source: trunk/source/processes/electromagnetic/adjoint/src/G4AdjointComptonModel.cc@ 1347

Last change on this file since 1347 was 1337, checked in by garnier, 15 years ago

tag geant4.9.4 beta 1 + modifs locales
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25//
26// $Id: G4AdjointComptonModel.cc,v 1.6 2009/12/16 17:50:03 gunter Exp $
27// GEANT4 tag $Name: geant4-09-04-beta-01 $
28//
29#include "G4AdjointComptonModel.hh"
30#include "G4AdjointCSManager.hh"
31
32
33#include "G4Integrator.hh"
34#include "G4TrackStatus.hh"
35#include "G4ParticleChange.hh"
36#include "G4AdjointElectron.hh"
37#include "G4AdjointGamma.hh"
38#include "G4Gamma.hh"
39#include "G4KleinNishinaCompton.hh"
40
41
42////////////////////////////////////////////////////////////////////////////////
43//
44G4AdjointComptonModel::G4AdjointComptonModel():
45 G4VEmAdjointModel("AdjointCompton")
46
47{ SetApplyCutInRange(false);
48 SetUseMatrix(true);
49 SetUseMatrixPerElement(true);
50 SetUseOnlyOneMatrixForAllElements(true);
51 theAdjEquivOfDirectPrimPartDef =G4AdjointGamma::AdjointGamma();
52 theAdjEquivOfDirectSecondPartDef=G4AdjointElectron::AdjointElectron();
53 theDirectPrimaryPartDef=G4Gamma::Gamma();
54 second_part_of_same_type=false;
55 theDirectEMModel=new G4KleinNishinaCompton(G4Gamma::Gamma(),"ComptonDirectModel");
56
57}
58////////////////////////////////////////////////////////////////////////////////
59//
60G4AdjointComptonModel::~G4AdjointComptonModel()
61{;}
62////////////////////////////////////////////////////////////////////////////////
63//
64void G4AdjointComptonModel::SampleSecondaries(const G4Track& aTrack,
65 G4bool IsScatProjToProjCase,
66 G4ParticleChange* fParticleChange)
67{
68 if (!UseMatrix) return RapidSampleSecondaries(aTrack,IsScatProjToProjCase,fParticleChange);
69
70 //A recall of the compton scattering law is
71 //Egamma2=Egamma1/(1+(Egamma1/E0_electron)(1.-cos_th))
72 //Therefore Egamma2_max= Egamma2(cos_th=1) = Egamma1
73 //Therefore Egamma2_min= Egamma2(cos_th=-1) = Egamma1/(1+2.(Egamma1/E0_electron))
74
75
76 const G4DynamicParticle* theAdjointPrimary =aTrack.GetDynamicParticle();
77 G4double adjointPrimKinEnergy = theAdjointPrimary->GetKineticEnergy();
78 if (adjointPrimKinEnergy>HighEnergyLimit*0.999){
79 return;
80 }
81
82
83 //Sample secondary energy
84 //-----------------------
85 G4double gammaE1;
86 gammaE1 = SampleAdjSecEnergyFromCSMatrix(adjointPrimKinEnergy,
87 IsScatProjToProjCase);
88
89
90 //gammaE2
91 //-----------
92
93 G4double gammaE2 = adjointPrimKinEnergy;
94 if (!IsScatProjToProjCase) gammaE2 = gammaE1 - adjointPrimKinEnergy;
95
96
97
98
99
100
101 //Cos th
102 //-------
103// G4cout<<"Compton scattering "<<gammaE1<<'\t'<<gammaE2<<G4endl;
104 G4double cos_th = 1.+ electron_mass_c2*(1./gammaE1 -1./gammaE2);
105 if (!IsScatProjToProjCase) {
106 G4double p_elec=theAdjointPrimary->GetTotalMomentum();
107 cos_th = (gammaE1 - gammaE2*cos_th)/p_elec;
108 }
109 G4double sin_th = 0.;
110 if (std::abs(cos_th)>1){
111 //G4cout<<"Problem in compton scattering with cos_th "<<cos_th<<G4endl;
112 if (cos_th>0) {
113 cos_th=1.;
114 }
115 else cos_th=-1.;
116 sin_th=0.;
117 }
118 else sin_th = std::sqrt(1.-cos_th*cos_th);
119
120
121
122
123 //gamma0 momentum
124 //--------------------
125
126
127 G4ThreeVector dir_parallel=theAdjointPrimary->GetMomentumDirection();
