How to trigger to test MDT with How to trigger to test MDT with cosmic rays?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

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BIL

MDT

300~70

cos

112

Test in the lab.

Trigger:

1. Cosmic trigger. RPC hodoscope (t0’s 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 triggerEncoding 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

tidrift= ti

drift - tmindrift

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

autocalautotrig

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

Plot chi2, pchi2

Random triggerChanging 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 h n. Tracks per h foreseen cosmics per h

2.2 750

3.2 970

6.4 1900

12.8 3990

25.6 7182

rATLAS << r Rome Reduction factor 30

fATLAS >> f Rome Rome daq rate 300 Hz