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27 //
28 // Geant4 Class file
29 //
30 // File name: G4PolarizedAnnihilation
31 //
32 // Author: A. Schaelicke on base of Vladimir Ivanchenko / Michel Maire code
33 //
34 // Class Description:
35 // Polarized process of e+ annihilation into 2 gammas
36
37 #include "G4PolarizedAnnihilation.hh"
38
39 #include "G4DynamicParticle.hh"
40 #include "G4MaterialCutsCouple.hh"
41 #include "G4PhysicsTableHelper.hh"
42 #include "G4PhysicsVector.hh"
43 #include "G4PolarizationHelper.hh"
44 #include "G4PolarizationManager.hh"
45 #include "G4PolarizedAnnihilationModel.hh"
46 #include "G4ProductionCutsTable.hh"
47 #include "G4SystemOfUnits.hh"
48 #include "G4StokesVector.hh"
49
50 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
51 G4PolarizedAnnihilation::G4PolarizedAnnihilation(const G4String& name)
52 : G4eplusAnnihilation(name)
53 , fAsymmetryTable(nullptr)
54 , fTransverseAsymmetryTable(nullptr)
55 {
56 fEmModel = new G4PolarizedAnnihilationModel();
57 SetEmModel(fEmModel);
58 }
59
60 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
61 G4PolarizedAnnihilation::~G4PolarizedAnnihilation() { CleanTables(); }
62
63 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
64 void G4PolarizedAnnihilation::CleanTables()
65 {
66 if(fAsymmetryTable)
67 {
68 fAsymmetryTable->clearAndDestroy();
69 delete fAsymmetryTable;
70 fAsymmetryTable = nullptr;
71 }
72 if(fTransverseAsymmetryTable)
73 {
74 fTransverseAsymmetryTable->clearAndDestroy();
75 delete fTransverseAsymmetryTable;
76 fTransverseAsymmetryTable = nullptr;
77 }
78 }
79
80 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
81 G4double G4PolarizedAnnihilation::GetMeanFreePath(const G4Track& track,
82 G4double previousStepSize,
83 G4ForceCondition* condition)
84 {
85 G4double mfp =
86 G4VEmProcess::GetMeanFreePath(track, previousStepSize, condition);
87
88 if(nullptr != fAsymmetryTable && nullptr != fTransverseAsymmetryTable && mfp < DBL_MAX)
89 {
90 mfp *= ComputeSaturationFactor(track);
91 }
92 if(verboseLevel >= 2)
93 {
94 G4cout << "G4PolarizedAnnihilation::MeanFreePath: " << mfp / mm << " mm "
95 << G4endl;
96 }
97 return mfp;
98 }
99
100 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
101 G4double G4PolarizedAnnihilation::PostStepGetPhysicalInteractionLength(
102 const G4Track& track, G4double previousStepSize, G4ForceCondition* condition)
103 {
104 // save previous values
105 G4double nLength = theNumberOfInteractionLengthLeft;
106 G4double iLength = currentInteractionLength;
107
108 // *** compute unpolarized step limit ***
109 // this changes theNumberOfInteractionLengthLeft and currentInteractionLength
110 G4double x = G4VEmProcess::PostStepGetPhysicalInteractionLength(
111 track, previousStepSize, condition);
112 G4double x0 = x;
113 G4double satFact = 1.0;
114
115 // *** add corrections on polarisation ***
116 if(nullptr != fAsymmetryTable && nullptr != fTransverseAsymmetryTable && x < DBL_MAX)
117 {
118 satFact = ComputeSaturationFactor(track);
119 G4double curLength = currentInteractionLength * satFact;
120 G4double prvLength = iLength * satFact;
121 if(nLength > 0.0)
122 {
123 theNumberOfInteractionLengthLeft =
124 std::max(nLength - previousStepSize / prvLength, 0.0);
125 }
126 x = theNumberOfInteractionLengthLeft * curLength;
127 }
128 if(verboseLevel >= 2)
129 {
130 G4cout << "G4PolarizedAnnihilation::PostStepGPIL: " << std::setprecision(8)
