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// $Id: G4PolarizedBhabhaCrossSection.hh,v 1.2 2006/11/17 14:14:17 vnivanch Exp $
// GEANT4 tag $Name: geant4-09-03 $
//
// GEANT4 Class file
//
//
// File name:     G4PolarizedBhabhaCrossSection
//
// Author:        Andreas Schaelicke and Pavel Starovoitov
//
// Creation date: 12.01.2006
//
// Modifications:
//   16-01-06 included cross section as calculated by P.Starovoitov
//
// Class Description:
//   * calculates the differential cross section (ME squared, without phase space) 
//     incomming positron (along positive z direction) scatters at an electron at rest
//   * phi denotes the angle between the scattering plane and the incoming PRF X-axis
//   * all stokes vectors refer to spins in the Global System (X,Y,Z)
//
#ifndef G4PolarizedBhabhaCrossSection_h
#define G4PolarizedBhabhaCrossSection_h 1

#include "G4StokesVector.hh"
#include "G4VPolarizedCrossSection.hh"

class G4PolarizedBhabhaCrossSection : public G4VPolarizedCrossSection
{
public:
  G4PolarizedBhabhaCrossSection();
  virtual ~G4PolarizedBhabhaCrossSection();
public:
  void Initialize(G4double x, G4double y, G4double phi, 
		  const G4StokesVector & p0,const G4StokesVector & p1,
		  G4int flag=0); 

  G4double XSection(const G4StokesVector & pol2,const G4StokesVector & pol3); 
  G4double TotalXSection(G4double xmin, G4double xmax, G4double y,
			 const G4StokesVector & pol0,
			 const G4StokesVector & pol1); 
  // return expected mean polarisation
  G4StokesVector GetPol2();
  G4StokesVector GetPol3();
private:
  G4double phi0;
  // - part depending on the polarization of the final positron
  G4ThreeVector phi2; 
  // - part depending on the polarization of the final electron
  G4ThreeVector phi3;

};
#endif
