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25 // 25 //
>> 26 // $Id: G4eBremsstrahlungRelModel.cc,v 1.12 2008/11/13 23:28:27 schaelic Exp $
>> 27 // GEANT4 tag $Name: geant4-09-02 $
26 // 28 //
27 // ------------------------------------------- 29 // -------------------------------------------------------------------
28 // 30 //
29 // GEANT4 Class file 31 // GEANT4 Class file
30 // 32 //
31 // 33 //
32 // File name: G4eBremsstrahlungRelModel 34 // File name: G4eBremsstrahlungRelModel
33 // 35 //
34 // Author: Andreas Schaelicke << 36 // Author: Andreas Schaelicke
35 // 37 //
36 // Creation date: 12.08.2008 38 // Creation date: 12.08.2008
37 // 39 //
38 // Modifications: 40 // Modifications:
39 // 41 //
40 // 13.11.08 add SetLPMflag and SetLPMconsta 42 // 13.11.08 add SetLPMflag and SetLPMconstant methods
41 // 13.11.08 change default LPMconstant valu 43 // 13.11.08 change default LPMconstant value
42 // 13.10.10 add angular distributon interfa <<
43 // 31.05.16 change LPMconstant such that it <<
44 // that consistent to Migdal's one <<
45 // computation; better agreement w <<
46 // 15.07.18 improved LPM suppression functi <<
47 // steps), code cleanup and optimi <<
48 // model related comments, consist <<
49 // 44 //
50 // Main References: 45 // Main References:
51 // Y.-S.Tsai, Rev. Mod. Phys. 46 (1974) 815; << 46 // Y.-S.Tsai, Rev. Mod. Phys. 46 (1974) 815; Rev. Mod. Phys. 49 (1977) 421.
52 // S.Klein, Rev. Mod. Phys. 71 (1999) 1501. 47 // S.Klein, Rev. Mod. Phys. 71 (1999) 1501.
53 // T.Stanev et.al., Phys. Rev. D25 (1982) 129 48 // T.Stanev et.al., Phys. Rev. D25 (1982) 1291.
54 // M.L.Ter-Mikaelian, High-energy Electromagn << 49 // M.L.Ter-Mikaelian, High-energy Electromagnetic Processes in Condensed Media, Wiley, 1972.
55 // Wiley, 1972. <<
56 // 50 //
57 // ------------------------------------------- 51 // -------------------------------------------------------------------
58 // 52 //
>> 53 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
>> 54 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
59 55
60 #include "G4eBremsstrahlungRelModel.hh" 56 #include "G4eBremsstrahlungRelModel.hh"
61 #include "G4PhysicalConstants.hh" <<
62 #include "G4SystemOfUnits.hh" <<
63 #include "G4Electron.hh" 57 #include "G4Electron.hh"
>> 58 #include "G4Positron.hh"
64 #include "G4Gamma.hh" 59 #include "G4Gamma.hh"
65 #include "Randomize.hh" 60 #include "Randomize.hh"
66 #include "G4Material.hh" 61 #include "G4Material.hh"
67 #include "G4Element.hh" 62 #include "G4Element.hh"
68 #include "G4ElementVector.hh" 63 #include "G4ElementVector.hh"
>> 64 #include "G4ProductionCutsTable.hh"
69 #include "G4ParticleChangeForLoss.hh" 65 #include "G4ParticleChangeForLoss.hh"
70 #include "G4ModifiedTsai.hh" << 66 #include "G4LossTableManager.hh"
71 #include "G4Exp.hh" << 67
72 #include "G4Log.hh" << 68
73 #include "G4Pow.hh" << 69 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
74 #include "G4EmParameters.hh" <<
75 #include "G4AutoLock.hh" <<
76 #include <thread> <<
77 <<
78 const G4int G4eBremsstrahlungRelModel::gMaxZet <<
79 <<
80 // constant DCS factor: 16\alpha r_0^2/3 <<
81 const G4double G4eBremsstrahlungRelModel::gBre <<
82 = 16. * CLHEP::fine_structure_const * CLHEP: <<
83 * CLHEP::classic_electr_radius/3.; <<
84 <<
85 // Migdal's constant: 4\pi r_0*electron_reduce <<
86 const G4double G4eBremsstrahlungRelModel::gMig <<
87 = 4. * CLHEP::pi * CLHEP::classic_electr_rad <<
88 * CLHEP::electron_Compton_length * CLHEP:: <<
89 <<
90 // LPM constant: \alpha(mc^2)^2/(4\pi*\hbar c) <<
91 const G4double G4eBremsstrahlungRelModel::gLPM <<
92 = CLHEP::fine_structure_const * CLHEP::elect <<
93 * CLHEP::electron_mass_c2 / (4. * CLHEP::p <<
94 <<
95 // abscissas and weights of an 8 point Gauss-L <<
96 // for numerical integration on [0,1] <<
97 const G4double G4eBremsstrahlungRelModel::gXGL <<
98 1.98550718e-02, 1.01666761e-01, 2.37233795e- <<
99 5.91717321e-01, 7.62766205e-01, 8.98333239e- <<
100 }; <<
101 const G4double G4eBremsstrahlungRelModel::gWGL <<
102 5.06142681e-02, 1.11190517e-01, 1.56853323e- <<
103 1.81341892e-01, 1.56853323e-01, 1.11190517e- <<
104 }; <<
105 <<
106 // elastic and inelatic radiation logarithms f <<
107 // Thomas-Fermi model doesn't work): computed <<
108 const G4double G4eBremsstrahlungRelModel::gFel <<
109 0.0, 5.3104, 4.7935, 4.7402, 4.7112, 4.6694, <<
110 }; <<
111 const G4double G4eBremsstrahlungRelModel::gFin <<
112 0.0, 5.9173, 5.6125, 5.5377, 5.4728, 5.4174, <<
113 }; <<
114 <<
115 // LPM supression functions evaluated at initi <<
116 std::shared_ptr<G4eBremsstrahlungRelModel::LPM <<
117 { <<
118 // We have to use shared pointer for the LPM <<
119 // by the G4eBremsstrahlungRelModel used in <<
120 // model is owned (well deleted) by (at leas <<
121 // a G4SeltzerBergerModel which is owned by <<
122 // which owned by a G4ThreadLocalSingleton<G <<
123 // which is a static global and thus deleted <<
124 // is deleted. <<
125 static auto _instance = std::make_shared<G4e <<
126 return _instance; <<
127 } <<
128 <<
129 // special data structure per element i.e. per <<
130 std::shared_ptr<std::vector<G4eBremsstrahlungR <<
131 { <<
132 // Same code comment as for gLPMFuncs. <<
133 static auto _instance = std::make_shared<std <<
134 return _instance; <<
135 } <<
136 70
137 static std::once_flag applyOnce; << 71 const G4double G4eBremsstrahlungRelModel::xgi[]={ 0.0199, 0.1017, 0.2372, 0.4083,
>> 72 0.5917, 0.7628, 0.8983, 0.9801 };
>> 73 const G4double G4eBremsstrahlungRelModel::wgi[]={ 0.0506, 0.1112, 0.1569, 0.1813,
>> 74 0.1813, 0.1569, 0.1112, 0.0506 };
>> 75 const G4double G4eBremsstrahlungRelModel::Fel_light[] = {0., 5.31 , 4.79 , 4.74 , 4.71} ;
>> 76 const G4double G4eBremsstrahlungRelModel::Finel_light[] = {0., 6.144 , 5.621 , 5.805 , 5.924} ;
138 77
139 namespace << 78
>> 79 using namespace std;
>> 80
