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//
// $Id: G4GammaConversion.hh,v 1.10 2002/04/09 17:34:40 vnivanch Exp $
// GEANT4 tag $Name: geant4-05-00 $
//
//------------------ G4GammaConversion physics process -------------------------
//                   by Michel Maire, 24 May 1996
//
// 11-06-96, Added GetRandomAtom() method and new data member
//           for cumulative total cross section, by M.Maire
// 21-06-96, SetCuts inplementation, M.Maire
// 16-09-96, Dynamical array PartialSumSigma, M.Maire
// 14-01-97, crossection table + meanfreepath table.
//           PartialSumSigma removed, M.Maire
// 14-03-97, new physics scheme for geant4alpha, M.Maire
// 13-08-98, new methods SetBining() PrintInfo()
// 03-08-01, new methods Store/Retrieve PhysicsTable (mma)
// 06-08-01, BuildThePhysicsTable() called from constructor (mma)
// 19-09-01, come back to previous ProcessName: "conv"
// 20-09-01, DoIt: fminimalEnergy = 1*eV (mma) 
// 01-10-01, come back to BuildPhysicsTable(const G4ParticleDefinition&)    
// -----------------------------------------------------------------------------

// class description
//
// gamma ---> e+ e- 
// inherit from G4VDiscreteProcess
//

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#ifndef G4GammaConversion_h
#define G4GammaConversion_h 1

#include "G4ios.hh" 
#include "globals.hh"
#include "Randomize.hh" 
#include "G4VDiscreteProcess.hh"
#include "G4PhysicsTable.hh"
#include "G4PhysicsLogVector.hh"
#include "G4Element.hh"
#include "G4Gamma.hh" 
#include "G4Electron.hh"
#include "G4Positron.hh"
#include "G4Step.hh"

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class G4GammaConversion : public G4VDiscreteProcess
 
{  
  public:  // with description
 
     G4GammaConversion(const G4String& processName ="conv");
 
    ~G4GammaConversion();

     G4bool IsApplicable(const G4ParticleDefinition&);
       // true for Gamma only.
          
     void SetPhysicsTableBining(G4double lowE, G4double highE, G4int nBins);
       // Allows to define the binning of the PhysicsTables, 
       // before to build them.
     
     void BuildPhysicsTable(const G4ParticleDefinition&);
       // It builds the total CrossSectionPerAtom table, for Gamma,
       // and for every element contained in the elementTable.
       // It builds the MeanFreePath table, for Gamma,
       // and for every material contained in the materialTable.       
       
     G4bool StorePhysicsTable(G4ParticleDefinition* ,
			      const G4String& directory, G4bool);
       // store CrossSection and MeanFreePath tables into an external file
       // specified by 'directory' (must exist before invokation)

     G4bool RetrievePhysicsTable(G4ParticleDefinition* ,
				 const G4String& directory, G4bool);
       // retrieve CrossSection and MeanFreePath tables from an external file
       // specified by 'directory' 
       				         	                          
     void PrintInfoDefinition();
       // Print few lines of informations about the process: validity range,
       // origine ..etc..
       // Invoked by BuildThePhysicsTable(). 

     G4double GetMeanFreePath(const G4Track& aTrack,
                              G4double previousStepSize,
                              G4ForceCondition* condition);
       // It returns the MeanFreePath of the process for the current track :
       // (energy, material)
       // The previousStepSize and G4ForceCondition* are not used.
       // This function overloads a virtual function of the base class.	
       // It is invoked by the ProcessManager of the Particle.
       
     G4double GetCrossSectionPerAtom(const G4DynamicParticle* aDynamicGamma,
                                           G4Element*         anElement);
       // It returns the total CrossSectionPerAtom of the process, 
       // for the current DynamicGamma (energy), in anElement.	
       
     G4VParticleChange* PostStepDoIt(const G4Track& aTrack,
                                    const G4Step& aStep);
       // It computes the final state of the process (at end of step),
       // returned as a ParticleChange object.			    
       // This function overloads a virtual function of the base class.
       // It is invoked by the ProcessManager of the Particle.
        
  protected:

     virtual G4double ComputeCrossSectionPerAtom(G4double GammaEnergy, 
                                                 G4double AtomicNumber);

     virtual G4double ComputeMeanFreePath (G4double GammaEnergy, 
                                           G4Material* aMaterial);

  private:

     G4Element* SelectRandomAtom(const G4DynamicParticle* aDynamicGamma,
                                 G4Material* aMaterial);

     G4double ScreenFunction1(G4double ScreenVariable);

     G4double ScreenFunction2(G4double ScreenVariable);
     
  private:
  
     // hide assignment operator as private 
     G4GammaConversion& operator=(const G4GammaConversion &right);
     G4GammaConversion(const G4GammaConversion& );
     
  private:
  
     G4PhysicsTable* theCrossSectionTable;    // table for crossection
     G4PhysicsTable* theMeanFreePathTable;
     
     G4double LowestEnergyLimit ;     // low  energy limit of the tables
     G4double HighestEnergyLimit ;    // high energy limit of the tables 
     G4int NumbBinTable ;             // number of bins in the tables
     
     G4double fminimalEnergy;         // minimalEnergy of produced particles
    
     G4double MeanFreePath;           // actual MeanFreePath (current medium)
};

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#include "G4GammaConversion.icc"
  
#endif