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28 //
29 // GEANT4 Class file
30 //
31 //
32 // File name: G4eBremParametrizedModel
33 //
34 // Author: Andreas Schaelicke
35 //
36 // Creation date: 06.04.2011
37 //
38 // Modifications:
39 //
40 // Main References:
41 // - based on G4eBremsstrahlungModel and G4eBremsstrahlungRelModel
42 // -------------------------------------------------------------------
43 //
44 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
45 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
46
47 #include "G4eBremParametrizedModel.hh"
48 #include "G4PhysicalConstants.hh"
49 #include "G4SystemOfUnits.hh"
50 #include "G4Electron.hh"
51 #include "G4Positron.hh"
52 #include "G4Gamma.hh"
53 #include "Randomize.hh"
54 #include "G4Material.hh"
55 #include "G4Element.hh"
56 #include "G4ElementVector.hh"
57 #include "G4ProductionCutsTable.hh"
58 #include "G4ParticleChangeForLoss.hh"
59 #include "G4LossTableManager.hh"
60 #include "G4ModifiedTsai.hh"
61 #include "G4Exp.hh"
62 #include "G4Log.hh"
63
64 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
65
66 const G4double G4eBremParametrizedModel::xgi[]={ 0.0199, 0.1017, 0.2372, 0.4083,
67 0.5917, 0.7628, 0.8983, 0.9801 };
68 const G4double G4eBremParametrizedModel::wgi[]={ 0.0506, 0.1112, 0.1569, 0.1813,
69 0.1813, 0.1569, 0.1112, 0.0506 };
70
71 static const G4double tlow = 1.*CLHEP::MeV;
72
73 //
74 // GEANT4 internal units.
75 //
76 static const G4double
77 ah10 = 4.67733E+00, ah11 =-6.19012E-01, ah12 = 2.02225E-02,
78 ah20 =-7.34101E+00, ah21 = 1.00462E+00, ah22 =-3.20985E-02,
79 ah30 = 2.93119E+00, ah31 =-4.03761E-01, ah32 = 1.25153E-02;
80
81 static const G4double
82 bh10 = 4.23071E+00, bh11 =-6.10995E-01, bh12 = 1.95531E-02,
83 bh20 =-7.12527E+00, bh21 = 9.69160E-01, bh22 =-2.74255E-02,
84 bh30 = 2.69925E+00, bh31 =-3.63283E-01, bh32 = 9.55316E-03;
85
86 static const G4double
87 al00 =-2.05398E+00, al01 = 2.38815E-02, al02 = 5.25483E-04,
88 al10 =-7.69748E-02, al11 =-6.91499E-02, al12 = 2.22453E-03,
89 al20 = 4.06463E-02, al21 =-1.01281E-02, al22 = 3.40919E-04;
90
91 static const G4double
92 bl00 = 1.04133E+00, bl01 =-9.43291E-03, bl02 =-4.54758E-04,
93 bl10 = 1.19253E-01, bl11 = 4.07467E-02, bl12 =-1.30718E-03,
94 bl20 =-1.59391E-02, bl21 = 7.27752E-03, bl22 =-1.94405E-04;
95
96 using namespace std;
97
98 G4eBremParametrizedModel::G4eBremParametrizedModel(const G4ParticleDefinition* p,
99 const G4String& nam)
100 : G4VEmModel(nam),
101 particle(nullptr),
102 fMigdalConstant(classic_electr_radius*electron_Compton_length*electron_Compton_length*4.0*pi),
103 bremFactor(fine_structure_const*classic_electr_radius*classic_electr_radius*16./3.),
104 isInitialised(false),
105 isElectron(true)
106 {
107 theGamma = G4Gamma::Gamma();
108
109 minThreshold = 0.1*keV;
110 lowKinEnergy = 10.*MeV;
111 SetLowEnergyLimit(lowKinEnergy);
112
113 nist = G4NistManager::Instance();
114
115 SetAngularDistribution(new G4ModifiedTsai());
116
117 particleMass = kinEnergy = totalEnergy = currentZ = z13 = z23 = lnZ = Fel = Finel
118 = densityFactor = densityCorr = fMax = fCoulomb = 0.;