128 G4double phi =G4UniformRand()*2.*3.1415926;
129 G4ThreeVector gammaMomentum1 = gammaE1*G4ThreeVector(std::cos(phi)*sin_th,std::sin(phi)*sin_th,cos_th);
130 gammaMomentum1.rotateUz(dir_parallel);
131// G4cout<<gamma0Energy<<'\t'<<gamma0Momentum<<G4endl;
132
133
134 //It is important to correct the weight of particles before adding the secondary
135 //------------------------------------------------------------------------------
136 CorrectPostStepWeight(fParticleChange,
137 aTrack.GetWeight(),
138 adjointPrimKinEnergy,
139 gammaE1,
140 IsScatProjToProjCase);
141
142 if (!IsScatProjToProjCase){ //kill the primary and add a secondary
143 fParticleChange->ProposeTrackStatus(fStopAndKill);
144 fParticleChange->AddSecondary(new G4DynamicParticle(theAdjEquivOfDirectPrimPartDef,gammaMomentum1));
145 //G4cout<<"gamma0Momentum "<<gamma0Momentum<<G4endl;
146 }
147 else {
148 fParticleChange->ProposeEnergy(gammaE1);
149 fParticleChange->ProposeMomentumDirection(gammaMomentum1.unit());
150 }
151
152
153}
154////////////////////////////////////////////////////////////////////////////////
155//
156void G4AdjointComptonModel::RapidSampleSecondaries(const G4Track& aTrack,
157 G4bool IsScatProjToProjCase,
158 G4ParticleChange* fParticleChange)
159{
160
161 const G4DynamicParticle* theAdjointPrimary =aTrack.GetDynamicParticle();
162 DefineCurrentMaterial(aTrack.GetMaterialCutsCouple());
163
164
165 G4double adjointPrimKinEnergy = theAdjointPrimary->GetKineticEnergy();
166
167
168 if (adjointPrimKinEnergy>HighEnergyLimit*0.999){
169 return;
170 }
171
172
173 G4double diffCSUsed=currentMaterial->GetElectronDensity()*twopi_mc2_rcl2;
174 G4double gammaE1=0.;
175 G4double gammaE2=0.;
176 if (!IsScatProjToProjCase){
177
178 G4double Emax = GetSecondAdjEnergyMaxForProdToProjCase(adjointPrimKinEnergy);
179 G4double Emin= GetSecondAdjEnergyMinForProdToProjCase(adjointPrimKinEnergy);;
180 if (Emin>=Emax) return;
181 G4double f1=(Emin-adjointPrimKinEnergy)/Emin;
182 G4double f2=(Emax-adjointPrimKinEnergy)/Emax/f1;
183 gammaE1=adjointPrimKinEnergy/(1.-f1*std::pow(f2,G4UniformRand()));;
184 gammaE2=gammaE1-adjointPrimKinEnergy;
185 diffCSUsed= diffCSUsed*(1.+2.*std::log(1.+electron_mass_c2/adjointPrimKinEnergy))*adjointPrimKinEnergy/gammaE1/gammaE2;
186
187
188 }
189 else { G4double Emax = GetSecondAdjEnergyMaxForScatProjToProjCase(adjointPrimKinEnergy);
190 G4double Emin = GetSecondAdjEnergyMinForScatProjToProjCase(adjointPrimKinEnergy,currentTcutForDirectSecond);
191 if (Emin>=Emax) return;
192 gammaE2 =adjointPrimKinEnergy;
193 gammaE1=Emin*std::pow(Emax/Emin,G4UniformRand());
194 diffCSUsed= diffCSUsed/gammaE1;
195
196 }
197
198
199
200
201 //Weight correction
202 //-----------------------
203 //First w_corr is set to the ratio between adjoint total CS and fwd total CS
204 G4double w_corr=G4AdjointCSManager::GetAdjointCSManager()->GetPostStepWeightCorrection();
205
206 //Then another correction is needed due to the fact that a biaised differential CS has been used rather than the
207 //one consistent with the direct model
208
209
210 G4double diffCS = DiffCrossSectionPerAtomPrimToScatPrim(gammaE1, gammaE2,1,0.);
211 if (diffCS >0) diffCS /=G4direct_CS; // here we have the normalised diffCS
212 diffCS*=theDirectEMProcess->GetLambda(gammaE1,currentCouple);
213 //diffCS*=theDirectEMModel->CrossSectionPerVolume(currentMaterial,G4Gamma::Gamma(),gammaE1,0.,2.*gammaE1);
