source: trunk/source/processes/electromagnetic/muons/src/G4MuBremsstrahlungModel.cc@ 1036

Last change on this file since 1036 was 1007, checked in by garnier, 17 years ago

update to geant4.9.2
File size: 15.2 KB
Line 
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// $Id: G4MuBremsstrahlungModel.cc,v 1.32 2008/07/22 16:11:34 vnivanch Exp $
27// GEANT4 tag $Name: geant4-09-02 $
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.Ivanchenko)
49// 03-08-05 Angular correlations according to PRM (V.Ivanchenko)
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// 28-02-08 Use precomputed Z^1/3 and Log(A) (V.Ivanchenko)
54//
55
56//
57// Class Description:
58//
59//
60// -------------------------------------------------------------------
61//
62//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
63//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
64
65#include "G4MuBremsstrahlungModel.hh"
66#include "G4Gamma.hh"
67#include "G4MuonMinus.hh"
68#include "G4MuonPlus.hh"
69#include "Randomize.hh"
70#include "G4Material.hh"
71#include "G4Element.hh"
72#include "G4ElementVector.hh"
73#include "G4ProductionCutsTable.hh"
74#include "G4ParticleChangeForLoss.hh"
75
76//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
77//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
78
79using namespace std;
80
81G4MuBremsstrahlungModel::G4MuBremsstrahlungModel(const G4ParticleDefinition* p,
82 const G4String& nam)
83 : G4VEmModel(nam),
84 particle(0),
85 sqrte(sqrt(exp(1.))),
86 bh(202.4),
87 bh1(446.),
88 btf(183.),
89 btf1(1429.),
90 fParticleChange(0),
91 lowestKinEnergy(1.0*GeV),
92 minThreshold(1.0*keV)
93{
94 theGamma = G4Gamma::Gamma();
95 nist = G4NistManager::Instance();
96 if(p) SetParticle(p);
97}
98
99//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
100
101G4MuBremsstrahlungModel::~G4MuBremsstrahlungModel()
102{
103 size_t n = partialSumSigma.size();
104 if(n > 0) {
105 for(size_t i=0; i<n; i++) {
106 delete partialSumSigma[i];
107 }
108 }
109}
110
111//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
112
113void G4MuBremsstrahlungModel::Initialise(const G4ParticleDefinition* p,
114 const G4DataVector& cuts)
115{
116 if(p) SetParticle(p);
117
118 highKinEnergy = HighEnergyLimit();
119
120 // partial cross section is computed for fixed energy
121 G4double fixedEnergy = 0.5*highKinEnergy;
122
123 const G4ProductionCutsTable* theCoupleTable=
124 G4ProductionCutsTable::GetProductionCutsTable();
125 if(theCoupleTable) {
126 G4int numOfCouples = theCoupleTable->GetTableSize();
127
128 // clear old data
129 G4int nn = partialSumSigma.size();
130 G4int nc = cuts.size();
131 if(nn > 0) {
132 for (G4int ii=0; ii<nn; ii++){
133 G4DataVector* a=partialSumSigma[ii];
134 if ( a ) delete a;
135 }
136 partialSumSigma.clear();
137 }
138 // fill new data
139 if (numOfCouples>0) {
140 for (G4int i=0; i<numOfCouples; i++) {
141 G4double cute = DBL_MAX;
142
143 // protection for usage with extrapolator
144 if(i < nc) cute = cuts[i];
145
146 const G4MaterialCutsCouple* couple =
