Muon Trigger Overview

The muon trigger runs in two main modes: RoI based and Full scan.

The primary RoI mode start from a L1 muon RoI and runs the following steps:

1. Fast Muon Spectrometer (MS) tracking
2. Fast ID tracking + Fast MS-ID combination
3. Precision MS tracking
4. Precision ID tracking + precision MS-ID combination

There are several variations on this, such as adding isolation or invariant mass cuts after step 4, or running only the MS track building.

graph LR
A[L1 RoI] --> B[Fast MS tracking]
B -->|RoI centered on muFast muon| C[Fast ID tracking + CB Muons]
C --> D[Precision MS tracking]
D --> E[Precision ID tracking + CB Muons]

The full scan mode runs in two steps:

1. The precision MS tracking runs in the full detector
2. The ID tracking and precision ID MS-ID combination runs in RoIs centered on the MS tracks created in step 1.

Typically, the full scan muon trigger runs as part of a multi-muon trigger, where the first muon is found in a RoI (to reduce CPU usage).

graph LR
A[Full Scan RoI] --> B[Precision MS tracking]
B -->|RoIs built around MS tracks| C[ID tracking + Precision CB Muons]

Variations of Muon Triggers

• noL1: full scan muon
  • nscan: Require final muons to be within dR=0.5 of each other
• msonly: only run SA muon reconstruction
  • 3layersEC: apply requirement of hits in 3 layers of MS in endcaps
• lateMu: Run late muon reconstruction to find muons in next bunch crossing
• l2io: Run inside-out reconstruction for muFast (to recover close-by muons)
• l2mt: Run multi-track reconstruction for muFast (to recover close-by muons)
• 0eta105: |eta| less than 1.05 (barrel only)
• muoncalib: Runs only muFast for muon calibration
• LRT: run large radius tracking
  • d0loose/medium/tight: apply cut on d0 of muons
• muonqual: apply some muon quality requirements to final combined muons
• idperf: Runs usual reconstruction but don't cut on anything that requires ID track information (used for ID performance)
• invm: apply invariant mass cut
  • os: require muons in invariant mass calculation to have opposite sign
• cosmic: purely a label for cosmic triggers in the menu. Does not have any impact on reconctruction

Modules in this directory

• GenerateMuonChainDefs
  • Called by the menu code to pass the chain dict into the ChainConfiguration object
• MuonChainConfiguration
  • Defines the ChainConfiguration object that interprets the chain dict and builds the chain
• MuonMenuSequences
  • Defines the top-level sequences containing the input maker and hypothesis alg
  • For more descriptions of the various sequences, see SequenceOverview
• MuonRecoSequences
  • Assembles the sequences for each stage of reconstruction
  • For more information on the algorithms, see MuonTriggerDocumentation