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May 26, 2011 FDC meeting


  1. Production (Dave)
    • HVAC status
    • Cathodes
    • Wire planes
    • Other
  2. Engineering (Bill)
    • Pin rail modification: CMM measurements
    • Rigid-flex gluing
    • Other: encoder, parts/tools for chamber assembly
  3. Electronics (Fernando, Chris)
    • Update
    • Package grounding scheme
  4. Chamber testing (Beni)
  5. Other


Participants: Eugene, Bill, Dave, Chris, Simon, Beni, Caleb Massey (summer student) and Lubomir.


- Dave: HVAC didn't work starting Tuesday evening (likely), and today Ron Bartek replaced a fuse in line with the transformer that failed before, but was replaced with a more powerful one. So, the same problem again; people from the clean room company will be there next week. Wednesday and Thursday morning the humidity was 50-60% and all the gluing was postponed.

- Cathodes: two ready, except gluing the daughter cards to the frame, that will be done today (conductive epoxy to the copper surface and Scotch-weld epoxy on the sides). Third one is ready for gluing the rigid-flexes. The fourth has been tensioned and the frame glued. Fifth cathode foil is ready, as well. End window: Anatoly is finishing the first one.

- Wire frames: the two wires of the first wire frame were fixed. We will keep it on the table to study the sensor problem: today we had problems not only with the field wires, but also with the sense wires. Dave will coordinate with Ron Bartek how to turn off the AC units to study the vibration effects. Caleb will work on this problem. Eugene pointed out that before trying to mitigate the vibrations we have to make sure that they are the origin of the sensor problem.


- The second modification of the pin rail was successful. Results from CMM measurements of the front pin positions are shown at page 567; the width of the distribution is 10u (sigma). New dowel pins were put on the rail to make sure the two parts of top plate can't move. Bill will install monuments on the table and strong-back that will help fixing wires. Today we had to align the strong-back so that the new replaced wires are parallel to the rest.

- The new tool for gluing the rigid-flexes works reliably only with the tinned flexes. On the first two cathodes we used tinned ones, except at two places. Bill thinks it is the new foot that has to be modified to fix the problem, and will try to do it a.s.a.p. After that we will make again several samples and also work on the testing cathode to investigate the problem. Eugene insisted that before continuing with the production we have to make sure the tool works as before. All the samples that we investigate before were made with the old tool, that in principle we can also use but we had some problems with the foot attachment.

- Encoder: Larry was yesterday at Blue Crab and offered us a replacement encoder from Renishaw for ~$2k, resolution of 0.5u. Bill will look into the technical data; also the mounting of the scale on the encoder rail will be tricky.

- Gussets for the production chamber package: Bill explained us his ideas for a tool that makes the gusset as one ring from carbon-fiber-glass material.


- Chris asked if we have decided about the type of the connectors (tinned/untinned); we have not. He has 166 more rigid-flexes to be populated. All the signal cables should arrive by middle of July. Most likely they will be stored (after testing in 126) at the new staging area that has AC. Chris is also working on the new testing card with the LEDs on the top that will make rigid-flex testing easier.

- We started discussing the scheme for grounding the packages. While different people have different ideas, everybody agrees that we should prototype it first. For that purpose we will use Cu-Be clips (from TechEtch) that can be easily attached/detached to different places around the frame perimeter, and to which one can solder shielding mesh or wires.

Chamber testing

- Beni collected the stuff for the testing at Blue Crab again and it was transported right after the meeting. Last Friday we moved the full-scale prototype there, as well. We will use different parts from the prototype for the first production chamber assembly. The Norrell rings will go on the bottom, and the aluminum plates that are now on the prototype will be on the top of the assembly. Instead, on the prototype we will put one of the two lexan sheets. We will use also the six steel pins and all the hubs from the prototype; they will be replaced with other threaded rods. We discussed also if we will need a rack for testing at Blue Crab; due to space limits at the room there we will decide about this later.