131 << x / mm << " mm;" << G4endl
132 << " unpolarized value: "
133 << std::setprecision(8) << x0 / mm << " mm." << G4endl;
134 }
135 return x;
136 }
137
138 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
139 G4double G4PolarizedAnnihilation::ComputeSaturationFactor(const G4Track& track)
140 {
141 const G4Material* aMaterial = track.GetMaterial();
142 G4VPhysicalVolume* aPVolume = track.GetVolume();
143 G4LogicalVolume* aLVolume = aPVolume->GetLogicalVolume();
144
145 G4PolarizationManager* polarizationManager =
146 G4PolarizationManager::GetInstance();
147
148 const G4bool volumeIsPolarized = polarizationManager->IsPolarized(aLVolume);
149 G4StokesVector electronPolarization =
150 polarizationManager->GetVolumePolarization(aLVolume);
151
152 G4double factor = 1.0;
153
154 if(volumeIsPolarized)
155 {
156 // *** get asymmetry, if target is polarized ***
157 const G4DynamicParticle* aDynamicPositron = track.GetDynamicParticle();
158 const G4double positronEnergy = aDynamicPositron->GetKineticEnergy();
159 const G4StokesVector positronPolarization =
160 G4StokesVector(track.GetPolarization());
161 const G4ParticleMomentum positronDirection0 =
162 aDynamicPositron->GetMomentumDirection();
163
164 if(verboseLevel >= 2)
165 {
166 G4cout << "G4PolarizedAnnihilation::ComputeSaturationFactor: " << G4endl;
167 G4cout << " Mom " << positronDirection0 << G4endl;
168 G4cout << " Polarization " << positronPolarization << G4endl;
169 G4cout << " MaterialPol. " << electronPolarization << G4endl;
170 G4cout << " Phys. Volume " << aPVolume->GetName() << G4endl;
171 G4cout << " Log. Volume " << aLVolume->GetName() << G4endl;
172 G4cout << " Material " << aMaterial << G4endl;
173 }
174
175 std::size_t midx = CurrentMaterialCutsCoupleIndex();
176 const G4PhysicsVector* aVector = nullptr;
177 const G4PhysicsVector* bVector = nullptr;
178 if(midx < fAsymmetryTable->size())
179 {
180 aVector = (*fAsymmetryTable)(midx);
181 }
182 if(midx < fTransverseAsymmetryTable->size())
183 {
184 bVector = (*fTransverseAsymmetryTable)(midx);
185 }
186 if(aVector && bVector)
187 {
188 G4double lAsymmetry = aVector->Value(positronEnergy);
189 G4double tAsymmetry = bVector->Value(positronEnergy);
190 G4double polZZ =
191 positronPolarization.z() * (electronPolarization * positronDirection0);
192 G4double polXX =
193 positronPolarization.x() *
194 (electronPolarization *
195 G4PolarizationHelper::GetParticleFrameX(positronDirection0));
196 G4double polYY =
197 positronPolarization.y() *
198 (electronPolarization *
199 G4PolarizationHelper::GetParticleFrameY(positronDirection0));
200
201 factor /= (1. + polZZ * lAsymmetry + (polXX + polYY) * tAsymmetry);
202
203 if(verboseLevel >= 2)
204 {
205 G4cout << " Asymmetry: " << lAsymmetry << ", " << tAsymmetry
206 << G4endl;
207 G4cout << " PolProduct: " << polXX << ", " << polYY << ", " << polZZ
208 << G4endl;
209 G4cout << " Factor: " << factor << G4endl;
210 }
211 }
212 else
213 {
214 G4ExceptionDescription ed;
215 ed << "Problem with asymmetry tables: material index " << midx
216 << " is out of range or tables are not filled";
217 G4Exception("G4PolarizedAnnihilation::ComputeSaturationFactor", "em0048",
218 JustWarning, ed, "");
219 }
220 }
221 return factor;
222 }
223
224 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
225 void G4PolarizedAnnihilation::BuildPhysicsTable(
