Overview of Trigger in CMS experiment

  • Bunch crossing rate : 40MHz
  • proton Collision rate : 10^9 Hz
  • it is not easy to handle all events at once, so "Triggering" is very neccessary for valued analysis.
  • Generally, can separate two parts - L1 trigger and High Level Trigger(HLT)
  • L1 trigger will be done in the online with Muon system detectors.
  • After L1, we can reduce the rate into 100kHz.
  • Triggering goal is to decrease their rate upto 100Hz as long as possible

Muon Triggering

- L1 trigger : Global Muon Triggger (GMT) - Using all muon hits : online selection

* Pt cut requirement (depending on HLT menu, but this is general case following TDR)

  • single muon : > 5 GeV?/c
  • double muon : > 3 GeV?/c

- L2 trigger : StandAlone? Muon

  • Seeded by Level-1 muon
  • Refitting muon track with Kalman filtering technique only in muon chambers (DT/CSC/RPC track segments)
  • Trajectory works from inside out, Fitting works from outside in

- L3 trigger : Including inner tracker hits

  • Track reconstruction and matching with track in muon chamber and inner track (pixel seeds, and propagate from innermost layers out including muon)
  • Vertex finder method : divisive, histogramming method

-- DongHoMoon - 20 Aug 2009

Topic attachments
I Attachment History Action Size Date Who Comment
PNGpng ppL1trigger.png r1 manage 29.0 K 2009-08-20 - 10:00 UnknownUser  
PNGpng ppTrigger01.png r1 manage 399.7 K 2009-08-20 - 10:01 UnknownUser  
PNGpng ppTriggerMuonTracking.png r1 manage 215.8 K 2009-08-20 - 10:01 UnknownUser  
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Topic revision: r2 - 2010-07-08 - DongHoMoon
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