source: trunk/source/processes/electromagnetic/standard/include/G4PairProductionRelModel.hh @ 1315

Last change on this file since 1315 was 1228, checked in by garnier, 14 years ago

update geant4.9.3 tag
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26// $Id: G4PairProductionRelModel.hh,v 1.3 2009/06/04 13:45:53 gunter Exp $
27// GEANT4 tag $Name: geant4-09-03 $
28//
29// -------------------------------------------------------------------
30//
31// GEANT4 Class header file
32//
33//
34// File name:     G4PairProductionRelModel
35//
36// Author:        Andreas Schaelicke
37//
38// Creation date: 02.04.2009
39//
40// Modifications:
41//
42// Class Description:
43//
44// Implementation of gamma convertion to e+e- in the field of a nucleus
45// relativistic approximation
46//
47
48// -------------------------------------------------------------------
49//
50
51#ifndef G4PairProductionRelModel_h
52#define G4PairProductionRelModel_h 1
53
54#include "G4VEmModel.hh"
55#include "G4PhysicsTable.hh"
56#include "G4NistManager.hh"
57
58class G4ParticleChangeForGamma;
59
60class G4PairProductionRelModel : public G4VEmModel
61{
62
63public:
64
65  G4PairProductionRelModel(const G4ParticleDefinition* p = 0, 
66                      const G4String& nam = "Bethe-Heitler");
67 
68  virtual ~G4PairProductionRelModel();
69
70  virtual void Initialise(const G4ParticleDefinition*, const G4DataVector&);
71
72  virtual G4double ComputeCrossSectionPerAtom(
73                                const G4ParticleDefinition*,
74                                      G4double kinEnergy, 
75                                      G4double Z, 
76                                      G4double A=0., 
77                                      G4double cut=0.,
78                                      G4double emax=DBL_MAX);
79
80  virtual void SampleSecondaries(std::vector<G4DynamicParticle*>*,
81                                 const G4MaterialCutsCouple*,
82                                 const G4DynamicParticle*,
83                                 G4double tmin,
84                                 G4double maxEnergy);
85
86  virtual void SetupForMaterial(const G4ParticleDefinition*,
87                                const G4Material*,G4double);
88
89  // * fast inline functions *
90  inline void SetCurrentElement(const G4double);
91
92  // set / get methods
93  inline void SetLPMconstant(G4double val);
94  inline G4double LPMconstant() const;
95
96  inline void SetLPMflag(G4bool);
97  inline G4bool LPMflag() const;
98
99protected:
100  // screening functions
101  inline G4double Phi1(G4double delta) const;
102  inline G4double Phi2(G4double delta) const;
103  inline G4double DeltaMax() const;
104  inline G4double DeltaMin(G4double) const;
105  // lpm functions
106  void  CalcLPMFunctions(G4double k, G4double eplus);
107
108  // obsolete
109  G4double ScreenFunction1(G4double ScreenVariable);
110  G4double ScreenFunction2(G4double ScreenVariable);
111
112
113
114
115  G4double ComputeXSectionPerAtom(G4double totalEnergy, G4double Z);
116
117  G4double ComputeDXSectionPerAtom(G4double eplusEnergy, G4double totalEnergy, G4double Z);
118  G4double ComputeRelDXSectionPerAtom(G4double eplusEnergy, G4double totalEnergy, G4double Z);
119
120  // hide assignment operator
121  G4PairProductionRelModel & operator=(const G4PairProductionRelModel &right);
122  G4PairProductionRelModel(const  G4PairProductionRelModel&);
123
124  G4NistManager*              nist;
125
126  G4ParticleDefinition*     theGamma;
127  G4ParticleDefinition*     theElectron;
128  G4ParticleDefinition*     thePositron;
129  G4ParticleChangeForGamma* fParticleChange;
130  G4PhysicsTable*           theCrossSectionTable; 
131
132  G4double                  lowGammaEnergy;
133  G4double                  highGammaEnergy;
134
135  G4int                     nbins;
136  size_t                    indexZ[120];
