source: trunk/source/processes/electromagnetic/highenergy/src/G4eeToHadronsModel.cc @ 1337

Last change on this file since 1337 was 1337, checked in by garnier, 14 years ago

tag geant4.9.4 beta 1 + modifs locales
File size: 12.2 KB
Line 
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: G4eeToHadronsModel.cc,v 1.9 2008/07/10 18:06:39 vnivanch Exp $
27// GEANT4 tag $Name: geant4-09-04-beta-01 $
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
Note: See TracBrowser for help on using the repository browser.