Local Performance of the Local Cathode Strip Chamber Trigger in a Muon Beam Test

1
Local Performance of the Local Cathode Strip
Chamber Trigger in a Muon Beam Test
2
Overview

• Introduction to LHC
• Overview of CMS
• Overview of Trigger Architecture
• Overview of Cathode Strip Chamber (CSC)
• Level-1 Trigger System
• Plots for efficiency
• Conclusion

3
LHC

• 14 TeV center of mass energy
• 27 km circumference

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CMS (Compact Muon Solenoid)
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CMS
What is a muon?
Muons are point particles identical to electrons
except over 200 times more massive (105.2 MeV)
The illustration shows the smaller orbit for
muons in a hydrogynic atom due to their mass
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CMS
Why Muons?

• Muons are penetrating.
• Electrons are too light to make it through
  absorbers
• Taus are too unstable to make it through
  absorbers
• Hadrons interact strongly with matter

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Trigger Architecture

• Need Trigger System to filter out data

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Cathode Strip Chambers (CSC)

• Provide 3-D tracks of charged particles called
  Local Charge Tracks (LCTs)

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Level-1 Trigger System
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Level-1 Trigger System

• ALCT and CLCT find 2-D tracks
• TMB receives and correlates these tracks to make
  a 3-D Correlated LCT
• MPC receives up to 18 LCTs from the different
  TMBs and selects the best 3
• SR/SP receives the 3 LCTs from the TMB

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2004 Test Beam

• 100GeV muons for asynchronous run
• 100GeV pions for synchronous run (along with
  muons)

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ALCT Trigger Modes

• Trigger Mode 0 Accelerator Pattern or Collision
  Pattern
• Trigger Mode 1 Acc. Pattern Only
• Trigger Mode 2 Collision Pattern Only
• Trigger Mode 3 Acc. Or Coll. But Acc. Pattern
  vetoes Coll.

Coll. Pattern Acc. Pattern
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Ghosts and Di-Muons
Ghosts
Di-muons

• Is the converse of a Ghost
• If two LCTs are found and they dont fit the
  definition of a Ghost, then it must be a TRUE
  di-muon

• Occurs when 1 muon returns two LCTs
• Considered the same LCT if it occurs on the same
  strip AND differs by less than two wire groups

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Ghost and Di-Muon Rates
Di-muons Rates
Ghost Rates
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Angle vs. ALCT Trigger Mode
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Different Collision Patterns
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Coll. Pattern vs. ALCT Trigger Mode
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Number of Layers Required?
There Are six possible layers
We can require any number of those six the
default is 4 out of six This means that if any 4
of those layers matches then it is an LCT
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Minimum Number of Layers Required vs. ALCT
Trigger Mode (for Miss4 Pattern)
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Ghost Rates for Miss4 Coll. Pattern
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Conclusions

• Miss4 has high efficiency and provides very good
  discrimination against collision vs. accelerator
  patterns
• Other parameters varied ALCT delay, with and
  without an iron block, old and new ALCT firmware