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: G4PolarizedAnnihilationModel.cc,v 1.9 2009/11/12 12:57:15 schaelic Exp $ |
---|
27 | // GEANT4 tag $Name: geant4-09-03 $ |
---|
28 | // |
---|
29 | // ------------------------------------------------------------------- |
---|
30 | // |
---|
31 | // GEANT4 Class file |
---|
32 | // |
---|
33 | // |
---|
34 | // File name: G4PolarizedAnnihilationModel |
---|
35 | // |
---|
36 | // Author: Andreas Schaelicke |
---|
37 | // |
---|
38 | // Creation date: 01.05.2005 |
---|
39 | // |
---|
40 | // Modifications: |
---|
41 | // 18-07-06 use newly calculated cross sections (P. Starovoitov) |
---|
42 | // 21-08-06 update interface (A. Schaelicke) |
---|
43 | // 17-11-06 add protection agaist e+ zero energy PostStep (V.Ivanchenko) |
---|
44 | // 10-07-07 copied Initialise() method from G4eeToTwoGammaModel to provide a |
---|
45 | // local ParticleChangeForGamma object and reduce overhead |
---|
46 | // in SampleSecondaries() (A. Schaelicke) |
---|
47 | // |
---|
48 | // |
---|
49 | // Class Description: |
---|
50 | // |
---|
51 | // Implementation of polarized gamma Annihilation scattering on free electron |
---|
52 | // |
---|
53 | |
---|
54 | // ------------------------------------------------------------------- |
---|
55 | #include "G4PolarizedAnnihilationModel.hh" |
---|
56 | #include "G4PolarizationManager.hh" |
---|
57 | #include "G4PolarizationHelper.hh" |
---|
58 | #include "G4StokesVector.hh" |
---|
59 | #include "G4PolarizedAnnihilationCrossSection.hh" |
---|
60 | #include "G4ParticleChangeForGamma.hh" |
---|
61 | #include "G4TrackStatus.hh" |
---|
62 | #include "G4Gamma.hh" |
---|
63 | |
---|
64 | G4PolarizedAnnihilationModel::G4PolarizedAnnihilationModel(const G4ParticleDefinition* p, |
---|
65 | const G4String& nam) |
---|
66 | : G4eeToTwoGammaModel(p,nam),crossSectionCalculator(0),gParticleChange(0), |
---|
67 | gIsInitialised(false) |
---|
68 | { |
---|
69 | crossSectionCalculator=new G4PolarizedAnnihilationCrossSection(); |
---|
70 | } |
---|
71 | |
---|
72 | G4PolarizedAnnihilationModel::~G4PolarizedAnnihilationModel() |
---|
73 | { |
---|
74 | if (crossSectionCalculator) delete crossSectionCalculator; |
---|
75 | } |
---|
76 | |
---|
77 | |
---|
78 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
---|
79 | |
---|
80 | void G4PolarizedAnnihilationModel::Initialise(const G4ParticleDefinition*, |
---|
81 | const G4DataVector&) |
---|
82 | { |
---|
83 | // G4eeToTwoGammaModel::Initialise(part,dv); |
---|
84 | if(gIsInitialised) return; |
---|
85 | gParticleChange = GetParticleChangeForGamma(); |
---|
86 | gIsInitialised = true; |
---|
87 | } |
---|
88 | |
---|
89 | G4double G4PolarizedAnnihilationModel::ComputeCrossSectionPerElectron( |
---|
90 | const G4ParticleDefinition* pd, |
---|
91 | G4double kinEnergy, |
---|
92 | G4double cut, |
---|
93 | G4double emax) |
---|
94 | { |
---|
95 | G4double xs = G4eeToTwoGammaModel::ComputeCrossSectionPerElectron(pd,kinEnergy, |
