Dimuon Triggering

Overview of Trigger in CMS experiment

• Bunching cross rate : 40MHz
• proton Collision rate : 10^9 Hz
• it is not easy to handle all events at once, so "Triggering" is very neccessary for useful analysis.
• Generally, can separate two parts - L1 trigger and High Level Trigger(HLT)
• L1 trigger will be done in the offline 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

* Pt cut reguirement

• 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

Porting "L1L2L3DimuonTrigger.cpp" from ORCA to CMSSW

- L1 triggered GMTMuon Collection (show us L1 trigger information such as numbers, eta, phi, pt etc)

- L2 triggered StandAlone? Collection (show us L2 trigger information such as numbers, innermost position)

- L3 triggered L3 inner track reconstruction (Find pixel seeds, propagate from innermost layers out, vertex constraint) and making the muon track pair

L1 test result (very preliminary)

-- DongHoMoon - 29 Oct 2007