include/Geant4/G4NuclearFermiDensity.hh

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0027
0028 #ifndef G4NuclearFermiDensity_h
0029 #define G4NuclearFermiDensity_h 1
0030
0031 #include "globals.hh"
0032 #include "G4ThreeVector.hh"
0033 #include "G4VNuclearDensity.hh"
0034
0035 #include <CLHEP/Units/PhysicalConstants.h>  // pi, fermi,..
0036 #include "G4Exp.hh"
0037 #include "G4Log.hh"
0038 //#include <cmath>              // pow
0039
0040 class G4NuclearFermiDensity : public G4VNuclearDensity
0041 {
0042   public:
0043     G4NuclearFermiDensity(G4int anA, G4int aZ);
0044     ~G4NuclearFermiDensity();
0045
0046     G4double GetRelativeDensity(const G4ThreeVector & aPosition) const
0047     {
0048       return 1./(1.+G4Exp((aPosition.mag()-theR)/a));
0049     }
0050
0051     G4double GetRadius(const G4double maxRelativeDenisty) const
0052     {
0053       return (maxRelativeDenisty>0 && maxRelativeDenisty <= 1 ) ?
0054              (theR + a*G4Log((1-maxRelativeDenisty+G4Exp(-1*theR/a))/maxRelativeDenisty))  : DBL_MAX;
0055     }
0056
0057     G4double GetDeriv(const G4ThreeVector & aPosition) const
0058     {
0059       G4double currentR=aPosition.mag();
0060       if (currentR > 40*theR  ) {return 0;}
0061       else return -G4Exp((currentR-theR)/a) * sqr(GetDensity(aPosition)) / (a*Getrho0());
0062     }
0063
0064   private:
0065     G4int theA;
0066     G4double theR;      // Nuclear Radius
0067     const G4double a;   // Determines the nuclear surface thickness
0068 };
0069
0070 #endif
0071