JMatch3B.hh

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#ifndef __JTRIGGER__JMATCH3B__
#define __JTRIGGER__JMATCH3B__

#include "JPhysics/JConstants.hh"

#include "JTrigger/JMatch.hh"


/**
 * \file
 *
 * Match operator for Cherenkov light from muon in any direction.
 * \author mdejong
 */
namespace JTRIGGER {}
namespace JPP { using namespace JTRIGGER; }

namespace JTRIGGER {

  using JPHYSICS::getInverseSpeedOfLight;
  using JPHYSICS::getIndexOfRefraction;
  using JPHYSICS::getTanThetaC;
  using JPHYSICS::getSinThetaC;


  /** 
   * 3D match criterion with road width.
   * This match algorithm is intented for muon signals.
   *
   * B. Bakker, "Trigger studies for the Antares and KM3NeT detector.",
   * Master thesis, University of Amsterdam.
   */
  template<class JHit_t>
  class JMatch3B  :
    public JClonable< JMatch<JHit_t>, JMatch3B<JHit_t> >
  {
  public:
    /**
     * Constructor.
     *
     * \param  road_width_m     maximal road width [m]
     * \param  Tmax_ns          maximal extra time [ns]
     */
    JMatch3B(const double road_width_m,
             const double Tmax_ns = 0.0) :
      roadWidth_m (road_width_m),
      TMaxExtra_ns(Tmax_ns),
      x(0.0),
      y(0.0),
      z(0.0),
      d(0.0),
      t(0.0),
      dmin(0.0),
      dmax(0.0),
      d2(0.0)
    {
      //
      // calculation D2 in thesis is wrong, here correct
      //
      const double tt2 = getTanThetaC() * getTanThetaC();

      D0 = roadWidth_m;
      D1 = roadWidth_m * 2.0;
      D2 = roadWidth_m * 0.5 * sqrt(tt2 + 10.0 + 9.0/tt2);

      D02 = D0 * D0;
      D12 = D1 * D1;
      D22 = D2 * D2;

      const double R  = roadWidth_m;
      const double Rs = R * getSinThetaC();

      R2  = R  * R;
      Rs2 = Rs * Rs;
      Rst = Rs * getTanThetaC();
      Rt  = R  * getTanThetaC();
    }


    /**
     * Match operator.
     *
     * \param  first    hit
     * \param  second   hit
     * \return          match result
     */
    virtual bool operator()(const JHit_t& first, const JHit_t& second) const override 
    {
      x  = first.getX() - second.getX();
      y  = first.getY() - second.getY();
      z  = first.getZ() - second.getZ();
      d2 = x*x + y*y + z*z;
      t  = fabs(first.getT() - second.getT());

      if (d2 < D02)
        dmax = sqrt(d2) * getIndexOfRefraction();
      else 
        dmax = sqrt(d2 - Rs2) + Rst;

      if (t > dmax * getInverseSpeedOfLight()  +  TMaxExtra_ns) {
        return false;
      }

      if      (d2 > D22)
        dmin = sqrt(d2 - R2) - Rt;
      else if (d2 > D12)
        dmin = sqrt(d2 - D12);
      else
        return true;

      return t >= dmin * getInverseSpeedOfLight()  -  TMaxExtra_ns;
    }


    double roadWidth_m;
    double TMaxExtra_ns;

  private:
    double D0;
    double D1;
    double D2;
    mutable double x;
    mutable double y;
    mutable double z;
    mutable double d;
    mutable double t;
    mutable double dmin;
    mutable double dmax;

    double D02;
    double D12;
    double D22;
    double Rs2;
    double Rst;
    double Rt;
    double R2;
    mutable double d2;
  };
}

#endif