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25 //
26 //
27 // Author: Luciano Pandola
28 //
29 // History:
30 // --------
31 // 13 Jan 2010 L Pandola First implementation (updated to Penelope08)
32 // 24 May 2011 L Pandola Renamed (make v2008 as default Penelope)
33 // 18 Sep 2013 L Pandola Migration to MT paradigm. Only master model deals with
34 // data and creates shared tables
35 //
36
37 #include "G4PenelopeGammaConversionModel.hh"
38 #include "G4PhysicalConstants.hh"
39 #include "G4SystemOfUnits.hh"
40 #include "G4ParticleDefinition.hh"
41 #include "G4MaterialCutsCouple.hh"
42 #include "G4ProductionCutsTable.hh"
43 #include "G4DynamicParticle.hh"
44 #include "G4Element.hh"
45 #include "G4Gamma.hh"
46 #include "G4Electron.hh"
47 #include "G4Positron.hh"
48 #include "G4PhysicsFreeVector.hh"
49 #include "G4MaterialCutsCouple.hh"
50 #include "G4AutoLock.hh"
51 #include "G4Exp.hh"
52
53 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
54 const G4int G4PenelopeGammaConversionModel::fMaxZ;
55 G4PhysicsFreeVector* G4PenelopeGammaConversionModel::fLogAtomicCrossSection[] = {nullptr};
56 G4double G4PenelopeGammaConversionModel::fAtomicScreeningRadius[] = {0., //pad a zero, so to use fAtomicScreeningRadius[Z]
57 1.2281e+02,7.3167e+01,6.9228e+01,6.7301e+01,
58 6.4696e+01,6.1228e+01,5.7524e+01,5.4033e+01,
59 5.0787e+01,4.7851e+01,4.6373e+01,4.5401e+01,
60 4.4503e+01,4.3815e+01,4.3074e+01,4.2321e+01,
61 4.1586e+01,4.0953e+01,4.0524e+01,4.0256e+01,
62 3.9756e+01,3.9144e+01,3.8462e+01,3.7778e+01,
63 3.7174e+01,3.6663e+01,3.5986e+01,3.5317e+01,
64 3.4688e+01,3.4197e+01,3.3786e+01,3.3422e+01,
65 3.3068e+01,3.2740e+01,3.2438e+01,3.2143e+01,
66 3.1884e+01,3.1622e+01,3.1438e+01,3.1142e+01,
67 3.0950e+01,3.0758e+01,3.0561e+01,3.0285e+01,
68 3.0097e+01,2.9832e+01,2.9581e+01,2.9411e+01,
69 2.9247e+01,2.9085e+01,2.8930e+01,2.8721e+01,
70 2.8580e+01,2.8442e+01,2.8312e+01,2.8139e+01,
71 2.7973e+01,2.7819e+01,2.7675e+01,2.7496e+01,
72 2.7285e+01,2.7093e+01,2.6911e+01,2.6705e+01,
73 2.6516e+01,2.6304e+01,2.6108e+01,2.5929e+01,
74 2.5730e+01,2.5577e+01,2.5403e+01,2.5245e+01,
75 2.5100e+01,2.4941e+01,2.4790e+01,2.4655e+01,
76 2.4506e+01,2.4391e+01,2.4262e+01,2.4145e+01,
77 2.4039e+01,2.3922e+01,2.3813e+01,2.3712e+01,
78 2.3621e+01,2.3523e+01,2.3430e+01,2.3331e+01,
79 2.3238e+01,2.3139e+01,2.3048e+01,2.2967e+01,
80 2.2833e+01,2.2694e+01,2.2624e+01,2.2545e+01,
81 2.2446e+01,2.2358e+01,2.2264e+01};
82
83 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
84
85 G4PenelopeGammaConversionModel::G4PenelopeGammaConversionModel(const G4ParticleDefinition* part,
86 const G4String& nam)
87 :G4VEmModel(nam),fParticleChange(nullptr),fParticle(nullptr),
88 fEffectiveCharge(nullptr),fMaterialInvScreeningRadius(nullptr),
89 fScreeningFunction(nullptr),fIsInitialised(false),fLocalTable(false)
90 {
91 fIntrinsicLowEnergyLimit = 2.0*electron_mass_c2;
92 fIntrinsicHighEnergyLimit = 100.0*GeV;
93 fSmallEnergy = 1.1*MeV;
94
95 if (part)
96 SetParticle(part);
97
98 // SetLowEnergyLimit(fIntrinsicLowEnergyLimit);
99 SetHighEnergyLimit(fIntrinsicHighEnergyLimit);
100 //
101 fVerboseLevel= 0;
102 // Verbosity scale:
103 // 0 = nothing
104 // 1 = warning for energy non-conservation
105 // 2 = details of energy budget