---|
96 | cut,emax); |
---|
97 | |
---|
98 | G4double polzz = theBeamPolarization.z()*theTargetPolarization.z(); |
---|
99 | G4double poltt = theBeamPolarization.x()*theTargetPolarization.x() |
---|
100 | + theBeamPolarization.y()*theTargetPolarization.y(); |
---|
101 | if (polzz!=0 || poltt!=0) { |
---|
102 | G4double xval,lasym,tasym; |
---|
103 | ComputeAsymmetriesPerElectron(kinEnergy,xval,lasym,tasym); |
---|
104 | xs*=(1.+polzz*lasym+poltt*tasym); |
---|
105 | } |
---|
106 | |
---|
107 | return xs; |
---|
108 | } |
---|
109 | |
---|
110 | void G4PolarizedAnnihilationModel::ComputeAsymmetriesPerElectron(G4double ene, |
---|
111 | G4double & valueX, |
---|
112 | G4double & valueA, |
---|
113 | G4double & valueT) |
---|
114 | { |
---|
115 | // *** calculate asymmetries |
---|
116 | G4double gam = 1. + ene/electron_mass_c2; |
---|
117 | G4double xs0=crossSectionCalculator->TotalXSection(0.,1.,gam, |
---|
118 | G4StokesVector::ZERO, |
---|
119 | G4StokesVector::ZERO); |
---|
120 | G4double xsA=crossSectionCalculator->TotalXSection(0.,1.,gam, |
---|
121 | G4StokesVector::P3, |
---|
122 | G4StokesVector::P3); |
---|
123 | G4double xsT1=crossSectionCalculator->TotalXSection(0.,1.,gam, |
---|
124 | G4StokesVector::P1, |
---|
125 | G4StokesVector::P1); |
---|
126 | G4double xsT2=crossSectionCalculator->TotalXSection(0.,1.,gam, |
---|
127 | G4StokesVector::P2, |
---|
128 | G4StokesVector::P2); |
---|
129 | G4double xsT=0.5*(xsT1+xsT2); |
---|
130 | |
---|
131 | valueX=xs0; |
---|
132 | valueA=xsA/xs0-1.; |
---|
133 | valueT=xsT/xs0-1.; |
---|
134 | // G4cout<<valueX<<"\t"<<valueA<<"\t"<<valueT<<" energy = "<<gam<<G4endl; |
---|
135 | if ( (valueA < -1) || (1 < valueA)) { |
---|
136 | G4cout<< " ERROR PolarizedAnnihilationPS::ComputeAsymmetries \n"; |
---|
137 | G4cout<< " something wrong in total cross section calculation (valueA)\n"; |
---|
138 | G4cout<<"*********** LONG "<<valueX<<"\t"<<valueA<<"\t"<<valueT<<" energy = "<<gam<<G4endl; |
---|
139 | } |
---|
140 | if ( (valueT < -1) || (1 < valueT)) { |
---|
141 | G4cout<< " ERROR PolarizedAnnihilationPS::ComputeAsymmetries \n"; |
---|
142 | G4cout<< " something wrong in total cross section calculation (valueT)\n"; |
---|
143 | G4cout<<"****** TRAN "<<valueX<<"\t"<<valueA<<"\t"<<valueT<<" energy = "<<gam<<G4endl; |
---|
144 | } |
---|
145 | } |
---|
146 | |
---|
147 | |
---|
148 | void G4PolarizedAnnihilationModel::SampleSecondaries(std::vector<G4DynamicParticle*>* fvect, |
---|
149 | const G4MaterialCutsCouple* /*couple*/, |
---|
150 | const G4DynamicParticle* dp, |
---|
151 | G4double /*tmin*/, |
---|
152 | G4double /*maxEnergy*/) |
---|
153 | { |
---|
154 | // G4ParticleChangeForGamma* gParticleChange |
---|
155 | // = dynamic_cast<G4ParticleChangeForGamma*>(pParticleChange); |
---|
156 | const G4Track * aTrack = gParticleChange->GetCurrentTrack(); |
---|
157 | |
---|
158 | // kill primary |
---|
159 | gParticleChange->SetProposedKineticEnergy(0.); |
