1. Overview Goal Study GEM variables in SVAC ntuple
So far in Italy we have not used the GASU
Came to SLAC to learn about the GEM variables and how the trigger works
Prepare for final LAT data analysis
Instrument Analysis Workshop 6 (see Eduardo’s talk)
Data Runs used for this talk
8 tower data (validated run by SVAC)
Run
my reference for this talk
16 tower data (test run)
Run
there could be problems here since it is a test run

2. Number of Triggered Towers
Run
(8 tower data: events, 1803 s)
~78000/1803 = 43 Hz
~800/1803 = 0.44 Hz
(Trigger threshold ~ 100 MeV)

3. Number of towers triggered
Run
(8 tower data)
Most of the events occur in 1 or 2 towers
1 Track
Events
Only TKR triggers
TKR opens
trigger window
CAL opens
trigger window

4. Trigger Rate (16 tower data)
Run
(16 tower data, events in 1804s)
~ 80000/1800 = 44 Hz ! (as expected)
Log Scale
Linear Scale

5. Number of Triggered Towers (16 tower data)
Run
1 Track
Events
Only TKR triggers
CAL is not allowed to open the
trigger window for this test run
TKR opens
trigger window

6. Summary Preliminary Look at Trigger rates for 16 towers
agree with expectations
Recommendation
add this plot to the SVAC reports
Future
Plan to study GEM variables when LAT data is available
will continue developing scripts using existing data