106 // 3 = calculation of cross sections, file openings, sampling of atoms
107 // 4 = entering in methods
108 }
109
110 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
111
112 G4PenelopeGammaConversionModel::~G4PenelopeGammaConversionModel()
113 {
114 //Delete shared tables, they exist only in the master model
115 if (IsMaster() || fLocalTable)
116 {
117 for(G4int i=0; i<=fMaxZ; ++i)
118 {
119 if(fLogAtomicCrossSection[i]) {
120 delete fLogAtomicCrossSection[i];
121 fLogAtomicCrossSection[i] = nullptr;
122 }
123 }
124 if (fEffectiveCharge)
125 delete fEffectiveCharge;
126 if (fMaterialInvScreeningRadius)
127 delete fMaterialInvScreeningRadius;
128 if (fScreeningFunction)
129 delete fScreeningFunction;
130 }
131 }
132
133 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
134
135 void G4PenelopeGammaConversionModel::Initialise(const G4ParticleDefinition* part,
136 const G4DataVector&)
137 {
138 if (fVerboseLevel > 3)
139 G4cout << "Calling G4PenelopeGammaConversionModel::Initialise()" << G4endl;
140
141 SetParticle(part);
142
143 //Only the master model creates/fills/destroys the tables
144 if (IsMaster() && part == fParticle)
145 {
146 //delete old material data...
147 if (fEffectiveCharge)
148 {
149 delete fEffectiveCharge;
150 fEffectiveCharge = nullptr;
151 }
152 if (fMaterialInvScreeningRadius)
153 {
154 delete fMaterialInvScreeningRadius;
155 fMaterialInvScreeningRadius = nullptr;
156 }
157 if (fScreeningFunction)
158 {
159 delete fScreeningFunction;
160 fScreeningFunction = nullptr;
161 }
162 //and create new ones
163 fEffectiveCharge = new std::map<const G4Material*,G4double>;
164 fMaterialInvScreeningRadius = new std::map<const G4Material*,G4double>;
165 fScreeningFunction = new std::map<const G4Material*,std::pair<G4double,G4double> >;
166
167 G4ProductionCutsTable* theCoupleTable =
168 G4ProductionCutsTable::GetProductionCutsTable();
169
170 for (G4int i=0;i<(G4int)theCoupleTable->GetTableSize();++i)
171 {
172 const G4Material* material =
173 theCoupleTable->GetMaterialCutsCouple(i)->GetMaterial();
174 const G4ElementVector* theElementVector = material->GetElementVector();
175
176 for (std::size_t j=0;j<material->GetNumberOfElements();++j)
177 {
178 G4int iZ = theElementVector->at(j)->GetZasInt();
179 //read data files only in the master
180 if (iZ <= fMaxZ && !fLogAtomicCrossSection[iZ])
181 ReadDataFile(iZ);
182 }
183
184 //check if material data are available
185 if (!fEffectiveCharge->count(material))
186 InitializeScreeningFunctions(material);
187 }
188 if (fVerboseLevel > 0) {
189 G4cout << "Penelope Gamma Conversion model v2008 is initialized " << G4endl
190 << "Energy range: "
191 << LowEnergyLimit() / MeV << " MeV - "
192 << HighEnergyLimit() / GeV << " GeV"
193 << G4endl;
194 }
195 }
196 if(fIsInitialised) return;
197 fParticleChange = GetParticleChangeForGamma();
198 fIsInitialised = true;
199 }
200
201 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
202
203 void G4PenelopeGammaConversionModel::InitialiseLocal(const G4ParticleDefinition* part,
204 G4VEmModel *masterModel)
205 {
206 if (fVerboseLevel > 3)
207 G4cout << "Calling G4PenelopeGammaConversionModel::InitialiseLocal()" << G4endl;
208 //
209 //Check that particle matches: one might have multiple master models (e.g.
210 //for e+ and e-).