---|
160 | gParticleChange->ProposeTrackStatus(fStopAndKill); |
---|
161 | |
---|
162 | // V.Ivanchenko add protection against zero kin energy |
---|
163 | G4double PositKinEnergy = dp->GetKineticEnergy(); |
---|
164 | |
---|
165 | if(PositKinEnergy < DBL_MIN) { |
---|
166 | |
---|
167 | G4double cosTeta = 2.*G4UniformRand()-1.; |
---|
168 | G4double sinTeta = std::sqrt((1.0 - cosTeta)*(1.0 + cosTeta)); |
---|
169 | G4double phi = twopi * G4UniformRand(); |
---|
170 | G4ThreeVector dir(sinTeta*std::cos(phi), sinTeta*std::sin(phi), cosTeta); |
---|
171 | fvect->push_back( new G4DynamicParticle(G4Gamma::Gamma(), dir, electron_mass_c2)); |
---|
172 | fvect->push_back( new G4DynamicParticle(G4Gamma::Gamma(),-dir, electron_mass_c2)); |
---|
173 | return; |
---|
174 | } |
---|
175 | |
---|
176 | // *** obtain and save target and beam polarization *** |
---|
177 | G4PolarizationManager * polarizationManager = G4PolarizationManager::GetInstance(); |
---|
178 | |
---|
179 | // obtain polarization of the beam |
---|
180 | theBeamPolarization = aTrack->GetPolarization(); |
---|
181 | |
---|
182 | // obtain polarization of the media |
---|
183 | G4VPhysicalVolume* aPVolume = aTrack->GetVolume(); |
---|
184 | G4LogicalVolume* aLVolume = aPVolume->GetLogicalVolume(); |
---|
185 | const G4bool targetIsPolarized = polarizationManager->IsPolarized(aLVolume); |
---|
186 | theTargetPolarization = polarizationManager->GetVolumePolarization(aLVolume); |
---|
187 | |
---|
188 | // transfer target electron polarization in frame of positron |
---|
189 | if (targetIsPolarized) |
---|
190 | theTargetPolarization.rotateUz(dp->GetMomentumDirection()); |
---|
191 | |
---|
192 | G4ParticleMomentum PositDirection = dp->GetMomentumDirection(); |
---|
193 | |
---|
194 | // polar asymmetry: |
---|
195 | G4double polarization = theBeamPolarization.p3()*theTargetPolarization.p3(); |
---|
196 | |
---|
197 | G4double gamam1 = PositKinEnergy/electron_mass_c2; |
---|
198 | G4double gama = gamam1+1. , gamap1 = gamam1+2.; |
---|
199 | G4double sqgrate = std::sqrt(gamam1/gamap1)/2. , sqg2m1 = std::sqrt(gamam1*gamap1); |
---|
200 | |
---|
201 | // limits of the energy sampling |
---|
202 | G4double epsilmin = 0.5 - sqgrate , epsilmax = 0.5 + sqgrate; |
---|
203 | G4double epsilqot = epsilmax/epsilmin; |
---|
204 | |
---|
205 | // |
---|
206 | // sample the energy rate of the created gammas |
---|
207 | // note: for polarized partices, the actual dicing strategy |
---|
208 | // will depend on the energy, and the degree of polarization !! |
---|
209 | // |
---|
210 | G4double epsil; |
---|
211 | G4double gmax=1. + std::fabs(polarization); // crude estimate |
---|
212 | |
---|
213 | G4bool check_range=true; |
---|
214 | |
---|
215 | crossSectionCalculator->Initialize(epsilmin, gama, 0., theBeamPolarization, theTargetPolarization); |
---|
216 | if (crossSectionCalculator->DiceEpsilon()<0) { |
---|
217 | G4cout<<"ERROR in PolarizedAnnihilationPS::PostStepDoIt\n" |
