August 31, 2011 Tracking CDC/FDC

Meeting Time and Place

Wednesday August 31, 2011 at 11:00am At Jefferson Lab, the meeting will be held in F326

Connections

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Agenda

1. Announcements
2. FDC Update logbook
3. CDC Update

Minutes

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

FDC Update

1. During the hurricane everything in the clean room was packed/covered. Fortunately we didn't lose power and the particle counts and humidity were OK.
2. We started stacking the first production package. The first cell is installed, flushing now with gas. For the first package we have all the cathodes and end-windows ready. Another wire plane will be ready by the end of the week, so we need four more wire planes that we expect to produce by the end of September.
3. The plan is to do some tests with the first package at Blue Crab and then move it to JLab for the full tests. Beni: we will not have electronics for all the cathode channels, but hopefully we will have enough TDCs for all the wire channels.
4. Beni for the second cell tests at EEL: don't understand the time-to-distance dependence; it's not linear as expected for 90/10 Ar/CO2. Could be a field configuration problem due to geometry or not high enough HV.
5. On the chamber that is installed now in the first package we didn't change the HV capacitors because it showed low leakage current and the capacitor problem was identified later. Eugene asked if we still can replace these capacitors. Lubomir: it will be difficult because we can damaged the wires, especially if we have Humi-seal on the caps. To replace the wires we will need to remove the epoxy from the board.

CDC Update

1. Straw installation - the final row (28) was started this week, 20 straws are in place so far. All the straws for the layer have been cut. When gluing in the straws yesterday the techs noticed that the straws were approx 1mm shorter than usual, this was tracked to the end-stop on the cutting bench having been displaced slightly, so the straws had 2mm gap rather than the usual 1mm. 90 straws have had donuts glued in already. These are being glued into the chamber with a small wedge underneath to maintain the gap at the upstream (Al) end. This will later be filled with nonconducting epoxy. For the 120 remaining donutless straws we will test to see if the donuts can be retracted 0.5mm each before gluing them in place whilst retaining the correct orientation.
2. Tension tests - the wire tension was remeasured in rows 1-4. No more broken wires were found, the one wire found with low tension (20g) will be removed and restrung. All wires were measured to have the same tension that they had during measurements in June.
3. Gary has been working on the clamshell hub, joining 3 sections approx 4 ft long by splicing with a separate 3 inch long piece of G10. After gluing in the splices and bending the hub to shape the splices snapped. He will try again with aluminum splices.
4. Tim reported that the cheeseplate contract has been awarded to a local company.
5. The front central hub has arrived at CMU.
6. Tim would like to call a meeting later in the week to discuss the drawings and remaining components, including a labelling system (from Beni) for the HVB standoffs.