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 (144+144 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