119
120 InitialiseConstants();
121 if(nullptr != p) { SetParticle(p); }
122 }
123
124 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
125
126 void G4eBremParametrizedModel::InitialiseConstants()
127 {
128 facFel = G4Log(184.15);
129 facFinel = G4Log(1194.);
130 }
131
132 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
133
134 G4eBremParametrizedModel::~G4eBremParametrizedModel() = default;
135
136 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
137
138 void G4eBremParametrizedModel::SetParticle(const G4ParticleDefinition* p)
139 {
140 particle = p;
141 particleMass = p->GetPDGMass();
142 if(p == G4Electron::Electron()) { isElectron = true; }
143 else { isElectron = false;}
144 }
145
146 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
147
148 G4double G4eBremParametrizedModel::MinEnergyCut(const G4ParticleDefinition*,
149 const G4MaterialCutsCouple*)
150 {
151 return minThreshold;
152 }
153
154 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
155
156 void G4eBremParametrizedModel::SetupForMaterial(const G4ParticleDefinition*,
157 const G4Material* mat,
158 G4double kineticEnergy)
159 {
160 densityFactor = mat->GetElectronDensity()*fMigdalConstant;
161
162 // calculate threshold for density effect
163 kinEnergy = kineticEnergy;
164 totalEnergy = kineticEnergy + particleMass;
165 densityCorr = densityFactor*totalEnergy*totalEnergy;
166 }
167
168
169 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
170
171 void G4eBremParametrizedModel::Initialise(const G4ParticleDefinition* p,
172 const G4DataVector& cuts)
173 {
174 if(p) { SetParticle(p); }
175
176 lowKinEnergy = LowEnergyLimit();
177
178 currentZ = 0.;
179
180 if(IsMaster()) { InitialiseElementSelectors(p, cuts); }
181
182 if(isInitialised) { return; }
183 fParticleChange = GetParticleChangeForLoss();
184 isInitialised = true;
185 }
186
187 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
188
189 void G4eBremParametrizedModel::InitialiseLocal(const G4ParticleDefinition*,
190 G4VEmModel* masterModel)
191 {
192 SetElementSelectors(masterModel->GetElementSelectors());
193 }
194
195 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
196
197 G4double G4eBremParametrizedModel::ComputeDEDXPerVolume(
198 const G4Material* material,
199 const G4ParticleDefinition* p,
200 G4double kineticEnergy,
201 G4double cutEnergy)
202 {
203 if(!particle) { SetParticle(p); }
204 if(kineticEnergy < lowKinEnergy) { return 0.0; }
205 G4double cut = std::min(cutEnergy, kineticEnergy);
206 if(cut == 0.0) { return 0.0; }
207
208 SetupForMaterial(particle, material,kineticEnergy);
209
210 const G4ElementVector* theElementVector = material->GetElementVector();
211 const G4double* theAtomicNumDensityVector = material->GetAtomicNumDensityVector();
212
213 G4double dedx = 0.0;
214
215 // loop for elements in the material
216 for (size_t i=0; i<material->GetNumberOfElements(); i++) {
217
218 G4VEmModel::SetCurrentElement((*theElementVector)[i]);
219 SetCurrentElement((*theElementVector)[i]->GetZ());
220
221 dedx += theAtomicNumDensityVector[i]*currentZ*currentZ*ComputeBremLoss(cut);
