ECAL Hybrid Superclusters


Superclusters are an important part of several physics objects, especially electrons and photons. How deposits of energy in the ECAL are arranged and stored in "Superclusters" will be described here.

Step by step

The paramaters that control supercluster creation are in the file: RecoEcal/EgammaClusterProducers/python/

Here is an outline of how superclusters are created:

  1. An ordered list of crystals with ET > 1 GeV is created, these become the "seeds". (Threshold controlled by parameter "HybridBarrelSeedThr")
  2. Starting with a seed, a process of stepping along φ is begun. "Dominos" of either 1x3 or 1x5 crystals are added to the supercluster if their energy is > 0.1 GeV (set by "ethresh"). A 1x5 domino is used if 1x3 has an energy > 0.
  3. This process stepping along φ and adding dominos continues until one has stepped 17 crystals in phi. The stepping happens in both positive and negative in φ so, at max, a supercluster can be made of 35 crystals in φ and 5 crystals in η.

Example Hybrid Superclusters


Isolated Photon

Photon Deposit A high-energy isolated photon can result in a fairly narrow deposit of energy, with most of the energy deposited in 3x3 crystals.

Pizero decay to two photons

Pizero Deposit Two photons from a pizero decay can deposit their energy close enough to each other to result in them being merged into one hybrid supercluster.

Revision Info

Reviewer/Editor and Date (copy from screen) Comments
Mike Anderson - 3 Feb 2009 Created Page
Topic attachments
I Attachment History Action Size Date WhoSorted ascending Comment
PNGpng photon2.png r1 manage 23.2 K 2009-02-03 - 22:04 MikeAnderson Supercluster from high energy isolated photon
PNGpng pizero.png r1 manage 29.9 K 2009-02-03 - 21:58 MikeAnderson Supercluster from pizero
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Topic revision: r1 - 2009-02-03 - MikeAnderson
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