226 const G4ParticleDefinition& part)
227 {
228 G4VEmProcess::BuildPhysicsTable(part);
229 if(isTheMaster)
230 {
231 BuildAsymmetryTables(part);
232 }
233 }
234
235 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
236 void G4PolarizedAnnihilation::BuildAsymmetryTables(
237 const G4ParticleDefinition& part)
238 {
239 // cleanup old, initialise new table
240 CleanTables();
241 fAsymmetryTable = G4PhysicsTableHelper::PreparePhysicsTable(fAsymmetryTable);
242 fTransverseAsymmetryTable =
243 G4PhysicsTableHelper::PreparePhysicsTable(fTransverseAsymmetryTable);
244 if(nullptr == fAsymmetryTable) return;
245
246 // Access to materials
247 const G4ProductionCutsTable* theCoupleTable =
248 G4ProductionCutsTable::GetProductionCutsTable();
249 G4int numOfCouples = (G4int)theCoupleTable->GetTableSize();
250 for(G4int i = 0; i < numOfCouples; ++i)
251 {
252 if(fAsymmetryTable->GetFlag(i))
253 {
254 // create physics vector and fill it
255 const G4MaterialCutsCouple* couple =
256 theCoupleTable->GetMaterialCutsCouple(i);
257
258 // use same parameters as for lambda
259 G4PhysicsVector* aVector = LambdaPhysicsVector(couple);
260 G4PhysicsVector* tVector = LambdaPhysicsVector(couple);
261 G4int nn = (G4int)aVector->GetVectorLength();
262 for(G4int j = 0; j < nn; ++j)
263 {
264 G4double energy = aVector->Energy(j);
265 G4double tasm = 0.;
266 G4double asym = ComputeAsymmetry(energy, couple, part, 0., tasm);
267 aVector->PutValue(j, asym);
268 tVector->PutValue(j, tasm);
269 }
270 if(aVector->GetSpline()) {
271 aVector->FillSecondDerivatives();
272 tVector->FillSecondDerivatives();
273 }
274 G4PhysicsTableHelper::SetPhysicsVector(fAsymmetryTable, i, aVector);
275 G4PhysicsTableHelper::SetPhysicsVector(fTransverseAsymmetryTable, i,
276 tVector);
277 }
278 }
279 }
280
281 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
282 G4double G4PolarizedAnnihilation::ComputeAsymmetry(
283 G4double energy, const G4MaterialCutsCouple* couple,
284 const G4ParticleDefinition& aParticle, G4double cut, G4double& tAsymmetry)
285 {
286 G4double lAsymmetry = 0.0;
287 tAsymmetry = 0.0;
288
289 // calculate polarized cross section
290 G4ThreeVector targetPolarization = G4ThreeVector(0., 0., 1.);
291 fEmModel->SetTargetPolarization(targetPolarization);
292 fEmModel->SetBeamPolarization(targetPolarization);
293 G4double sigma2 =
294 fEmModel->CrossSection(couple, &aParticle, energy, cut, energy);
295
296 // calculate transversely polarized cross section
297 targetPolarization = G4ThreeVector(1., 0., 0.);
298 fEmModel->SetTargetPolarization(targetPolarization);
299 fEmModel->SetBeamPolarization(targetPolarization);
300 G4double sigma3 =
301 fEmModel->CrossSection(couple, &aParticle, energy, cut, energy);
302
303 // calculate unpolarized cross section
304 targetPolarization = G4ThreeVector();
305 fEmModel->SetTargetPolarization(targetPolarization);
306 fEmModel->SetBeamPolarization(targetPolarization);
307 G4double sigma0 =
308 fEmModel->CrossSection(couple, &aParticle, energy, cut, energy);
309
310 // determine asymmetries
311 if(sigma0 > 0.)
312 {
313 lAsymmetry = sigma2 / sigma0 - 1.;
314 tAsymmetry = sigma3 / sigma0 - 1.;
315 }
316 return lAsymmetry;
317 }
318
319 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
320 void G4PolarizedAnnihilation::ProcessDescription(std::ostream& out) const
321 {
322 out << "Polarized model for positron annihilation into 2 photons.\n";
323 }
324