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)
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)
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.

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;
}