>> 81 G4eBremsstrahlungRelModel::G4eBremsstrahlungRelModel(const G4ParticleDefinition* p,
>> 82 const G4String& name)
>> 83 : G4VEmModel(name),
>> 84 particle(0),
>> 85 fXiLPM(0), fPhiLPM(0), fGLPM(0),
>> 86 isElectron(true),
>> 87 fMigdalConstant(classic_electr_radius*electron_Compton_length*electron_Compton_length*4.0*pi),
>> 88 fLPMconstant(fine_structure_const*electron_mass_c2*electron_mass_c2/(4.*pi*hbarc)*0.5),
>> 89 bremFactor(fine_structure_const*classic_electr_radius*classic_electr_radius*16./3.),
>> 90 use_completescreening(true),isInitialised(false)
140 { 91 {
141 G4Mutex theBremRelMutex = G4MUTEX_INITIALIZE << 92 if(p) SetParticle(p);
>> 93 theGamma = G4Gamma::Gamma();
>> 94
>> 95 minThreshold = 1.0*keV;
>> 96 SetLowEnergyLimit(GeV);
>> 97
>> 98 nist = G4NistManager::Instance();
>> 99 InitialiseConstants();
>> 100
>> 101 SetLPMFlag(true);
142 } 102 }
143 103
144 G4eBremsstrahlungRelModel::G4eBremsstrahlungRe << 104 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
145 << 105
146 : G4VEmModel(nam), fLPMFuncs(gLPMFuncs()), fEl << 106 void G4eBremsstrahlungRelModel::InitialiseConstants()
147 { 107 {
148 fGammaParticle = G4Gamma::Gamma(); << 108 facFel = log(184.15);
149 // << 109 facFinel = log(1194.);
150 fLowestKinEnergy = 1.0*CLHEP::MeV; << 110
151 SetLowEnergyLimit(fLowestKinEnergy); << 111 preS1 = 1./(184.15*184.15);
152 // << 112 logTwo = log(2.);
153 fLPMEnergyThreshold = 1.e+39; <<
154 fLPMEnergy = 0.; <<
155 SetAngularDistribution(new G4ModifiedTsai()) <<
156 // <<
157 if (nullptr != p) { <<
158 SetParticle(p); <<
159 } <<
160 } 113 }
161 114
>> 115 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
>> 116
162 G4eBremsstrahlungRelModel::~G4eBremsstrahlungR 117 G4eBremsstrahlungRelModel::~G4eBremsstrahlungRelModel()
163 { 118 {
164 if (fIsInitializer) { <<
165 // clear ElementData container <<
166 for (auto const & ptr : *fElementData) { d <<
167 fElementData->clear(); <<
168 // clear LPMFunctions (if any) <<
169 if (fLPMFuncs->fIsInitialized) { <<
170 fLPMFuncs->fLPMFuncG.clear(); <<
171 fLPMFuncs->fLPMFuncPhi.clear(); <<
172 fLPMFuncs->fIsInitialized = false; <<
173 } <<
174 } <<
175 } 119 }
176 120
177 void G4eBremsstrahlungRelModel::Initialise(con << 121 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
178 con <<
179 { <<
180 // parameters in each thread <<
181 if (fPrimaryParticle != p) { <<
182 SetParticle(p); <<
183 } <<
184 fUseLPM = G4EmParameters::Instance()->LPM(); <<
185 fCurrentIZ = 0; <<
186 <<
187 // init static element data and precompute L <<
188 std::call_once(applyOnce, [this]() { fIsInit <<
189 <<
190 // for all treads and derived classes <<
191 if (fIsInitializer || fElementData->empty()) <<
192 G4AutoLock l(&theBremRelMutex); <<
193 if (fElementData->empty()) { <<
194 fElementData->resize(gMaxZet+1, nullptr) <<
195 } <<
196 InitialiseElementData(); <<
197 InitLPMFunctions(); <<
198 l.unlock(); <<
199 } <<
200 122
201 // element selectors are initialized in the << 123 void G4eBremsstrahlungRelModel::SetParticle(const G4ParticleDefinition* p)
202 if (IsMaster()) { << 124 {
203 InitialiseElementSelectors(p, cuts); << 125 particle = p;
204 } << 126 particleMass = p->GetPDGMass();
205 // initialisation in all threads << 127 if(p == G4Electron::Electron()) isElectron = true;
206 if (nullptr == fParticleChange) { << 128 else isElectron = false;
207 fParticleChange = GetParticleChangeForLoss <<
208 } <<
209 if (GetTripletModel()) { <<
210 GetTripletModel()->Initialise(p, cuts); <<
211 fIsScatOffElectron = true; <<
212 } <<
213 } 129 }
214 130
215 void G4eBremsstrahlungRelModel::InitialiseLoca << 131 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
216 << 132
>> 133 G4double G4eBremsstrahlungRelModel::MinEnergyCut(const G4ParticleDefinition*,
>> 134 const G4MaterialCutsCouple*)
217 { 135 {
218 SetElementSelectors(masterModel->GetElementS << 136 return minThreshold;
219 } 137 }
220 138
221 void G4eBremsstrahlungRelModel::SetParticle(co << 139 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
>> 140
>> 141 void G4eBremsstrahlungRelModel::SetupForMaterial(const G4ParticleDefinition*,
>> 142 const G4Material* mat, G4double kineticEnergy)
222 { 143 {
223 fPrimaryParticle = p; << 144 densityFactor = mat->GetElectronDensity()*fMigdalConstant;
224 fPrimaryParticleMass = p->GetPDGMass(); << 145 lpmEnergy = mat->GetRadlen()*fLPMconstant;
225 fIsElectron = (p==G4Electron::Elect << 146
>> 147 // Threshold for LPM effect (i.e. below which LPM hidden by density effect)
>> 148 if (LPMFlag())
>> 149 energyThresholdLPM=sqrt(densityFactor)*lpmEnergy;
>> 150 else
>> 151 energyThresholdLPM=1.e39; // i.e. do not use LPM effect
>> 152
>> 153 // calculate threshold for density effect
>> 154 kinEnergy = kineticEnergy;
>> 155 totalEnergy = kineticEnergy + particleMass;
>> 156 densityCorr = densityFactor*totalEnergy*totalEnergy;
>> 157
>> 158 // define critical gamma energies (important for integration/dicing)
>> 159 klpm=totalEnergy*totalEnergy/lpmEnergy;
>> 160 kp=sqrt(densityCorr);
>> 161
226 } 162 }
227 163
228 // Sets kinematical variables like E_kin, E_t << 164
229 // variables like LPM energy and characteristi << 165 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
230 // k_p^2) for the Ter-Mikaelian suppression ef << 166
231 void G4eBremsstrahlungRelModel::SetupForMateri << 167 void G4eBremsstrahlungRelModel::Initialise(const G4ParticleDefinition* p,
232 << 168 const G4DataVector& cuts)
233 <<
234 { 169 {
235 fDensityFactor = gMigdalConstant*mat->GetEle << 170 if(p) SetParticle(p);
236 fLPMEnergy = gLPMconstant*mat->GetRadlen << 171
237 // threshold for LPM effect (i.e. below whic << 172 highKinEnergy = HighEnergyLimit();
238 if (fUseLPM) { << 173 lowKinEnergy = LowEnergyLimit();
239 fLPMEnergyThreshold = std::sqrt(fDensityFa << 174
>> 175 currentZ = 0.;
>> 176
>> 177 InitialiseElementSelectors(p, cuts);
