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28 //
29 // GEANT4 Class header file
30 //
31 //
32 // File name: G4eeToHadronsModel
33 //
34 // Author: Vladimir Ivanchenko
35 //
36 // Creation date: 12.08.2003
37 //
38 // Modifications:
39 // 08-04-05 Major optimisation of internal interfaces (V.Ivantchenko)
40 // 18-05-05 Use optimized interfaces (V.Ivantchenko)
41 //
42 //
43 // -------------------------------------------------------------------
44 //
45
46
47 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
48 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
49
50 #include "G4eeToHadronsModel.hh"
51 #include "Randomize.hh"
52 #include "G4PhysicalConstants.hh"
53 #include "G4SystemOfUnits.hh"
54 #include "G4Electron.hh"
55 #include "G4Gamma.hh"
56 #include "G4Positron.hh"
57 #include "G4PionPlus.hh"
58 #include "Randomize.hh"
59 #include "G4Vee2hadrons.hh"
60 #include "G4PhysicsVector.hh"
61 #include "G4PhysicsLogVector.hh"
62 #include "G4Log.hh"
63 #include "G4Exp.hh"
64
65 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
66
67 using namespace std;
68
69 G4eeToHadronsModel::G4eeToHadronsModel(G4Vee2hadrons* mod, G4int ver,
70 const G4String& nam)
71 : G4VEmModel(nam),
72 model(mod),
73 verbose(ver)
74 {
75 theGamma = G4Gamma::Gamma();
76 highKinEnergy = HighEnergyLimit();
77 lowKinEnergy = LowEnergyLimit();
78 emin = lowKinEnergy;
79 emax = highKinEnergy;
80 peakKinEnergy = highKinEnergy;
81 epeak = emax;
82 //verbose = 1;
83 }
84
85 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
86
87 G4eeToHadronsModel::~G4eeToHadronsModel()
88 {
89 delete model;
90 }
91
92 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
93
94 void G4eeToHadronsModel::Initialise(const G4ParticleDefinition*,
95 const G4DataVector&)
96 {
97 if(isInitialised) { return; }
98 isInitialised = true;
99
100 // CM system
101 emin = model->LowEnergy();
102 emax = model->HighEnergy();
103
104 // peak energy
105 epeak = std::min(model->PeakEnergy(), emax);
106
107 if(verbose>0) {
108 G4cout << "G4eeToHadronsModel::Initialise: " << G4endl;
109 G4cout << "CM System: emin(MeV)= " << emin/MeV
110 << " epeak(MeV)= " << epeak/MeV
111 << " emax(MeV)= " << emax/MeV
112 << G4endl;
113 }
114
115 crossBornPerElectron = model->PhysicsVector();
116 crossPerElectron = model->PhysicsVector();
117 nbins = (G4int)crossPerElectron->GetVectorLength();
118 for(G4int i=0; i<nbins; ++i) {
119 G4double e = crossPerElectron->Energy(i);
120 G4double cs = model->ComputeCrossSection(e);
121 crossBornPerElectron->PutValue(i, cs);
122 }
123 ComputeCMCrossSectionPerElectron();
124
125 if(verbose>1) {
126 G4cout << "G4eeToHadronsModel: Cross sections per electron"
127 << " nbins= " << nbins
128 << " emin(MeV)= " << emin/MeV
129 << " emax(MeV)= " << emax/MeV
130 << G4endl;
131 for(G4int i=0; i<nbins; ++i) {
132 G4double e = crossPerElectron->Energy(i);
133 G4double s1 = crossPerElectron->Value(e);
134 G4double s2 = crossBornPerElectron->Value(e);
135 G4cout << "E(MeV)= " << e/MeV
136 << " cross(nb)= " << s1/nanobarn
137 << " crossBorn(nb)= " << s2/nanobarn
138 << G4endl;
139 }
140 }
141 }
142
143 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
144
145 G4double G4eeToHadronsModel::CrossSectionPerVolume(
146 const G4Material* mat,
147 const G4ParticleDefinition* p,
