source: trunk/source/processes/hadronic/models/chiral_inv_phase_space/interface/include/G4QElectronNuclearCrossSection.hh @ 1055

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27// GEANT4 tag $Name: geant4-09-03-beta-cand-01 $
28//
29//
30// GEANT4 physics class: G4QElectronNuclearCrossSection -- header file
31// M.V. Kossov, ITEP(Moscow), 24-OCT-01
32// The last update: M.V. Kossov, CERN/ITEP (Moscow) 25-Sept-03
33//
34// --------------------------------------------------------------------------------
35// Short description: reaction cross-sections for electron-nuclear reactions, which
36// are integrals over virtual equivalent photons photons.
37// --------------------------------------------------------------------------------
38
39#ifndef G4QElectronNuclearCrossSection_h
40#define G4QElectronNuclearCrossSection_h 1
41
42#include "G4VCrossSectionDataSet.hh"
43#include "G4DynamicParticle.hh"
44#include "G4Element.hh"
45#include "G4ParticleTable.hh"
46#include "G4NucleiProperties.hh"
47#include <vector>
48#include "Randomize.hh"
49#include "G4Electron.hh"
50#include "G4Positron.hh"
51#include "G4VQCrossSection.hh"
52
53class G4QElectronNuclearCrossSection : public G4VQCrossSection
54{
55protected:
56
57  G4QElectronNuclearCrossSection()  {}               // Constructor
58
59public:
60
61  ~G4QElectronNuclearCrossSection() {}
62
63  static G4VQCrossSection* GetPointer(); // Gives a pointer to this singletone
64
65  G4double ThresholdEnergy(G4int Z, G4int N, G4int PDG=11);
66
67  // At present momentum (pMom) must be in GeV (@@ Units)
68  virtual G4double GetCrossSection(G4bool fCS, G4double pMom, G4int tgZ, G4int tgN,
69                                                                             G4int pPDG=0);
70
71  G4double CalculateCrossSection(G4bool CS, G4int F, G4int I, G4int PDG, G4int Z, G4int N,
72                                                                        G4double Momentum);
73
74  G4int    GetExchangePDGCode();
75
76  G4double GetExchangeEnergy();
77
78  G4double GetVirtualFactor(G4double nu, G4double Q2);
79
80  G4double GetExchangeQ2(G4double nu);
81
82private:
83  G4int    GetFunctions(G4double a, G4double* x, G4double* y, G4double* z);
84  G4double HighEnergyJ1(G4double lE);
85  G4double HighEnergyJ2(G4double lE);
86  G4double HighEnergyJ3(G4double lE);
87  G4double SolveTheEquation(G4double f);
88  G4double Fun(G4double x);
89  G4double DFun(G4double x);
90
91// Body
92private:
93  static G4bool    onlyCS;   // flag to calculate only CrossSection
94  static G4double  lastSig;  // Last calculated cross section
95  static G4int     lastL;    // Last used in the cross section TheLastBin
96  static G4double  lastE;    // Last used in the cross section Energy
97  static G4int     lastF;    // Last used in the cross section TheFirstBin
98  static G4double  lastG;    // Last value of gamma=lnE-ln(m)
99  static G4double  lastH;    // Last value of the High energy A-dependence
100  static G4double* lastJ1;   // Pointer to the last array of the J1 function
101  static G4double* lastJ2;   // Pointer to the last array of the J2 function
102  static G4double* lastJ3;   // Pointer to the last array of the J3 function
103  static G4int     lastPDG;  // The last projectile PDG
104  static G4int     lastN;    // The last N of calculated nucleus
105  static G4int     lastZ;    // The last Z of calculated nucleus
106  static G4double  lastP;    // Last used in the cross section Momentum
107  static G4double  lastTH;   // Last value of the Momentum Threshold
108  static G4double  lastCS;   // Last value of the Cross Section
109  static G4int     lastI;    // The last position in the DAMDB
110};
111
112inline G4double G4QElectronNuclearCrossSection::DFun(G4double x)//PhotoNucCSParametrization
113{
114  static const G4double shd=1.0734;                    // HE PomShadowing(D)
115  static const G4double poc=0.0375;                    // HE Pomeron coefficient
116  static const G4double pos=16.5;                      // HE Pomeron shift
117  static const G4double reg=.11;                       // HE Reggeon slope
118  static const G4double mel=0.5109989;                 // Mass of an electron in MeV
119  static const G4double lmel=std::log(mel);            // Log of an electron mass
120  G4double y=std::exp(x-lastG-lmel);                   // y for the x
121  G4double flux=lastG*(2.-y*(2.-y))-1.;                // flux factor
122  return (poc*(x-pos)+shd*std::exp(-reg*x))*flux;
123}
124
125inline G4double G4QElectronNuclearCrossSection::Fun(G4double x) // Integrated PhoNucCS
126{
127  G4double dlg1=lastG+lastG-1.;
128  G4double lgoe=lastG/lastE;
129  G4double HE2=HighEnergyJ2(x);
130  return dlg1*HighEnergyJ1(x)-lgoe*(HE2+HE2-HighEnergyJ3(x)/lastE);
131}
132
133inline G4double G4QElectronNuclearCrossSection::HighEnergyJ1(G4double lEn)
134{
135  static const G4double le=std::log(50000.); // log(E0)
136  static const G4double le2=le*le;           // log(E0)^2
137  static const G4double a=.0375;             // a
138  static const G4double ha=a*.5;             // a/2
139  static const G4double ab=a*16.5;           // a*b
140  static const G4double d=0.11;              // d
141  static const G4double cd=1.0734/d;         // c/d
142  static const G4double ele=std::exp(-d*le); // E0^(-d)
143  return ha*(lEn*lEn-le2)-ab*(lEn-le)-cd*(std::exp(-d*lEn)-ele);
144}
145
146inline G4double G4QElectronNuclearCrossSection::HighEnergyJ2(G4double lEn)
147{
148  static const G4double e=50000.;            // E0
149  static const G4double le=std::log(e);      // log(E0)
150  static const G4double le1=(le-1.)*e;       // (log(E0)-1)*E0
151  static const G4double a=.0375;             // a
152  static const G4double ab=a*16.5;           // a*b
153  static const G4double d=1.-0.11;           // 1-d
154  static const G4double cd=1.0734/d;         // c/(1-d)
155  static const G4double ele=std::exp(d*le);  // E0^(1-d)
156  G4double En=std::exp(lEn);
157  return a*((lEn-1.)*En-le1)-ab*(En-e)+cd*(std::exp(d*lEn)-ele);
158}
159
160inline G4double G4QElectronNuclearCrossSection::HighEnergyJ3(G4double lEn)
161{
162  static const G4double e=50000.;            // E0
163  static const G4double le=std::log(e);      // log(E0)
164  static const G4double e2=e*e;              // E0^2
165  static const G4double leh=(le-.5)*e2;      // (log(E0)-.5)*E0^2
166  static const G4double ha=.0375*.5;         // a/2
167  static const G4double hab=ha*16.5;         // a*b/2
168  static const G4double d=2.-.11;            // 2-d
169  static const G4double cd=1.0734/d;         // c/(2-d)
170  static const G4double ele=std::exp(d*le);  // E0^(2-d)
171  G4double lastE2=std::exp(lEn+lEn);
172  return ha*((lEn-.5)*lastE2-leh)-hab*(lastE2-e2)+cd*(std::exp(d*lEn)-ele);
173}
174
175#endif
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