source: trunk/source/processes/electromagnetic/muons/src/G4MuBremsstrahlungModel.cc@ 900

Last change on this file since 900 was 819, checked in by garnier, 17 years ago

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25//
26// $Id: G4MuBremsstrahlungModel.cc,v 1.24 2007/11/08 11:48:28 vnivanch Exp $
27// GEANT4 tag $Name: geant4-09-01-patch-02 $
28//
29// -------------------------------------------------------------------
30//
31// GEANT4 Class file
32//
33//
34// File name: G4MuBremsstrahlungModel
35//
36// Author: Vladimir Ivanchenko on base of Laszlo Urban code
37//
38// Creation date: 24.06.2002
39//
40// Modifications:
41//
42// 04-12-02 Change G4DynamicParticle constructor in PostStepDoIt (V.Ivanchenko)
43// 23-12-02 Change interface in order to move to cut per region (V.Ivanchenko)
44// 24-01-03 Fix for compounds (V.Ivanchenko)
45// 27-01-03 Make models region aware (V.Ivanchenko)
46// 13-02-03 Add name (V.Ivanchenko)
47// 10-02-04 Add lowestKinEnergy (V.Ivanchenko)
48// 08-04-05 Major optimisation of internal interfaces (V.Ivantchenko)
49// 03-08-05 Angular correlations according to PRM (V.Ivantchenko)
50// 13-02-06 add ComputeCrossSectionPerAtom (mma)
51// 21-03-06 Fix problem of initialisation in case when cuts are not defined (VI)
52// 07-11-07 Improve sampling of final state (A.Bogdanov)
53//
54
55//
56// Class Description:
57//
58//
59// -------------------------------------------------------------------
60//
61//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
62//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
63
64#include "G4MuBremsstrahlungModel.hh"
65#include "G4Gamma.hh"
66#include "G4MuonMinus.hh"
67#include "G4MuonPlus.hh"
68#include "Randomize.hh"
69#include "G4Material.hh"
70#include "G4Element.hh"
71#include "G4ElementVector.hh"
72#include "G4ProductionCutsTable.hh"
73#include "G4ParticleChangeForLoss.hh"
74
75//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
76
77// static members
78//
79G4double G4MuBremsstrahlungModel::zdat[]={1., 4., 13., 29., 92.};
80G4double G4MuBremsstrahlungModel::adat[]={1.01, 9.01, 26.98, 63.55, 238.03};
81G4double G4MuBremsstrahlungModel::tdat[]={1.e3, 1.e4, 1.e5, 1.e6, 1.e7, 1.e8,
82 1.e9, 1.e10};
83
84//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
85
86using namespace std;
87
88G4MuBremsstrahlungModel::G4MuBremsstrahlungModel(const G4ParticleDefinition* p,
89 const G4String& nam)
90 : G4VEmModel(nam),
91 particle(0),
92 lowestKinEnergy(1.0*GeV),
93 minThreshold(1.0*keV),
94 nzdat(5),
95 ntdat(8),
96 NBIN(1000),
97 cutFixed(0.98*keV),
98 ignoreCut(false),
99 samplingTablesAreFilled(false)
100{
101 theGamma = G4Gamma::Gamma();
102 if(p) SetParticle(p);
103}
104
105//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
106
107G4MuBremsstrahlungModel::~G4MuBremsstrahlungModel()
108{
109 size_t n = partialSumSigma.size();
110 if(n > 0) {
111 for(size_t i=0; i<n; i++) {
112 delete partialSumSigma[i];
113 }
114 }
115}
116
117//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
118
119G4double G4MuBremsstrahlungModel::MinEnergyCut(const G4ParticleDefinition*,
120 const G4MaterialCutsCouple*)
121{
122 return minThreshold;
123}
124
125//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
126
127void G4MuBremsstrahlungModel::SetParticle(const G4ParticleDefinition* p)
128{
129 if(!particle) {
130 particle = p;