---|
218 | <<"epsilmin DiceRoutine not appropriate ! "<<crossSectionCalculator->DiceEpsilon()<<G4endl; |
---|
219 | check_range=false; |
---|
220 | } |
---|
221 | |
---|
222 | crossSectionCalculator->Initialize(epsilmax, gama, 0., theBeamPolarization, theTargetPolarization); |
---|
223 | if (crossSectionCalculator->DiceEpsilon()<0) { |
---|
224 | G4cout<<"ERROR in PolarizedAnnihilationPS::PostStepDoIt\n" |
---|
225 | <<"epsilmax DiceRoutine not appropriate ! "<<crossSectionCalculator->DiceEpsilon()<<G4endl; |
---|
226 | check_range=false; |
---|
227 | } |
---|
228 | |
---|
229 | G4int ncount=0; |
---|
230 | G4double trejectmax=0.; |
---|
231 | G4double treject; |
---|
232 | |
---|
233 | |
---|
234 | do { |
---|
235 | // |
---|
236 | epsil = epsilmin*std::pow(epsilqot,G4UniformRand()); |
---|
237 | |
---|
238 | crossSectionCalculator->Initialize(epsil, gama, 0., theBeamPolarization, theTargetPolarization,1); |
---|
239 | |
---|
240 | treject = crossSectionCalculator->DiceEpsilon(); |
---|
241 | treject*=epsil; |
---|
242 | |
---|
243 | if (treject>gmax || treject<0.) |
---|
244 | G4cout<<"ERROR in PolarizedAnnihilationPS::PostStepDoIt\n" |
---|
245 | <<" eps ("<<epsil<<") rejection does not work properly: "<<treject<<G4endl; |
---|
246 | ++ncount; |
---|
247 | if (treject>trejectmax) trejectmax=treject; |
---|
248 | if (ncount>1000) { |
---|
249 | G4cout<<"WARNING in PolarizedAnnihilationPS::PostStepDoIt\n" |
---|
250 | <<"eps dicing very inefficient ="<<trejectmax/gmax |
---|
251 | <<", "<<treject/gmax<<". For secondary energy = "<<epsil<<" "<<ncount<<G4endl; |
---|
252 | break; |
---|
253 | } |
---|
254 | |
---|
255 | } while( treject < gmax*G4UniformRand() ); |
---|
256 | |
---|
257 | // |
---|
258 | // scattered Gamma angles. ( Z - axis along the parent positron) |
---|
259 | // |
---|
260 | |
---|
261 | G4double cost = (epsil*gamap1-1.)/(epsil*sqg2m1); |
---|
262 | G4double sint = std::sqrt((1.+cost)*(1.-cost)); |
---|
263 | G4double phi = 0.; |
---|
264 | G4double beamTrans = std::sqrt(sqr(theBeamPolarization.p1()) + sqr(theBeamPolarization.p2())); |
---|
265 | G4double targetTrans = std::sqrt(sqr(theTargetPolarization.p1()) + sqr(theTargetPolarization.p2())); |
---|
266 | |
---|
267 | // G4cout<<"phi dicing START"<<G4endl; |
---|
268 | do{ |
---|
269 | phi = twopi * G4UniformRand(); |
---|
270 | crossSectionCalculator->Initialize(epsil, gama, 0., theBeamPolarization, theTargetPolarization,2); |
---|
271 | |
---|
272 | G4double gdiced =crossSectionCalculator->getVar(0); |
---|
273 | gdiced += crossSectionCalculator->getVar(3)*theBeamPolarization.p3()*theTargetPolarization.p3(); |
---|
274 | gdiced += 1.*(std::fabs(crossSectionCalculator->getVar(1)) |
---|
275 | + std::fabs(crossSectionCalculator->getVar(2)))*beamTrans*targetTrans; |
---|
276 | gdiced += 1.*std::fabs(crossSectionCalculator->getVar(4)) |
---|
277 | *(std::fabs(theBeamPolarization.p3())*targetTrans + std::fabs(theTargetPolarization.p3())*beamTrans); |
