/afs/cern.ch/work/a/aaltunda/public/www/CMSSW_6_2_5/src/SimMuon/CSCDigitizer/src/CSCGasCollisions.h

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#ifndef MU_END_CSC_GAS_COLLISIONS_H
#define MU_END_CSC_GAS_COLLISIONS_H

#include "DataFormats/GeometryVector/interface/LocalPoint.h"
#include "SimDataFormats/TrackingHit/interface/PSimHit.h"
#include "SimMuon/CSCDigitizer/src/CSCCrossGap.h"
#include "SimGeneral/HepPDTRecord/interface/ParticleDataTable.h"
#include "CLHEP/Random/RandFlat.h"
#include "CLHEP/Random/RandExponential.h"

#include <vector>
#include <string>

class CSCGasCollisions {
public:

   CSCGasCollisions();
   virtual ~CSCGasCollisions();

   void setParticleDataTable(const ParticleDataTable * pdt);

   void setRandomEngine(CLHEP::HepRandomEngine & engine);

   void simulate(const PSimHit&, 
      std::vector<LocalPoint>& clusters, std::vector<int>& electrons );

   static const int N_GAMMA = 21;
   static const int N_ENERGY = 63;
   static const int N_ENTRIES = N_GAMMA*N_ENERGY;
   static const int MAX_STEPS = 400;

private:
   void readCollisionTable();
   void fillCollisionsForThisGamma( float, std::vector<float>& ) const;
   float lnEnergyLoss( float, const std::vector<float>& ) const;
   double generateStep( double avCollisions ) const;
   float generateEnergyLoss( double avCollisions, 
      double anmin, double anmax, const std::vector<float>& collisions ) const;

   void ionize( double energyTransferred, LocalPoint startHere) const;
        
   void writeSummary( int n_steps, double sum_steps, float dedx, float simHiteloss ) const;

   const std::string me;       // class name
   double gasDensity;     // Density of CSC gas mix
   // The question of what is reasonable for deCut is complex. But it seems clear that
   // this simulation is not credible if any delta electrons generated here
   // have ranges more than a few mm, or equivalently, energies above a few keV.
   // deCut = 1000 = 1 keV
   // deCut = 10000 = 10 keV
   double deCut;          // Delta electron cutoff in eV (Match GEANT!)
   double eion;           // ionization threshold (eV) (min. E for ionizatiom)
   double ework;          // effective work function (av. energy to create one ion pair)
   double clusterExtent;  // Precision of localization of ion clus. Typically 10 microns.

   std::vector<float> theGammaBins;
   std::vector<float> theEnergyBins;
   std::vector<float> theCollisionTable;

   CSCCrossGap* theCrossGap; // Owned by CSCGasCollisions
   const ParticleDataTable * theParticleDataTable;
   CLHEP::RandFlat * theRandFlat;
   CLHEP::RandExponential * theRandExponential;
   bool saveGasCollisions; // Simple Configurable to flag saving info w. debugV
};

#endif