131 mass = particle->GetPDGMass();
132 }
133}
134
135//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
136
137void G4MuBremsstrahlungModel::Initialise(const G4ParticleDefinition* p,
138 const G4DataVector& cuts)
139{
140 if(p) SetParticle(p);
141
142 highKinEnergy = HighEnergyLimit();
143
144 G4double fixedEnergy = 0.5*highKinEnergy;
145
146 const G4ProductionCutsTable* theCoupleTable=
147 G4ProductionCutsTable::GetProductionCutsTable();
148 if(theCoupleTable) {
149 G4int numOfCouples = theCoupleTable->GetTableSize();
150
151 G4int nn = partialSumSigma.size();
152 G4int nc = cuts.size();
153 if(nn > 0) {
154 for (G4int ii=0; ii<nn; ii++){
155 G4DataVector* a=partialSumSigma[ii];
156 if ( a ) delete a;
157 }
158 partialSumSigma.clear();
159 }
160 if (numOfCouples>0) {
161 for (G4int i=0; i<numOfCouples; i++) {
162 G4double cute = DBL_MAX;
163 if(i < nc) cute = cuts[i];
164 if(cute < cutFixed || ignoreCut) cute = cutFixed;
165 const G4MaterialCutsCouple* couple =
166 theCoupleTable->GetMaterialCutsCouple(i);
167 const G4Material* material = couple->GetMaterial();
168 G4DataVector* dv = ComputePartialSumSigma(material,fixedEnergy,cute);
169 partialSumSigma.push_back(dv);
170 }
171 }
172 }
173 if(!samplingTablesAreFilled) MakeSamplingTables();
174 if(pParticleChange)
175 fParticleChange =
176 reinterpret_cast<G4ParticleChangeForLoss*>(pParticleChange);
177 else
178 fParticleChange = new G4ParticleChangeForLoss();
179}
180
181//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
182
183G4double G4MuBremsstrahlungModel::ComputeDEDXPerVolume(
184 const G4Material* material,
185 const G4ParticleDefinition*,
186 G4double kineticEnergy,
187 G4double cutEnergy)
188{
189 G4double dedx = 0.0;
190 if (kineticEnergy <= lowestKinEnergy || ignoreCut) return dedx;
191
192 G4double tmax = kineticEnergy;
193 G4double cut = min(cutEnergy,tmax);
194 if(cut < cutFixed) cut = cutFixed;
195
196 const G4ElementVector* theElementVector = material->GetElementVector();
197 const G4double* theAtomicNumDensityVector =
198 material->GetAtomicNumDensityVector();
199
200 // loop for elements in the material
201 for (size_t i=0; i<material->GetNumberOfElements(); i++) {
202
203 G4double Z = (*theElementVector)[i]->GetZ();
204 G4double A = (*theElementVector)[i]->GetA()/(g/mole) ;
205
206 G4double loss = ComputMuBremLoss(Z, A, kineticEnergy, cut);
207
208 dedx += loss*theAtomicNumDensityVector[i];
209 }
210 if(dedx < 0.) dedx = 0.;
211 return dedx;
212}
213
214//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
215
216G4double G4MuBremsstrahlungModel::ComputMuBremLoss(G4double Z, G4double A,
217 G4double tkin, G4double cut)
218{
219 G4double totalEnergy = mass + tkin;
220 G4double ak1 = 0.05;
221 G4int k2=5;
222 G4double xgi[]={0.03377,0.16940,0.38069,0.61931,0.83060,0.96623};
223 G4double wgi[]={0.08566,0.18038,0.23396,0.23396,0.18038,0.08566};
224 G4double loss = 0.;
225
226 G4double vcut = cut/totalEnergy;
227 G4double vmax = tkin/totalEnergy;
228
229 G4double aaa = 0.;
230 G4double bbb = vcut;
231 if(vcut>vmax) bbb=vmax ;
232 G4int kkk = (G4int)((bbb-aaa)/ak1)+k2 ;
233 G4double hhh=(bbb-aaa)/float(kkk) ;
234
235 G4double aa = aaa;
236 for(G4int l=0; l<kkk; l++)
237 {
238 for(G4int i=0; i<6; i++)
239 {
240 G4double ep = (aa + xgi[i]*hhh)*totalEnergy;
241 loss += ep*wgi[i]*ComputeDMicroscopicCrossSection(tkin, Z, A, ep);
242 }
243 aa += hhh;
