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G4QTauNuclearCrossSection.hh
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30 // GEANT4 physics class: G4QTauNuclearCrossSection -- header file
31 // M.V. Kossov, CERN-ITEP(Moscow), 4-FEB-2004
32 // The last update: M.V. Kossov, CERN/ITEP (Moscow) 4-Feb-04
33 //
34 // Short description: this G4 singletone class calculates tau-lepton-nuclear cross section
35 // for the particular isotope (GetCrossSection member function)
36 // ****************************************************************************************
37 // ********* This HEADER is temporary moved from the photolepton_hadron directory *********
38 // ******* DO NOT MAKE ANY CHANGE! With time it'll move back to photolepton...(M.K.) ******
39 // ****************************************************************************************
40 // Short description: reaction cross-sections for tau-nuclear reactions, which
41 // are integrals over virtual equivalent photons photons. The tau-nuclear
42 // reactions do not exist in GHAD, so by the present physics lists it is not
43 // simulated at all.
44 // --------------------------------------------------------------------------------
45 
46 #ifndef G4QTauNuclearCrossSection_h
47 #define G4QTauNuclearCrossSection_h 1
48 
49 #include "G4ParticleTable.hh"
50 #include "G4NucleiProperties.hh"
51 #include <vector>
52 #include "Randomize.hh"
53 #include "G4MuonPlus.hh"
54 #include "G4MuonMinus.hh"
55 #include "G4VQCrossSection.hh"
56 
57 class G4QTauNuclearCrossSection : public G4VQCrossSection
58 {
59 protected:
60 
61  G4QTauNuclearCrossSection() {};
62 
63 public:
64 
65  ~G4QTauNuclearCrossSection();
66 
67  static G4VQCrossSection* GetPointer(); // Gives a pointer to this singletone
68 
69  G4double ThresholdEnergy(G4int Z, G4int N, G4int PDG=15);
70 
71  // At present momentum (pMom) must be in GeV (@@ Units)
72  virtual G4double GetCrossSection(G4bool fCS, G4double pMom, G4int tgZ, G4int tgN,
73  G4int pPDG=0);
74 
75  G4double CalculateCrossSection(G4bool CS, G4int F, G4int I, G4int PDG, G4int Z, G4int N,
76  G4double Momentum);
77 
78  G4int GetExchangePDGCode();
79 
80  G4double GetExchangeEnergy();
81 
82  G4double GetVirtualFactor(G4double nu, G4double Q2);
83 
84  G4double GetExchangeQ2(G4double nu);
85 
86 private:
87  G4int GetFunctions(G4double a, G4double* x, G4double* y, G4double* z);
88  G4double HighEnergyJ1(G4double lE);
89  G4double HighEnergyJ2(G4double lE);
90  G4double HighEnergyJ3(G4double lE);
91  G4double SolveTheEquation(G4double f);
92  G4double Fun(G4double x);
93  G4double DFun(G4double x);
94 
95 // Body
96 private:
97  static G4bool onlyCS; // flag to calculate only CS
98  static G4double lastSig; // Last calculated cross section
99  static G4int lastL; // Last used in the cross section TheLastBin
100  static G4double lastE; // Last used in the cross section Energy
101  static G4int lastF; // Last used in the cross section TheFirstBin
102  static G4double lastG; // Last value of gamma=lnE-ln(m)
103  static G4double lastH; // Last value of the High energy A-dependence
104  static G4double* lastJ1; // Pointer to the last array of the J1 function
105  static G4double* lastJ2; // Pointer to the last array of the J2 function
106  static G4double* lastJ3; // Pointer to the last array of the J3 function
107  static G4int lastPDG; // The last projectile PDG
108  static G4int lastN; // The last N of calculated nucleus
