FlightTimeEstimator.h

/**************************************************************************
 * basf2 (Belle II Analysis Software Framework)                           *
 * Author: The Belle II Collaboration                                     *
 *                                                                        *
 * See git log for contributors and copyright holders.                    *
 * This file is licensed under LGPL-3.0, see LICENSE.md.                  *
 **************************************************************************/
#pragma once
 
#include <tracking/trackFindingCDC/geometry/Vector3D.h>
#include <tracking/trackFindingCDC/geometry/Vector2D.h>
#include <tracking/trackFindingCDC/numerics/LookupTable.h>
 
#include <memory>
#include <cmath>
 
namespace Belle2 {
  namespace TrackFindingCDC {
 
    class FlightTimeEstimator {
 
    public:
      virtual ~FlightTimeEstimator() = default;
 
      virtual double
      getFlightTime2D(const Vector2D& /*pos2D*/, double /*alpha*/, double /*beta */ = 1) const
      {
        return 0;
      }
 
    public:
      static const FlightTimeEstimator&
      instance(std::unique_ptr<FlightTimeEstimator> replacement = nullptr);
    };
 
    class BeamEventFlightTimeEstimator : public FlightTimeEstimator {
 
    public:
      BeamEventFlightTimeEstimator();
 
      double getFlightTime2D(const Vector2D& pos2D, double alpha, double beta = 1) const override
      {
        double absAlpha = std::fabs(alpha);
        double directDist2D = pos2D.cylindricalR();
        return directDist2D * m_firstPeriodAlphaFlightTimeFactor(absAlpha) / beta;
      }
 
    private:
      LookupTable<float> m_firstPeriodAlphaFlightTimeFactor;
    };
 
    class CosmicRayFlightTimeEstimator : public FlightTimeEstimator {
 
    public:
      explicit CosmicRayFlightTimeEstimator(Vector3D triggerPoint = Vector3D(0, 0, 0));
 
      double getFlightTime2D(const Vector2D& pos2D, double alpha, double beta = 1) const override
      {
        Vector2D relPos2D = pos2D - m_triggerPoint.xy();
        double deltaAlpha = pos2D.angleWith(relPos2D);
        alpha += deltaAlpha;
        double absAlpha = std::fabs(alpha);
        double directDist2D = relPos2D.cylindricalR();
        return directDist2D * m_halfPeriodAlphaFlightTimeFactor(absAlpha) / beta;
      }
 
    private:
      Vector3D m_triggerPoint;
 
      LookupTable<float> m_halfPeriodAlphaFlightTimeFactor;
    };
 
  }
}