/home/bes3soft/bes3soft/Boss/7.0.2/dist/7.0.2/Generator/Mcgpj/Mcgpj-00-01-04/src/code3pi/inc/TPhoton_o.h

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#ifndef RAD_TPhoton_o
#define RAD_TPhoton_o

#include "TRandom.h"
#include "TLorentzVector.h"
namespace rb{
class TPhoton{
protected:
  TLorentzVector fk;
  double fknorm;
  double fNorm;
  double fE;
  double fP0;   // auxilary parameter 0
  double fP1;   // auxilary parameter 1
  double fX;    // emitted energy
  double fCosTheta; // cosine of photon on a big angle
  double fLnD;  // ln((1-beta*c1)/(1+beta*c1))
  double fBetaI;  // velocity of final particles
  double fiBetaI; // inverse velocity of final particles
  double fLnD_n;  // ln((1-beta*c1)/(1+beta*c1)*(1+beta*c2)/(1-beta*c2))
  double fBt;     // (1+beta*c1)/(1-beta*c1)
public:
  TPhoton(){}
  TPhoton(double E);
  TPhoton(double E, double Emin, double Emax);
  ~TPhoton(){}

  void SetEnergyRange(double Emin, double Emax);
  void SetThetaRange(double thmin, double thmax);
  void SetCosThetaRange(double c1, double c2);

  const TLorentzVector &GetPhoton(){
    return fk;
  }

  const TLorentzVector &GetNewPhoton();
  inline double GetPhotNorm(){return fknorm;}
  inline double GetEnergy(){
    fX = fP0*exp(gRandom->Rndm()*fP1);
    return fX;
  }
  inline double GetENorm(){return fX*fNorm;}
  inline double GetCosThetaF(){
    double d = fBt*exp(fLnD_n*gRandom->Rndm());
    fCosTheta = (d - 1)/(fBetaI*(d + 1));
    return fCosTheta;
  }
  inline double GetThNormF(){
    double k = fBetaI*fCosTheta;
    return 0.5*fiBetaI*fLnD_n*(1 - k*k);
  }
  inline double GetPhi(){
    return 2*M_PI*gRandom->Rndm();
  }
  inline double GetPhiNorm(){return 2*M_PI;}
};

class TPhotonD: public TPhoton{
public:
  TPhotonD():TPhoton(){};
  void Init(const double & delta, const double & beta){
    // Initializing photons in final state 
    // by distribution 1/x
    fP0 = delta;
    fP1 = 2/beta;
    fNorm = pow(delta,beta/2);
  }
  inline double GetEnergy(){
    double t1 = log(gRandom->Rndm())*fP1;
    fX = fP0*exp(t1);
    return fX;
  }
  inline double GetENorm(){return fNorm;}
};
}
#endif// RAD_TPhoton

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