>> 178
>> 179 if(isInitialised) return;
>> 180
>> 181 if(pParticleChange) {
>> 182 fParticleChange = reinterpret_cast<G4ParticleChangeForLoss*>(pParticleChange);
240 } else { 183 } else {
241 fLPMEnergyThreshold = 1.e+39; // i.e. do << 184 fParticleChange = new G4ParticleChangeForLoss();
242 } 185 }
243 // calculate threshold for density effect: k << 186 isInitialised = true;
244 fPrimaryKinEnergy = kineticEnergy; << 187 }
245 fPrimaryTotalEnergy = kineticEnergy+fPrimary << 188
246 fDensityCorr = fDensityFactor*fPrimar << 189 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
247 // set activation flag for LPM effects in th << 190
248 fIsLPMActive = (fPrimaryTotalEnergy>fLPMEner << 191 G4double G4eBremsstrahlungRelModel::ComputeDEDXPerVolume(
249 } << 192 const G4Material* material,
250 << 193 const G4ParticleDefinition* p,
251 // minimum primary (e-/e+) energy at which dis << 194 G4double kineticEnergy,
252 G4double G4eBremsstrahlungRelModel::MinPrimary << 195 G4double cutEnergy)
253 <<
254 <<
255 { <<
256 return std::max(fLowestKinEnergy, cut); <<
257 } <<
258 <<
259 // Computes the restricted dE/dx as the approp <<
260 // element contributions that are computed by <<
261 G4double <<
262 G4eBremsstrahlungRelModel::ComputeDEDXPerVolum <<
263 <<
264 <<
265 <<
266 { 196 {
>> 197 if(!particle) SetParticle(p);
>> 198 if(kineticEnergy < lowKinEnergy) return 0.0;
>> 199 G4double cut = std::min(cutEnergy, kineticEnergy);
>> 200 if(cut == 0.0) return 0.0;
>> 201
>> 202 SetupForMaterial(particle, material,kineticEnergy);
>> 203
>> 204 const G4ElementVector* theElementVector = material->GetElementVector();
>> 205 const G4double* theAtomicNumDensityVector = material->GetAtomicNumDensityVector();
>> 206
267 G4double dedx = 0.0; 207 G4double dedx = 0.0;
268 if (nullptr == fPrimaryParticle) { << 208
269 SetParticle(p); << 209 // loop for elements in the material
270 } << 210 for (size_t i=0; i<material->GetNumberOfElements(); i++) {
271 if (kineticEnergy < LowEnergyLimit()) { << 211
272 return dedx; << 212 G4VEmModel::SetCurrentElement((*theElementVector)[i]);
273 } << 213 SetCurrentElement((*theElementVector)[i]->GetZ());
274 // maximum value of the dE/dx integral (the << 214
275 G4double tmax = std::min(cutEnergy, kineticE << 215 dedx += theAtomicNumDensityVector[i]*currentZ*currentZ*ComputeBremLoss(cut);
276 if (tmax == 0.0) { <<
277 return dedx; <<
278 } <<
279 // sets kinematical and material related var <<
280 SetupForMaterial(fPrimaryParticle, material, <<
281 // get element compositions of the material <<
282 const G4ElementVector* theElemVector = mater <<
283 const G4double* theAtomNumDensVector = mater <<
284 const std::size_t numberOfElements = theElem <<
285 // loop over the elements of the material an <<
286 // the restricted dE/dx by numerical integra <<
287 for (std::size_t ie = 0; ie < numberOfElemen <<
288 G4VEmModel::SetCurrentElement((*theElemVec <<
289 G4int zet = (*theElemVector)[ie]->GetZasIn <<
290 fCurrentIZ = std::min(zet, gMaxZet); <<
291 dedx += (zet*zet)*theAtomNumD <<
292 } <<
293 // apply the constant factor C/Z = 16\alpha <<
294 dedx *= gBremFactor; <<
295 return std::max(dedx,0.); <<
296 } <<
297 <<
298 // Computes the integral part of the restricte <<
299 // element (Z) by numerically integrating the <<
300 // k_min=0 and k_max = tmax = min[gamma-cut, e <<
301 // The numerical integration is done by dividi <<
302 // subintervals and an 8 pint GL integral (on <<
303 // inteval by tranforming k to alpha=k/E_t (E_ <<
304 // and each sub-interavl is transformed to [0, <<
305 // in xi(alpha) = xi(k) = [k/E_t-alpha_i]/delt <<
306 // the i = 1,2,..,n-th sub-interval so xi(k) i <<
307 // This transformation from 'k' to 'xi(k)' res <<
308 // of E_t*delta at each step. <<
309 // The restricted dE/dx = N int_{0}^{k_max} k* <<
310 // one with LPM and one without LPM effects (s <<
311 // the ds/dk(Z,k) but ds/dk(Z,k)*[F*k/C] is co <<
312 // (i) what we need here is ds/dk*k and not <<
313 // (ii) the Ter-Mikaelian suppression i.e. F <<
314 // (iii) the constant factor C (includes Z^2 <<
315 G4double G4eBremsstrahlungRelModel::ComputeBre <<
316 { <<
317 // number of intervals and integration step <<
318 const G4double alphaMax = tmax/fPrimaryTotal <<
319 const G4int nSub = (G4int)(20*alphaMa <<
320 const G4double delta = alphaMax/((G4doubl <<
321 // set minimum value of the first sub-inteva <<
322 G4double alpha_i = 0.0; <<
323 G4double dedxInteg = 0.0; <<
324 for (G4int l = 0; l < nSub; ++l) { <<
325 for (G4int igl = 0; igl < 8; ++igl) { <<
326 // compute the emitted photon energy k <<
327 const G4double k = (alpha_i+gXGL[igl]* <<
328 // compute the DCS value at k (without t <<
329 const G4double dcs = fIsLPMActive <<
330 ? ComputeRelDXSectio <<
331 : ComputeDXSectionPe <<
332 // account Ter-Mikaelian suppression: ti <<
333 dedxInteg += gWGL[igl]*dcs/(1.0+fDensity <<
334 } <<
335 // update sub-interval minimum value <<
336 alpha_i += delta; <<
337 } 216 }
338 // apply corrections due to variable transfo << 217 dedx *= bremFactor;
339 dedxInteg *= delta*fPrimaryTotalEnergy; << 218
340 return std::max(dedxInteg,0.); << 219
>> 220 return dedx;
341 } 221 }
342 222
343 // Computes restrected atomic cross section by << 223 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
344 // DCS between the proper kinematical limits a << 224
345 G4double G4eBremsstrahlungRelModel::ComputeCro << 225 G4double G4eBremsstrahlungRelModel::ComputeBremLoss(G4double cut)
346 << 226 {
347 << 227 G4double loss = 0.0;
348 << 228
349 << 229 // number of intervals and integration step
350 << 230 G4double vcut = cut/totalEnergy;
351 << 231 G4int n = (G4int)(20*vcut) + 3;
352 { << 232 G4double delta = vcut/G4double(n);
353 G4double crossSection = 0.0; << 233
354 if (nullptr == fPrimaryParticle) { << 234 G4double e0 = 0.0;
355 SetParticle(p); << 235 G4double xs;
