Geant4IsotropeGenerator.h

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//==========================================================================
//  AIDA Detector description implementation 
//--------------------------------------------------------------------------
// Copyright (C) Organisation europeenne pour la Recherche nucleaire (CERN)
// All rights reserved.
//
// For the licensing terms see $DD4hepINSTALL/LICENSE.
// For the list of contributors see $DD4hepINSTALL/doc/CREDITS.
//
// Author     : M.Frank
//
//==========================================================================
 
#ifndef DDG4_GEANT4ISOTROPEGENERATOR_H
#define DDG4_GEANT4ISOTROPEGENERATOR_H
 
// Framework include files
#include <DDG4/Geant4ParticleGenerator.h>
 
// C/C++ include files
#include <array>
#include <cstdint>
#include <functional>
#include <mutex>
 
namespace dd4hep {
 
  namespace sim {
 
    // Forward declarations
    class Geant4Random;
 
 
    class Geant4IsotropeGenerator: public Geant4ParticleGenerator {
    protected:
      std::string m_distribution;
      double      m_phiMin;
      double      m_phiMax;
      double      m_thetaMin;
      double      m_thetaMax;
      bool        m_halton;
      uint64_t    m_haltonOffset;
      mutable uint64_t m_haltonIndex;
      mutable std::array<double,3> m_haltonShift;
      mutable std::once_flag m_haltonOnce;
 
      void initHalton(Geant4Random& rnd) const;
      static double haltonValue(uint64_t index, int base);
      double haltonScrambled(uint64_t index, unsigned int dim) const;
      std::function<double(unsigned int)> makeSampler(Geant4Random& rnd) const;
      void sampleMomentum(double h, double& momentum) const;
 
 
      virtual void getParticleDirection(int num, ROOT::Math::XYZVector& direction, double& momentum) const  override;
      void getParticleDirectionFFbar(int num, ROOT::Math::XYZVector& direction, double& momentum) const;
      void getParticleDirectionEta(int num, const std::function<double(unsigned int)>& sample, ROOT::Math::XYZVector& direction, double& momentum) const;
      void getParticleDirectionCosTheta(int num, const std::function<double(unsigned int)>& sample, ROOT::Math::XYZVector& direction, double& momentum) const;
      void getParticleDirectionUniform(int num, const std::function<double(unsigned int)>& sample, ROOT::Math::XYZVector& direction, double& momentum) const;
 
    public:
      Geant4IsotropeGenerator() = delete;
      Geant4IsotropeGenerator(const Geant4IsotropeGenerator& copy) = delete;
      Geant4IsotropeGenerator(Geant4Context* context, const std::string& name);
      virtual ~Geant4IsotropeGenerator();
    };
  }    // End namespace sim
}      // End namespace dd4hep
#endif // DDG4_GEANT4ISOTROPEGENERATOR_H