147 theCoupleTable->GetMaterialCutsCouple(i);
148 const G4Material* material = couple->GetMaterial();
149 G4DataVector* dv = ComputePartialSumSigma(material,fixedEnergy,cute);
150 partialSumSigma.push_back(dv);
151 }
152 }
153 }
154
155 // define pointer to G4ParticleChange
156 if(!fParticleChange) {
157 if(pParticleChange)
158 fParticleChange =
159 reinterpret_cast<G4ParticleChangeForLoss*>(pParticleChange);
160 else
161 fParticleChange = new G4ParticleChangeForLoss();
162 }
163}
164
165//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
166
167G4double G4MuBremsstrahlungModel::ComputeDEDXPerVolume(
168 const G4Material* material,
169 const G4ParticleDefinition*,
170 G4double kineticEnergy,
171 G4double cutEnergy)
172{
173 G4double dedx = 0.0;
174 if (kineticEnergy <= lowestKinEnergy) return dedx;
175
176 G4double tmax = kineticEnergy;
177 G4double cut = std::min(cutEnergy,tmax);
178 if(cut < minThreshold) cut = minThreshold;
179
180 const G4ElementVector* theElementVector = material->GetElementVector();
181 const G4double* theAtomicNumDensityVector =
182 material->GetAtomicNumDensityVector();
183
184 // loop for elements in the material
185 for (size_t i=0; i<material->GetNumberOfElements(); i++) {
186
187 G4double loss =
188 ComputMuBremLoss((*theElementVector)[i]->GetZ(), kineticEnergy, cut);
189
190 dedx += loss*theAtomicNumDensityVector[i];
191 }
192 // G4cout << "BR e= " << kineticEnergy << " dedx= " << dedx << G4endl;
193 if(dedx < 0.) dedx = 0.;
194 return dedx;
195}
196
197//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
198
199G4double G4MuBremsstrahlungModel::ComputMuBremLoss(G4double Z,
200 G4double tkin, G4double cut)
201{
202 G4double totalEnergy = mass + tkin;
203 G4double ak1 = 0.05;
204 G4int k2=5;
205 G4double xgi[]={0.03377,0.16940,0.38069,0.61931,0.83060,0.96623};
206 G4double wgi[]={0.08566,0.18038,0.23396,0.23396,0.18038,0.08566};
207 G4double loss = 0.;
208
209 G4double vcut = cut/totalEnergy;
210 G4double vmax = tkin/totalEnergy;
211
212 G4double aaa = 0.;
213 G4double bbb = vcut;
214 if(vcut>vmax) bbb=vmax ;
215 G4int kkk = (G4int)((bbb-aaa)/ak1)+k2 ;
216 G4double hhh=(bbb-aaa)/float(kkk) ;
217
218 G4double aa = aaa;
219 for(G4int l=0; l<kkk; l++)
220 {
221 for(G4int i=0; i<6; i++)
222 {
223 G4double ep = (aa + xgi[i]*hhh)*totalEnergy;
224 loss += ep*wgi[i]*ComputeDMicroscopicCrossSection(tkin, Z, ep);
225 }
226 aa += hhh;
227 }
228
229 loss *=hhh*totalEnergy ;
230
231 return loss;
232}
233
234//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
235
236G4double G4MuBremsstrahlungModel::ComputeMicroscopicCrossSection(
237 G4double tkin,
238 G4double Z,
239 G4double cut)
240{
241 G4double totalEnergy = tkin + mass;
242 G4double ak1 = 2.3;
243 G4int k2 = 4;
244 G4double xgi[]={0.03377,0.16940,0.38069,0.61931,0.83060,0.96623};
245 G4double wgi[]={0.08566,0.18038,0.23396,0.23396,0.18038,0.08566};
246 G4double cross = 0.;
247
248 if(cut >= tkin) return cross;
249
250 G4double vcut = cut/totalEnergy;
251 G4double vmax = tkin/totalEnergy;
252