---|
278 | |
---|
279 | G4double gdist = crossSectionCalculator->getVar(0); |
---|
280 | gdist += crossSectionCalculator->getVar(3)*theBeamPolarization.p3()*theTargetPolarization.p3(); |
---|
281 | gdist += crossSectionCalculator->getVar(1)*(std::cos(phi)*theBeamPolarization.p1() |
---|
282 | + std::sin(phi)*theBeamPolarization.p2()) |
---|
283 | *(std::cos(phi)*theTargetPolarization.p1() |
---|
284 | + std::sin(phi)*theTargetPolarization.p2()); |
---|
285 | gdist += crossSectionCalculator->getVar(2)*(std::cos(phi)*theBeamPolarization.p2() |
---|
286 | - std::sin(phi)*theBeamPolarization.p1()) |
---|
287 | *(std::cos(phi)*theTargetPolarization.p2() |
---|
288 | - std::sin(phi)*theTargetPolarization.p1()); |
---|
289 | gdist += crossSectionCalculator->getVar(4) |
---|
290 | *(std::cos(phi)*theBeamPolarization.p3()*theTargetPolarization.p1() |
---|
291 | + std::cos(phi)*theBeamPolarization.p1()*theTargetPolarization.p3() |
---|
292 | + std::sin(phi)*theBeamPolarization.p3()*theTargetPolarization.p2() |
---|
293 | + std::sin(phi)*theBeamPolarization.p2()*theTargetPolarization.p3()); |
---|
294 | |
---|
295 | treject = gdist/gdiced; |
---|
296 | //G4cout<<" treject = "<<treject<<" at phi = "<<phi<<G4endl; |
---|
297 | if (treject>1.+1.e-10 || treject<0){ |
---|
298 | G4cout<<"!!!ERROR in PolarizedAnnihilationPS::PostStepDoIt\n" |
---|
299 | <<" phi rejection does not work properly: "<<treject<<G4endl; |
---|
300 | G4cout<<" gdiced = "<<gdiced<<G4endl; |
---|
301 | G4cout<<" gdist = "<<gdist<<G4endl; |
---|
302 | G4cout<<" epsil = "<<epsil<<G4endl; |
---|
303 | } |
---|
304 | |
---|
305 | if (treject<1.e-3) { |
---|
306 | G4cout<<"!!!ERROR in PolarizedAnnihilationPS::PostStepDoIt\n" |
---|
307 | <<" phi rejection does not work properly: "<<treject<<"\n"; |
---|
308 | G4cout<<" gdiced="<<gdiced<<" gdist="<<gdist<<"\n"; |
---|
309 | G4cout<<" epsil = "<<epsil<<G4endl; |
---|
310 | } |
---|
311 | |
---|
312 | } while( treject < G4UniformRand() ); |
---|
313 | // G4cout<<"phi dicing END"<<G4endl; |
---|
314 | |
---|
315 | G4double dirx = sint*std::cos(phi) , diry = sint*std::sin(phi) , dirz = cost; |
---|
316 | |
---|
317 | // |
---|
318 | // kinematic of the created pair |
---|
319 | // |
---|
320 | G4double TotalAvailableEnergy = PositKinEnergy + 2*electron_mass_c2; |
---|
321 | G4double Phot1Energy = epsil*TotalAvailableEnergy; |
---|
322 | G4double Phot2Energy =(1.-epsil)*TotalAvailableEnergy; |
---|
323 | |
---|
324 | // *** prepare calculation of polarization transfer *** |
---|
325 | G4ThreeVector Phot1Direction (dirx, diry, dirz); |
---|
326 | |
---|
327 | // get interaction frame |
---|
328 | G4ThreeVector nInteractionFrame = |
---|
329 | G4PolarizationHelper::GetFrame(PositDirection,Phot1Direction); |
---|
330 | |
---|
331 | // define proper in-plane and out-of-plane component of initial spins |
---|
332 | theBeamPolarization.InvRotateAz(nInteractionFrame,PositDirection); |
---|
