L1 Trigger for ACDC

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L1 Trigger for ACDC
VELO ACDC Software Meeting 01/20/2006
Jianchun (JC) Wang Syracuse University
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Trigger for ACDC

• L0 scintillation counter (prime trigger)
• Can be used either on straight through track (by
  moving counters) or on interaction.
• Rates can be varied by changing either hole size
  (2 available) or moving along beam.
• L1 software trigger
• Number of hits trigger
• No requirements on alignment information.
• Requires stability and low noise.
• Vertex (backup to number of hits trigger)
• No strong requirement on beam condition, less
  dependent on noise performance.
• Require alignment information, may bias the
  alignment study.

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L0 Scintillation Trigger
Trigger 1 A0 ? (A1?A2) ? (B1?B2)
efficiency90 Trigger 2 A0 ? ((A1?B2) ?
(A2?B1)) efficiency60

• The scintillation counters are being
  constructed at Syracuse.
• Two pairs of B type with different sizes of
  hole (5?5cm2 and 3?3cm2) are made to incorporate
  beam size.

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Number of Hit Trigger (I)

• Requires that the sum of maximum number of R hits
  per station and maximum number of f hits per
  station be at least 20.
• The noise level is about 0.1. Only first 10 half
  stations are used. The selection efficiency is
  50. Essentially no bkg is selected.
• It favors events with more tracks, which is
  consistent with our goal.
• It also keeps events with interaction happened at
  the last stations.

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Number of Hit Trigger (II)

• Requires that total number of hits of all 10
  stations be at least 100.
• The noise level is about 0.1. Only first 10 half
  stations are used. The selection efficiency is
  67. No bkg is selected.
• It favors events with more tracks, and
  interactions happened at the beginning of the
  telescope.

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More on Number of Hit Trigger

• The two triggers are correlated, although not
  fully. Both favor more tracks in the event.
• Currently I keep both in the trigger 51?67
  71.
• Noise simulation in MC might be too ideal.
  Different stations have different noise
  performance. A calibrated noise level will be
  subtracted.
• If the noise level is much higher than 0.1 we
  can use hits with higher pulse height for trigger
  only.

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Status

• Code runs under DaVinci as a normal analysis
  program.
• Need to modify the code to have trigger
  interface.
• The CPU time will be measured. More MC data may
  be needed.