source: trunk/source/processes/electromagnetic/highenergy/src/G4eeToHadronsModel.cc@ 819

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[819]1//
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25//
26// $Id: G4eeToHadronsModel.cc,v 1.8 2007/05/22 17:37:30 vnivanch Exp $
27// GEANT4 tag $Name: $
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(const G4Vee2hadrons* m,
68 G4int ver,
69 const G4String& nam)
70 : G4VEmModel(nam),
71 model(m),
72 crossPerElectron(0),
73 crossBornPerElectron(0),
74 isInitialised(false),
75 nbins(100),
76 verbose(ver)
77{
78 theGamma = G4Gamma::Gamma();
79}
80
81//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
82
83G4eeToHadronsModel::~G4eeToHadronsModel()
84{
85 delete model;
86 delete crossPerElectron;
87 delete crossBornPerElectron;
88}
89
90//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
91
92void G4eeToHadronsModel::Initialise(const G4ParticleDefinition*,
93 const G4DataVector&)
94{
95 if(isInitialised) return;
96 isInitialised = true;
97
98 highKinEnergy = HighEnergyLimit();
99 lowKinEnergy = LowEnergyLimit();
100
101 emin = model->ThresholdEnergy();
102 emax = 2.0*electron_mass_c2*sqrt(1.0 + 0.5*highKinEnergy/electron_mass_c2);
103 if(emin > emax) emin = emax;
104
105 lowKinEnergy = 0.5*emin*emin/electron_mass_c2 - 2.0*electron_mass_c2;
106
107 epeak = min(model->PeakEnergy(), emax);
108 peakKinEnergy = 0.5*epeak*epeak/electron_mass_c2 - 2.0*electron_mass_c2;
109
110 if(verbose>0) {
111 G4cout << "G4eeToHadronsModel::Initialise: " << G4endl;
112 G4cout << "LabSystem: emin(GeV)= " << lowKinEnergy/GeV
113 << " epeak(GeV)= " << peakKinEnergy/GeV
114 << " emax(GeV)= " << highKinEnergy/GeV
115 << G4endl;
116 G4cout << "SM System: emin(MeV)= " << emin/MeV
117 << " epeak(MeV)= " << epeak/MeV
118 << " emax(MeV)= " << emax/MeV
119 << G4endl;
120 }
121
122 if(lowKinEnergy < peakKinEnergy) {
123 crossBornPerElectron = model->PhysicsVector(emin, emax);
124 crossPerElectron = model->PhysicsVector(emin, emax);
125 nbins = crossPerElectron->GetVectorLength();
126 for(G4int i=0; i<nbins; i++) {
127 G4double e = crossPerElectron->GetLowEdgeEnergy(i);
128 G4double cs = model->ComputeCrossSection(e);
129 crossBornPerElectron->PutValue(i, cs);
130 }
131 ComputeCMCrossSectionPerElectron();
132 }
133 if(verbose>1) {
134 G4cout << "G4eeToHadronsModel: Cross secsions per electron"
135 << " nbins= " << nbins
136 << " emin(MeV)= " << emin/MeV
137 << " emax(MeV)= " << emax/MeV
138 << G4endl;
139 G4bool b;
140 for(G4int i=0; i<nbins; i++) {
141 G4double e = crossPerElectron->GetLowEdgeEnergy(i);
142 G4double s1 = crossPerElectron->GetValue(e, b);
143 G4double s2 = crossBornPerElectron->GetValue(e, b);
144 G4cout << "E(MeV)= " << e/MeV
145 << " cross(nb)= " << s1/nanobarn
146 << " crossBorn(nb)= " << s2/nanobarn
147 << G4endl;
148 }
149 }
150}
151
152//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
153
154G4double G4eeToHadronsModel::ComputeCrossSectionPerElectron(
155 const G4ParticleDefinition*,
156 G4double kineticEnergy,
157 G4double, G4double)
158{
159 G4double cross = 0.0;
160 if(crossPerElectron) {
161 G4bool b;
162 G4double e = 2.0*electron_mass_c2*
163 sqrt(1.0 + 0.5*kineticEnergy/electron_mass_c2);
164 cross = crossPerElectron->GetValue(e, b);
165 }
166 // G4cout << "e= " << kineticEnergy << " cross= " << cross << G4endl;
167 return cross;
168}
169
170//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
171
172void G4eeToHadronsModel::SampleSecondaries(std::vector<G4DynamicParticle*>* newp,
173 const G4MaterialCutsCouple*,
174 const G4DynamicParticle* dParticle,
175 G4double,
176 G4double)
177{
178 if(crossPerElectron) {
179 G4double t = dParticle->GetKineticEnergy();
180 G4double e = 2.0*electron_mass_c2*sqrt(1.0 + 0.5*t/electron_mass_c2);
181 G4LorentzVector inlv = dParticle->Get4Momentum();
182 G4ThreeVector inBoost = inlv.boostVector();
183 if(e > emin) {
184 G4DynamicParticle* gamma = GenerateCMPhoton(e);
185 G4LorentzVector gLv = gamma->Get4Momentum();
186 G4LorentzVector lv(0.0,0.0,0.0,e);
187 lv -= gLv;
188 G4double m = lv.m();
189 G4ThreeVector boost = lv.boostVector();
190 const G4ThreeVector dir = gamma->GetMomentumDirection();
191 model->SampleSecondaries(newp, m, dir);
