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

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

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

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  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 • 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 • 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

  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. 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

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