356 } << 236
357 if (kineticEnergy < LowEnergyLimit()) { << 237 // integration
358 return crossSection; << 238 for(G4int l=0; l<n; l++) {
359 } << 239
360 // min/max kinetic energy limits of the DCS << 240 for(G4int i=0; i<8; i++) {
361 const G4double tmin = std::min(cut, kineticE << 241
362 const G4double tmax = std::min(maxEnergy, ki << 242 G4double eg = (e0 + xgi[i]*delta)*totalEnergy;
363 // zero restricted x-section if e- kinetic e << 243
364 if (tmin >= tmax) { << 244 if(totalEnergy > energyThresholdLPM) {
365 return crossSection; << 245 xs = ComputeRelDXSectionPerAtom(eg);
366 } << 246 } else {
367 fCurrentIZ = std::min(G4lrint(Z), gMaxZet); << 247 xs = ComputeDXSectionPerAtom(eg);
368 // integrate numerically (dependent part of) << 248 }
369 // a. integrate between tmin and kineticEner << 249 loss += wgi[i]*xs/(1.0 + densityCorr/(eg*eg));
370 crossSection = ComputeXSectionPerAtom(tmin); <<
371 // allow partial integration: only if maxEne <<
372 // b. integrate between tmax and kineticEner <<
373 // (so the result in this case is the integr <<
374 // maxEnergy) <<
375 if (tmax < kineticEnergy) { <<
376 crossSection -= ComputeXSectionPerAtom(tma <<
377 } <<
378 // multiply with the constant factors: 16\al <<
379 crossSection *= Z*Z*gBremFactor; <<
380 return std::max(crossSection, 0.); <<
381 } <<
382 <<
383 // Numerical integral of the (k dependent part <<
384 // k_max = E_k (where E_k is the kinetic energ <<
385 // minimum of energy of the emitted photon). <<
386 // transformed alpha(k) = ln(k/E_t) variable ( <<
387 // the primary e-). The integration range is d <<
388 // delta = [ln(k_min/E_t)-ln(k_max/E_t)]/n wid <<
389 // on [0,1] is applied on each sub-inteval so <<
390 // xi(alpha) = xi(k) = [ln(k/E_t)-alpha_i]/del <<
391 // (i-1)*delta for the i = 1,2,..,n-th sub-int <<
392 // sub-intevals. From the transformed xi, k(xi <<
393 // Since the integration is done in variable x <<
394 // transformation results in a multiplicative <<
395 // However, DCS differential in k is ~1/k so t <<
396 // becomes delta and the 1/k factor is dropped <<
397 // NOTE: <<
398 // - LPM suppression is accounted above thre <<
399 // flag is set in SetUpForMaterial() => 2 <<
400 // - Ter-Mikaelian suppression is always acc <<
401 G4double G4eBremsstrahlungRelModel::ComputeXSe <<
402 { <<
403 G4double xSection = 0.0; <<
404 const G4double alphaMin = G4Log(tmin/fPrimar <<
405 const G4double alphaMax = G4Log(fPrimaryKinE <<
406 const G4int nSub = std::max((G4int)(0.45*alp <<
407 const G4double delta = alphaMax/((G4double)n <<
408 // set minimum value of the first sub-inteva <<
409 G4double alpha_i = alphaMin; <<
410 for (G4int l = 0; l < nSub; ++l) { <<
411 for (G4int igl = 0; igl < 8; ++igl) { <<
412 // compute the emitted photon energy k <<
413 const G4double k = G4Exp(alpha_i+gXGL[ <<
414 // compute the DCS value at k (without t <<
415 const G4double dcs = fIsLPMActive <<
416 ? ComputeRelDXSectio <<
417 : ComputeDXSectionPe <<
418 // account Ter-Mikaelian suppression: ti <<
419 xSection += gWGL[igl]*dcs/(1.0+fDensityC <<
420 } <<
421 // update sub-interval minimum value <<
422 alpha_i += delta; <<
423 } <<
424 // apply corrections due to variable transfo <<
425 xSection *= delta; <<
426 // final check <<
427 return std::max(xSection, 0.); <<
428 } <<
429 <<
430 // DCS WITH LPM EFFECT: complete screening apr <<
431 // ds/dk(Z,k) = C/[F*k]*{ Xi(s*F)*[y^2*G/4 +(1 <<
432 // +(1-y)*[1+1/Z]/12} <<
433 // Xi(s),G(s), Phi(s) are LPM suppression func <<
434 // <<
435 // LPM SUPPRESSION: The 's' is the suppression <<
436 // 1+(k_p/k)^2 with k_p = hbar*w_p*E/(m*c^2) i <<
437 // dependent constant. F accounts the Ter-Mika <<
438 // transition in the emitted photon energy. Al <<
439 // goes to 0 when s goes to 0 and goes to 1 wh <<
440 // So evaluating the LPM suppression functions <<
441 // smooth transition depending on the emitted <<
442 // smoothly turned off i.e. Xi(sF)=G(sF)=Phi(s <<
443 // and sF ~ s when k >> k_p since F ~ 1 in tha <<
444 // HERE, ds/dk(Z,k)*[F*k/C] is computed since: <<
445 // (i) DCS ~ 1/k factor will disappear due <<
446 // v(k)=ln(k/E_t) -> dk/dv=E_t*e^v=k -> <<
447 // would cnacell out the 1/k factor => <<
448 // (ii) the constant factor C and Z don't de <<
449 // (iii) the 1/F(k) factor is accounted in th <<
450 // tion computation) or implicitly thro <<
451 // (in the final state sampling algorit <<
452 // COMPLETE SCREENING: see more at the DCS wit <<
453 G4double <<
454 G4eBremsstrahlungRelModel::ComputeRelDXSection <<
455 { <<
456 G4double dxsec = 0.0; <<
457 if (gammaEnergy < 0.) { <<
458 return dxsec; <<
459 } <<
460 const G4double y = gammaEnergy/fPrimaryT <<
461 const G4double onemy = 1.-y; <<
462 const G4double dum0 = 0.25*y*y; <<
463 // evaluate LPM functions (combined with the <<
464 G4double funcGS, funcPhiS, funcXiS; <<
465 ComputeLPMfunctions(funcXiS, funcGS, funcPhi <<
466 const ElementData* elDat = (*fElementData)[f <<
467 const G4double term1 = funcXiS*(dum0*fun <<
468 dxsec = term1*elDat->fZFactor1+onemy*elDat-> <<
469 // <<
470 if (fIsScatOffElectron) { <<
471 fSumTerm = dxsec; <<
472 fNucTerm = term1*elDat->fZFactor11 + onemy <<
473 } <<
474 return std::max(dxsec,0.0); <<
475 } <<
476 <<
477 // DCS WITHOUT LPM EFFECT: DCS with sceening ( <<
478 // ds/dk(Z,k)=C/[F*k]*{(1-y+3*y^2/4)*[(0.25*ph <<
479 // -2*ln(Z)/3)/Z]+ (1-y)*[(phi1(g)-phi2(g))+(p <<
480 // where f_c(Z) is the Coulomb correction fact <<
481 // psi2(e) are coherent and incoherent screeni <<
482 // model of the atom, the screening functions <<
483 // depend on Z (not explicitly). These numeric <<
484 // approximated as Tsai Eqs. [3.38-3.41] with <<
485 // e=epsilon given by Tsai Eqs. [3.30 and 3.31 <<
486 // ComputeScreeningFunctions()). Note, that in <<
487 // g = e = 0 => 0.25*phi1(0)-ln(Z)/3 = ln(184. <<