192 G4int np = newp->size();
193 for(G4int j=0; j<np; j++) {
194 G4DynamicParticle* dp = (*newp)[j];
195 G4LorentzVector v = dp->Get4Momentum();
196 v.boost(boost);
197 v.boost(inBoost);
198 dp->Set4Momentum(v);
199 }
200 gLv.boost(inBoost);
201 gamma->Set4Momentum(gLv);
202 newp->push_back(gamma);
203 }
204 }
205}
206
207//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
208
209void G4eeToHadronsModel::ComputeCMCrossSectionPerElectron()
210{
211 G4bool b;
212 for(G4int i=0; i<nbins; i++) {
213 G4double e = crossPerElectron->GetLowEdgeEnergy(i);
214 G4double cs = 0.0;
215 if(i > 0) {
216 G4double L = 2.0*log(e/electron_mass_c2);
217 G4double bt = 2.0*fine_structure_const*(L - 1.0)/pi;
218 G4double btm1= bt - 1.0;
219 G4double del = 1. + fine_structure_const*(1.5*L + pi*pi/3. -2.)/pi;
220 G4double s1 = crossBornPerElectron->GetValue(e, b);
221 G4double e1 = crossPerElectron->GetLowEdgeEnergy(i-1);
222 G4double x1 = 1. - e1/e;
223 cs += s1*(del*pow(x1,bt) - bt*(x1 - 0.25*x1*x1));
224 if(i > 1) {
225 G4double e2 = e1;
226 G4double x2 = x1;
227 G4double s2 = crossBornPerElectron->GetValue(e2, b);
228 G4double w2 = bt*(del*pow(x2,btm1) - 1.0 + 0.5*x2);
229
230 for(G4int j=i-2; j>=0; j--) {
231 e1 = crossPerElectron->GetLowEdgeEnergy(j);
232 x1 = 1. - e1/e;
233 G4double s1 = crossBornPerElectron->GetValue(e1, b);
234 G4double w1 = bt*(del*pow(x1,btm1) - 1.0 + 0.5*x1);
235 cs += 0.5*(x1 - x2)*(w2*s2 + w1*s1);
236 e2 = e1;
237 x2 = x1;
238 s2 = s1;
239 w2 = w1;
240 }
241 }
242 }
243 crossPerElectron->PutValue(i, cs);
244 // G4cout << "e= " << e << " cs= " << cs << G4endl;
245 }
246}
247
248//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
249
250G4DynamicParticle* G4eeToHadronsModel::GenerateCMPhoton(G4double e)
251{
252 G4bool b;
253 G4double x;
254 G4DynamicParticle* gamma = 0;
255 G4double L = 2.0*log(e/electron_mass_c2);
256 G4double bt = 2.0*fine_structure_const*(L - 1.)/pi;
257 G4double btm1= bt - 1.0;
258 G4double del = 1. + fine_structure_const*(1.5*L + pi*pi/3. -2.)/pi;
259
260 G4double s0 = crossBornPerElectron->GetValue(e, b);
261 G4double de = (emax - emin)/(G4double)nbins;
262 G4double x0 = min(de,e - emin)/e;
263 G4double ds = crossBornPerElectron->GetValue(e, b)
264 *(del*pow(x0,bt) - bt*(x0 - 0.25*x0*x0));
265 G4double e1 = e*(1. - x0);
266
267 if(e1 < emax && s0*G4UniformRand()<ds) {
268 x = x0*pow(G4UniformRand(),1./bt);
269 } else {
270
271 x = 1. - e1/e;
272 G4double s1 = crossBornPerElectron->GetValue(e1, b);
273 G4double w1 = bt*(del*pow(x,btm1) - 1.0 + 0.5*x);
274 G4double grej = s1*w1;
275 G4double f;
276 // G4cout << "e= " << e/GeV << " epeak= " << epeak/GeV
277 // << " s1= " << s1 << " w1= " << w1
278 // << " grej= " << grej << G4endl;
279 // Above emax cross section is 0
280 if(e1 > emax) {
281 x = 1. - emax/e;
282 G4double s2 = crossBornPerElectron->GetValue(emax, b);
283 G4double w2 = bt*(del*pow(x,btm1) - 1.0 + 0.5*x);
284 grej = s2*w2;
285 // G4cout << "emax= " << emax << " s2= " << s2 << " w2= " << w2
286 // << " grej= " << grej << G4endl;
287 }
288
289 if(e1 > epeak) {
290 x = 1. - epeak/e;
291 G4double s2 = crossBornPerElectron->GetValue(epeak, b);
292 G4double w2 = bt*(del*pow(x,btm1) - 1.0 + 0.5*x);
293 grej = max(grej,s2*w2);
294 //G4cout << "epeak= " << epeak << " s2= " << s2 << " w2= " << w2
295 // << " grej= " << grej << G4endl;
296 }
297 G4double xmin = 1. - e1/e;
298 if(e1 > emax) xmin = 1. - emax/e;
299 G4double xmax = 1. - emin/e;
300 do {
301 x = xmin + G4UniformRand()*(xmax - xmin);
302 G4double s2 = crossBornPerElectron->GetValue((1.0 - x)*e, b);
303 G4double w2 = bt*(del*pow(x,btm1) - 1.0 + 0.5*x);
304 //G4cout << "x= " << x << " xmin= " << xmin << " xmax= " << xmax
305 // << " s2= " << s2 << " w2= " << w2
306 // << G4endl;
307 f = s2*w2;
308 if(f > grej) {
309 G4cout << "G4DynamicParticle* G4eeToHadronsModel:WARNING "
310 << f << " > " << grej << " majorant is`small!"
311 << G4endl;
312 }
313 } while (f < grej*G4UniformRand());
314 }
315
316 G4ThreeVector dir(0.0,0.0,1.0);
317 gamma = new G4DynamicParticle(theGamma,dir,x*e);
318 return gamma;
319}
320
321//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
322
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