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Predrag's PhotonFinder

<!> everything has been simulated / tested / optimized for LDC00 <!> It assumes low energetic Photons (restricted to ECAL!), coming from the IP (input parameter to th cluster direction) ---


An exmaple steering file is marlinKIT.xml, which was used by Predrag for LDC00, as comparison of his method with other PFlow Algorhythms.


The PhotonFinder needs the Physical Geometrical database (PGDB) for fast acces to properties of the subdetectors. It has to be adopted to the chosen detector model.


The basic class for this photon finder.

  • To ease the nearest neighbour clustering, all cells are artificially shifted
    • to have equal diestance (10mm) in x, y and z. The Superhit knoes about their true and their shifted position. Be CAREFUL if the layer distance gets smaller then the cell width!
  • Searches for cluster seeds (connected hits)
  • calculates the center of each cluster,
  • their direction as direction between the center and the IP
    • CAREFUL: Cannot be used for non-pointing gammas!
  • the initial cluster start as closest hit in the first ECAL layer to the line
    • between cluster maximum and IP
  • the energy collected in the cluster as well as an estimate of the
    • true energy of this cluster
  • and the distance bewteen clusters.


contains all functions needed from Superhit to calculate distances, energies and so on.

Before getting started:


needed to get the calibration values that determine the true cluster energy, in dependence of the cluster level: E_cluster [level ] = a*E_true + b with E_min < E_true < E_max

Is needed as input for KIT ---


The main program where all ends meet, searching for em-showers in the ECAL. It depends on the Physical Geometrical Data Base PGDB, the Superhit class, and mathematical operations defined in MarlinMath. The required calibration values can be obtained from KALIBRATOR. KIT is working on the MIP scale. Each cluster level has to be tuned. As an output you get # clusters, energy in cluster, hits in cluster, estimated true energy in cluster, position, direction, and distance to other clusters.

NandaWattimena/PhotonFinder (last edited 2010-03-26 09:24:39 by NandaWattimena)