source: trunk/source/processes/electromagnetic/highenergy/src/G4eeToHadronsModel.cc@ 1192

Last change on this file since 1192 was 1007, checked in by garnier, 17 years ago

update to geant4.9.2
File size: 12.1 KB
Line 
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25//
26// $Id: G4eeToHadronsModel.cc,v 1.9 2008/07/10 18:06:39 vnivanch Exp $
27// GEANT4 tag $Name: geant4-09-02 $
28//
29// -------------------------------------------------------------------
30//
31// GEANT4 Class header file
32//
33//
34// File name: G4eeToHadronsModel
35//
36// Author: Vladimir Ivanchenko
37//
38// Creation date: 12.08.2003
39//
40// Modifications:
41// 08-04-05 Major optimisation of internal interfaces (V.Ivantchenko)
42// 18-05-05 Use optimized interfaces (V.Ivantchenko)
43//
44//
45// -------------------------------------------------------------------
46//
47
48
49//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
50//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
51
52#include "G4eeToHadronsModel.hh"
53#include "Randomize.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
63//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
64
65using namespace std;
66
67G4eeToHadronsModel::G4eeToHadronsModel(G4Vee2hadrons* m, G4int ver,
68 const G4String& nam)
69 : G4VEmModel(nam),
70 model(m),
71 crossPerElectron(0),
72 crossBornPerElectron(0),
73 isInitialised(false),
74 nbins(100),
75 verbose(ver)
76{
77 theGamma = G4Gamma::Gamma();
78}
79
80//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
81
82G4eeToHadronsModel::~G4eeToHadronsModel()
83{
84 delete model;
85 delete crossPerElectron;
86 delete crossBornPerElectron;
87}
88
89//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
90
91void G4eeToHadronsModel::Initialise(const G4ParticleDefinition*,
92 const G4DataVector&)
93{
94 if(isInitialised) return;
95 isInitialised = true;
96
97 // Lab system
98 highKinEnergy = HighEnergyLimit();
99 lowKinEnergy = LowEnergyLimit();
100
101 // CM system
102 emin = model->LowEnergy();
103 emax = model->HighEnergy();
104
105 G4double emin0 =
106 2.0*electron_mass_c2*sqrt(1.0 + 0.5*lowKinEnergy/electron_mass_c2);
107 G4double emax0 =
108 2.0*electron_mass_c2*sqrt(1.0 + 0.5*highKinEnergy/electron_mass_c2);
109
110 // recompute low energy
111 if(emin0 > emax) {
112 emin0 = emax;
113 model->SetLowEnergy(emin0);
114 }
115 if(emin > emin0) {
116 emin0 = emin;
117 lowKinEnergy = 0.5*emin*emin/electron_mass_c2 - 2.0*electron_mass_c2;
118 SetLowEnergyLimit(lowKinEnergy);
119 }
120
121 // recompute high energy
122 if(emax < emax0) {
123 emax0 = emax;
124 highKinEnergy = 0.5*emax*emax/electron_mass_c2 - 2.0*electron_mass_c2;
125 SetHighEnergyLimit(highKinEnergy);
126 }
127
128 // peak energy
129 epeak = std::min(model->PeakEnergy(), emax);
130 peakKinEnergy = 0.5*epeak*epeak/electron_mass_c2 - 2.0*electron_mass_c2;
131
132 if(verbose>0) {
133 G4cout << "G4eeToHadronsModel::Initialise: " << G4endl;
134 G4cout << "LabSystem: emin(GeV)= " << lowKinEnergy/GeV
135 << " epeak(GeV)= " << peakKinEnergy/GeV
136 << " emax(GeV)= " << highKinEnergy/GeV
137 << G4endl;
138 G4cout << "SM System: emin(MeV)= " << emin/MeV
139 << " epeak(MeV)= " << epeak/MeV
140 << " emax(MeV)= " << emax/MeV
141 << G4endl;
142 }
143
144 if(lowKinEnergy < peakKinEnergy) {
145 crossBornPerElectron = model->PhysicsVector(emin, emax);
146 crossPerElectron = model->PhysicsVector(emin, emax);
147 nbins = crossPerElectron->GetVectorLength();
148 for(G4int i=0; i<nbins; i++) {