214 //G4cout<<"diffCS/diffCSUsed "<<diffCS/diffCSUsed<<'\t'<<gammaE1<<'\t'<<gammaE2<<G4endl;
215
216 w_corr*=diffCS/diffCSUsed;
217
218 G4double new_weight = aTrack.GetWeight()*w_corr;
219 fParticleChange->SetParentWeightByProcess(false);
220 fParticleChange->SetSecondaryWeightByProcess(false);
221 fParticleChange->ProposeParentWeight(new_weight);
222
223
224
225 //Cos th
226 //-------
227
228 G4double cos_th = 1.+ electron_mass_c2*(1./gammaE1 -1./gammaE2);
229 if (!IsScatProjToProjCase) {
230 G4double p_elec=theAdjointPrimary->GetTotalMomentum();
231 cos_th = (gammaE1 - gammaE2*cos_th)/p_elec;
232 }
233 G4double sin_th = 0.;
234 if (std::abs(cos_th)>1){
235 //G4cout<<"Problem in compton scattering with cos_th "<<cos_th<<G4endl;
236 if (cos_th>0) {
237 cos_th=1.;
238 }
239 else cos_th=-1.;
240 sin_th=0.;
241 }
242 else sin_th = std::sqrt(1.-cos_th*cos_th);
243
244
245
246
247 //gamma0 momentum
248 //--------------------
249
250
251 G4ThreeVector dir_parallel=theAdjointPrimary->GetMomentumDirection();
252 G4double phi =G4UniformRand()*2.*3.1415926;
253 G4ThreeVector gammaMomentum1 = gammaE1*G4ThreeVector(std::cos(phi)*sin_th,std::sin(phi)*sin_th,cos_th);
254 gammaMomentum1.rotateUz(dir_parallel);
255
256
257
258
259 if (!IsScatProjToProjCase){ //kill the primary and add a secondary
260 fParticleChange->ProposeTrackStatus(fStopAndKill);
261 fParticleChange->AddSecondary(new G4DynamicParticle(theAdjEquivOfDirectPrimPartDef,gammaMomentum1));
262 //G4cout<<"gamma0Momentum "<<gamma0Momentum<<G4endl;
263 }
264 else {
265 fParticleChange->ProposeEnergy(gammaE1);
266 fParticleChange->ProposeMomentumDirection(gammaMomentum1.unit());
267 }
268
269
270
271}
272
273
274////////////////////////////////////////////////////////////////////////////////
275//
276//The implementation here is correct for energy loss process, for the photoelectric and compton scattering the method should be redefine
277G4double G4AdjointComptonModel::DiffCrossSectionPerAtomPrimToSecond(
278 G4double gamEnergy0,
279 G4double kinEnergyElec,
280 G4double Z,
281 G4double A)
282{
283 G4double gamEnergy1 = gamEnergy0 - kinEnergyElec;
284 G4double dSigmadEprod=0.;
285 if (gamEnergy1>0.) dSigmadEprod=DiffCrossSectionPerAtomPrimToScatPrim(gamEnergy0,gamEnergy1,Z,A);
286 return dSigmadEprod;
287}
288
289
290////////////////////////////////////////////////////////////////////////////////
291//
292G4double G4AdjointComptonModel::DiffCrossSectionPerAtomPrimToScatPrim(
293 G4double gamEnergy0,
294 G4double gamEnergy1,
295 G4double Z,
296 G4double )
297{ //Based on Klein Nishina formula
298 // In the forward case (see G4KleinNishinaModel) the cross section is parametrised while
299 // the secondaries are sampled from the
300 // Klein Nishida differential cross section
301 // The used diffrential cross section here is therefore the cross section multiplied by the normalised
302 //differential Klein Nishida cross section
303
304
305 //Klein Nishida Cross Section
306 //-----------------------------
307 G4double epsilon = gamEnergy0 / electron_mass_c2 ;
308 G4double one_plus_two_epsi =1.+2.*epsilon;
309 G4double gamEnergy1_max = gamEnergy0;
310 G4double gamEnergy1_min = gamEnergy0/one_plus_two_epsi;
311 if (gamEnergy1 >gamEnergy1_max || gamEnergy1<gamEnergy1_min) {
312 /*G4cout<<"the differential CS is null"<<G4endl;
