Triggers for Detectors

1
Triggers for Detectors

• Even though we have two kinds of detectors,
• Fast scintillation counters for timing
• Slower wire chambers for resolution
• There are three coupled general questions
• 1) Are the detectors making hits properly?
• 2) What are all these hits?
• 3) When are the muons?

2
Scintillation Counters

• Timing Measurements for trigger ID
• Example A-Layer Background

• B/C-Layer Background gt 30 ns late

3
What are these hits?

• Hits are mostly background
• Goal to identify and suppress sources
  (shielding?)
• Once the B.D. starts making clean beam, including
  scraping, we think the hits will come from
  collisions.
• Study minimum bias triggers
• We can easily test whether hits are noise and/or
  cosmics (beam off).
• We can test whether hits come from collisions or
  from the tunnel. Procedure is
• Take collisions record currents in wire chambers
  
• Separate the beam record currents in wire
  chambers
• Take collisions record currents in wire chambers

4
Proper Hits?

• How do we know if the detectors are making hits
  properly?
• Observed background features are sensible
• study trigger rate as a function of luminosity
• study time spectrum
• study position dependence
• Assuming 1 occupancy gt we need more than 100K
  minimum bias triggers and some zero bias triggers
  for comparison
• That would provide an integrated time spectrum
  and a notion of the position dependence.
• Identified Muons show high hit efficiency
• Requires 1000 muons to determine if detectors
  are generally working
• a large sample to determine if individual
  counters are working ( O100 muons per counter?)

5
When are the Muons?

• Requires actual muons
• Wed like to eventually tighten the trigger gates
  so as to avoid triggering on background.
• -2.58 sigma gate gt 99 effy
• Uncertainty in center of gate sn(-1/2)
• Uncertainty in sigma s(2n)(-1/2)
• If we want to position the gate to 0.2 ns and
  sigma 5 ns, we need 625 muons per unit
  detector, whatever that is.
• Doesnt matter what kind of muons they are?

6
Old Rates

• Trigger list (10.6) shows
• Muon trigger
• Run 1 L1 26 hz/1030 in etalt1
• L1.5 0.7 hz/1030
• L3 5x10-3 hz/1030 including
  best cal scint mutag _at_ pTgt15 GeV/c
• Call it 5x10-2 hz/1030 for lower pT and wider
  eta?
• Muon Jet (1,5,etalt2) trigger
• Run 1 L1 1.5hz/1030 in etalt1
• L1.5 0.6 hz/1030
• L3 1x10-3 hz/1030 including
  good cal scint _at_ pTgt15 GeV/c and
  similarly high Et jet
• Call it 5x10-2 hz/1030 for lower pT and wider
  eta?

7
Summarize

• Get well on to understanding
• 1) Are the detectors making hits properly?
• 2) What are all these hits?
• May not go so far on
• 1) Are the detectors making hits properly?
• 3) When are the muons?
• Need 105 minimum bias triggers (more is better)
• Need more muons than we expect to get.
• In the long run we need Z-gtmu mu for calibration,
  system efficiency.