CSCGasCollisions.h

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#ifndef MU_END_CSC_GAS_COLLISIONS_H
#define MU_END_CSC_GAS_COLLISIONS_H

#include "FWCore/ParameterSet/interface/ParameterSet.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 <vector>
#include <string>

namespace CLHEP {
  class HepRandomEngine;
}

class CSCGasCollisions {
public:

   CSCGasCollisions(const edm::ParameterSet & pset);
   virtual ~CSCGasCollisions();

   void setParticleDataTable(const ParticleDataTable * pdt);

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

   bool dumpGasCollisions( void ) const { return dumpGasCollisions_; }
   bool saveGasCollisions( void ) const { return saveGasCollisions_; }

   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, CLHEP::HepRandomEngine* ) const;
   float generateEnergyLoss( double avCollisions, 
                             double anmin, double anmax, const std::vector<float>& collisions,
                             CLHEP::HepRandomEngine* ) const;

   void ionize( double energyTransferred, LocalPoint startHere) const;
    
   void writeSummary( int n_try, int n_steps, double sum_steps, float dedx, const PSimHit& simhit ) 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;
   bool saveGasCollisions_; // write file of collisions details (not yet implemented in cmssw)
   bool dumpGasCollisions_; // flag to write summary
};

#endif