Straw Contribution to Material Budget

1
Straw Contribution to Material Budget

• OTR Module Material Budget

Module Element X / X0
Carbon Facing (4 x 80mm) 0.112
Panel Core (2 x Nomex) Panel Core (2 x Rohacel) 0.110 0.142
Aluminum Foil (2 x 20mm) 0.056
Glue joints (panel) 0.050
2 x Straw Layers 0.276
Glue joints (straws-panels) 0.050
Total Nomex Total Rohacel 0.658 0.690
Xstraw / Xmodule 40
Minimize Straw Material, but
2
Straws Gas Tightness
, without compromising the straw gas-tightness
Having gas-tight straws gives the possibility to
protect the counting gas from impurities entering
the gas envelope around the straws
3
New Straw Material
Replace 25?m Al ? pre-laminated 15mm Al glue
25mm Kapton
Avoid Aluminum-Kapton joint in winding/glueing
without significantly affecting straw material
budget Xstraw / X0 0.138 ? 0.115
4
New Straw Material (contd)
40?m Kapton XC-160
Laminated Kapton-Alu
(Straw winding material budget 0.12 of 1X0)
5
Straw Tests
Test sample of 100 straws with new
pre-laminated AlKapton foil delivered by LAMINA
Ltd. in August

• Tested successfully at Heidelberg and NIKHEF gas
  tightness within specs
• No difference observed between straws cured at
  room room and higher temperature

• These straws are acceptable
• Test reliability/reproducibility of LAMINA Ltd.
  batches

6
Straw Tube Summary

• Winded tubes (Lamina Dielectrics Ltd.)
• Materials (from inner toward outer)
• 40?m Kapton XC-160
• 25?m Kapton XC-100
• 12?m Aluminum

• CF4 presence ? chose polymer as cathode
  material
• Kapton XC-160 (25 volume doping with Carbon,
  370 W/cm2 ? 12 KW/m)
• Passed extensive ageing tests
• Second layer of Kapton improves gas-tightness
• a permeability of 10-6 m/bar/s gives less than
  5 volume loss per gas exchange
• Aluminum layer decreases level of analog
  (straw-to-straw) cross-talk
• Aluminum presence reduces cross-talk from 1.8
  to 0.5