211 //
212 if (part == fParticle)
213 {
214 //Get the const table pointers from the master to the workers
215 const G4PenelopeGammaConversionModel* theModel =
216 static_cast<G4PenelopeGammaConversionModel*> (masterModel);
217
218 //Copy pointers to the data tables
219 fEffectiveCharge = theModel->fEffectiveCharge;
220 fMaterialInvScreeningRadius = theModel->fMaterialInvScreeningRadius;
221 fScreeningFunction = theModel->fScreeningFunction;
222 for(G4int i=0; i<=fMaxZ; ++i)
223 fLogAtomicCrossSection[i] = theModel->fLogAtomicCrossSection[i];
224
225 //Same verbosity for all workers, as the master
226 fVerboseLevel = theModel->fVerboseLevel;
227 }
228
229 return;
230 }
231
232 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
233 namespace { G4Mutex PenelopeGammaConversionModelMutex = G4MUTEX_INITIALIZER; }
234
235 G4double G4PenelopeGammaConversionModel::ComputeCrossSectionPerAtom(
236 const G4ParticleDefinition*,
237 G4double energy,
238 G4double Z, G4double,
239 G4double, G4double)
240 {
241 //
242 // Penelope model v2008.
243 // Cross section (including triplet production) read from database and managed
244 // through the G4CrossSectionHandler utility. Cross section data are from
245 // M.J. Berger and J.H. Hubbel (XCOM), Report NBSIR 887-3598
246 //
247
248 if (energy < fIntrinsicLowEnergyLimit)
249 return 0;
250
251 G4int iZ = G4int(Z);
252
253 if (!fLogAtomicCrossSection[iZ])
254 {
255 //If we are here, it means that Initialize() was inkoved, but the MaterialTable was
256 //not filled up. This can happen in a UnitTest or via G4EmCalculator
257 if (fVerboseLevel > 0)
258 {
259 //Issue a G4Exception (warning) only in verbose mode
260 G4ExceptionDescription ed;
261 ed << "Unable to retrieve the cross section table for Z=" << iZ << G4endl;
262 ed << "This can happen only in Unit Tests or via G4EmCalculator" << G4endl;
263 G4Exception("G4PenelopeGammaConversionModel::ComputeCrossSectionPerAtom()",
264 "em2018",JustWarning,ed);
265 }
266 //protect file reading via autolock
267 G4AutoLock lock(&PenelopeGammaConversionModelMutex);
268 ReadDataFile(iZ);
269 lock.unlock();
270 fLocalTable = true;
271 }
272 G4double cs = 0;
273 G4double logene = G4Log(energy);
274 G4PhysicsFreeVector* theVec = fLogAtomicCrossSection[iZ];
275 G4double logXS = theVec->Value(logene);
276 cs = G4Exp(logXS);
277
278 if (fVerboseLevel > 2)
279 G4cout << "Gamma conversion cross section at " << energy/MeV << " MeV for Z=" << Z <<
280 " = " << cs/barn << " barn" << G4endl;
281 return cs;
282 }
283
284 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
285
286 void
287 G4PenelopeGammaConversionModel::SampleSecondaries(std::vector<G4DynamicParticle*>* fvect,
288 const G4MaterialCutsCouple* couple,
289 const G4DynamicParticle* aDynamicGamma,
290 G4double,
291 G4double)
292 {
293 //
294 // Penelope model v2008.
295 // Final state is sampled according to the Bethe-Heitler model with Coulomb
296 // corrections, according to the semi-empirical model of
297 // J. Baro' et al., Radiat. Phys. Chem. 44 (1994) 531.
298 //
299 // The model uses the high energy Coulomb correction from
300 // H. Davies et al., Phys. Rev. 93 (1954) 788
301 // and atomic screening radii tabulated from
302 // J.H. Hubbel et al., J. Phys. Chem. Ref. Data 9 (1980) 1023
303 // for Z= 1 to 92.