222 }
223 dedx *= bremFactor;
224
225 return dedx;
226 }
227
228 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
229
230 G4double G4eBremParametrizedModel::ComputeBremLoss(G4double cut)
231 {
232 G4double loss = 0.0;
233
234 // number of intervals and integration step
235 G4double vcut = cut/totalEnergy;
236 G4int n = (G4int)(20*vcut) + 3;
237 G4double delta = vcut/G4double(n);
238
239 G4double e0 = 0.0;
240 G4double xs;
241
242 // integration
243 for(G4int l=0; l<n; l++) {
244
245 for(G4int i=0; i<8; i++) {
246
247 G4double eg = (e0 + xgi[i]*delta)*totalEnergy;
248
249 xs = ComputeDXSectionPerAtom(eg);
250
251 loss += wgi[i]*xs/(1.0 + densityCorr/(eg*eg));
252 }
253 e0 += delta;
254 }
255
256 loss *= delta*totalEnergy;
257
258 return loss;
259 }
260
261 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
262
263 G4double G4eBremParametrizedModel::ComputeCrossSectionPerAtom(
264 const G4ParticleDefinition* p,
265 G4double kineticEnergy,
266 G4double Z, G4double,
267 G4double cutEnergy,
268 G4double maxEnergy)
269 {
270 if(!particle) { SetParticle(p); }
271 if(kineticEnergy < lowKinEnergy) { return 0.0; }
272 G4double cut = std::min(cutEnergy, kineticEnergy);
273 G4double tmax = std::min(maxEnergy, kineticEnergy);
274
275 if(cut >= tmax) { return 0.0; }
276
277 SetCurrentElement(Z);
278
279 G4double cross = ComputeXSectionPerAtom(cut);
280
281 // allow partial integration
282 if(tmax < kinEnergy) { cross -= ComputeXSectionPerAtom(tmax); }
283
284 cross *= Z*Z*bremFactor;
285
286 return cross;
287 }
288
289 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
290
291 G4double G4eBremParametrizedModel::ComputeXSectionPerAtom(G4double cut)
292 {
293 G4double cross = 0.0;
294
295 // number of intervals and integration step
296 G4double vcut = G4Log(cut/totalEnergy);
297 G4double vmax = G4Log(kinEnergy/totalEnergy);
298 G4int n = (G4int)(0.45*(vmax - vcut)) + 4;
299 // n=1; // integration test
300 G4double delta = (vmax - vcut)/G4double(n);
301
302 G4double e0 = vcut;
303 G4double xs;
304
305 // integration
306 for(G4int l=0; l<n; l++) {
307
308 for(G4int i=0; i<8; i++) {
309
310 G4double eg = G4Exp(e0 + xgi[i]*delta)*totalEnergy;
311
312 xs = ComputeDXSectionPerAtom(eg);
313
314 cross += wgi[i]*xs/(1.0 + densityCorr/(eg*eg));
315 }
316 e0 += delta;
317 }
318
319 cross *= delta;
320
321 return cross;
322 }
323
324 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
325
326 // compute the value of the screening function 3*PHI1 - PHI2
327
328 G4double G4eBremParametrizedModel::ScreenFunction1(G4double ScreenVariable)
329 {
330 G4double screenVal;
331
332 if (ScreenVariable > 1.)
333 screenVal = 42.24 - 8.368*G4Log(ScreenVariable+0.952);
334 else
335 screenVal = 42.392 - ScreenVariable* (7.796 - 1.961*ScreenVariable);
336
337 return screenVal;
338 }
339
340 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
341
342 // compute the value of the screening function 1.5*PHI1 - 0.5*PHI2
343
344 G4double G4eBremParametrizedModel::ScreenFunction2(G4double ScreenVariable)
345 {
346 G4double screenVal;
347
348 if (ScreenVariable > 1.)