253 G4double aaa = log(vcut);
254 G4double bbb = log(vmax);
255 G4int kkk = (G4int)((bbb-aaa)/ak1)+k2 ;
256 G4double hhh = (bbb-aaa)/G4double(kkk);
257
258 G4double aa = aaa;
259
260 for(G4int l=0; l<kkk; l++)
261 {
262 for(G4int i=0; i<6; i++)
263 {
264 G4double ep = exp(aa + xgi[i]*hhh)*totalEnergy;
265 cross += ep*wgi[i]*ComputeDMicroscopicCrossSection(tkin, Z, ep);
266 }
267 aa += hhh;
268 }
269
270 cross *=hhh;
271
272 //G4cout << "BR e= " << tkin<< " cross= " << cross/barn << G4endl;
273
274 return cross;
275}
276
277//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
278
279G4double G4MuBremsstrahlungModel::ComputeDMicroscopicCrossSection(
280 G4double tkin,
281 G4double Z,
282 G4double gammaEnergy)
283// differential cross section
284{
285 G4double dxsection = 0.;
286
287 if( gammaEnergy > tkin) return dxsection ;
288
289 G4double E = tkin + mass ;
290 G4double v = gammaEnergy/E ;
291 G4double delta = 0.5*mass*mass*v/(E-gammaEnergy) ;
292 G4double rab0=delta*sqrte ;
293
294 G4int iz = G4int(Z);
295 if(iz < 1) iz = 1;
296
297 G4double z13 = 1.0/nist->GetZ13(iz);
298 G4double dn = 1.54*nist->GetA27(iz);
299
300 G4double b,b1,dnstar ;
301
302 if(1 == iz)
303 {
304 b = bh;
305 b1 = bh1;
306 dnstar = dn;
307 }
308 else
309 {
310 b = btf;
311 b1 = btf1;
312 dnstar = dn/std::pow(dn, 1./Z);
313 }
314
315 // nucleus contribution logarithm
316 G4double rab1=b*z13;
317 G4double fn=log(rab1/(dnstar*(electron_mass_c2+rab0*rab1))*
318 (mass+delta*(dnstar*sqrte-2.))) ;
319 if(fn <0.) fn = 0. ;
320 // electron contribution logarithm
321 G4double epmax1=E/(1.+0.5*mass*rmass/E) ;
322 G4double fe=0.;
323 if(gammaEnergy<epmax1)
324 {
325 G4double rab2=b1*z13*z13 ;
326 fe=log(rab2*mass/((1.+delta*rmass/(electron_mass_c2*sqrte))*
327 (electron_mass_c2+rab0*rab2))) ;
328 if(fe<0.) fe=0. ;
329 }
330
331 dxsection = coeff*(1.-v*(1. - 0.75*v))*Z*(fn*Z + fe)/gammaEnergy;
332
333 return dxsection;
334}
335
336//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
337
338G4double G4MuBremsstrahlungModel::ComputeCrossSectionPerAtom(
339 const G4ParticleDefinition*,
340 G4double kineticEnergy,
341 G4double Z, G4double,
342 G4double cutEnergy,
343 G4double maxEnergy)
344{
345 G4double cross = 0.0;
346 if (kineticEnergy <= lowestKinEnergy) return cross;
347 G4double tmax = std::min(maxEnergy, kineticEnergy);
348 G4double cut = std::min(cutEnergy, kineticEnergy);
349 if(cut < minThreshold) cut = minThreshold;
350 if (cut >= tmax) return cross;
351
352 cross = ComputeMicroscopicCrossSection (kineticEnergy, Z, cut);
353 if(tmax < kineticEnergy) {
354 cross -= ComputeMicroscopicCrossSection(kineticEnergy, Z, tmax);
355 }
356 return cross;
357}
358
359//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
360
361G4DataVector* G4MuBremsstrahlungModel::ComputePartialSumSigma(
362 const G4Material* material,
363 G4double kineticEnergy,
364 G4double cut)
365
366// Build the table of cross section per element.
367// The table is built for material
368// This table is used to select randomly an element in the material.