488 // 0.25*psi1(0)-2*ln(Z)/3=ln(1193.923/Z^(2/3)) <<
489 // psi1(0)-psi2(0) = 2/3 so the DCS in complet <<
490 // COMPLETE SCREENING: <<
491 // ds/dk(Z,k)=C/k*{(1-y+3*y^2/4)*[L_el-f_c+L_i <<
492 // used in case of DCS with LPM above (if all <<
493 // absent i.e. their value = 1). <<
494 // Since the Thomas-Fermi model of the atom is <<
495 // complete screening is used here at low Z(<5 <<
496 // computed by using the Dirac-Fock model of t <<
497 // NOTE: that the Ter-Mikaelian suppression is <<
498 // 1/F factor but it is included in the caller <<
499 // HERE, ds/dk(Z,k)*[F*k/C] is computed exactl <<
500 G4double <<
501 G4eBremsstrahlungRelModel::ComputeDXSectionPer <<
502 { <<
503 G4double dxsec = 0.0; <<
504 if (gammaEnergy < 0.) { <<
505 return dxsec; <<
506 } <<
507 const G4double y = gammaEnergy/fPrim <<
508 const G4double onemy = 1.-y; <<
509 const G4double dum0 = onemy+0.75*y*y; <<
510 const ElementData* elDat = (*fElementData)[f <<
511 // use complete screening and L_el, L_inel f <<
512 if (fCurrentIZ < 5 || fIsUseCompleteScreenin <<
513 dxsec = dum0*elDat->fZFactor1; <<
514 dxsec += onemy*elDat->fZFactor2; <<
515 if (fIsScatOffElectron) { <<
516 fSumTerm = dxsec; <<
517 fNucTerm = dum0*elDat->fZFactor11+onemy/ <<
518 } <<
519 } else { <<
520 // use Tsai's analytical approx. (Tsai Eqs <<
521 // numerical screening functions computed <<
522 const G4double invZ = 1./(G4double)fCur <<
523 const G4double Fz = elDat->fFz; <<
524 const G4double logZ = elDat->fLogZ; <<
525 const G4double dum1 = y/(fPrimaryTotalE <<
526 const G4double gamma = dum1*elDat->fGamm <<
527 const G4double epsilon = dum1*elDat->fEpsi <<
528 // evaluate the screening functions <<
529 G4double phi1, phi1m2, psi1, psi1m2; <<
530 ComputeScreeningFunctions(phi1, phi1m2, ps <<
531 dxsec = dum0*((0.25*phi1-Fz) + (0.25*psi1 <<
532 dxsec += 0.125*onemy*(phi1m2 + psi1m2*invZ <<
533 if (fIsScatOffElectron) { <<
534 fSumTerm = dxsec; <<
535 fNucTerm = dum0*(0.25*phi1-Fz) + 0.125*o <<
536 } 250 }
>> 251 e0 += delta;
537 } 252 }
538 return std::max(dxsec,0.0); << 253
>> 254 loss *= delta*totalEnergy;
>> 255
>> 256 return loss;
539 } 257 }
540 258
541 // Coherent and incoherent screening function << 259 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
542 // Eqs.[3.38-3.41]). Tsai's analytical approxi << 260
543 // functions computed by using the Thomas-Ferm << 261 G4double G4eBremsstrahlungRelModel::ComputeCrossSectionPerAtom(
544 // ximation to the numerical TF screening func << 262 const G4ParticleDefinition* p,
545 // screening functions can be expressed in a ' << 263 G4double kineticEnergy,
546 // pendent variable (see Tsai Eqs. Eqs. [3.30 << 264 G4double Z, G4double,
547 void G4eBremsstrahlungRelModel::ComputeScreeni << 265 G4double cutEnergy,
548 << 266 G4double maxEnergy)
549 << 267 {
550 << 268 if(!particle) SetParticle(p);
551 << 269 if(kineticEnergy < lowKinEnergy) return 0.0;
552 << 270 G4double cut = std::min(cutEnergy, kineticEnergy);
553 { << 271 G4double tmax = std::min(maxEnergy, kineticEnergy);
554 const G4double gam2 = gam*gam; << 272
555 phi1 = 16.863-2.0*G4Log(1.0+0.311877*gam2) << 273 if(cut >= tmax) return 0.0;
556 +1.6*G4Exp(-1.5*gam); << 274
557 phi1m2 = 2.0/(3.0+19.5*gam+18.0*gam2); // << 275 SetCurrentElement(Z);
558 const G4double eps2 = eps*eps; << 276
559 psi1 = 24.34-2.0*G4Log(1.0+13.111641*eps2) << 277 G4double cross = ComputeXSectionPerAtom(cut);
560 +1.2*G4Exp(-29.2*eps); << 278
561 psi1m2 = 2.0/(3.0+120.0*eps+1200.0*eps2); // << 279 // allow partial integration
562 } << 280 if(tmax < kinEnergy) cross -= ComputeXSectionPerAtom(tmax);
563 << 281
564 void << 282 cross *= Z*Z*bremFactor;
565 G4eBremsstrahlungRelModel::SampleSecondaries(s << 283
566 c << 284 return cross;
567 c <<
568 G <<
569 G <<
570 { <<
571 const G4double kineticEnergy = dp->GetKin <<
572 if (kineticEnergy < LowEnergyLimit()) { <<
573 return; <<
574 } <<
575 // min, max kinetic energy limits <<
576 const G4double tmin = std::min(cutEnergy, ki <<
577 const G4double tmax = std::min(maxEnergy, ki <<
578 if (tmin >= tmax) { <<
579 return; <<
580 } <<
581 // <<
582 SetupForMaterial(fPrimaryParticle, couple->G <<
583 const G4Element* elm = SelectTargetAtom(coup <<
584 dp-> <<
585 // <<
586 fCurrentIZ = elm->GetZasInt(); <<
587 const ElementData* elDat = (*fElementData)[f <<
588 const G4double funcMax = elDat->fZFactor1+el <<
589 // get the random engine <<
590 G4double rndm[2]; <<
591 CLHEP::HepRandomEngine* rndmEngine = G4Rando <<
592 // min max of the transformed variable: x(k) <<
593 const G4double xmin = G4Log(tmin*tmin+fDen <<
594 const G4double xrange = G4Log(tmax*tmax+fDen <<
595 G4double gammaEnergy, funcVal; <<
596 do { <<
597 rndmEngine->flatArray(2, rndm); <<
598 gammaEnergy = std::sqrt(std::max(G4Exp(xmi <<
599 funcVal = fIsLPMActive <<
600 ? ComputeRelDXSectionPerAtom( <<
601 : ComputeDXSectionPerAtom(gam <<
602 // cross-check of proper function maximum <<
603 // if (funcVal > funcMax) { <<
604 // G4cout << "### G4eBremsstrahlungRelMod <<
605 // << funcVal << " > " << funcMax <<
606 // << " Egamma(MeV)= " << gammaEnergy <<
607 // << " Ee(MeV)= " << kineticEnergy <<
608 // << " " << GetName() <<
609 // << G4endl; <<
610 // } <<
611 // Loop checking, 03-Aug-2015, Vladimir Iv <<
612 } while (funcVal < funcMax*rndm[1]); <<
613 // <<
614 // scattering off nucleus or off e- by tripl <<
615 if (fIsScatOffElectron && rndmEngine->flat() <<
616 GetTripletModel()->SampleSecondaries(vdp, <<
617 return; <<
618 } <<
619 // <<
620 // angles of the emitted gamma. ( Z - axis a <<
621 // use general interface <<
622 G4ThreeVector gamDir = <<
623 GetAngularDistribution()->SampleDirection( <<
624 <<
625 // create G4DynamicParticle object for the G <<
626 auto gamma = new G4DynamicParticle(fGammaPar <<
627 vdp->push_back(gamma); <<
628 // compute post-interaction kinematics of pr <<