304 //
305 if (fVerboseLevel > 3)
306 G4cout << "Calling SamplingSecondaries() of G4PenelopeGammaConversionModel" << G4endl;
307
308 G4double photonEnergy = aDynamicGamma->GetKineticEnergy();
309
310 // Always kill primary
311 fParticleChange->ProposeTrackStatus(fStopAndKill);
312 fParticleChange->SetProposedKineticEnergy(0.);
313
314 if (photonEnergy <= fIntrinsicLowEnergyLimit)
315 {
316 fParticleChange->ProposeLocalEnergyDeposit(photonEnergy);
317 return ;
318 }
319
320 G4ParticleMomentum photonDirection = aDynamicGamma->GetMomentumDirection();
321 const G4Material* mat = couple->GetMaterial();
322
323 //Either Initialize() was not called, or we are in a slave and InitializeLocal() was
324 //not invoked
325 if (!fEffectiveCharge)
326 {
327 //create a **thread-local** version of the table. Used only for G4EmCalculator and
328 //Unit Tests
329 fLocalTable = true;
330 fEffectiveCharge = new std::map<const G4Material*,G4double>;
331 fMaterialInvScreeningRadius = new std::map<const G4Material*,G4double>;
332 fScreeningFunction = new std::map<const G4Material*,std::pair<G4double,G4double> >;
333 }
334
335 if (!fEffectiveCharge->count(mat))
336 {
337 //If we are here, it means that Initialize() was inkoved, but the MaterialTable was
338 //not filled up. This can happen in a UnitTest or via G4EmCalculator
339 if (fVerboseLevel > 0)
340 {
341 //Issue a G4Exception (warning) only in verbose mode
342 G4ExceptionDescription ed;
343 ed << "Unable to allocate the EffectiveCharge data for " <<
344 mat->GetName() << G4endl;
345 ed << "This can happen only in Unit Tests" << G4endl;
346 G4Exception("G4PenelopeGammaConversionModel::SampleSecondaries()",
347 "em2019",JustWarning,ed);
348 }
349 //protect file reading via autolock
350 G4AutoLock lock(&PenelopeGammaConversionModelMutex);
351 InitializeScreeningFunctions(mat);
352 lock.unlock();
353 }
354
355 // eps is the fraction of the photon energy assigned to e- (including rest mass)
356 G4double eps = 0;
357 G4double eki = electron_mass_c2/photonEnergy;
358
359 //Do it fast for photon energy < 1.1 MeV (close to threshold)
360 if (photonEnergy < fSmallEnergy)
361 eps = eki + (1.0-2.0*eki)*G4UniformRand();
362 else
363 {
364 //Complete calculation
365 G4double effC = fEffectiveCharge->find(mat)->second;
366 G4double alz = effC*fine_structure_const;
367 G4double T = std::sqrt(2.0*eki);
368 G4double F00=(-1.774-1.210e1*alz+1.118e1*alz*alz)*T
369 +(8.523+7.326e1*alz-4.441e1*alz*alz)*T*T
370 -(1.352e1+1.211e2*alz-9.641e1*alz*alz)*T*T*T
371 +(8.946+6.205e1*alz-6.341e1*alz*alz)*T*T*T*T;
372
373 G4double F0b = fScreeningFunction->find(mat)->second.second;
374 G4double g0 = F0b + F00;
375 G4double invRad = fMaterialInvScreeningRadius->find(mat)->second;
376 G4double bmin = 4.0*eki/invRad;
377 std::pair<G4double,G4double> scree = GetScreeningFunctions(bmin);
378 G4double g1 = scree.first;
379 G4double g2 = scree.second;
380 G4double g1min = g1+g0;
381 G4double g2min = g2+g0;
382 G4double xr = 0.5-eki;
383 G4double a1 = 2.*g1min*xr*xr/3.;
384 G4double p1 = a1/(a1+g2min);
385
386 G4bool loopAgain = false;
387 //Random sampling of eps
388 do{
389 loopAgain = false;
390 if (G4UniformRand() <= p1)
391 {
392 G4double ru2m1 = 2.0*G4UniformRand()-1.0;
393 if (ru2m1 < 0)
394 eps = 0.5-xr*std::pow(std::abs(ru2m1),1./3.);
395 else
396 eps = 0.5+xr*std::pow(ru2m1,1./3.);
397 G4double B = eki/(invRad*eps*(1.0-eps));
398 scree = GetScreeningFunctions(B);
399 g1 = scree.first;
400 g1 = std::max(g1+g0,0.);
401 if (G4UniformRand()*g1min > g1)
402 loopAgain = true;
403 }
404 else
405 {
406 eps = eki+2.0*xr*G4UniformRand();
407 G4double B = eki/(invRad*eps*(1.0-eps));
408 scree = GetScreeningFunctions(B);
409 g2 = scree.second;
410 g2 = std::max(g2+g0,0.);
411 if (G4UniformRand()*g2min > g2)
412 loopAgain = true;
413 }
414 }while(loopAgain);
415 }
416 if (fVerboseLevel > 4)
417 G4cout << "Sampled eps = " << eps << G4endl;
418
419 G4double electronTotEnergy = eps*photonEnergy;
420 G4double positronTotEnergy = (1.0-eps)*photonEnergy;
421
422 // Scattered electron (positron) angles. ( Z - axis along the parent photon)
423
424 //electron kinematics
