CDC time spikes

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Prototype at 2100V, 50/50 Ar/CO2

Tilted detectors


Trigger signals

Scint and coinc logic signals, scope triggered on coinc (magenta)
Same, with TI busy signal (green)
Same, different timebase


Histograms of threshold-crossing bins in central bank of 16 straws, different thresholds (ignore the histo titles)

ADC-value=150 crossing (~approx ped + 5sigma)
3.5sigma crossing (approx ADC value 112 = (55 + 3x16.5))
ADC-value=100 crossing


Histograms of ADC value=100 threshold-crossing bins in individual straws (search started at bin 160)

ADC-value=100 crossing


Same data after more normal analysis (Search forward to find pedestal+5sigma crossing, then backwards to find 4sigma and then 1sigma crossings)

5sigma crossing
4sigma crossing
1sigma crossing
extrapolation to local pedestal crossing
drift time (ns)


2-d histograms of ADC value=mean pedestal+50 (= c. 105 to 110) threshold-crossing bins in each straw vs same for one particular straw Data are plotted for events with non-zero threshold-crossing in both straws. The histos in each image (set of plots) are arranged as in the prototype, these are the images for the bottom row of straws.

straw 9
straw 1
straw 0
straw 8

Noise run (triggered on 20us pulser) ADC=100 crossing bins

ADC=100 crossing bin, triggered on pulser
3.5sigma crossing bin, triggered on pulser
5sigma crossing bin, triggered on pulser

Noise run (triggered on scintillator when prototype was not above/beneath it) ADC=100 crossing bins

ADC=100 crossing bin, random trigger
3.5sigma crossing bin, random trigger
5sigma crossing bin, random trigger

Noise run (triggered on scintillator when prototype was not above/beneath it) 2-d histograms of ADC value=mean pedestal+50 (= c. 105 to 110) threshold-crossing bins in each straw vs same for one particular straw Data are plotted for events with non-zero threshold-crossing in both straws. The histos in each image (set of plots) are arranged as in the prototype, these are the images for the bottom row of straws.

straw 9
straw 1
straw 0
straw 8

Some events from the previous cosmics run with data from all ADCs plotted on same graph. Trigger time is sample 200.

Event 8
Event 8, zoomed in
Event 9
Event 9, zoomed in
Event 12
Event 12, zoomed in


From a run with HV = 0

Event 5, different offset added to each fADC channel (to separate them)
Event 5, zoomed in
Event 5, histogram of samples where a single channel has a jump in value of 10 or more since previous sample
All events, histogram of samples where 18 or more channels have a jump in value of 10 or more since previous sample
All events, zoomed in