CDC prototype runs at CMU

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The prototype runs at CMU were made with the prototype sitting along the top of one scintillator. The scintillator is only slightly larger than the prototype.
Run 2016 at JLab was a cosmics run with the BCAL trigger.
The CDC runs at CMU used two scintillators in coincidence, the scintillators were above and below the CDC, separated by approx 2m. We had two sets of scintillators, one set are approx 9" wide and 6ft long, the smaller set are approx 9" x 19". Using the small scintillators, the cosmic rays would have been much closer to vertical than for the recent prototype and JLab measurements. Using the large scintillators, oriented parallel to the straw tubes, the cosmic ray angles would be similar to those with the recent prototype setup and at JLab.

First article/prototype preamp & HVB were used for all but one of the prototype runs. One run was made using JLab preamp & HVB with all other settings unaltered since the previous run; as expected, the resulting data look very similar.

Recent prototype runs

Prototype, 2100V, 50/50 Ar/CO2
max amp
drift time
Prototype, 2100V, 55/45 Ar/CO2
max amp
drift time
Prototype, 2100V, 55/45 Ar/CO2 JLab electronics
max amp
drift time
Prototype, 2100V, 60/40 Ar/CO2
max amp
drift time

CDC measurements at JLab

CDC straw 496 2100V JLab run 2016 (cosmics, BCAL trigger)
max amp
drift time
CDC (sum) 2100V JLab run 2016 (cosmics, BCAL trigger)
max amp
drift time

CDC measurements at CMU in 2013

CDC (72ch) at CMU, 2100V, 50/50 Ar/CO2 with large scint paddles along the length of the CDC
max amp
drift time w terrible fit


CDC at CMU had MPV at ~190 for 2110V, 50/50 Ar/CO2.

CDC wire is 20um and straw radius is 0.77cm, prototype wire is 17.8um (7 mil), and prototype straw radius is 0.79375cm.

from Blum & Rolandi
root [4] Double_t prototype = 1.0/log((Double_t)0.79375/(Double_t)17.8)
root [5] Double_t cdc = 1.0/log((Double_t)0.77/(Double_t)20.0)
root [6] prototype/cdc
(double)1.04723572482852867e+00
root [0] Double_t prototype_observed_mpv = 204
root [1] Double_t cdc_observed_mpv = 172
root [2] prototype_observed_mpv/cdc_observed_mpv
(double)1.18604651162790709e+00