425 G4double electronKineEnergy = std::max(0.,electronTotEnergy - electron_mass_c2) ;
426 G4double costheta_el = G4UniformRand()*2.0-1.0;
427 G4double kk = std::sqrt(electronKineEnergy*(electronKineEnergy+2.*electron_mass_c2));
428 costheta_el = (costheta_el*electronTotEnergy+kk)/(electronTotEnergy+costheta_el*kk);
429 G4double phi_el = twopi * G4UniformRand() ;
430 G4double dirX_el = std::sqrt(1.-costheta_el*costheta_el) * std::cos(phi_el);
431 G4double dirY_el = std::sqrt(1.-costheta_el*costheta_el) * std::sin(phi_el);
432 G4double dirZ_el = costheta_el;
433
434 //positron kinematics
435 G4double positronKineEnergy = std::max(0.,positronTotEnergy - electron_mass_c2) ;
436 G4double costheta_po = G4UniformRand()*2.0-1.0;
437 kk = std::sqrt(positronKineEnergy*(positronKineEnergy+2.*electron_mass_c2));
438 costheta_po = (costheta_po*positronTotEnergy+kk)/(positronTotEnergy+costheta_po*kk);
439 G4double phi_po = twopi * G4UniformRand() ;
440 G4double dirX_po = std::sqrt(1.-costheta_po*costheta_po) * std::cos(phi_po);
441 G4double dirY_po = std::sqrt(1.-costheta_po*costheta_po) * std::sin(phi_po);
442 G4double dirZ_po = costheta_po;
443
444 // Kinematics of the created pair:
445 // the electron and positron are assumed to have a symetric angular
446 // distribution with respect to the Z axis along the parent photon
447 G4double localEnergyDeposit = 0. ;
448
449 if (electronKineEnergy > 0.0)
450 {
451 G4ThreeVector electronDirection ( dirX_el, dirY_el, dirZ_el);
452 electronDirection.rotateUz(photonDirection);
453 G4DynamicParticle* electron = new G4DynamicParticle (G4Electron::Electron(),
454 electronDirection,
455 electronKineEnergy);
456 fvect->push_back(electron);
457 }
458 else
459 {
460 localEnergyDeposit += electronKineEnergy;
461 electronKineEnergy = 0;
462 }
463
464 //Generate the positron. Real particle in any case, because it will annihilate. If below
465 //threshold, produce it at rest
466 if (positronKineEnergy < 0.0)
467 {
468 localEnergyDeposit += positronKineEnergy;
469 positronKineEnergy = 0; //produce it at rest
470 }
471 G4ThreeVector positronDirection(dirX_po,dirY_po,dirZ_po);
472 positronDirection.rotateUz(photonDirection);
473 G4DynamicParticle* positron = new G4DynamicParticle(G4Positron::Positron(),
474 positronDirection, positronKineEnergy);
475 fvect->push_back(positron);
476
477 //Add rest of energy to the local energy deposit
478 fParticleChange->ProposeLocalEnergyDeposit(localEnergyDeposit);
479
480 if (fVerboseLevel > 1)
481 {
482 G4cout << "-----------------------------------------------------------" << G4endl;
483 G4cout << "Energy balance from G4PenelopeGammaConversion" << G4endl;
484 G4cout << "Incoming photon energy: " << photonEnergy/keV << " keV" << G4endl;
485 G4cout << "-----------------------------------------------------------" << G4endl;
486 if (electronKineEnergy)
487 G4cout << "Electron (explicitly produced) " << electronKineEnergy/keV << " keV"
488 << G4endl;
489 if (positronKineEnergy)
490 G4cout << "Positron (not at rest) " << positronKineEnergy/keV << " keV" << G4endl;
491 G4cout << "Rest masses of e+/- " << 2.0*electron_mass_c2/keV << " keV" << G4endl;
492 if (localEnergyDeposit)
493 G4cout << "Local energy deposit " << localEnergyDeposit/keV << " keV" << G4endl;
494 G4cout << "Total final state: " << (electronKineEnergy+positronKineEnergy+
495 localEnergyDeposit+2.0*electron_mass_c2)/keV <<
496 " keV" << G4endl;
497 G4cout << "-----------------------------------------------------------" << G4endl;
498 }
499 if (fVerboseLevel > 0)
500 {
501 G4double energyDiff = std::fabs(electronKineEnergy+positronKineEnergy+
502 localEnergyDeposit+2.0*electron_mass_c2-photonEnergy);
503 if (energyDiff > 0.05*keV)
504 G4cout << "Warning from G4PenelopeGammaConversion: problem with energy conservation: "
505 << (electronKineEnergy+positronKineEnergy+
506 localEnergyDeposit+2.0*electron_mass_c2)/keV
507 << " keV (final) vs. " << photonEnergy/keV << " keV (initial)" << G4endl;
508 }
509 }
510
511 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
512
513 void G4PenelopeGammaConversionModel::ReadDataFile(const G4int Z)
514 {
515 if (!IsMaster())
516 //Should not be here!
