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//
//
// ---------------------------------------------------------------
//
// G4ILawForceFreeFlight
//
// Class Description:
//     A G4VBiasingInteractionLaw representing the "interaction" law
//  for a force free flight, ie, a particle which does not interact.
//  It is a limit case for which the non-interaction probability over
//  a segment is always 1, and the effective cross-section always
//  zero.
//     This singular behavior is signaled by the IsSingular()
//  method returning always true.
//
// ---------------------------------------------------------------
//   Initial version                         Nov. 2013 M. Verderi
#ifndef G4ILawForceFreeFlight_hh
#define G4ILawForceFreeFlight_hh 1

#include "G4VBiasingInteractionLaw.hh"

class G4ILawForceFreeFlight : public G4VBiasingInteractionLaw
{
public:
  G4ILawForceFreeFlight(G4String name = "forceFreeFlightLaw");
  virtual ~G4ILawForceFreeFlight();
  
public:
  virtual G4double     ComputeEffectiveCrossSectionAt(G4double               length) const;
  virtual G4double ComputeNonInteractionProbabilityAt(G4double               length) const;
  // -- sample the distribution
  virtual  G4double           SampleInteractionLength();
  // -- move by true path length, this position becomes the new initial point
  virtual G4double     UpdateInteractionLengthForStep(G4double       truePathLength);
  virtual G4bool IsSingular() const {return true;}
};

#endif
