Improved timing

• Work in progress - intended more as a logbook than presentation of results*

CDC prototype cosmics data

• 50/50 mixed Ar, CO₂
• Recalibrated MFCs
• Outer plenum added to CDC prototype to prevent leaks
• New pre-production HVB
• 2050V
• Modified preamp4 (terminating resistors removed)
• Prototype tilted at 30^o to enclosing scintillators (scints trigger the daq)

Fed scintillator signals post-discriminator and coincidence signal through then level converter to ECL, then attenuator, into fADC. Took threshold as half peak value (also tried 1/4 and 3/4 peak but these broadened the timing spectra). Used interpolation algo. (The DAQ is triggered by the coinc signal.) The time offset in the first set is equal to the (uninterpolated threshold crossing bin - 10) x 8 ns.

Interpolated signals for many events, ADC value vs time, time in ns after an offset

Histogram of threshold crossing time

Scintillator threshold crossing time

Histogram of threshold crossing time - coincidence time for scintillators and 2D plot

Drift time histogram (for all straws) and expanded about t0

Drift times

Drift times

T0 was taken as the x-intercept of a straight line fitted to the leading edge over 10% to 90% of the maximum value. Here this value is 91.3ns.