333 | theTargetPolarization.InvRotateAz(nInteractionFrame,PositDirection); |
---|
334 | |
---|
335 | // calculate spin transfere matrix |
---|
336 | |
---|
337 | crossSectionCalculator->Initialize(epsil,gama,phi,theBeamPolarization,theTargetPolarization,2); |
---|
338 | |
---|
339 | // ********************************************************************** |
---|
340 | |
---|
341 | Phot1Direction.rotateUz(PositDirection); |
---|
342 | // create G4DynamicParticle object for the particle1 |
---|
343 | G4DynamicParticle* aParticle1= new G4DynamicParticle (G4Gamma::Gamma(), |
---|
344 | Phot1Direction, Phot1Energy); |
---|
345 | finalGamma1Polarization=crossSectionCalculator->GetPol2(); |
---|
346 | G4double n1=finalGamma1Polarization.mag2(); |
---|
347 | if (n1>1) { |
---|
348 | G4cout<<"ERROR: PolarizedAnnihilation Polarization Vector at epsil = " |
---|
349 | <<epsil<<" is too large!!! \n" |
---|
350 | <<"annihi pol1= "<<finalGamma1Polarization<<", ("<<n1<<")\n"; |
---|
351 | finalGamma1Polarization*=1./std::sqrt(n1); |
---|
352 | } |
---|
353 | |
---|
354 | // define polarization of first final state photon |
---|
355 | finalGamma1Polarization.SetPhoton(); |
---|
356 | finalGamma1Polarization.RotateAz(nInteractionFrame,Phot1Direction); |
---|
357 | aParticle1->SetPolarization(finalGamma1Polarization.p1(), |
---|
358 | finalGamma1Polarization.p2(), |
---|
359 | finalGamma1Polarization.p3()); |
---|
360 | |
---|
361 | fvect->push_back(aParticle1); |
---|
362 | |
---|
363 | |
---|
364 | // ********************************************************************** |
---|
365 | |
---|
366 | G4double Eratio= Phot1Energy/Phot2Energy; |
---|
367 | G4double PositP= std::sqrt(PositKinEnergy*(PositKinEnergy+2.*electron_mass_c2)); |
---|
368 | G4ThreeVector Phot2Direction (-dirx*Eratio, -diry*Eratio, |
---|
369 | (PositP-dirz*Phot1Energy)/Phot2Energy); |
---|
370 | Phot2Direction.rotateUz(PositDirection); |
---|
371 | // create G4DynamicParticle object for the particle2 |
---|
372 | G4DynamicParticle* aParticle2= new G4DynamicParticle (G4Gamma::Gamma(), |
---|
373 | Phot2Direction, Phot2Energy); |
---|
374 | |
---|
375 | // define polarization of second final state photon |
---|
376 | finalGamma2Polarization=crossSectionCalculator->GetPol3(); |
---|
377 | G4double n2=finalGamma2Polarization.mag2(); |
---|
378 | if (n2>1) { |
---|
379 | G4cout<<"ERROR: PolarizedAnnihilation Polarization Vector at epsil = "<<epsil<<" is too large!!! \n"; |
---|
380 | G4cout<<"annihi pol2= "<<finalGamma2Polarization<<", ("<<n2<<")\n"; |
---|
381 | |
---|
382 | finalGamma2Polarization*=1./std::sqrt(n2); |
---|
383 | } |
---|
384 | finalGamma2Polarization.SetPhoton(); |
---|
385 | finalGamma2Polarization.RotateAz(nInteractionFrame,Phot2Direction); |
---|
386 | aParticle2->SetPolarization(finalGamma2Polarization.p1(), |
---|
387 | finalGamma2Polarization.p2(), |
---|
388 | finalGamma2Polarization.p3()); |
---|
389 | |
---|
390 | fvect->push_back(aParticle2); |
---|
391 | } |
---|