244 }
245
246 loss *=hhh*totalEnergy ;
247
248 return loss;
249}
250
251//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
252
253G4double G4MuBremsstrahlungModel::ComputeMicroscopicCrossSection(
254 G4double tkin,
255 G4double Z,
256 G4double A,
257 G4double cut)
258{
259 G4double totalEnergy = tkin + mass;
260 G4double ak1 = 2.3;
261 G4int k2 = 4;
262 G4double xgi[]={0.03377,0.16940,0.38069,0.61931,0.83060,0.96623};
263 G4double wgi[]={0.08566,0.18038,0.23396,0.23396,0.18038,0.08566};
264 G4double cross = 0.;
265
266 if(cut >= tkin) return cross;
267
268 G4double vcut = cut/totalEnergy;
269 G4double vmax = tkin/totalEnergy;
270
271 G4double aaa = log(vcut);
272 G4double bbb = log(vmax);
273 G4int kkk = (G4int)((bbb-aaa)/ak1)+k2 ;
274 G4double hhh = (bbb-aaa)/float(kkk);
275
276 G4double aa = aaa;
277
278 for(G4int l=0; l<kkk; l++)
279 {
280 for(G4int i=0; i<6; i++)
281 {
282 G4double ep = exp(aa + xgi[i]*hhh)*totalEnergy;
283 cross += ep*wgi[i]*ComputeDMicroscopicCrossSection(tkin, Z, A, ep);
284 }
285 aa += hhh;
286 }
287
288 cross *=hhh;
289
290 return cross;
291}
292
293//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
294
295G4double G4MuBremsstrahlungModel::ComputeDMicroscopicCrossSection(
296 G4double tkin,
297 G4double Z,
298 G4double A,
299 G4double gammaEnergy)
300// differential cross section
301{
302 static const G4double sqrte=sqrt(exp(1.)) ;
303 static const G4double bh=202.4,bh1=446.,btf=183.,btf1=1429. ;
304 static const G4double rmass=mass/electron_mass_c2 ;
305 static const G4double cc=classic_electr_radius/rmass ;
306 static const G4double coeff= 16.*fine_structure_const*cc*cc/3. ;
307
308 G4double dxsection = 0.;
309
310 if( gammaEnergy > tkin) return dxsection ;
311
312 G4double E = tkin + mass ;
313 G4double v = gammaEnergy/E ;
314 G4double delta = 0.5*mass*mass*v/(E-gammaEnergy) ;
315 G4double rab0=delta*sqrte ;
316
317 G4double z13 = exp(-log(Z)/3.) ;
318 G4double dn = 1.54*exp(0.27*log(A)) ;
319
320 G4double b,b1,dnstar ;
321
322 if(Z<1.5)
323 {
324 b=bh;
325 b1=bh1;
326 dnstar=dn ;
327 }
328 else
329 {
330 b=btf;
331 b1=btf1;
332 dnstar = exp((1.-1./Z)*log(dn)) ;
333 }
334
335 // nucleus contribution logarithm
336 G4double rab1=b*z13;
337 G4double fn=log(rab1/(dnstar*(electron_mass_c2+rab0*rab1))*
338 (mass+delta*(dnstar*sqrte-2.))) ;
339 if(fn <0.) fn = 0. ;
340 // electron contribution logarithm
341 G4double epmax1=E/(1.+0.5*mass*rmass/E) ;
342 G4double fe=0.;
343 if(gammaEnergy<epmax1)
344 {
345 G4double rab2=b1*z13*z13 ;
346 fe=log(rab2*mass/((1.+delta*rmass/(electron_mass_c2*sqrte))*
347 (electron_mass_c2+rab0*rab2))) ;
348 if(fe<0.) fe=0. ;
349 }
350
351 dxsection = coeff*(1.-v*(1. - 0.75*v))*Z*(fn*Z + fe)/gammaEnergy;
352
353 return dxsection;
354}
355
356//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
357
358G4double G4MuBremsstrahlungModel::ComputeCrossSectionPerAtom(
359 const G4ParticleDefinition*,
360 G4double kineticEnergy,
361 G4double Z, G4double A,
362 G4double cutEnergy,
363 G4double)
364{
365 G4double cut = min(cutEnergy, kineticEnergy);
366 if(cut < cutFixed || ignoreCut) cut = cutFixed;
367 G4double cross =
368 ComputeMicroscopicCrossSection (kineticEnergy, Z, A/(g/mole), cut);
369 return cross;
370}
371
372//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
373
374G4double G4MuBremsstrahlungModel::CrossSectionPerVolume(