629 // energy-momentum conservation <<
630 const G4double totMomentum = std::sqrt(kinet <<
631 fPrimaryTotalEn <<
632 G4ThreeVector dir = <<
633 (totMomentum*dp->GetMomentumDirec <<
634 const G4double finalE = kineticEnergy-gamm <<
635 // if secondary gamma energy is higher than <<
636 // then stop tracking the primary particle a <<
637 // instead of the primary one <<
638 if (gammaEnergy > SecondaryThreshold()) { <<
639 fParticleChange->ProposeTrackStatus(fStopA <<
640 fParticleChange->SetProposedKineticEnergy( <<
641 auto el = new G4DynamicParticle( <<
642 const_cast<G4ParticleDefinition* <<
643 vdp->push_back(el); <<
644 } else { // continue tracking the primary e- <<
645 fParticleChange->SetProposedMomentumDirect <<
646 fParticleChange->SetProposedKineticEnergy( <<
647 } <<
648 } 285 }
>> 286
>> 287 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
>> 288
649 289
650 void G4eBremsstrahlungRelModel::InitialiseElem << 290 G4double G4eBremsstrahlungRelModel::ComputeXSectionPerAtom(G4double cut)
651 { 291 {
652 // create for all elements that are in the d << 292 G4double cross = 0.0;
653 auto elemTable = G4Element::GetElementTable( << 293
654 for (auto const & elem : *elemTable) { << 294 // number of intervals and integration step
655 const G4double zet = elem->GetZ(); << 295 G4double vcut = log(cut/totalEnergy);
656 const G4int izet = std::min(elem->GetZasIn << 296 G4double vmax = log(kinEnergy/totalEnergy);
657 if (nullptr == (*fElementData)[izet]) { << 297 G4int n = (G4int)(0.45*(vmax - vcut)) + 4;
658 auto elemData = new ElementData(); << 298 // n=1; // integration test
659 const G4double fc = elem->GetfCoulomb(); << 299 G4double delta = (vmax - vcut)/G4double(n);
660 G4double Fel = 1.; << 300
661 G4double Finel = 1.; << 301 G4double e0 = vcut;
662 elemData->fLogZ = G4Log(zet); << 302 G4double xs;
663 elemData->fFz = elemData->fLogZ/3.+f << 303
664 if (izet < 5) { << 304 // integration
665 Fel = gFelLowZet[izet]; << 305 for(G4int l=0; l<n; l++) {
666 Finel = gFinelLowZet[izet]; << 306
>> 307 for(G4int i=0; i<8; i++) {
>> 308
>> 309 G4double eg = exp(e0 + xgi[i]*delta)*totalEnergy;
>> 310
>> 311 if(totalEnergy > energyThresholdLPM) {
>> 312 xs = ComputeRelDXSectionPerAtom(eg);
667 } else { 313 } else {
668 Fel = G4Log(184.15) - elemData->f << 314 xs = ComputeDXSectionPerAtom(eg);
669 Finel = G4Log(1194) - 2.*elemData->f <<
670 } 315 }
671 const G4double z13 = G4Pow::GetInstance( << 316 cross += wgi[i]*xs/(1.0 + densityCorr/(eg*eg));
672 const G4double z23 = z13*z13; <<
673 elemData->fZFactor1 = (Fel-fc)+Fine <<
674 elemData->fZFactor11 = (Fel-fc); // <<
675 elemData->fZFactor2 = (1.+1./zet)/1 <<
676 elemData->fVarS1 = z23/(184.15*1 <<
677 elemData->fILVarS1Cond = 1./(G4Log(std <<
678 elemData->fILVarS1 = 1./G4Log(elem <<
679 elemData->fGammaFactor = 100.0*electro <<
680 elemData->fEpsilonFactor = 100.0*electro <<
681 (*fElementData)[izet] = elemData; <<
682 } 317 }
>> 318 e0 += delta;
683 } 319 }
>> 320
>> 321 cross *= delta;
>> 322
>> 323 return cross;
684 } 324 }
685 325
686 void G4eBremsstrahlungRelModel::ComputeLPMfunc << 326 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
687 << 327 void G4eBremsstrahlungRelModel::CalcLPMFunctions(G4double k)
688 << 328 {
689 << 329 // *** calculate lpm variable s & sprime ***
690 { << 330 // Klein eqs. (78) & (79)
691 static const G4double sqrt2 = std::sqrt(2.); << 331 G4double sprime = sqrt(0.125*k*lpmEnergy/(totalEnergy*(totalEnergy-k)));
692 const G4double redegamma = egamma/fPrimar << 332
693 const G4double varSprime = std::sqrt(0.12 << 333 G4double s1 = preS1*z23;
694 ((1.0-redegamm << 334 G4double logS1 = 2./3.*lnZ-2.*facFel;
695 const ElementData* elDat = (*fElementData << 335 G4double logTS1 = logTwo+logS1;
696 const G4double varS1 = elDat->fVarS1; << 336
697 const G4double condition = sqrt2*varS1; << 337 xiLPM = 2.;
698 G4double funcXiSprime = 2.0; << 338
699 if (varSprime > 1.0) { << 339 if (sprime>1)
700 funcXiSprime = 1.0; << 340 xiLPM = 1.;
701 } else if (varSprime > condition) { << 341 else if (sprime>sqrt(2.)*s1) {
702 const G4double ilVarS1Cond = elDat->fILVar << 342 G4double h = log(sprime)/logTS1;
703 const G4double funcHSprime = G4Log(varSpri << 343 xiLPM = 1+h-0.08*(1-h)*(1-sqr(1-h))/logTS1;
704 funcXiSprime = 1.0 + funcHSprime - 0.08*(1 <<
705 *(2.0-fu <<
706 } <<
707 const G4double varS = varSprime/std::sqrt <<
708 // - include dielectric suppression effect i <<
709 const G4double varShat = varS*(1.0+fDensityC <<
710 funcXiS = 2.0; <<
711 if (varShat > 1.0) { <<
712 funcXiS = 1.0; <<
713 } else if (varShat > varS1) { <<
714 funcXiS = 1.0+G4Log(varShat)*elDat->fILVar <<
715 } 344 }
716 GetLPMFunctions(funcGS, funcPhiS, varShat); << 345
717 //ComputeLPMGsPhis(funcGS, funcPhiS, varShat << 346 G4double s = sprime/sqrt(xiLPM);
718 // << 347
719 //MAKE SURE SUPPRESSION IS SMALLER THAN 1: d << 348 // *** merging with density effect*** should be only necessary in region "close to" kp, e.g. k<100*kp
720 if (funcXiS*funcPhiS > 1. || varShat > 0.57) << 349 // using Ter-Mikaelian eq. (20.9)
721 funcXiS=1./funcPhiS; << 350 G4double k2 = k*k;
>> 351 s = s * (1 + (densityCorr/k2) );
>> 352
>> 353 // recalculate Xi using modified s above
>> 354 // Klein eq. (75)
>> 355 xiLPM = 1.;
>> 356 if (s<=s1) xiLPM = 2.;
>> 357 else if ( (s1<s) && (s<=1) ) xiLPM = 1. + log(s)/logS1;
>> 358
>> 359
>> 360 // *** calculate supression functions phi and G ***
>> 361 // Klein eqs. (77)
>> 362 G4double s2=s*s;
>> 363 G4double s3=s*s2;
>> 364 G4double s4=s2*s2;
>> 365
>> 366 if (s<0.1) {
>> 367 // high suppression limit
>> 368 phiLPM = 6.*s - 18.84955592153876*s2 + 39.47841760435743*s3
>> 369 - 57.69873135166053*s4;
>> 370 gLPM = 37.69911184307752*s2 - 236.8705056261446*s3 + 807.7822389*s4;
>> 371 }
>> 372 else if (s<1.9516) {
>> 373 // intermediate suppression
>> 374 // using eq.77 approxim. valid s<2.