148 G4double kineticEnergy,
149 G4double, G4double)
150 {
151 return mat->GetElectronDensity()*
152 ComputeCrossSectionPerElectron(p, kineticEnergy);
153 }
154
155 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
156
157 G4double G4eeToHadronsModel::ComputeCrossSectionPerAtom(
158 const G4ParticleDefinition* p,
159 G4double kineticEnergy,
160 G4double Z, G4double,
161 G4double, G4double)
162 {
163 return Z*ComputeCrossSectionPerElectron(p, kineticEnergy);
164 }
165
166 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
167
168 G4double G4eeToHadronsModel::ComputeCrossSectionPerElectron(
169 const G4ParticleDefinition*,
170 G4double energy,
171 G4double, G4double)
172 {
173 return crossPerElectron->Value(energy);
174 }
175
176 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
177
178 void G4eeToHadronsModel::SampleSecondaries(std::vector<G4DynamicParticle*>* newp,
179 const G4MaterialCutsCouple*,
180 const G4DynamicParticle* dParticle,
181 G4double,
182 G4double)
183 {
184 G4double t = dParticle->GetKineticEnergy() + 2*electron_mass_c2;
185 G4LorentzVector inlv = dParticle->Get4Momentum() +
186 G4LorentzVector(0.0,0.0,0.0,electron_mass_c2);
187 G4double e = inlv.m();
188 G4ThreeVector inBoost = inlv.boostVector();
189 //G4cout << "G4eeToHadronsModel::SampleSecondaries e= " << e
190 // << " " << inlv << " " << inBoost <<G4endl;
191 if(e > emin) {
192 G4DynamicParticle* gamma = GenerateCMPhoton(e);
193 G4LorentzVector gLv = gamma->Get4Momentum();
194 G4LorentzVector lv(0.0,0.0,0.0,e);
195 lv -= gLv;
196 G4double mass = lv.m();
197 //G4cout << "mass= " << mass << " " << lv << G4endl;
198 G4ThreeVector boost = lv.boostVector();
199 //G4cout << "mass= " << mass << " " << boost << G4endl;
200 const G4ThreeVector dir = gamma->GetMomentumDirection();
201 model->SampleSecondaries(newp, mass, dir);
202 std::size_t np = newp->size();
203 for(std::size_t j=0; j<np; ++j) {
204 G4DynamicParticle* dp = (*newp)[j];
205 G4LorentzVector v = dp->Get4Momentum();
206 v.boost(boost);
207 //G4cout << j << ". " << v << G4endl;
208 v.boost(inBoost);
209 //G4cout << " " << v << G4endl;
210 dp->Set4Momentum(v);
211 t -= v.e();
212 }
213 //G4cout << "Gamma " << gLv << G4endl;
214 gLv.boost(inBoost);
215 //G4cout << " " << gLv << G4endl;
216 gamma->Set4Momentum(gLv);
217 t -= gLv.e();
218 newp->push_back(gamma);
219 if(std::abs(t) > CLHEP::MeV) {
220 G4cout << "G4eeToHadronsModel::SampleSecondaries: Ebalance(MeV)= "
221 << t/MeV << " primary 4-momentum: " << inlv << G4endl;
222 }
223 }
224 }
225
226 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
227
228 void G4eeToHadronsModel::ComputeCMCrossSectionPerElectron()
229 {
230 for(G4int i=0; i<nbins; i++) {
231 G4double e = crossPerElectron->Energy(i);
232 G4double cs = 0.0;
233 if(i > 0) {
234 G4double LL = 2.0*G4Log(e/electron_mass_c2);
235 G4double bt = 2.0*fine_structure_const*(LL - 1.0)/pi;
236 G4double btm1= bt - 1.0;
237 G4double del = 1. + fine_structure_const*(1.5*LL + pi*pi/3. -2.)/pi;
238 G4double s1 = crossBornPerElectron->Value(e);
239 G4double e1 = crossPerElectron->Energy(i-1);
240 G4double x1 = 1. - e1/e;
241 cs += s1*(del*G4Exp(G4Log(x1)*bt) - bt*(x1 - 0.25*x1*x1));
242 if(i > 1) {
243 G4double e2 = e1;
244 G4double x2 = x1;
245 G4double s2 = crossBornPerElectron->Value(e2);