375 const G4Material* material,
376 const G4ParticleDefinition*,
377 G4double kineticEnergy,
378 G4double cutEnergy,
379 G4double maxEnergy)
380{
381 G4double cross = 0.0;
382 if (cutEnergy >= maxEnergy || kineticEnergy <= lowestKinEnergy) return cross;
383
384 G4double tmax = min(maxEnergy, kineticEnergy);
385 G4double cut = min(cutEnergy, tmax);
386 if(cut < cutFixed || ignoreCut) cut = cutFixed;
387
388 const G4ElementVector* theElementVector = material->GetElementVector();
389 const G4double* theAtomNumDensityVector =
390 material->GetAtomicNumDensityVector();
391
392 for (size_t i=0; i<material->GetNumberOfElements(); i++) {
393
394 G4double Z = (*theElementVector)[i]->GetZ();
395 G4double A = (*theElementVector)[i]->GetA()/(g/mole);
396
397 G4double cr = ComputeMicroscopicCrossSection(kineticEnergy, Z, A, cut);
398
399 if(tmax < kineticEnergy) {
400 cr -= ComputeMicroscopicCrossSection(kineticEnergy, Z, A, tmax);
401 }
402 cross += theAtomNumDensityVector[i] * cr;
403 }
404
405 return cross;
406}
407
408//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
409
410G4DataVector* G4MuBremsstrahlungModel::ComputePartialSumSigma(
411 const G4Material* material,
412 G4double kineticEnergy,
413 G4double cut)
414
415// Build the table of cross section per element. The table is built for MATERIAL
416// This table is used by DoIt to select randomly an element in the material.
417{
418 G4int nElements = material->GetNumberOfElements();
419 const G4ElementVector* theElementVector = material->GetElementVector();
420 const G4double* theAtomNumDensityVector =
421 material->GetAtomicNumDensityVector();
422
423 G4DataVector* dv = new G4DataVector();
424
425 G4double cross = 0.0;
426
427 for (G4int i=0; i<nElements; i++ ) {
428
429 G4double Z = (*theElementVector)[i]->GetZ();
430 G4double A = (*theElementVector)[i]->GetA()/(g/mole) ;
431 cross += theAtomNumDensityVector[i]
432 * ComputeMicroscopicCrossSection(kineticEnergy, Z, A, cut);
433 dv->push_back(cross);
434 }
435 return dv;
436}
437
438//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
439
440void G4MuBremsstrahlungModel::MakeSamplingTables()
441{
442
443 G4double AtomicNumber,AtomicWeight,KineticEnergy,
444 TotalEnergy,Maxep;
445
446 for (G4int iz=0; iz<nzdat; iz++)
447 {
448 AtomicNumber = zdat[iz];
449 AtomicWeight = adat[iz]*g/mole ;
450
451 for (G4int it=0; it<ntdat; it++)
452 {
453 KineticEnergy = tdat[it];
454 TotalEnergy = KineticEnergy + mass;
455 Maxep = KineticEnergy ;
456
457 G4double CrossSection = 0.0 ;
458
459 // calculate the differential cross section
460 // numerical integration in
461 // log ...............
462 G4double c = log(Maxep/cutFixed) ;
463 G4double ymin = -5. ;
464 G4double ymax = 0. ;
465 G4double dy = (ymax-ymin)/NBIN ;
466
467 G4double y = ymin - 0.5*dy ;
468 G4double yy = ymin - dy ;
469 G4double x = exp(y);
470 G4double fac = exp(dy);
471 G4double dx = exp(yy)*(fac - 1.0);
472
473 for (G4int i=0 ; i<NBIN; i++)
474 {
475 y += dy ;
476 x *= fac;
477 dx*= fac;
478 G4double ep = cutFixed*exp(c*x) ;
479
480 CrossSection += ep*dx*ComputeDMicroscopicCrossSection(
481 KineticEnergy,AtomicNumber,
482 AtomicWeight,ep) ;
483 ya[i]=y ;
484 proba[iz][it][i] = CrossSection ;
485
486 }
487
488 proba[iz][it][NBIN] = CrossSection ;
489 ya[NBIN] = 0. ; // !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
490
491 if(CrossSection > 0.)
