ALEPH · LEP1 event display

Every converted Z-pole event of 1991–1995, drawn in the ALEPH detector

Event
Go to run / event
Filter
tracks ≥calo ≥GeV
Jets
About the data, the event types, the EDIR classes and the jets

The data

  • Runs and events:
  • Source: ALEPH's raw data tapes (POT files, last processing), converted to EDM4hep
  • What is drawn: ALEPH's own reconstruction from the tape (JULIA tracks, calorimeter clusters, V0s)
  • Computed here: only the jets

Event types

  • hadronic: ≥ 5 good tracks, and their energy > 15% of Ecm (summing the good tracks with p ≤ Ecm/2)
  • no track: no reconstructed track
  • 1-4 tracks: 1 to 4 tracks, not hadronic
  • ≥ 5 tracks, not hadronic: enough tracks but fails the hadronic cuts

A good track

  • ≥ 4 TPC hits
  • |d0| < 2 cm and |z0| < 10 cm
  • pT > 0.2 GeV and p < 50 GeV
  • |cos θ| < 0.95

Jets

  • Durham algorithm (exclusive), clustered to exactly 2 jets
  • Inputs: the tracks and the neutral calorimeter objects
  • Shown as colours in the 3D view and the event's jet list

Filtering

  • EDIR classes: pick one or more; any of or all of them
  • Each event shows all 30 flags, on or off; classes are picked in the filter only
  • Next / previous (or the arrow keys) follow the filter, also into the next run

EDIR classes

  • ALEPH's event directory classes for LEP1 data (ALPHA manual, appendix G)
  • Set by ALEPH's reconstruction when the data were processed; an event can be in several
  • Class k is bit k−1 of the class word in the event header (REVH)
  • Classes 11-14 (high voltage on) are summarised in one chip; a warning chip if any is off

     

    ALEPH

    EDIR class flags
    Event contents
    


    


    

    



    

    

    ALEPH
    

    


    



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