Minutes-5-19-2008

FDC/CDC Meeting

Date: May 19, 2008

Participants: Daniel, Simon, Fernando, Mark, Beni, David, Curtis (phone), Yves (phone)

Next Meeting: June 2, 2008 @ 1:30 p.m.

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FDC ASIC Dynamic Range Characterization

 - Simon has been continuing to analyze cosmic ray data acquired with the
   small-scale prototype.  Recently he has found that the cathode strips
   seemed to be plagued by random high-frequency noise.  Simon has been
   working on algorithms to cut this noise out so that our amplitude
   and charge plots are not biased.  His first cut was to require a 
   minimum total charge in the FADC spectrum (5-microsec) wide of 600 pC.
   The noise events have a distribution that is basically centered about
   zero (qualitatively).  
 - During the discussion, we laid out several alternative cuts and
   requirements to try to better separate the noise events from the good
   events.  Note that Simon noticed that the anode signals are not as
   prone to noise as the cathode strips.  This may be because the chamber
   grounding configuration has changed when Simon reassembled it with
   the 2 micron thick Cu planes.  This will be looked into.
 - Fernando has all of the hardware necessary to characterize the gain
   of the ASIC boards, the shaper, and the 18-m long cable.  He will
   perform measurements this week and circulate the results.

CDC ASIC Dynamic Range Characterization

 - The CMU folks have tilted the CDC prototype to 60 deg (from the
   horizontal) and have been collecting pulse samples as a function
   of HV.  These samples have been compared to the 0 deg configuration.
   At the nominal operating point chosen, it appears that the pulses
   are saturated, pointing to running (possibly) at too high a gain, and
   also to the ASICs/shaper having too high a gain.

Minutes prepared by Daniel. Send any comments or corrections along.