137
138  G4double fLPMconstant;
139  G4bool   fLPMflag;
140
141  // cash
142  G4double z13, z23, lnZ;
143  G4double Fel, Finel, fCoulomb; 
144  G4double currentZ;
145
146  // LPM effect
147  G4double lpmEnergy;
148  G4double xiLPM, phiLPM, gLPM;
149
150  // consts
151  G4bool   use_completescreening;
152
153  static const G4double xgi[8], wgi[8];
154  static const G4double Fel_light[5];
155  static const G4double Finel_light[5];
156  static const G4double facFel;
157  static const G4double facFinel;
158
159  static const G4double preS1, logTwo;
160
161};
162
163
164//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
165
166inline 
167void G4PairProductionRelModel::SetLPMconstant(G4double val) 
168{
169  fLPMconstant = val;
170}
171
172//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
173
174inline 
175G4double G4PairProductionRelModel::LPMconstant() const 
176{
177  return fLPMconstant;
178}
179
180//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
181
182inline 
183void G4PairProductionRelModel::SetLPMflag(G4bool val) 
184{
185  fLPMflag = val;
186}
187
188//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
189
190inline 
191G4bool G4PairProductionRelModel::LPMflag() const 
192{
193  return fLPMflag;
194}
195
196//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
197
198inline void G4PairProductionRelModel::SetCurrentElement(const G4double Z)
199{
200  if(Z != currentZ) {
201    currentZ = Z;
202
203    G4int iz = G4int(Z);
204    z13 = nist->GetZ13(iz);
205    z23 = z13*z13;
206    lnZ = nist->GetLOGZ(iz);
207
208    if (iz <= 4) {
209      Fel = Fel_light[iz]; 
210      Finel = Finel_light[iz] ; 
211    }
212    else {
213      Fel = facFel - lnZ/3. ;
214      Finel = facFinel - 2.*lnZ/3. ;
215    }
216
217    fCoulomb=GetCurrentElement()->GetfCoulomb();
218  }
219}
220//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
221
222inline G4double G4PairProductionRelModel::Phi1(G4double delta) const
223{
224   G4double screenVal;
225
226   if (delta > 1.)
227     screenVal = 21.12 - 4.184*std::log(delta+0.952);
228   else
229     screenVal = 20.868 - delta*(3.242 - 0.625*delta);
230
231   return screenVal;
232}
233
234//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
235
236inline G4double G4PairProductionRelModel::Phi2(G4double delta) const
237{
238   G4double screenVal;
239
240   if (delta > 1.)
241     screenVal = 21.12 - 4.184*std::log(delta+0.952);
242   else
243     screenVal = 20.209 - delta*(1.930 + 0.086*delta);
244
245   return screenVal;
246}
247
248inline G4double G4PairProductionRelModel::ScreenFunction1(G4double ScreenVariable)
249
250// compute the value of the screening function 3*PHI1 - PHI2
251
252{
253   G4double screenVal;
254
255   if (ScreenVariable > 1.)
256     screenVal = 42.24 - 8.368*std::log(ScreenVariable+0.952);
257   else
258     screenVal = 42.392 - ScreenVariable*(7.796 - 1.961*ScreenVariable);
259
260   return screenVal;
261}
262
263//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
264
265inline G4double G4PairProductionRelModel::ScreenFunction2(G4double ScreenVariable)
266
267// compute the value of the screening function 1.5*PHI1 + 0.5*PHI2
268
269{
270   G4double screenVal;
271
272   if (ScreenVariable > 1.)
273     screenVal = 42.24 - 8.368*std::log(ScreenVariable+0.952);
274   else
275     screenVal = 41.405 - ScreenVariable*(5.828 - 0.8945*ScreenVariable);
276
277   return screenVal;
278}
279
280//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
281
282
283inline G4double G4PairProductionRelModel::DeltaMax() const
284{
285  // k > 50 MeV
286  G4double FZ = 8.*(lnZ/3. + fCoulomb);
287  return std::exp( (42.24-FZ)/8.368 ) + 0.952;
288}
289
290inline G4double G4PairProductionRelModel::DeltaMin(G4double k) const
291{
292  return 4.*136./z13*(electron_mass_c2/k);
293}
294
295
296
297#endif
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