149 G4double e = crossPerElectron->GetLowEdgeEnergy(i);
150 G4double cs = model->ComputeCrossSection(e);
151 crossBornPerElectron->PutValue(i, cs);
152 }
153 ComputeCMCrossSectionPerElectron();
154 }
155 if(verbose>1) {
156 G4cout << "G4eeToHadronsModel: Cross secsions per electron"
157 << " nbins= " << nbins
158 << " emin(MeV)= " << emin/MeV
159 << " emax(MeV)= " << emax/MeV
160 << G4endl;
161 G4bool b;
162 for(G4int i=0; i<nbins; i++) {
163 G4double e = crossPerElectron->GetLowEdgeEnergy(i);
164 G4double s1 = crossPerElectron->GetValue(e, b);
165 G4double s2 = crossBornPerElectron->GetValue(e, b);
166 G4cout << "E(MeV)= " << e/MeV
167 << " cross(nb)= " << s1/nanobarn
168 << " crossBorn(nb)= " << s2/nanobarn
169 << G4endl;
170 }
171 }
172}
173
174//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
175
176G4double G4eeToHadronsModel::CrossSectionPerVolume(
177 const G4Material* mat,
178 const G4ParticleDefinition* p,
179 G4double kineticEnergy,
180 G4double, G4double)
181{
182 return mat->GetElectronDensity()*
183 ComputeCrossSectionPerElectron(p, kineticEnergy);
184}
185
186//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
187
188G4double G4eeToHadronsModel::ComputeCrossSectionPerAtom(
189 const G4ParticleDefinition* p,
190 G4double kineticEnergy,
191 G4double Z, G4double,
192 G4double, G4double)
193{
194 return Z*ComputeCrossSectionPerElectron(p, kineticEnergy);
195}
196
197//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
198
199G4double G4eeToHadronsModel::ComputeCrossSectionPerElectron(
200 const G4ParticleDefinition*,
201 G4double kineticEnergy,
202 G4double, G4double)
203{
204 G4double cross = 0.0;
205 if(crossPerElectron) {
206 G4bool b;
207 G4double e = 2.0*electron_mass_c2*
208 sqrt(1.0 + 0.5*kineticEnergy/electron_mass_c2);
209 cross = crossPerElectron->GetValue(e, b);
210 }
211 // G4cout << "e= " << kineticEnergy << " cross= " << cross << G4endl;
212 return cross;
213}
214
215//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
216
217void G4eeToHadronsModel::SampleSecondaries(std::vector<G4DynamicParticle*>* newp,
218 const G4MaterialCutsCouple*,
219 const G4DynamicParticle* dParticle,
220 G4double,
221 G4double)
222{
223 if(crossPerElectron) {
224 G4double t = dParticle->GetKineticEnergy();
225 G4double e = 2.0*electron_mass_c2*sqrt(1.0 + 0.5*t/electron_mass_c2);
226 G4LorentzVector inlv = dParticle->Get4Momentum();
227 G4ThreeVector inBoost = inlv.boostVector();
228 if(e > emin) {
229 G4DynamicParticle* gamma = GenerateCMPhoton(e);
230 G4LorentzVector gLv = gamma->Get4Momentum();
231 G4LorentzVector lv(0.0,0.0,0.0,e);
232 lv -= gLv;
233 G4double m = lv.m();
234 G4ThreeVector boost = lv.boostVector();
235 const G4ThreeVector dir = gamma->GetMomentumDirection();
236 model->SampleSecondaries(newp, m, dir);
237 G4int np = newp->size();
238 for(G4int j=0; j<np; j++) {
239 G4DynamicParticle* dp = (*newp)[j];
240 G4LorentzVector v = dp->Get4Momentum();
241 v.boost(boost);
242 v.boost(inBoost);
243 dp->Set4Momentum(v);
244 }
245 gLv.boost(inBoost);
246 gamma->Set4Momentum(gLv);
247 newp->push_back(gamma);
248 }
249 }
250}
251
252//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
253
254void G4eeToHadronsModel::ComputeCMCrossSectionPerElectron()
255{
256 G4bool b;
257 for(G4int i=0; i<nbins; i++) {
258 G4double e = crossPerElectron->GetLowEdgeEnergy(i);
259 G4double cs = 0.0;
260 if(i > 0) {
261 G4double L = 2.0*log(e/electron_mass_c2);
262 G4double bt = 2.0*fine_structure_const*(L - 1.0)/pi;