313 G4cout<<gamEnergy0<<G4endl;
314 G4cout<<gamEnergy1<<G4endl;
315 G4cout<<gamEnergy1_min<<G4endl;*/
316 return 0.;
317 }
318
319
320 G4double epsi2 = epsilon *epsilon ;
321 G4double one_plus_two_epsi_2=one_plus_two_epsi*one_plus_two_epsi;
322
323
324 G4double CS=std::log(one_plus_two_epsi)*(1.- 2.*(1.+epsilon)/epsi2);
325 CS+=4./epsilon +0.5*(1.-1./one_plus_two_epsi_2);
326 CS/=epsilon;
327 //Note that the pi*re2*Z factor is neglected because it is suppresed when computing dCS_dE1/CS;
328 // in the differential cross section
329
330
331 //Klein Nishida Differential Cross Section
332 //-----------------------------------------
333 G4double epsilon1 = gamEnergy1 / electron_mass_c2 ;
334 G4double v= epsilon1/epsilon;
335 G4double term1 =1.+ 1./epsilon -1/epsilon1;
336 G4double dCS_dE1= 1./v +v + term1*term1 -1.;
337 dCS_dE1 *=1./epsilon/gamEnergy0;
338
339
340 //Normalised to the CS used in G4
341 //-------------------------------
342
343 G4direct_CS = theDirectEMModel->ComputeCrossSectionPerAtom(G4Gamma::Gamma(),
344 gamEnergy0,
345 Z, 0., 0.,0.);
346
347 dCS_dE1 *= G4direct_CS/CS;
348/* G4cout<<"the differential CS is not null"<<G4endl;
349 G4cout<<gamEnergy0<<G4endl;
350 G4cout<<gamEnergy1<<G4endl;*/
351
352 return dCS_dE1;
353
354
355}
356
357////////////////////////////////////////////////////////////////////////////////
358//
359G4double G4AdjointComptonModel::GetSecondAdjEnergyMaxForScatProjToProjCase(G4double PrimAdjEnergy)
360{ G4double inv_e_max = 1./PrimAdjEnergy - 2./electron_mass_c2;
361 G4double e_max = HighEnergyLimit;
362 if (inv_e_max > 0. ) e_max=std::min(1./inv_e_max,HighEnergyLimit);
363 return e_max;
364}
365////////////////////////////////////////////////////////////////////////////////
366//
367G4double G4AdjointComptonModel::GetSecondAdjEnergyMinForProdToProjCase(G4double PrimAdjEnergy)
368{ G4double half_e=PrimAdjEnergy/2.;
369 G4double term=std::sqrt(half_e*(electron_mass_c2+half_e));
370 G4double emin=half_e+term;
371 return emin;
372}
373////////////////////////////////////////////////////////////////////////////////
374//
375G4double G4AdjointComptonModel::AdjointCrossSection(const G4MaterialCutsCouple* aCouple,
376 G4double primEnergy,
377 G4bool IsScatProjToProjCase)
378{
379 if (UseMatrix) return G4VEmAdjointModel::AdjointCrossSection(aCouple,primEnergy,IsScatProjToProjCase);
380 DefineCurrentMaterial(aCouple);
381
382
383 G4double Cross=0.;
384 G4double Emax_proj =0.;
385 G4double Emin_proj =0.;
386 if (!IsScatProjToProjCase ){
387 Emax_proj = GetSecondAdjEnergyMaxForProdToProjCase(primEnergy);
388 Emin_proj = GetSecondAdjEnergyMinForProdToProjCase(primEnergy);
389 if (Emax_proj>Emin_proj ){
390 Cross= std::log((Emax_proj-primEnergy)*Emin_proj/Emax_proj/(Emin_proj-primEnergy))
391 *(1.+2.*std::log(1.+electron_mass_c2/primEnergy));
392 }
393 }
394 else {
395 Emax_proj = GetSecondAdjEnergyMaxForScatProjToProjCase(primEnergy);
396 Emin_proj = GetSecondAdjEnergyMinForScatProjToProjCase(primEnergy,0.);
397 if (Emax_proj>Emin_proj) {
398 Cross = std::log(Emax_proj/Emin_proj);
399 //+0.5*primEnergy*primEnergy(1./(Emin_proj*Emin_proj) - 1./(Emax_proj*Emax_proj)); neglected at the moment
400 }
401
402
403 }
404
405 Cross*=currentMaterial->GetElectronDensity()*twopi_mc2_rcl2;
406 lastCS=Cross;
407 return Cross;
408}
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