G4QTauNuclearCrossSection.hh

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00027 // $Id$
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00029 //
00030 // GEANT4 physics class: G4QTauNuclearCrossSection -- header file
00031 // M.V. Kossov, CERN-ITEP(Moscow), 4-FEB-2004
00032 // The last update: M.V. Kossov, CERN/ITEP (Moscow) 4-Feb-04
00033 //
00034 // Short description: this G4 singletone class calculates tau-lepton-nuclear cross section
00035 // for the particular isotope (GetCrossSection member function)
00036 // ****************************************************************************************
00037 // ********* This HEADER is temporary moved from the photolepton_hadron directory *********
00038 // ******* DO NOT MAKE ANY CHANGE! With time it'll move back to photolepton...(M.K.) ******
00039 // ****************************************************************************************
00040 // Short description: reaction cross-sections for tau-nuclear reactions, which
00041 // are integrals over virtual equivalent photons photons. The tau-nuclear
00042 // reactions do not exist in GHAD, so by the present physics lists it is not
00043 // simulated at all.
00044 // --------------------------------------------------------------------------------
00045 
00046 #ifndef G4QTauNuclearCrossSection_h
00047 #define G4QTauNuclearCrossSection_h 1
00048 
00049 #include "G4ParticleTable.hh"
00050 #include "G4NucleiProperties.hh"
00051 #include <vector>
00052 #include "Randomize.hh"
00053 #include "G4MuonPlus.hh"
00054 #include "G4MuonMinus.hh"
00055 #include "G4VQCrossSection.hh"
00056 
00057 class G4QTauNuclearCrossSection : public G4VQCrossSection
00058 {
00059 protected:
00060 
00061   G4QTauNuclearCrossSection()  {};
00062 
00063 public:
00064 
00065   ~G4QTauNuclearCrossSection();
00066 
00067   static G4VQCrossSection* GetPointer(); // Gives a pointer to this singletone
00068 
00069   G4double ThresholdEnergy(G4int Z, G4int N, G4int PDG=15);
00070 
00071   // At present momentum (pMom) must be in GeV (@@ Units)
00072   virtual G4double GetCrossSection(G4bool fCS, G4double pMom, G4int tgZ, G4int tgN,
00073                                                                              G4int pPDG=0);
00074 
00075   G4double CalculateCrossSection(G4bool CS, G4int F, G4int I, G4int PDG, G4int Z, G4int N,
00076                                                                         G4double Momentum);
00077 
00078   G4int    GetExchangePDGCode();
00079 
00080   G4double GetExchangeEnergy();
00081 
00082   G4double GetVirtualFactor(G4double nu, G4double Q2);
00083 
00084   G4double GetExchangeQ2(G4double nu);
00085 
00086 private:
00087   G4int    GetFunctions(G4double a, G4double* x, G4double* y, G4double* z);
00088   G4double HighEnergyJ1(G4double lE);
00089   G4double HighEnergyJ2(G4double lE);
00090   G4double HighEnergyJ3(G4double lE);
00091   G4double SolveTheEquation(G4double f);
00092   G4double Fun(G4double x);
00093   G4double DFun(G4double x);
00094 
00095 // Body
00096 private:
00097   static G4bool    onlyCS;   // flag to calculate only CS
00098   static G4double  lastSig;  // Last calculated cross section
00099   static G4int     lastL;    // Last used in the cross section TheLastBin
00100   static G4double  lastE;    // Last used in the cross section Energy
00101   static G4int     lastF;    // Last used in the cross section TheFirstBin
00102   static G4double  lastG;    // Last value of gamma=lnE-ln(m)
00103   static G4double  lastH;    // Last value of the High energy A-dependence
00104   static G4double* lastJ1;   // Pointer to the last array of the J1 function
00105   static G4double* lastJ2;   // Pointer to the last array of the J2 function
00106   static G4double* lastJ3;   // Pointer to the last array of the J3 function
00107   static G4int     lastPDG;  // The last projectile PDG
00108   static G4int     lastN;    // The last N of calculated nucleus
