TrackPAI.hh

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#ifndef G_TRACK_PAI
#define G_TRACK_PAI
 
#include <string>
#include <array>
 
#include "Track.hh"
 
namespace Garfield {
 
/// Energy loss calculation using the Photoabsorption-Ionisation Model.
 
class TrackPAI : public Track {
 public:
  struct Cluster {
    double x, y, z, t;
    double energy;
  };
 
  // Constructor
  TrackPAI();
  // Destructor
  virtual ~TrackPAI() {}
 
  bool NewTrack(const double x0, const double y0, const double z0,
                const double t0, const double dx0, const double dy0,
                const double dz0) override;
 
  bool GetCluster(double& xc, double& yc, double& zc, double& tc, int& nc,
                  double& ec, double& extra) override;
  const std::vector<Cluster>& GetClusters() const { return m_clusters; }
 
  double GetClusterDensity() override;
  double GetStoppingPower() override;
 
 private:
  // Particle speed.
  double m_speed = 0.;
  // Max. energy transfer in a collision
  double m_emax = 0.;
 
  // Total inelastic mean free path
  double m_imfp = 0.;
  // Stopping power
  double m_dedx = 0.;
 
  // Dielectric function
  static constexpr size_t m_nSteps = 1000;
  std::array<double, m_nSteps> m_eps1;
  std::array<double, m_nSteps> m_eps2;
  std::array<double, m_nSteps> m_epsInt;
 
  // Tables for interpolation of cumulative distribution functions
  std::array<double, m_nSteps> m_energies;
  std::array<double, m_nSteps> m_cdf;
  std::array<double, m_nSteps> m_rutherford;
 
  std::vector<Cluster> m_clusters;
  size_t m_cluster = 0;
 
  // Medium properties
  std::string m_mediumName = "";
  double m_mediumDensity = 0.;
  double m_electronDensity = 0.;
 
  bool SetupMedium(Medium* medium);
  bool SetupCrossSectionTable();
 
  double ComputeMaxTransfer() const;
 
  double ComputeCsTail(const double emin, const double emax);
  double ComputeDeDxTail(const double emin, const double emax);
 
  std::pair<double, double> SampleEnergyDeposit(const double u) const;
  double SampleAsymptoticCs(double u) const;
  double SampleAsymptoticCsSpinZero(const double emin, double u) const;
  double SampleAsymptoticCsSpinHalf(const double emin, double u) const;
  double SampleAsymptoticCsSpinOne(const double emin, double u) const;
  double SampleAsymptoticCsElectron(const double emin, double u) const;
  double SampleAsymptoticCsPositron(const double emin, double u) const;
 
  double LossFunction(const double eps1, const double eps2) const {
    const double eps = eps1 * eps1 + eps2 * eps2;
    return eps > 0. ? eps2 / eps : 0.;
  }
};
}
 
#endif