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?

• Front disc (without isometric view)
  • [ADDRESSED] section B-B: inner plexiglass holder -> why the step
  • [OPEN QUESTION] inner shell: how will it be attached?
  • Is there anything foreseen for (grounding) standoffs?
  • Label to mark the start of each layer?
  • Survey mark for alignment at outer radius?

• Front disc (with isometric view)
  • The holes:
    • what are the two holes on the top, outside the gas volume?
    • 6 holes starting at 0 degrees outside the gas volume are fiducials?
    • 6 big holes at the top are for gas exaust (main volume to outside plenum)?
    • 12 holes starting at 15 degrees are rods?
    • 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)?
    • 24 tap holes (12 starting at 5 degrees and 12 starting at 25 degrees) as standoff for the swiss chees plate. Will this be enough for gas-tightness?
    • We noticed the 6 gas-thru holes in the top are at a different radius (larger) than the other holes, why larger?
    • Also in the bottom area we see holes at 2 slightly different radii, what is the reason for that?
  • 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?

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.