CandidateMatchHelpers Namespace Reference

Functions
Amg::Vector3D	approxXYZwrtPoint (const xAOD::CaloCluster &cluster, const Amg::Vector3D &point, const bool isEndCap)
	Function to get the (x,y,z) of the cluster wrt to a point (x0,y0,z0) More...
Amg::Vector3D	approxXYZwrtATLAS (const xAOD::CaloCluster &clusterEta, const bool isEndCap)
	Function to get the (x,y,z) of the cluster in the ATLAS frame origin (0,0,0) More...
double	PhiROT (const double pt, const double eta, const int charge, const double r_start, const bool isEndCap)
	Function to calculate the approximate rotation in phi/bending of a track until it reaches the calo. More...

Function Documentation

approxXYZwrtATLAS()

Amg::Vector3D CandidateMatchHelpers::approxXYZwrtATLAS	(	const xAOD::CaloCluster &	clusterEta,
		const bool	isEndCap
	)

Function to get the (x,y,z) of the cluster in the ATLAS frame origin (0,0,0)

Definition at line 19 of file CandidateMatchHelpers.cxx.

{
  // These are at the face of the calorimeter
  const double RfaceCalo = 1500;
  const double ZfaceCalo = 3700;
  // Get the Rclus , Zclus given the cluster eta
  double Rclus = RfaceCalo;
  double Zclus = ZfaceCalo;
  const double clusterEta = cluster.eta();
  if (clusterEta != 0) {
    /*
     * tahn(eta) == cos(theta)
     * 1/cosh(clusterEta) == sin(theta)
     * tan =sin/cos
     */
    const double tanthetaclus = (1.0 / std::cosh(clusterEta)) / std::tanh(clusterEta);
    if (isEndCap) {
      Rclus = std::abs(ZfaceCalo * (tanthetaclus));
      // Negative Eta ---> negative Z
      if (clusterEta < 0) {
        Zclus = -Zclus;
      }
    } else {
      if (tanthetaclus != 0) {
        Zclus = RfaceCalo / (tanthetaclus);
      }
    }
  } else { // when eta ==0
    Zclus = 0;
  }
 
  const double clusterPhi = cluster.phi();
  return { Rclus * std::cos(clusterPhi), Rclus * std::sin(clusterPhi), Zclus };
}

approxXYZwrtPoint()

Amg::Vector3D CandidateMatchHelpers::approxXYZwrtPoint	(	const xAOD::CaloCluster &	cluster,
		const Amg::Vector3D &	point,
		const bool	isEndCap
	)

Function to get the (x,y,z) of the cluster wrt to a point (x0,y0,z0)

Definition at line 10 of file CandidateMatchHelpers.cxx.

{
 
  return approxXYZwrtATLAS(cluster, isEndCap) - point;
}

PhiROT()

double CandidateMatchHelpers::PhiROT	(	const double	pt,
		const double	eta,
		const int	charge,
		const double	r_start,
		const bool	isEndCap
	)

Function to calculate the approximate rotation in phi/bending of a track until it reaches the calo.

Definition at line 56 of file CandidateMatchHelpers.cxx.

{
  // Used in order to derive the formula below
  const double Rcalo = 1200;
 
  // correct phi for extrapolation to calo
  double phiRot = 0.0;
  double ecCorr = 1.0;
  if (isEndCap) {
    const double ecFactor = 1.0 / (0.8 * std::atan(15.0 / 34.0));
    const double sinTheta0 = 2.0 * std::atan(std::exp(-std::abs(Eta)));
    ecCorr = sinTheta0 * std::sqrt(sinTheta0) * ecFactor;
  }
  const double Rscaled = (Rcalo - r_first) * (1. / Rcalo);
  phiRot = Rscaled * ecCorr * charge * 430. / (Et);
  return phiRot;
}