1. TriggerLatchingEffLAT_2005-05-13.ppt1 Status report of overall Trigger and Latching Efficiencies study Instrument Analysis meeting, May 13, 2005 Tsunefumi Mizuno (Hiroshima Univ./SLAC), Hiromitsu Takahashi (Tokyo Univ.), T. Kamae, G. Godfrey and H. Tajima (SLAC)

2. TriggerLatchingEffLAT_2005-05-13.ppt2 Test Configuration “Method 1”: without muon telescope Select muon-like events with TKR (keep bias as small as possible; use only several top layers and the bottommost one) Test of intermediate layers Comparison with Gleam simulation (direction/position measured by TKR) “Method 2”: with muon telescope Select muon-like events with muon telescope (plastic scintillators) Unbiased overall efficiency study Comparison with Gleam simulation (require muons to cross plastic scintillators) Reference: Tune’s presentation at April 29 th Instrument Analysis Meeting. http://www- glast.slac.stanford.edu/IntegrationTest/SVAC/Instrument_Analysis/Meetings/04292005/TriggerLatchingEffLAT.pdf single tower/ two towers Objective: measure and monitor local/overall “trigger/latching” efficiencies with minimum interference with LAT I&T activity two towers

3. TriggerLatchingEffLAT_2005-05-13.ppt3 Muon Telescope one small and one big scintillators above the Two Towers Two Towers inside the black sheet The other small/big scintillators below the towers Reference: configuration description: http://www.slac.stanford.edu/~mizuno/GLAST/FM/muonTelescope.ppthttp://www.slac.stanford.edu/~mizuno/GLAST/FM/muonTelescope.ppt photos: http://www.slac.stanford.edu/~mizuno/Photos/muonTelescope/thumbnail.html TkrFMB TkrFMA x y

4. TriggerLatchingEffLAT_2005-05-13.ppt4 Preliminary Result (1) – Method 1 with single tower data -- Latching/Trigger efficiencies>=95% (consistent with gap size) good agreement with simulation with measured position/direction of muons (bad strips to be taken into account) Run id: 135001042 (baseline run with TEM diagnostic ON, 158k events) Event selection Criteria: One and only one cluster in top 3 layers and the bottommost one The number of clusters<=1 for all layers (will be off in next step for unbiased selection) Acceptable least-square fit to a straight line (rms<0.2mm) X-planes Y-planes latching efficiencies normalized to 1 plane number Eff. of each layer latch efficiency trigger efficiency Gleam prediction (error comparable to data) test region

5. TriggerLatchingEffLAT_2005-05-13.ppt5 Preliminary Result(2) -- Method 1 with two tower data -- Run id: 135002153 (two tower with TEM ON and muon telescope, 213k events) Event selection criteria Similar criteria for one tower, require track pass from the top of TkrA to the bottom of TkrB Latched/triggered event ratio of each ayer X-planes plane number TkrA btm top TkrB btm top will simulate muons of measured position/direction and normalize data to measure efficiencies as done in slide#4. will also analyze/simulate events coincide with muon telescope (“method2”). See also Gary’s talk. planes used for event selection (The ratio degraded down to 0 since track missed the layer)

6. TriggerLatchingEffLAT_2005-05-13.ppt6 Future Plan Simulate with bad strips (Anderson already gave us an instruction) and compare with data in more detail. Analyze more data (to make statistical error smaller and evaluate efficiencies to ~1% level) Look at events coincide with muon telescope in detail. Simulate two tower configuration (for both methods 1 and 2) and compare with data. Automate the analysis for efficiency monitoring.

7. TriggerLatchingEffLAT_2005-05-13.ppt7 Acknowledgement T. M. and H. T. would like to thank to Gary Godfrey (muon telescope preparation/data taking) Jamas Chiang (FileSource class implementation) Toby Burnett (surface muon generator) Leon Rochester and Anderson Borgland (valuable instructions in Gleam simulation) And all others (extensive work of hardware/software)