June 30, 2009 CDC Meeting

Meeting Time and Place

Tuesday June 30 2009 at 11:00am At Jefferson Lab, the meeting will be held in room ARC 428

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Agenda

1. CDC Endplate Drawings Drawings
2. CDC Donut/Feedthru Drawings Donuts

Questions/notes on the end plates

• Back disc (without isometric view)
  • Point 5: counter-bore for stereo layers, why such a large diameter (.578), while diameter of the head of the feed thru is .500 in.?
    • Not required, we will change it to .531
  • Section B-B: why is the groove so deep (0.080 = 1/3 of the plate thickness)?
    • Wish to get as long a glue joint as possible
  • What about the inner gas shell? Is there supposed to be a groove for the inner shell?
    • We discussed this with Curtis at JLAB 7-7-09. We will put a C'bore for solid carbon fiber or fiberglass tube in upstream plate. Downstream will glue shell to inner bore of plate. Slav will create a layout showing this.
  • Is there a label foreseen to mark the start of each layer?
    • Yes, this is now on the drawing.
  • Is there a survey mark on the outside diameter of each plate for initial alignment?
    • Curtis to discus with Gary what type of mark and where.

• Back disk (with isometric view)
  • We assume that inner/outer gas shell is not drawn?
    • yes
  • The holes:
    • What are the 2 top holes (outside gas volume) for? (2x .265)
      • Lifting features
    • 2 holes at +-50 degrees outside gas volumes are fiducials?
      • Yes
    • 12 holes starting at 15 degrees (I count counter clockwise) are for rods?
      • Yes
    • 6 remaining holes are for getting the gas inlets to the downstream end-plenum? Why are they so "far" away from the rods? We thought they are going to be cable-tied to the rods? Why is the diameter of those holes not larger?
  • Are there standoffs for the mylar sheet?
    • We anticipate that these will be rohacel rods glued to end plate.

• Front disc (without isometric view)
  • [ADDRESSED] section B-B: inner plexiglass holder -> why the step
    • Step will be move to inner surface for gluing inner shell
  • [OPEN QUESTION] inner shell: how will it be attached?
    • Glue, Slav to produce layout
  • Is there anything foreseen for (grounding) standoffs?
    • After discussions with Fernando, the grounding will be done outside of the gas plenum.
  • Label to mark the start of each layer?
    • Yes
  • Survey mark for alignment at outer radius?
    • To be specified by Curtis and Gary.

• Front disc (with isometric view)
  • The holes:
    • what are the two holes on the top, outside the gas volume?
      • Lifting
    • 6 holes starting at 0 degrees outside the gas volume are fiducials?
      • Yes
    • 6 big holes at the top are for gas exaust (main volume to outside plenum)?
      • Yes
    • 12 holes starting at 15 degrees are rods?
      • Yes
    • We found again 6 holes relatively close (but not close enough we think) to the rods: gas to the downstream end-plenum? Why is diameter not larger (like 6 upper ones)?
      • The 6 on top are for exhaust. They are bigger to keep pressure from building. The gas tubes can be tied off in multiple places to the support tubes.
    • 24 tap holes (12 starting at 5 degrees and 12 starting at 25 degrees) as standoff for the swiss cheese plate. Will this be enough for gas-tightness?
      • There are also 12 standoffs additional. Total of 36. They are less than 4" apart. The plate can be 5/8" thick. Should be good.
    • We noticed the 6 gas-thru holes in the top are at a different radius (larger) than the other holes, why larger?
      • Same as above
    • Also in the bottom area we see holes at 2 slightly different radii, what is the reason for that?
      • Which 2 holes?
  • Gas: we think there are 6 holes missing in the top of this end plate: bleeding holes so the gas can "leak" into the main gas volume between the straws, are we missing something here?
    • This needs a bit more discussion as we are not positive how the gas will flow. We may put features in both areas until an analysis can be don. Then plug holes we do not need.

Notes

• CDC Front Disc
  • Section B-B, what is the small step? Small step to engage the inner hub.
  • What will hold the inner tube to the end plates? Without the gas plenum, there is 3/8" on radius and after the polycarbonate, at least that much.
  • OPEN How thick is ring on which inner tube is glued?
  • Threaded inserts? These are for screwing in the gas plenum. Used in conjunction with the above mentioned groove to position plenum.
• Holes Sizes

• Crimp pin to plastic insert - CMU will think about the fit.
  • Plastic inserts are all the same, make go 0.1" past the feed-thru.(Looks like 1.2).
  • Gary wants a slip interference fit. line-to-line fit.

• Plastic Insert
  • Want the counter-bored shoulder.

• Donuts and feed through both have glue port and vent.
• Feed through groove moved from 0.19 to 0.25" from tip on both Noryl and Al.
• Depth of drilled holes changes (Noryl is 0.56", AL is 0.7").
• Material for injection molding, HallB used glass-filled Noryl, What did Hall A use, does Eugene know?
• Get Mac-Master Carr part & grade for Noryl for donuts and feed thrus.