492 {
493 for(G4int ib=0; ib<=NBIN; ib++)
494 {
495 proba[iz][it][ib] /= CrossSection ;
496 }
497 }
498 }
499 }
500 samplingTablesAreFilled = true;
501}
502
503//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
504
505void G4MuBremsstrahlungModel::SampleSecondaries(std::vector<G4DynamicParticle*>* vdp,
506 const G4MaterialCutsCouple* couple,
507 const G4DynamicParticle* dp,
508 G4double minEnergy,
509 G4double maxEnergy)
510{
511 G4double kineticEnergy = dp->GetKineticEnergy();
512 // check against insufficient energy
513 G4double tmax = min(kineticEnergy, maxEnergy);
514 G4double tmin = min(kineticEnergy, minEnergy);
515 if(tmin < cutFixed || ignoreCut) tmin = cutFixed;
516 if(tmin >= tmax) return;
517
518 // ===== the begining of a new code ======
519 // ===== sampling of energy transfer ======
520
521 G4ParticleMomentum partDirection = dp->GetMomentumDirection();
522
523 // select randomly one element constituing the material
524 const G4Element* anElement = SelectRandomAtom(couple);
525
526 G4double totalEnergy = kineticEnergy + mass;
527 G4double totalMomentum = sqrt(kineticEnergy*(kineticEnergy + 2.0*mass));
528
529 G4double AtomicNumber = anElement->GetZ();
530 G4double AtomicWeight = anElement->GetA()/(g/mole);
531
532 G4double func1 = tmin*ComputeDMicroscopicCrossSection(
533 kineticEnergy,AtomicNumber,
534 AtomicWeight,tmin);
535
536 G4double lnepksi, epksi;
537 G4double func2;
538 G4double ksi2;
539
540 do {
541 lnepksi = log(tmin) + G4UniformRand()*log(kineticEnergy/tmin);
542 epksi = exp(lnepksi);
543 func2 = epksi*ComputeDMicroscopicCrossSection(
544 kineticEnergy,AtomicNumber,
545 AtomicWeight,epksi);
546 ksi2 = G4UniformRand();
547
548 } while(func2/func1 < ksi2);
549
550 // ===== the end of a new code =====
551
552 // create G4DynamicParticle object for the Gamma
553 G4double gEnergy = epksi;
554
555 // sample angle
556 G4double gam = totalEnergy/mass;
557 G4double rmax = gam*min(1.0, totalEnergy/gEnergy - 1.0);
558 rmax *= rmax;
559 G4double x = G4UniformRand()*rmax/(1.0 + rmax);
560
561 G4double theta = sqrt(x/(1.0 - x))/gam;
562 G4double sint = sin(theta);
563 G4double phi = twopi * G4UniformRand() ;
564 G4double dirx = sint*cos(phi), diry = sint*sin(phi), dirz = cos(theta) ;
565
566 G4ThreeVector gDirection(dirx, diry, dirz);
567 gDirection.rotateUz(partDirection);
568
569 partDirection *= totalMomentum;
570 partDirection -= gEnergy*gDirection;
571 partDirection = partDirection.unit();
572
573 // primary change
574 kineticEnergy -= gEnergy;
575 fParticleChange->SetProposedKineticEnergy(kineticEnergy);
576 fParticleChange->SetProposedMomentumDirection(partDirection);
577
578 // save secondary
579 G4DynamicParticle* aGamma = new G4DynamicParticle(theGamma,gDirection,gEnergy);
580 vdp->push_back(aGamma);
581}
582
583//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
584
585const G4Element* G4MuBremsstrahlungModel::SelectRandomAtom(
586 const G4MaterialCutsCouple* couple) const
587{
588 // select randomly 1 element within the material
589
590 const G4Material* material = couple->GetMaterial();
591 G4int nElements = material->GetNumberOfElements();
592 const G4ElementVector* theElementVector = material->GetElementVector();
593 if(1 == nElements) return (*theElementVector)[0];
594 else if(1 > nElements) return 0;
595
596 G4DataVector* dv = partialSumSigma[couple->GetIndex()];
597 G4double rval = G4UniformRand()*((*dv)[nElements-1]);
598 for (G4int i=0; i<nElements; i++) {
599 if (rval <= (*dv)[i]) return (*theElementVector)[i];
600 }
601 return (*theElementVector)[nElements-1];
602}
603
604//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
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