>> 375 phiLPM = 1.-exp(-6.*s*(1.+(3.-pi)*s)
>> 376 +s3/(0.623+0.795*s+0.658*s2));
>> 377 if (s<0.415827397755) {
>> 378 // using eq.77 approxim. valid 0.07<s<2
>> 379 G4double psiLPM = 1-exp(-4*s-8*s2/(1+3.936*s+4.97*s2-0.05*s3+7.50*s4));
>> 380 gLPM = 3*psiLPM-2*phiLPM;
>> 381 }
>> 382 else {
>> 383 // using alternative parametrisiation
>> 384 G4double pre = -0.16072300849123999 + s*3.7550300067531581 + s2*-1.7981383069010097
>> 385 + s3*0.67282686077812381 + s4*-0.1207722909879257;
>> 386 gLPM = tanh(pre);
>> 387 }
>> 388 }
>> 389 else {
>> 390 // low suppression limit valid s>2.
>> 391 phiLPM = 1. - 0.0119048/s4;
>> 392 gLPM = 1. - 0.0230655/s4;
722 } 393 }
>> 394
>> 395 // *** make sure suppression is smaller than 1 ***
>> 396 // *** caused by Migdal approximation in xi ***
>> 397 if (xiLPM*phiLPM>1. || s>0.57) xiLPM=1./phiLPM;
>> 398 }
>> 399
>> 400 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
>> 401
>> 402
>> 403 G4double G4eBremsstrahlungRelModel::ComputeRelDXSectionPerAtom(G4double gammaEnergy)
>> 404 // Ultra relativistic model
>> 405 // only valid for very high energies, but includes LPM suppression
>> 406 // * complete screening
>> 407 {
>> 408 if(gammaEnergy < 0.0) return 0.0;
>> 409
>> 410 G4double y = gammaEnergy/totalEnergy;
>> 411 G4double y2 = y*y*.25;
>> 412 G4double yone2 = (1.-y+2.*y2);
>> 413
>> 414 // ** form factors complete screening case **
>> 415
>> 416 // ** calc LPM functions -- include ter-mikaelian merging with density effect **
>> 417 // G4double xiLPM, gLPM, phiLPM; // to be made member variables !!!
>> 418 CalcLPMFunctions(gammaEnergy);
>> 419
>> 420 G4double mainLPM = xiLPM*(y2 * gLPM + yone2*phiLPM) * ( (Fel-fCoulomb) + Finel/currentZ );
>> 421 G4double secondTerm = (1.-y)/12.*(1.+1./currentZ);
>> 422
>> 423 G4double cross = mainLPM+secondTerm;
>> 424 return cross;
723 } 425 }
724 426
725 void G4eBremsstrahlungRelModel::ComputeLPMGsPh << 427 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
726 << 428
727 << 429 G4double G4eBremsstrahlungRelModel::ComputeDXSectionPerAtom(G4double gammaEnergy)
>> 430 // Relativistic model
>> 431 // only valid for high energies (and if LPM suppression does not play a role)
>> 432 // * screening according to thomas-fermi-Model (only valid for Z>5)
>> 433 // * no LPM effect
728 { 434 {
729 if (varShat < 0.01) { << 435
730 funcPhiS = 6.0*varShat*(1.0-CLHEP::pi*varS << 436 if(gammaEnergy < 0.0) return 0.0;
731 funcGS = 12.0*varShat-2.0*funcPhiS; << 437
732 } else { << 438 G4double y = gammaEnergy/totalEnergy;
733 const G4double varShat2 = varShat*varShat; << 439
734 const G4double varShat3 = varShat*varShat2 << 440 G4double main=0.,secondTerm=0.;
735 const G4double varShat4 = varShat2*varShat << 441
736 // use Stanev approximation: for \psi(s) a << 442 if (use_completescreening|| currentZ<5) {
737 if (varShat < 0.415827) { << 443 // ** form factors complete screening case **
738 funcPhiS = 1.0-G4Exp(-6.0*varShat*(1.0+v << 444 main = (3./4.*y*y - y + 1.) * ( (Fel-fCoulomb) + Finel/currentZ );
739 + varShat3/(0.623+0.796*varSha << 445 secondTerm = (1.-y)/12.*(1.+1./currentZ);
740 // 1-\exp \left\{-4s-\frac{8s^2}{1+3.936 << 446 }
741 const G4double funcPsiS = 1.0 - G4Exp(-4 << 447 else {
742 - 8.0*varShat2/ << 448 // ** intermediate screening using Thomas-Fermi FF from Tsai only valid for Z>=5**
743 - 0.05*varShat3 << 449 G4double dd=100.*electron_mass_c2*y/(totalEnergy-gammaEnergy);
744 // G(s) = 3 \psi(s) - 2 \phi(s) << 450 G4double gg=dd*z13;
745 funcGS = 3.0*funcPsiS - 2.0*funcPhiS; << 451 G4double eps=dd*z23;
746 } else if (varShat<1.55) { << 452 G4double phi1=Phi1(gg,currentZ), phi1m2=Phi1M2(gg,currentZ);
747 funcPhiS = 1.0-G4Exp(-6.0*varShat*(1.0+v << 453 G4double psi1=Psi1(eps,currentZ), psi1m2=Psi1M2(eps,currentZ);
748 + varShat3/(0.623+0.796*varSha << 454
749 const G4double dum0 = -0.160723 << 455 main = (3./4.*y*y - y + 1.) * ( (0.25*phi1-1./3.*lnZ-fCoulomb) + (0.25*psi1-2./3.*lnZ)/currentZ );
750 -1.798138*varShat << 456 secondTerm = (1.-y)/8.*(phi1m2+psi1m2/currentZ);
751 -0.120772*varShat <<
752 funcGS = std::tanh(dum0); <<
753 } else { <<
754 funcPhiS = 1.0-0.011905/varShat4; <<
755 if (varShat<1.9156) { <<
756 const G4double dum0 = -0.160723 <<
757 -1.798138*varSha <<
758 -0.120772*varSha <<
759 funcGS = std::tanh(dum0); <<
760 } else { <<
761 funcGS = 1.0-0.023065/varShat4; <<
762 } <<
763 } <<
764 } 457 }
>> 458 G4double cross = main+secondTerm;
>> 459 return cross;
765 } 460 }
766 461
767 // s goes up to 2 with ds = 0.01 to be the def << 462 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
