::sqrt(4. * primAdjEnergy * primAdjEnergy + 16. * fMass * fMass +
337 8. * primAdjEnergy * fMass * (1. / fRatio + fRatio))) /
338 4.;
339 }
340