246 G4double w2 = bt*(del*G4Exp(G4Log(x2)*btm1) - 1.0 + 0.5*x2);
247 G4double w1;
248
249 for(G4int j=i-2; j>=0; --j) {
250 e1 = crossPerElectron->Energy(j);
251 x1 = 1. - e1/e;
252 s1 = crossBornPerElectron->Value(e1);
253 w1 = bt*(del*G4Exp(G4Log(x1)*btm1) - 1.0 + 0.5*x1);
254 cs += 0.5*(x1 - x2)*(w2*s2 + w1*s1);
255 e2 = e1;
256 x2 = x1;
257 s2 = s1;
258 w2 = w1;
259 }
260 }
261 }
262 crossPerElectron->PutValue(i, cs);
263 }
264 }
265
266 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
267
268 G4DynamicParticle* G4eeToHadronsModel::GenerateCMPhoton(G4double e)
269 {
270 G4double x;
271 G4DynamicParticle* gamma = nullptr;
272 G4double LL = 2.0*G4Log(e/electron_mass_c2);
273 G4double bt = 2.0*fine_structure_const*(LL - 1.)/pi;
274 G4double btm1= bt - 1.0;
275 G4double del = 1. + fine_structure_const*(1.5*LL + pi*pi/3. -2.)/pi;
276
277 G4double s0 = crossBornPerElectron->Value(e);
278 G4double de = (emax - emin)/(G4double)nbins;
279 G4double xmax = 0.5*(1.0 - (emin*emin)/(e*e));
280 G4double xmin = std::min(de/e, xmax);
281 G4double ds = s0*(del*G4Exp(G4Log(xmin)*bt) - bt*(xmin - 0.25*xmin*xmin));
282 G4double e1 = e*(1. - xmin);
283
284 //G4cout << "e1= " << e1 << G4endl;
285 if(e1 < emax && s0*G4UniformRand()<ds) {
286 x = xmin*G4Exp(G4Log(G4UniformRand())/bt);
287 } else {
288
289 x = xmin;
290 G4double s1 = crossBornPerElectron->Value(e1);
291 G4double w1 = bt*(del*G4Exp(G4Log(x)*btm1) - 1.0 + 0.5*x);
292 G4double grej = s1*w1;
293 G4double f;
294 /*
295 G4cout << "e(GeV)= " << e/GeV << " epeak(GeV)= " << epeak/GeV
296 << " s1= " << s1 << " w1= " << w1
297 << " grej= " << grej << G4endl;
298 */
299 // Above emax cross section is const
300 if(e1 > emax) {
301 x = 0.5*(1. - (emax*emax)/(e*e));
302 G4double s2 = crossBornPerElectron->Value(emax);
303 G4double w2 = bt*(del*G4Exp(G4Log(x)*btm1) - 1.0 + 0.5*x);
304 grej = s2*w2;
305 //G4cout << "emax= " << emax << " s2= " << s2 << " w2= " << w2
306 // << " grej= " << grej << G4endl;
307 }
308
309 if(e1 > epeak) {
310 x = 0.5*(1.0 - (epeak*epeak)/(e*e));
311 G4double s2 = crossBornPerElectron->Value(epeak);
312 G4double w2 = bt*(del*G4Exp(G4Log(x)*btm1) - 1.0 + 0.5*x);
313 grej = std::max(grej,s2*w2);
314 //G4cout << "epeak= " << epeak << " s2= " << s2 << " w2= " << w2
315 // << " grej= " << grej << G4endl;
316 }
317 G4int ii = 0;
318 const G4int iimax = 1000;
319 do {
320 x = xmin + G4UniformRand()*(xmax - xmin);
321
322 G4double s2 = crossBornPerElectron->Value(sqrt(1.0 - 2*x)*e);
323 G4double w2 = bt*(del*G4Exp(G4Log(x)*btm1) - 1.0 + 0.5*x);
324 /*
325 G4cout << "x= " << x << " xmin= " << xmin << " xmax= " << xmax
326 << " s2= " << s2 << " w2= " << w2 << G4endl;
327 */
328 f = s2*w2;
329 if(f > grej) {
330 G4cout << "G4DynamicParticle* G4eeToHadronsModel:WARNING "
331 << f << " > " << grej << " majorant is`small!"
332 << G4endl;
333 }
334 if(++ii >= iimax) { break; }
335 // Loop checking, 07-Aug-2015, Vladimir Ivanchenko
336 } while (f < grej*G4UniformRand());
337 }
338
339 G4ThreeVector dir(0.0,0.0,1.0);
340 if(G4UniformRand() > 0.5) { dir.set(0.0,0.0,-1.0); }
341 //G4cout << "Egamma(MeV)= " << x*e << " " << dir << G4endl;
342 gamma = new G4DynamicParticle(theGamma,dir,x*e);
343 return gamma;
344 }
345
346 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
347