349 screenVal = 42.24 - 8.368*G4Log(ScreenVariable+0.952);
350 else
351 screenVal = 41.734 - ScreenVariable* (6.484 - 1.250*ScreenVariable);
352
353 return screenVal;
354 }
355
356 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
357
358 // Parametrized cross section
359 G4double G4eBremParametrizedModel::ComputeParametrizedDXSectionPerAtom(
360 G4double kineticEnergy,
361 G4double gammaEnergy, G4double Z)
362 {
363 SetCurrentElement(Z);
364 G4double FZ = lnZ* (4.- 0.55*lnZ);
365 G4double Z3 = z13;
366 G4double ZZ = z13*nist->GetZ13(G4lrint(Z)+1);
367
368 totalEnergy = kineticEnergy + electron_mass_c2;
369
370 // G4double x, epsil, greject, migdal, grejmax, q;
371 G4double epsil, greject;
372 G4double U = G4Log(kineticEnergy/electron_mass_c2);
373 G4double U2 = U*U;
374
375 // precalculated parameters
376 G4double ah, bh;
377
378 if (kineticEnergy > tlow) {
379
380 G4double ah1 = ah10 + ZZ* (ah11 + ZZ* ah12);
381 G4double ah2 = ah20 + ZZ* (ah21 + ZZ* ah22);
382 G4double ah3 = ah30 + ZZ* (ah31 + ZZ* ah32);
383
384 G4double bh1 = bh10 + ZZ* (bh11 + ZZ* bh12);
385 G4double bh2 = bh20 + ZZ* (bh21 + ZZ* bh22);
386 G4double bh3 = bh30 + ZZ* (bh31 + ZZ* bh32);
387
388 ah = 1. + (ah1*U2 + ah2*U + ah3) / (U2*U);
389 bh = 0.75 + (bh1*U2 + bh2*U + bh3) / (U2*U);
390
391 // limit of the screening variable
392 G4double screenfac =
393 136.*electron_mass_c2/(Z3*totalEnergy);
394
395 epsil = gammaEnergy/totalEnergy; // epsil = x*kineticEnergy/totalEnergy;
396 G4double screenvar = screenfac*epsil/(1.0-epsil);
397 G4double F1 = max(ScreenFunction1(screenvar) - FZ ,0.);
398 G4double F2 = max(ScreenFunction2(screenvar) - FZ ,0.);
399
400
401 greject = (F1 - epsil* (ah*F1 - bh*epsil*F2))/8.; // 1./(42.392 - FZ);
402
403 std::cout << " yy = "<<epsil<<std::endl;
404 std::cout << " F1/(...) "<<F1/(42.392 - FZ)<<std::endl;
405 std::cout << " F2/(...) "<<F2/(42.392 - FZ)<<std::endl;
406 std::cout << " (42.392 - FZ) " << (42.392 - FZ) <<std::endl;
407
408 } else {
409
410 G4double al0 = al00 + ZZ* (al01 + ZZ* al02);
411 G4double al1 = al10 + ZZ* (al11 + ZZ* al12);
412 G4double al2 = al20 + ZZ* (al21 + ZZ* al22);
413
414 G4double bl0 = bl00 + ZZ* (bl01 + ZZ* bl02);
415 G4double bl1 = bl10 + ZZ* (bl11 + ZZ* bl12);
416 G4double bl2 = bl20 + ZZ* (bl21 + ZZ* bl22);
417
418 ah = al0 + al1*U + al2*U2;
419 bh = bl0 + bl1*U + bl2*U2;
420
421 G4double x=gammaEnergy/kineticEnergy;
422 greject=(1. + x* (ah + bh*x));
423
424 /*
425 // Compute the maximum of the rejection function
426 grejmax = max(1. + xmin* (ah + bh*xmin), 1.+ah+bh);
427 G4double xm = -ah/(2.*bh);
428 if ( xmin < xm && xm < xmax) grejmax = max(grejmax, 1.+ xm* (ah + bh*xm));
429 */
430 }
431
432 return greject;
433 }
434
435 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
436
437 G4double G4eBremParametrizedModel::ComputeDXSectionPerAtom(G4double gammaEnergy)
438 {
439
440 if(gammaEnergy < 0.0) { return 0.0; }
441
442 G4double y = gammaEnergy/totalEnergy;
443
444 G4double main=0.;
445 //secondTerm=0.;
446
447 // ** form factors complete screening case **
448 // only valid for high energies (and if LPM suppression does not play a role)
449 main = (3./4.*y*y - y + 1.) * ( (Fel-fCoulomb) + Finel/currentZ );
450 // secondTerm = (1.-y)/12.*(1.+1./currentZ);
451
452 std::cout<<" F1(0) "<<ScreenFunction1(0.) <<std::endl;
453 std::cout<<" F1(0) "<<ScreenFunction2(0.) <<std::endl;
454 std::cout<<"Ekin = "<<kinEnergy<<std::endl;