517 G4Exception("G4PenelopeGammaConversionModel::ReadDataFile()",
518 "em0100",FatalException,"Worker thread in this method");
519
520 if (fVerboseLevel > 2)
521 {
522 G4cout << "G4PenelopeGammaConversionModel::ReadDataFile()" << G4endl;
523 G4cout << "Going to read Gamma Conversion data files for Z=" << Z << G4endl;
524 }
525
526 const char* path = G4FindDataDir("G4LEDATA");
527 if(!path)
528 {
529 G4String excep =
530 "G4PenelopeGammaConversionModel - G4LEDATA environment variable not set!";
531 G4Exception("G4PenelopeGammaConversionModel::ReadDataFile()",
532 "em0006",FatalException,excep);
533 return;
534 }
535
536 /*
537 Read the cross section file
538 */
539 std::ostringstream ost;
540 if (Z>9)
541 ost << path << "/penelope/pairproduction/pdgpp" << Z << ".p08";
542 else
543 ost << path << "/penelope/pairproduction/pdgpp0" << Z << ".p08";
544 std::ifstream file(ost.str().c_str());
545 if (!file.is_open())
546 {
547 G4String excep = "G4PenelopeGammaConversionModel - data file " +
548 G4String(ost.str()) + " not found!";
549 G4Exception("G4PenelopeGammaConversionModel::ReadDataFile()",
550 "em0003",FatalException,excep);
551 }
552
553 //I have to know in advance how many points are in the data list
554 //to initialize the G4PhysicsFreeVector()
555 std::size_t ndata=0;
556 G4String line;
557 while( getline(file, line) )
558 ndata++;
559 ndata -= 1; //remove one header line
560
561 file.clear();
562 file.close();
563 file.open(ost.str().c_str());
564 G4int readZ =0;
565 file >> readZ;
566
567 if (fVerboseLevel > 3)
568 G4cout << "Element Z=" << Z << G4endl;
569
570 //check the right file is opened.
571 if (readZ != Z)
572 {
573 G4ExceptionDescription ed;
574 ed << "Corrupted data file for Z=" << Z << G4endl;
575 G4Exception("G4PenelopeGammaConversionModel::ReadDataFile()",
576 "em0005",FatalException,ed);
577 }
578
579 fLogAtomicCrossSection[Z] = new G4PhysicsFreeVector(ndata);
580 G4double ene=0,xs=0;
581 for (std::size_t i=0;i<ndata;++i)
582 {
583 file >> ene >> xs;
584 //dimensional quantities
585 ene *= eV;
586 xs *= barn;
587 if (xs < 1e-40*cm2) //protection against log(0)
588 xs = 1e-40*cm2;
589 fLogAtomicCrossSection[Z]->PutValue(i,G4Log(ene),G4Log(xs));
590 }
591 file.close();
592
593 return;
594 }
595
596 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
597
598 void G4PenelopeGammaConversionModel::InitializeScreeningFunctions(const G4Material* material)
599 {
600 // This is subroutine GPPa0 of Penelope
601 //
602 // 1) calculate the effective Z for the purpose
603 //
604 G4double zeff = 0;
605 G4int intZ = 0;
606 G4int nElements = (G4int)material->GetNumberOfElements();
607 const G4ElementVector* elementVector = material->GetElementVector();
608
609 //avoid calculations if only one building element!
