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//	G4ScreeningMottCrossSection.hh
//-------------------------------------------------------------------
//
// GEANT4 Class header file
//
// File name:    G4ScreeningMottCrossSection
//
// Author:      Cristina Consolandi
//
// Creation date: 20.10.2011
//
// Modifications:
//
// Class Description:
//      Computation of electron Coulomb Scattering Cross Section.
//      Suitable for high energy electrons and light target materials.
//
//      Reference:
//      M.J. Boschini et al.
//     "Non Ionizing Energy Loss induced by Electrons in the Space Environment"
//      Proc. of the 13th Int. Conf. on Particle Physics and Advanced Technology
//      (13th ICPPAT, Como 3-7/10/2011), World Scientific (Singapore).
//      Available at: http://arxiv.org/abs/1111.4042v4
//
//      1) Mott Differential Cross Section Approximation:
//         For Target material up to Z=92 (U):
//         As described in http://arxiv.org/abs/1111.4042v4
//         par. 2.1 , eq. (16)-(17)
//         Else (Z>92):
//         W. A. McKinley and H. Fashbach, Phys. Rev. 74, (1948) 1759.
//      2) Screening coefficient:
//      vomn G. Moliere, Z. Naturforsh A2 (1947), 133-145; A3 (1948), 78.
//      3) Nuclear Form Factor:
//      A.V. Butkevich et al. Nucl. Instr. Meth. A488 (2002), 282-294.
//
// -----------------------------------------------------------------------------

//
#ifndef G4ScreeningMottCrossSection_h
#define G4ScreeningMottCrossSection_h 1

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#include "globals.hh"
#include "G4ParticleDefinition.hh"
#include <vector>

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static const G4int DIMMOTT = 750;

class G4NistManager;
class G4Pow;

class G4ScreeningMottCrossSection
{

public:

  explicit G4ScreeningMottCrossSection();

  ~G4ScreeningMottCrossSection();

  void Initialise(const G4ParticleDefinition*, G4double cosThetaLim);

  void SetupKinematic(G4double kinEnergy, G4int Z);

  G4double NuclearCrossSection(G4int form, G4int fast);
  G4double GetScatteringAngle(G4int form, G4int fast);

  G4double RatioMottRutherford(G4double tet);
  G4double RatioMottRutherfordCosT(G4double sin2t2);

  G4double McFcorrection(G4double sin2t2);
  inline void SetupParticle(const G4ParticleDefinition*);

  G4ScreeningMottCrossSection & operator=
  (const G4ScreeningMottCrossSection &right) = delete;
  G4ScreeningMottCrossSection(const G4ScreeningMottCrossSection&) = delete;

private:

  G4double ComputeAngle(G4int idx, G4double& rand);

  G4double FormFactor2ExpHof(G4double sin2t2);
  G4double FormFactor2Gauss(G4double sin2t2);
  G4double FormFactor2UniformHelm(G4double sin2t2);
  G4double DifferentialXSection(G4int idx, G4int form);

  G4double  GetTransitionRandom();

  G4NistManager*  fNistManager;
  G4Pow*          fG4pow;

  const G4ParticleDefinition* particle;

  G4double 	        fTotalCross;
  //cost - min - max
  G4double              cosThetaMin;// def 1.0
  G4double              cosThetaMax;// def -1.0

  G4double      	cosTetMinNuc;
  G4double	        cosTetMaxNuc;

  //energy cut
  G4double              ecut;
  G4double              etag;

  G4double              spin;
  G4double              mass;

  //lab of incedent particle
  G4double              tkinLab;
  G4double              momLab2;
  G4double              invbetaLab2;

  //relative system with nucleus
  G4double 		mu_rel;
  G4double              tkin;
  G4double              mom2;
  G4double              invbeta2;
  G4double		beta;
  G4double		gamma;

  //constants
  G4double              alpha;
  G4double              htc2;
  G4double              e2;

  // target nucleus
  G4double              targetMass;
  G4double 		As;
  G4int                 targetZ;
  G4int 	        targetA;

  // working array
  std::vector<G4double> cross;
};


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inline 
void G4ScreeningMottCrossSection::SetupParticle(const G4ParticleDefinition* p)
{
  particle = p;
  mass = particle->GetPDGMass();
  spin = particle->GetPDGSpin();
  if(0.0 != spin) { spin = 0.5; }
  tkin = 0.0;
}

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#endif