263 G4double btm1= bt - 1.0;
264 G4double del = 1. + fine_structure_const*(1.5*L + pi*pi/3. -2.)/pi;
265 G4double s1 = crossBornPerElectron->GetValue(e, b);
266 G4double e1 = crossPerElectron->GetLowEdgeEnergy(i-1);
267 G4double x1 = 1. - e1/e;
268 cs += s1*(del*pow(x1,bt) - bt*(x1 - 0.25*x1*x1));
269 if(i > 1) {
270 G4double e2 = e1;
271 G4double x2 = x1;
272 G4double s2 = crossBornPerElectron->GetValue(e2, b);
273 G4double w2 = bt*(del*pow(x2,btm1) - 1.0 + 0.5*x2);
274
275 for(G4int j=i-2; j>=0; j--) {
276 e1 = crossPerElectron->GetLowEdgeEnergy(j);
277 x1 = 1. - e1/e;
278 G4double s1 = crossBornPerElectron->GetValue(e1, b);
279 G4double w1 = bt*(del*pow(x1,btm1) - 1.0 + 0.5*x1);
280 cs += 0.5*(x1 - x2)*(w2*s2 + w1*s1);
281 e2 = e1;
282 x2 = x1;
283 s2 = s1;
284 w2 = w1;
285 }
286 }
287 }
288 crossPerElectron->PutValue(i, cs);
289 // G4cout << "e= " << e << " cs= " << cs << G4endl;
290 }
291}
292
293//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
294
295G4DynamicParticle* G4eeToHadronsModel::GenerateCMPhoton(G4double e)
296{
297 G4bool b;
298 G4double x;
299 G4DynamicParticle* gamma = 0;
300 G4double L = 2.0*log(e/electron_mass_c2);
301 G4double bt = 2.0*fine_structure_const*(L - 1.)/pi;
302 G4double btm1= bt - 1.0;
303 G4double del = 1. + fine_structure_const*(1.5*L + pi*pi/3. -2.)/pi;
304
305 G4double s0 = crossBornPerElectron->GetValue(e, b);
306 G4double de = (emax - emin)/(G4double)nbins;
307 G4double x0 = min(de,e - emin)/e;
308 G4double ds = crossBornPerElectron->GetValue(e, b)
309 *(del*pow(x0,bt) - bt*(x0 - 0.25*x0*x0));
310 G4double e1 = e*(1. - x0);
311
312 if(e1 < emax && s0*G4UniformRand()<ds) {
313 x = x0*pow(G4UniformRand(),1./bt);
314 } else {
315
316 x = 1. - e1/e;
317 G4double s1 = crossBornPerElectron->GetValue(e1, b);
318 G4double w1 = bt*(del*pow(x,btm1) - 1.0 + 0.5*x);
319 G4double grej = s1*w1;
320 G4double f;
321 // G4cout << "e= " << e/GeV << " epeak= " << epeak/GeV
322 // << " s1= " << s1 << " w1= " << w1
323 // << " grej= " << grej << G4endl;
324 // Above emax cross section is 0
325 if(e1 > emax) {
326 x = 1. - emax/e;
327 G4double s2 = crossBornPerElectron->GetValue(emax, b);
328 G4double w2 = bt*(del*pow(x,btm1) - 1.0 + 0.5*x);
329 grej = s2*w2;
330 // G4cout << "emax= " << emax << " s2= " << s2 << " w2= " << w2
331 // << " grej= " << grej << G4endl;
332 }
333
334 if(e1 > epeak) {
335 x = 1. - epeak/e;
336 G4double s2 = crossBornPerElectron->GetValue(epeak, b);
337 G4double w2 = bt*(del*pow(x,btm1) - 1.0 + 0.5*x);
338 grej = max(grej,s2*w2);
339 //G4cout << "epeak= " << epeak << " s2= " << s2 << " w2= " << w2
340 // << " grej= " << grej << G4endl;
341 }
342 G4double xmin = 1. - e1/e;
343 if(e1 > emax) xmin = 1. - emax/e;
344 G4double xmax = 1. - emin/e;
345 do {
346 x = xmin + G4UniformRand()*(xmax - xmin);
347 G4double s2 = crossBornPerElectron->GetValue((1.0 - x)*e, b);
348 G4double w2 = bt*(del*pow(x,btm1) - 1.0 + 0.5*x);
349 //G4cout << "x= " << x << " xmin= " << xmin << " xmax= " << xmax
350 // << " s2= " << s2 << " w2= " << w2
351 // << G4endl;
352 f = s2*w2;
353 if(f > grej) {
354 G4cout << "G4DynamicParticle* G4eeToHadronsModel:WARNING "
355 << f << " > " << grej << " majorant is`small!"
356 << G4endl;
357 }
358 } while (f < grej*G4UniformRand());
359 }
360
361 G4ThreeVector dir(0.0,0.0,1.0);
362 gamma = new G4DynamicParticle(theGamma,dir,x*e);
363 return gamma;
364}
365
366//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
367
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