109  static G4int lastZ; // The last Z of calculated nucleus
110  static G4double lastP; // Last used in the cross section Momentum
111  static G4double lastTH; // Last value of the Momentum Threshold
112  static G4double lastCS; // Last value of the Cross Section
113  static G4int lastI; // The last position in the DAMDB
114  static std::vector <G4double*>* J1; // Vector of pointers to the J1 tabulated functions
115  static std::vector <G4double*>* J2; // Vector of pointers to the J2 tabulated functions
116  static std::vector <G4double*>* J3; // Vector of pointers to the J3 tabulated functions
117 };
118 
119 inline G4double G4QTauNuclearCrossSection::DFun(G4double x)// Parametrization of PhotNucCS
120 {
121  static const G4double shd=1.0734; // HE PomShadowing(D)
122  static const G4double poc=0.0375; // HE Pomeron coefficient
123  static const G4double pos=16.5; // HE Pomeron shift
124  static const G4double reg=.11; // HE Reggeon slope
125  static const G4double mtu=1777.; // Mass of a muon in MeV
126  static const G4double lmtu=std::log(mtu); // Log of a muon mass
127  G4double y=std::exp(x-lastG-lmtu); // y for the x
128  G4double flux=lastG*(2.-y*(2.-y))-1.; // flux factor
129  return (poc*(x-pos)+shd*std::exp(-reg*x))*flux;
130 }
131 
132 inline G4double G4QTauNuclearCrossSection::Fun(G4double x) // Integrated PhoNucCS
133 {
134  G4double dlg1=lastG+lastG-1.;
135  G4double lgoe=lastG/lastE;
136  G4double HE2=HighEnergyJ2(x);
137  return dlg1*HighEnergyJ1(x)-lgoe*(HE2+HE2-HighEnergyJ3(x)/lastE);
138 }
139 
140 inline G4double G4QTauNuclearCrossSection::HighEnergyJ1(G4double lEn)
141 {
142  static const G4double le=std::log(50000.); // log(E0)
143  static const G4double le2=le*le; // log(E0)^2
144  static const G4double a=.0375; // a
145  static const G4double ha=a*.5; // a/2
146  static const G4double ab=a*16.5; // a*b
147  static const G4double d=0.11; // d
148  static const G4double cd=1.0734/d; // c/d
149  static const G4double ele=std::exp(-d*le); // E0^(-d)
150  return ha*(lEn*lEn-le2)-ab*(lEn-le)-cd*(std::exp(-d*lEn)-ele);
151 }
152 
153 inline G4double G4QTauNuclearCrossSection::HighEnergyJ2(G4double lEn)
154 {
155  static const G4double e=50000.; // E0
156  static const G4double le=std::log(e); // log(E0)
157  static const G4double le1=(le-1.)*e; // (log(E0)-1)*E0
158  static const G4double a=.0375; // a
159  static const G4double ab=a*16.5; // a*b
160  static const G4double d=1.-0.11; // 1-d
161  static const G4double cd=1.0734/d; // c/(1-d)
162  static const G4double ele=std::exp(d*le); // E0^(1-d)
163  G4double En=std::exp(lEn);
164  return a*((lEn-1.)*En-le1)-ab*(En-e)+cd*(std::exp(d*lEn)-ele);
165 }
166 
167 inline G4double G4QTauNuclearCrossSection::HighEnergyJ3(G4double lEn)
168 {
169  static const G4double e=50000.; // E0
170  static const G4double le=std::log(e); // log(E0)
171  static const G4double e2=e*e; // E0^2
172  static const G4double leh=(le-.5)*e2; // (log(E0)-.5)*E0^2
173  static const G4double ha=.0375*.5; // a/2
174  static const G4double hab=ha*16.5; // a*b/2
175  static const G4double d=2.-.11; // 2-d
176  static const G4double cd=1.0734/d; // c/(2-d)
177  static const G4double ele=std::exp(d*le); // E0^(2-d)
178  G4double lastE2=std::exp(lEn+lEn);
179  return ha*((lEn-.5)*lastE2-leh)-hab*(lastE2-e2)+cd*(std::exp(d*lEn)-ele);
180 }
181 
182 #endif
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