September 14, 2011 Tracking CDC/FDC

Meeting Time and Place

Wednesday September 14, 2011 at 11:00am At Jefferson Lab, the meeting will be held in F326

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Agenda

Announcements
Collaboration Meeting
1. CDC status talk
2. FDC status talk
3. Other talks? 125FADC?
FDC Update logbook
CDC Update
1. Construction status
2. Prototype results with cosmics (histograms moved to minutes)

Minutes

Participants: Curtis, Naomi, Eugene, Beni, Simon, Dave, Lubomir, Elton, Mark, Tim

Collaboration meeting

In addition to the FDC and CDC construction status talks, Beni would like to make a presentation on the positioning of the FDC modules.

FDC Update

Last week we disassembled the first cell in the first package then replaced a broken wire and fixed two cathode channels by re-heating the conductive tape.
Then we stacked in the package two cells: in total four cathodes, two wire frames, and two end windows. They were running with gas and HV since last Friday. All the channels on the first cell were checked again and were OK. On the second cell (the new one) we found two problems: no signal from one wire and one noisy wire. In addition we had some increased gas leakage.
Therefore, today we disassembled the two cells to replace all the O-rings and fix the two wires. The missing signal was due to a broken wire. The noise was visible not only on that wire but also on clusters of top and bottom strips. Thus, the top, bottom strips, and the wire define three lines that cross at one point. Looking at the sense wire at that point one could see some kind of imperfection, but it was difficult without microscope to identify the problem. The two wires were replaced.
The third cell is ready, as well, so the plan is to assemble all the three cells.

CDC Update

Straw installation - the remaining Al components arrived and have been checked, cleaned and glued into straws. We expect to finish straw installation in the next few days. After that the CDC will be moved to its horizontal position ready to install the outer hubs and shell. The strips to make the outer hubs are now ready to be glued into the endplates.
Remaining parts/manufacturing - we had a meeting with Tim and Slava last week to arrange who would purchase or make the remaining CDC parts.
Naomi presented some recent results with the prototype using improved triggering for cosmics (below).

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

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 (hit threshold=5sigma) this value is 91.3ns.
50/50 Ar/CO₂ results at 2050V