How to trigger to test MDT with cosmic rays? authors

Trigger rate (f ) limited by the DAQ system to about 300 Hz Time encoding programmable window (T ) varied between 2 s and 35 s Cosmic rays rate (r ): If rT <<1 and 700 ns << T << 1/f Number of events in a time interval t with a two multilayer track: N=rTf t =300 s -1 · T( s) ·10-6 s · 300 s-1 · t(h) · 3600 h = 324 T( s) t(h) ev/h

Test in the lab. Trigger: 1.Cosmic trigger. RPC hodoscope (t0s and trigger time available) 2.Random (time unit pulser) 2 BIL chambers ( tubes) Standard threshold. (Noise level? plot) Data collection: cut on word count corresponding to 2 hits in the event. Analysis: -Standard reconstruction for cosmics using all available information from the trigger -Track reconstruction for random trigger samples: event by event fit of t0 -Track reconstruction of cosmic samples with t0 fit (for comparison)

Hit multiplicity Random trigger Encoding window = 2.2 s Recorded events (at least 2 hit in the event required) Number of hits in ML1 vs Number of hits in ML2 in one chamber

Tracking Alghoritm Track fit and t0 determination: 1)Correct all the drift times with respect to the smallest t i drift = t i drift - t min drift 2) Iterative search of the best time to add to the measurements to minimize chi2 Calibration of the rt relation required but... (forthcoming slides) Tube track (pattern recognition): find at least 6 tubes aligned on a possible straight track.

Panettone standard su autotrigger Spettro tdc standard su autotrigger

autocal autotrig

autocal autotrig

Comparison trigger- no trigger Check (cosmic trigger file) drift time diff theta diff

Plot chi2, pchi2

Random trigger Changing time encoding window

Panettone autotrigger (diverso da quello con trigger rpc?) Panettone con hit on pattern vs panettone con hit on track

Window ( s) n. Pattern per hn. Tracks per hforeseen cosmics per h r ATLAS << r Rome Reduction factor 30 f ATLAS >> f Rome Rome daq rate 300 Hz