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 * MinHitSplit  * MinHitSplit: Minimum number of hits for the ith level, before splitting the cluster = 4 (don't touch!)
 * Coscut: cosine of the opening angle in which to expect a cluster, hits outside will be considered as 2nd cluster
 * Distcut: Minimum distance between 2 clusters in mm, if smaller they will be merged
 * Rcut: N_{hits}[level i]/N_{hits}[level i-1] = 0.4 (don't touch)

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).


Steering

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

steering parameters are:

  • Cleaning: Apply topological cleaning, to get rid of muons, neutrons, ... = YES
  • TopologicalCut: If Cleaning = YES, require > N neighbouring hits to accept this as a photon candidate

  • NumberOfLevels: Number of threshold levels i in which the hits will be divided for clustering /!\ < 16

  • Levels: Set the thresholds for the i levels in mip: 0.5 1.5 2.5 4.0 6.0 9.0 16.0 26.0 41.0 65.0
  • MinHit0: Minimum number of hits required in the 0th level (the one containing all other levels)

  • MinHitSplit: Minimum number of hits for the ith level, before splitting the cluster = 4 (don't touch!)

  • Coscut: cosine of the opening angle in which to expect a cluster, hits outside will be considered as 2nd cluster
  • Distcut: Minimum distance between 2 clusters in mm, if smaller they will be merged
  • Rcut: N_{hits}[level i]/N_{hits}[level i-1] = 0.4 (don't touch)

PGDB

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.

Superhit

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.

MarlinMath

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


Before getting started:

KALIBRATOR

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


KITdev

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)