610 if (nElements == 1)
611 {
612 zeff = (*elementVector)[0]->GetZ();
613 intZ = (G4int) zeff;
614 }
615 else // many elements...let's do the calculation
616 {
617 const G4double* fractionVector = material->GetVecNbOfAtomsPerVolume();
618
619 G4double atot = 0;
620 for (G4int i=0;i<nElements;i++)
621 {
622 G4double Zelement = (*elementVector)[i]->GetZ();
623 G4double Aelement = (*elementVector)[i]->GetAtomicMassAmu();
624 atot += Aelement*fractionVector[i];
625 zeff += Zelement*Aelement*fractionVector[i]; //average with the number of nuclei
626 }
627 atot /= material->GetTotNbOfAtomsPerVolume();
628 zeff /= (material->GetTotNbOfAtomsPerVolume()*atot);
629
630 intZ = (G4int) (zeff+0.25);
631 if (intZ <= 0)
632 intZ = 1;
633 if (intZ > fMaxZ)
634 intZ = fMaxZ;
635 }
636
637 if (fEffectiveCharge)
638 fEffectiveCharge->insert(std::make_pair(material,zeff));
639
640 //
641 // 2) Calculate Coulomb Correction
642 //
643 G4double alz = fine_structure_const*zeff;
644 G4double alzSquared = alz*alz;
645 G4double fc = alzSquared*(0.202059-alzSquared*
646 (0.03693-alzSquared*
647 (0.00835-alzSquared*(0.00201-alzSquared*
648 (0.00049-alzSquared*
649 (0.00012-alzSquared*0.00003)))))
650 +1.0/(alzSquared+1.0));
651 //
652 // 3) Screening functions and low-energy corrections
653 //
654 G4double matRadius = 2.0/ fAtomicScreeningRadius[intZ];
655 if (fMaterialInvScreeningRadius)
656 fMaterialInvScreeningRadius->insert(std::make_pair(material,matRadius));
657
658 std::pair<G4double,G4double> myPair(0,0);
659 G4double f0a = 4.0*G4Log(fAtomicScreeningRadius[intZ]);
660 G4double f0b = f0a - 4.0*fc;
661 myPair.first = f0a;
662 myPair.second = f0b;
663
664 if (fScreeningFunction)
665 fScreeningFunction->insert(std::make_pair(material,myPair));
666
667 if (fVerboseLevel > 2)
668 {
669 G4cout << "Average Z for material " << material->GetName() << " = " <<
670 zeff << G4endl;
671 G4cout << "Effective radius for material " << material->GetName() << " = " <<
672 fAtomicScreeningRadius[intZ] << " m_e*c/hbar --> BCB = " <<
673 matRadius << G4endl;
674 G4cout << "Screening parameters F0 for material " << material->GetName() << " = " <<
675 f0a << "," << f0b << G4endl;
676 }
677 return;
678 }
679
680 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
681
682 std::pair<G4double,G4double>
683 G4PenelopeGammaConversionModel::GetScreeningFunctions(G4double B)
684 {
685 // This is subroutine SCHIFF of Penelope
686 //
687 // Screening Functions F1(B) and F2(B) in the Bethe-Heitler differential cross
688 // section for pair production
689 //
690 std::pair<G4double,G4double> result(0.,0.);
691 G4double BSquared = B*B;
692 G4double f1 = 2.0-2.0*G4Log(1.0+BSquared);
693 G4double f2 = f1 - 6.66666666e-1; // (-2/3)
694 if (B < 1.0e-10)
695 f1 = f1-twopi*B;
696 else
697 {
698 G4double a0 = 4.0*B*std::atan(1./B);
699 f1 = f1 - a0;
700 f2 += 2.0*BSquared*(4.0-a0-3.0*G4Log((1.0+BSquared)/BSquared));
701 }
702 G4double g1 = 0.5*(3.0*f1-f2);
703 G4double g2 = 0.25*(3.0*f1+f2);
704
705 result.first = g1;
706 result.second = g2;
707
708 return result;
709 }
710
711 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...
712
713 void G4PenelopeGammaConversionModel::SetParticle(const G4ParticleDefinition* p)
714 {
715 if(!fParticle) {
716 fParticle = p;
717 }
718 }
719