#ifndef STNTUPLE_TStnSiGeantIsect
#define STNTUPLE_TStnSiGeantIsect
//-----------------------------------------------------------------------------
//  This is a pared down version of the CDF object
//  SimulationObjects/PropagatedSiParticle.  It contains the
//  information from the simulation in one intersection of a particle
//  as GEANT tracked it through an active detector volume.
//
//  The OBSP number of the particle that made the intersection is
//  stored in the fUniqueID, as is done in Stntuple/obj/TObspParticle.
//  Because the TObspBlock is made such that the OBSP number is the
//  index into the TClonesArray of TObspParticle's, it is easy to find
//  the correct particle from the unique id of the TStnSiGeantIsect.
//  See TSiGeantIsectBlock for more info.
//
//  Since there are many such silicon intersections in an event, you
//  might not want to make this block during a normal job.
//
//  Author:    Aaron Dominguez (CDF/LBNL)
//  Date:      June 6 2001
//-----------------------------------------------------------------------------
#include "TObject.h"
#include "TVector3.h"
#include "TLorentzVector.h"
#include "Stntuple/obj/TStnSiDigiCode.hh"
#include "Stntuple/base/TBitset.hh"

class TStnSiGeantIsect: public TObject {

public:
//------------------------------------------------------------------------------
//  data members
//------------------------------------------------------------------------------
  TStnSiDigiCode fDigiCode; // The (repacked) SiDigiCode of the detector element

  TLorentzVector fEntryMomentum; // The momentum of the particle at the
			         // entrance to the detector element
  TLorentzVector fExitMomentum;  // The momentum of the particle at the
			         // exit from the detector element
  
  TVector3 fEntry, fExit;   // The entry and exit point in global CDF coords.
  
  TBitset fActiveRegion;    // Did the particle pass thru the active
			    // region(s) of the detector element?
                            // Bit   =1 -> Yes
                            // ---   ------------------------------
                            // 0     Entrance in Phi area of side 0
                            // 1     Entrance in Z area of side 0
                            // 2     Entrance in Z area of side 1
                            // 4     Entrance in Phi area of side 1
                            // 5     Exit in Phi area of side 0
                            // 6     Exit in Z area of side 0
                            // 7     Exit in Z area of side 1
                            // 8     Exit in Phi area of side 1

  Float_t fDE;              // The total energy loss in GeV in this
			    // detector element.
  Float_t fRadLen;          // Fraction of radiation length traversed
			    // in this detector element.
  
  Float_t fPhiStrip;        // Axial strip num of (exit-entrance)/2
  Float_t fZStrip;          // Same for stereo side (=0, if no
			    // stereo).

  Int_t fInitPhi;           // Initial hit phi strip
  Int_t fFinalPhi;          // Final hit phi strip
  Int_t fInitZ;             // Initial hit stereo strip (=0 if no stereo)
  Int_t fFinalZ;            // Final hit stereo strip

//------------------------------------------------------------------------------
//  functions
//------------------------------------------------------------------------------
					// ****** constructors and destructor
  TStnSiGeantIsect();
  virtual ~TStnSiGeantIsect();
					// ****** accessors
  TStnSiDigiCode* DigiCode()     {return &fDigiCode;}
  TLorentzVector* EntryMomentum(){return &fEntryMomentum;}
  TLorentzVector* ExitMomentum() {return &fExitMomentum;}
  TVector3*       Entry()        {return &fEntry;}
  TVector3*       Exit()         {return &fExit;}
  Float_t         DE()           {return  fDE;}
  Float_t         RadLen()       {return  fRadLen;}
  TBitset*        ActiveRegion() {return &fActiveRegion;}
  Float_t         PhiStrip()     {return  fPhiStrip;}
  Float_t         ZStrip()       {return  fZStrip;}
  Int_t           InitPhi()      {return  fInitPhi;}
  Int_t           FinalPhi()     {return  fFinalPhi;}
  Int_t           InitZ()        {return  fInitZ;}
  Int_t           FinalZ()       {return  fFinalZ;}

  void Print(Option_t* option = "") const;

  ClassDef(TStnSiGeantIsect,5)
};

#endif