369{
370 G4int nElements = material->GetNumberOfElements();
371 const G4ElementVector* theElementVector = material->GetElementVector();
372 const G4double* theAtomNumDensityVector =
373 material->GetAtomicNumDensityVector();
374
375 G4DataVector* dv = new G4DataVector();
376
377 G4double cross = 0.0;
378
379 for (G4int i=0; i<nElements; i++ ) {
380 cross += theAtomNumDensityVector[i]
381 * ComputeMicroscopicCrossSection(kineticEnergy,
382 (*theElementVector)[i]->GetZ(), cut);
383 dv->push_back(cross);
384 }
385 return dv;
386}
387
388//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
389
390void G4MuBremsstrahlungModel::SampleSecondaries(
391 std::vector<G4DynamicParticle*>* vdp,
392 const G4MaterialCutsCouple* couple,
393 const G4DynamicParticle* dp,
394 G4double minEnergy,
395 G4double maxEnergy)
396{
397 G4double kineticEnergy = dp->GetKineticEnergy();
398 // check against insufficient energy
399 G4double tmax = std::min(kineticEnergy, maxEnergy);
400 G4double tmin = std::min(kineticEnergy, minEnergy);
401 if(tmin < minThreshold) tmin = minThreshold;
402 if(tmin >= tmax) return;
403
404 // ===== sampling of energy transfer ======
405
406 G4ParticleMomentum partDirection = dp->GetMomentumDirection();
407
408 // select randomly one element constituing the material
409 const G4Element* anElement = SelectRandomAtom(couple);
410 G4double Z = anElement->GetZ();
411
412 G4double totalEnergy = kineticEnergy + mass;
413 G4double totalMomentum = sqrt(kineticEnergy*(kineticEnergy + 2.0*mass));
414
415 G4double func1 = tmin*
416 ComputeDMicroscopicCrossSection(kineticEnergy,Z,tmin);
417
418 G4double lnepksi, epksi;
419 G4double func2;
420
421 do {
422 lnepksi = log(tmin) + G4UniformRand()*log(kineticEnergy/tmin);
423 epksi = exp(lnepksi);
424 func2 = epksi*ComputeDMicroscopicCrossSection(kineticEnergy,Z,epksi);
425
426 } while(func2 < func1*G4UniformRand());
427
428 G4double gEnergy = epksi;
429
430 // ===== sample angle =====
431
432 G4double gam = totalEnergy/mass;
433 G4double rmax = gam*std::min(1.0, totalEnergy/gEnergy - 1.0);
434 G4double rmax2= rmax*rmax;
435 G4double x = G4UniformRand()*rmax2/(1.0 + rmax2);
436
437 G4double theta = sqrt(x/(1.0 - x))/gam;
438 G4double sint = sin(theta);
439 G4double phi = twopi * G4UniformRand() ;
440 G4double dirx = sint*cos(phi), diry = sint*sin(phi), dirz = cos(theta) ;
441
442 G4ThreeVector gDirection(dirx, diry, dirz);
443 gDirection.rotateUz(partDirection);
444
445 partDirection *= totalMomentum;
446 partDirection -= gEnergy*gDirection;
447 partDirection = partDirection.unit();
448
449 // primary change
450 kineticEnergy -= gEnergy;
451 fParticleChange->SetProposedKineticEnergy(kineticEnergy);
452 fParticleChange->SetProposedMomentumDirection(partDirection);
453
454 // save secondary
455 G4DynamicParticle* aGamma =
456 new G4DynamicParticle(theGamma,gDirection,gEnergy);
457 vdp->push_back(aGamma);
458}
459
460//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
461
462const G4Element* G4MuBremsstrahlungModel::SelectRandomAtom(
463 const G4MaterialCutsCouple* couple) const
464{
465 // select randomly 1 element within the material
466
467 const G4Material* material = couple->GetMaterial();
468 G4int nElements = material->GetNumberOfElements();
469 const G4ElementVector* theElementVector = material->GetElementVector();
470 if(1 == nElements) return (*theElementVector)[0];
471 else if(1 > nElements) return 0;
472
473 G4DataVector* dv = partialSumSigma[couple->GetIndex()];
474 G4double rval = G4UniformRand()*((*dv)[nElements-1]);
475 for (G4int i=0; i<nElements; i++) {
476 if (rval <= (*dv)[i]) return (*theElementVector)[i];
477 }
478 return (*theElementVector)[nElements-1];
479}
480
481//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
Note: See TracBrowser for help on using the repository browser.