455 std::cout<<"Z = "<<currentZ<<std::endl;
456 std::cout<<"main = "<<main<<std::endl;
457 std::cout<<" y = "<<y<<std::endl;
458 std::cout<<" Fel-fCoulomb "<< (Fel-fCoulomb) <<std::endl;
459
460 G4double main2 = ComputeParametrizedDXSectionPerAtom(kinEnergy,gammaEnergy,currentZ);
461 std::cout<<"main2 = "<<main2<<std::endl;
462 std::cout<<"main2tot = "<<main2 * ( (Fel-fCoulomb) + Finel/currentZ )/(Fel-fCoulomb);
463
464 G4double cross = main2; //main+secondTerm;
465 return cross;
466 }
467
468 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
469
470 void G4eBremParametrizedModel::SampleSecondaries(
471 std::vector<G4DynamicParticle*>* vdp,
472 const G4MaterialCutsCouple* couple,
473 const G4DynamicParticle* dp,
474 G4double cutEnergy,
475 G4double maxEnergy)
476 {
477 G4double kineticEnergy = dp->GetKineticEnergy();
478 if(kineticEnergy < lowKinEnergy) { return; }
479 G4double cut = std::min(cutEnergy, kineticEnergy);
480 G4double emax = std::min(maxEnergy, kineticEnergy);
481 if(cut >= emax) { return; }
482
483 SetupForMaterial(particle, couple->GetMaterial(),kineticEnergy);
484
485 const G4Element* elm = SelectTargetAtom(couple,particle,kineticEnergy,
486 dp->GetLogKineticEnergy(),cut,emax);
487 SetCurrentElement(elm->GetZ());
488
489 kinEnergy = kineticEnergy;
490 totalEnergy = kineticEnergy + particleMass;
491 densityCorr = densityFactor*totalEnergy*totalEnergy;
492
493 G4double xmin = G4Log(cut*cut + densityCorr);
494 G4double xmax = G4Log(emax*emax + densityCorr);
495 G4double gammaEnergy, f, x;
496
497 CLHEP::HepRandomEngine* rndmEngine = G4Random::getTheEngine();
498
499 do {
500 x = G4Exp(xmin + rndmEngine->flat()*(xmax - xmin)) - densityCorr;
501 if(x < 0.0) x = 0.0;
502 gammaEnergy = sqrt(x);
503 f = ComputeDXSectionPerAtom(gammaEnergy);
504
505 if ( f > fMax ) {
506 G4cout << "### G4eBremParametrizedModel Warning: Majoranta exceeded! "
507 << f << " > " << fMax
508 << " Egamma(MeV)= " << gammaEnergy
509 << " E(mEV)= " << kineticEnergy
510 << G4endl;
511 }
512
513 // Loop checking, 03-Aug-2015, Vladimir Ivanchenko
514 } while (f < fMax*rndmEngine->flat());
515
516 //
517 // angles of the emitted gamma. ( Z - axis along the parent particle)
518 // use general interface
519 //
520 G4ThreeVector gammaDirection =
521 GetAngularDistribution()->SampleDirection(dp, totalEnergy-gammaEnergy,
522 G4lrint(currentZ),
523 couple->GetMaterial());
524
525 // create G4DynamicParticle object for the Gamma
526 auto gamma = new G4DynamicParticle(theGamma,gammaDirection, gammaEnergy);
527 vdp->push_back(gamma);
528
529 G4double totMomentum = sqrt(kineticEnergy*(totalEnergy + electron_mass_c2));
530 G4ThreeVector direction = (totMomentum*dp->GetMomentumDirection()
531 - gammaEnergy*gammaDirection).unit();
532
533 // energy of primary
534 G4double finalE = kineticEnergy - gammaEnergy;
535
536 // stop tracking and create new secondary instead of primary
537 if(gammaEnergy > SecondaryThreshold()) {
538 fParticleChange->ProposeTrackStatus(fStopAndKill);
539 fParticleChange->SetProposedKineticEnergy(0.0);
540 auto el =
541 new G4DynamicParticle(const_cast<G4ParticleDefinition*>(particle),
542 direction, finalE);
543 vdp->push_back(el);
544
545 // continue tracking
546 } else {
547 fParticleChange->SetProposedMomentumDirection(direction);
548 fParticleChange->SetProposedKineticEnergy(finalE);
549 }
550 }
551
552 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
553
554
555