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

4. CMS (Compact Muon Solenoid)

5. 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

6. 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

7. Trigger Architecture
Need Trigger System to filter out data

8. Cathode Strip Chambers (CSC)
Provide 3-D tracks of charged particles called Local Charge Tracks (LCT’s)

9. Level-1 Trigger System

10. 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 LCT’s from the different TMB’s and selects the best 3
SR/SP receives the 3 LCT’s from the TMB

11. 2004 Test Beam 100GeV muons for asynchronous run
100GeV pions for synchronous run (along with muons)

12. 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

13. Ghosts and Di-Muons Ghosts Di-muons Is the converse of a Ghost
If two LCT’s are found and they don’t fit the definition of a Ghost, then it must be a TRUE di-muon
Occurs when 1 muon returns two LCT’s
Considered the same LCT if it occurs on the same strip AND differs by less than two wire groups

14. Ghost and Di-Muon Rates
Di-muons Rates
Ghost Rates

15. Angle vs. ALCT Trigger Mode

16. Different Collision Patterns

17. Coll. Pattern vs. ALCT Trigger Mode

18. 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

19. Minimum Number of Layers Required vs
Minimum Number of Layers Required vs. ALCT Trigger Mode (for “Miss4” Pattern)

20. Ghost Rates for Miss4 Coll. Pattern

21. 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