768 void G4eBremsstrahlungRelModel::InitLPMFunctio << 463
>> 464 void G4eBremsstrahlungRelModel::SampleSecondaries(
>> 465 std::vector<G4DynamicParticle*>* vdp,
>> 466 const G4MaterialCutsCouple* couple,
>> 467 const G4DynamicParticle* dp,
>> 468 G4double cutEnergy,
>> 469 G4double maxEnergy)
769 { 470 {
770 if (!fLPMFuncs->fIsInitialized) { << 471 G4double kineticEnergy = dp->GetKineticEnergy();
771 const G4int num = fLPMFuncs->fSLimit*fLPMF << 472 if(kineticEnergy < lowKinEnergy) return;
772 fLPMFuncs->fLPMFuncG.resize(num); << 473 G4double cut = std::min(cutEnergy, kineticEnergy);
773 fLPMFuncs->fLPMFuncPhi.resize(num); << 474 G4double emax = std::min(maxEnergy, kineticEnergy);
774 for (G4int i = 0; i < num; ++i) { << 475 if(cut >= emax) return;
775 const G4double sval=i/fLPMFuncs->fISDelt << 476
776 ComputeLPMGsPhis(fLPMFuncs->fLPMFuncG[i] << 477 SetupForMaterial(particle, couple->GetMaterial(),kineticEnergy);
>> 478
>> 479 const G4Element* elm =
>> 480 SelectRandomAtom(couple,particle,kineticEnergy,cut,emax);
>> 481 SetCurrentElement(elm->GetZ());
>> 482
>> 483 kinEnergy = kineticEnergy;
>> 484 totalEnergy = kineticEnergy + particleMass;
>> 485 densityCorr = densityFactor*totalEnergy*totalEnergy;
>> 486 G4ThreeVector direction = dp->GetMomentumDirection();
>> 487
>> 488 // G4double fmax= fMax;
>> 489 G4bool highe = true;
>> 490 if(totalEnergy < energyThresholdLPM) highe = false;
>> 491
>> 492 G4double xmin = log(cut*cut + densityCorr);
>> 493 G4double xmax = log(emax*emax + densityCorr);
>> 494 G4double gammaEnergy, f, x;
>> 495
>> 496 do {
>> 497 x = exp(xmin + G4UniformRand()*(xmax - xmin)) - densityCorr;
>> 498 if(x < 0.0) x = 0.0;
>> 499 gammaEnergy = sqrt(x);
>> 500 if(highe) f = ComputeRelDXSectionPerAtom(gammaEnergy);
>> 501 else f = ComputeDXSectionPerAtom(gammaEnergy);
>> 502
>> 503 if ( f > fMax ) {
>> 504 G4cout << "### G4eBremsstrahlungRelModel Warning: Majoranta exceeded! "
>> 505 << f << " > " << fMax
>> 506 << " Egamma(MeV)= " << gammaEnergy
>> 507 << " E(mEV)= " << kineticEnergy
>> 508 << G4endl;
777 } 509 }
778 fLPMFuncs->fIsInitialized = true; <<
779 } <<
780 } <<
781 510
782 void G4eBremsstrahlungRelModel::GetLPMFunction << 511 } while (f < fMax*G4UniformRand());
783 << 512
784 << 513 //
785 { << 514 // angles of the emitted gamma. ( Z - axis along the parent particle)
786 if (sval < fLPMFuncs->fSLimit) { << 515 //
787 G4double val = sval*fLPMFuncs->fISDelt << 516 // universal distribution suggested by L. Urban
788 const G4int ilow = (G4int)val; << 517 // (Geant3 manual (1993) Phys211),
789 val -= ilow; << 518 // derived from Tsai distribution (Rev Mod Phys 49,421(1977))
790 lpmGs = (fLPMFuncs->fLPMFuncG[ilow+1]-fL << 519
791 + fLPMFuncs->fLPMFuncG[ilow]; << 520 G4double u;
792 lpmPhis = (fLPMFuncs->fLPMFuncPhi[ilow+1]- << 521 const G4double a1 = 0.625 , a2 = 3.*a1 , d = 27. ;
793 + fLPMFuncs->fLPMFuncPhi[ilow]; << 522
>> 523 if (9./(9.+d) > G4UniformRand()) u = - log(G4UniformRand()*G4UniformRand())/a1;
>> 524 else u = - log(G4UniformRand()*G4UniformRand())/a2;
>> 525
>> 526 G4double theta = u*particleMass/totalEnergy;
>> 527 G4double sint = sin(theta);
>> 528 G4double phi = twopi * G4UniformRand();
>> 529 G4ThreeVector gammaDirection(sint*cos(phi),sint*sin(phi), cos(theta));
>> 530 gammaDirection.rotateUz(direction);
>> 531
>> 532 // create G4DynamicParticle object for the Gamma
>> 533 G4DynamicParticle* g = new G4DynamicParticle(theGamma,gammaDirection,
>> 534 gammaEnergy);
>> 535 vdp->push_back(g);
>> 536
>> 537 G4double totMomentum = sqrt(kineticEnergy*(totalEnergy + electron_mass_c2));
>> 538 G4ThreeVector dir = totMomentum*direction - gammaEnergy*gammaDirection;
>> 539 direction = dir.unit();
>> 540
>> 541 // energy of primary
>> 542 G4double finalE = kineticEnergy - gammaEnergy;
>> 543
>> 544 // stop tracking and create new secondary instead of primary
>> 545 if(gammaEnergy > SecondaryThreshold()) {
>> 546 fParticleChange->ProposeTrackStatus(fStopAndKill);
>> 547 fParticleChange->SetProposedKineticEnergy(0.0);
>> 548 G4DynamicParticle* el =
>> 549 new G4DynamicParticle(const_cast<G4ParticleDefinition*>(particle),
>> 550 direction, finalE);
>> 551 vdp->push_back(el);
>> 552
>> 553 // continue tracking
794 } else { 554 } else {
795 G4double ss = sval*sval; << 555 fParticleChange->SetProposedMomentumDirection(direction);
796 ss *= ss; << 556 fParticleChange->SetProposedKineticEnergy(finalE);
797 lpmPhis = 1.0-0.01190476/ss; <<
798 lpmGs = 1.0-0.0230655/ss; <<
799 } 557 }
800 } 558 }
>> 559
>> 560 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
>> 561
801 562
802 563