Helium Bag Readiness

1
Helium Bag Readiness
2

Scattering chamber Clamshell flange (not here
yet) Coffee can collimator
20 H target
Electron Beam
?E Plane E Plane
0.005 Polyurethane Balloon (sides only)
10 ?m mylar foil

Front wire chamber
10 ?m Mylar Balloon
Upgraded Rear wire chamber
3
Transport of low energy protons (200-600 MeV/c)
from target through BigBite to MWDC

• Transport protons using helium a few mm above
  atmospheric pressure. Almost as good as using
  vacuum. More convenient and cheaper.
• Use company that makes polyurethane helium
  filled balloons of all shapes and sizes.
  Polyurethane skin 0.15 - 0.005 thick. Will lose
  helium slowly over a few days. Test leakage rate.
• Flexible enough to have limited angular
  movement of BigBite. Show sample material.
• Stretched over circular snout fixed to
  scattering chamber and hot glued
• Stretched over rectangular angle aluminum
  attached to wire chamber frame and hot glued
• Investigate stability of the system and
  radiation damage of polyurethane and glue and
  measure helium loss rates.

4
(No Transcript)
5
Shape of Polyurethane Helium Filled Balloon
Stretch over aluminum support frame and hot glue
poly and terminate with 10 ?m mylar
Stretch over coffee can collimator and hot glue
157.8 cm
18 Deg
Side view
33.8 cm
18 Deg
82.3 cm
5 cm
122.9 cm
33.1 cm
5 cm
2 Deg
25.2 cm
Bottom view
38.7 cm
44.0 cm
206.2 cm
6
Test on Balloons

• Need to always keep inflated above atmospheric
  pressure
• Monitor during the experiment. This is crucial.
• Mechanical stability of of joints and seams and
  leak rates
• On the polyurethane balloons and mylar balloons
• Conduct radiation damage test on both types.
• Effects on hot glue joints
• Effects on seams
• Effects on polyurethane

7
Balloon Milestones

• March
• Design/Draft shape of polyurethane helium
  containment balloon
• Design Coupling balloon to chamber
• Order sample polyurethane balloon material
• April
• Order prototype polyurethane balloon ( 0.005
  thick) and prototype
• and 10 ?m mylar pillow shape balloon.
• Order two extra balloons for protecting PMTs from
  helium leaks
• Design Helium gas handling system for balloon
• May
• Test all prototype balloons for helium leak rate
  and radiation damage
• Test gas handling system.
• June-July
• Evaluate test results and make modifications.
  Decide on many balloons and type. Purchase final
  balloons
• August
• Assemble flanges, collimator, window, gas
  handling system, and balloon for further testing.
• September , November, and December
• Continue checking out system and measure loss
  rates over long term