00109   static G4int     lastZ;    // The last Z of calculated nucleus
00110   static G4double  lastP;    // Last used in the cross section Momentum
00111   static G4double  lastTH;   // Last value of the Momentum Threshold
00112   static G4double  lastCS;   // Last value of the Cross Section
00113   static G4int     lastI;    // The last position in the DAMDB
00114   static std::vector <G4double*>* J1; // Vector of pointers to the J1 tabulated functions
00115   static std::vector <G4double*>* J2; // Vector of pointers to the J2 tabulated functions
00116   static std::vector <G4double*>* J3; // Vector of pointers to the J3 tabulated functions
00117 };
00118 
00119 inline G4double G4QTauNuclearCrossSection::DFun(G4double x)// Parametrization of PhotNucCS
00120 {
00121   static const G4double shd=1.0734;                    // HE PomShadowing(D)
00122   static const G4double poc=0.0375;                    // HE Pomeron coefficient
00123   static const G4double pos=16.5;                      // HE Pomeron shift
00124   static const G4double reg=.11;                       // HE Reggeon slope
00125   static const G4double mtu=1777.;                     // Mass of a muon in MeV
00126   static const G4double lmtu=std::log(mtu);            // Log of a muon mass
00127   G4double y=std::exp(x-lastG-lmtu);                   // y for the x
00128   G4double flux=lastG*(2.-y*(2.-y))-1.;                // flux factor
00129   return (poc*(x-pos)+shd*std::exp(-reg*x))*flux;
00130 }
00131 
00132 inline G4double G4QTauNuclearCrossSection::Fun(G4double x) // Integrated PhoNucCS
00133 {
00134   G4double dlg1=lastG+lastG-1.;
00135   G4double lgoe=lastG/lastE;
00136   G4double HE2=HighEnergyJ2(x);
00137   return dlg1*HighEnergyJ1(x)-lgoe*(HE2+HE2-HighEnergyJ3(x)/lastE);
00138 }
00139 
00140 inline G4double G4QTauNuclearCrossSection::HighEnergyJ1(G4double lEn)
00141 {
00142   static const G4double le=std::log(50000.); // log(E0)
00143   static const G4double le2=le*le;           // log(E0)^2
00144   static const G4double a=.0375;             // a
00145   static const G4double ha=a*.5;             // a/2
00146   static const G4double ab=a*16.5;           // a*b
00147   static const G4double d=0.11;              // d
00148   static const G4double cd=1.0734/d;         // c/d
00149   static const G4double ele=std::exp(-d*le); // E0^(-d)
00150   return ha*(lEn*lEn-le2)-ab*(lEn-le)-cd*(std::exp(-d*lEn)-ele);
00151 }
00152 
00153 inline G4double G4QTauNuclearCrossSection::HighEnergyJ2(G4double lEn)
00154 {
00155   static const G4double e=50000.;            // E0
00156   static const G4double le=std::log(e);      // log(E0)
00157   static const G4double le1=(le-1.)*e;       // (log(E0)-1)*E0
00158   static const G4double a=.0375;             // a
00159   static const G4double ab=a*16.5;           // a*b
00160   static const G4double d=1.-0.11;           // 1-d
00161   static const G4double cd=1.0734/d;         // c/(1-d)
00162   static const G4double ele=std::exp(d*le);  // E0^(1-d)
00163   G4double En=std::exp(lEn);
00164   return a*((lEn-1.)*En-le1)-ab*(En-e)+cd*(std::exp(d*lEn)-ele);
00165 }
00166 
00167 inline G4double G4QTauNuclearCrossSection::HighEnergyJ3(G4double lEn)
00168 {
00169   static const G4double e=50000.;            // E0
00170   static const G4double le=std::log(e);      // log(E0)
00171   static const G4double e2=e*e;              // E0^2
00172   static const G4double leh=(le-.5)*e2;      // (log(E0)-.5)*E0^2
00173   static const G4double ha=.0375*.5;         // a/2
00174   static const G4double hab=ha*16.5;         // a*b/2
00175   static const G4double d=2.-.11;            // 2-d
00176   static const G4double cd=1.0734/d;         // c/(2-d)
00177   static const G4double ele=std::exp(d*le);  // E0^(2-d)
00178   G4double lastE2=std::exp(lEn+lEn);
00179   return ha*((lEn-.5)*lastE2-leh)-hab*(lastE2-e2)+cd*(std::exp(d*lEn)-ele);
00180 }
00181 
00182 #endif

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