Zebulun Krahn

1
Straw Tubes and Hall D
Zebulun Krahn
Carnegie Mellon University
Advisor Curtis Meyer Technician Gary Wilkin
GlueX Collaboration Meeting
December 11-13, 2003
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Outline of the Talk

• Work Done to Date

• Gas simulations, endplate production, etc

• Current Work

• Straws, feed-through system, glue tests,
  stringing

• Future Plans

• Electronics, DAQ, prototype testing

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Built Gas Mixing System
Matches JLAB equipment
Can mix up to three gases
Completed June 02
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Garfield Gas Simulations
Lorentz Angle vs. Drift Time
Note 62 -Completed Nov. 02
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Studies of BNL Chamber
Studied performance of chamber with cosmics and
Ru106

• Studied coincidence between tubes

• Studied position dependence

• Dissection to analyze construction methods

Completed Dec. 02 Note 54
Note Very Leaky!
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Prototype Endplates
¼ endplates machined checked at JLAB
Straight and Stereo layers
2-3 man months set-up and machining
Completed June 03
Note 61
Final Accomplishment Successfully closed out a
JLAB RD account
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Current Work
Goal Build a prototype full scale ¼ chamber at
CMU
Since May of 03
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Issues with Straw Tubes
Straw Tube vendors

• Vendors differ widely in price and service

• On preliminary order, as many as ¾ of the
  tubes, not usable

• Shipping of Tubes

How do you cut a 4 mil walled straw tube?
12,000RPM with a 10 mil blade
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Issues with Straw Tube Chambers
They leak!

• Look for design that allows for gas-tight system

• Determine methods of containing leaks that do
  exist

• System design and product testing

• Epoxy testing

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Epoxy Testing
Pressure Gauges
Two important criteria

• Gas-tight seal

• Electrical conductivity

Used a known non-conductive epoxy as
baseline 3M Scotch-Weld 2216
Two candidates, to date might use both

• Resin-Tech TIGA 920-H

• Tra-Con 2907

Held 2.5 PSI for several weeks
Fill Valve
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Feed-Through System
Two main components

• Donuts

• Inserted in end of straw tube

Tube

• Hole and V-notch allow injection of epoxy

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Feed-Through System II

• Feed-Through

• Inserted through
• endplate and
• captures donut

• Chamfer allows space for glue

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Gas Flow System
Towards Gas-Tight goal

• Learned a lot from BNL chamber minimize leaks

• Plenum Design

Gas Seal

• Plexiglas plenum covers

• Stand-offs

• Electronics?

Gas Seal
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Stringing Method
Axle system for stringing

• Whole chamber rotates on axis

• Hook Swivel

• Ball Joint Base Plate

• Tension cables prevent bowing

Note We are building stringing apparatus for
actual full size chamber!
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Sliding Collars
Allow for capture of inner radius of endplates
Lower collar bolted to axle for strength
Upper collar allowed to slide capture, set
screwed in
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Hook Swivel Joint
Steel plug inserted into aluminum axle

• Allows for use of crane/winch

• Mobility

• Allows for rotation of chamber

This steel plug will also be the anchor point for
tension cable/rods
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Ball Joint Base Plate
Steel Plug inserted into aluminum axle

• Captures the bottom of axle

• Allows for rotation
• and more!

• Stereo layers

Base Plate will bolt to floor
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The Axle
Specifications
Limiting factor ability to machine the axle

• Length 10 feet

• Radius 5.5 inch OD

• Wall Thickness ½ inch

• Weight 93 lbs

• Maximal Deflection for 600lb chamber 1.6 mm

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Future Work

1. Actual Manufacture of required pieces

• Donuts, Feed-Throughs, sliding collars, 50 tube
  prototype

1. Electronics

• PC-Boards and Pre-Amps

1. Setting up DAQ

1. Upon completion of prototype, testing will be
   needed

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Conclusion

• Work Done to Date

• Gas simulations, endplate production, etc

• Current Work

• Straws, feed-through system, glue tests,
  stringing

• Future Plans

• Electronics, DAQ, prototype testing