November 29, 2002 NIKHEF-1 Hans de Vries Status RF foil RF/vacuum foil  Purpose  Production methods used  Deformations: static - overpressure  Electrical properties  Coating  Cables  Interference Silicons

November 29, 2002 NIKHEF-2 Hans de Vries RF and vacuum separation foil(1) Protect against RF effects Wakefields in Vertex vessel EMI in detectors Good conductivity Why? Separation extreme-high-vacuum of LHC from Detector vacuum – (outgassing electronics, cables, NEG coating,…!) Stiffness Physics requirement: Restrict amount of material –preferably low-Z (small radiation length) Thin Detectors should overlap –Alignment –Stereo angle Complicated shape

November 29, 2002 NIKHEF-3 Hans de Vries RF and vacuum separation foil(2) Production from foil: Requirements for: Stiffness Welding Thickness Shape Choice of material Methods to be used

November 29, 2002 NIKHEF-4 Hans de Vries VELO Overview

November 29, 2002 NIKHEF-5 Hans de Vries Secondary vacuum box

November 29, 2002 NIKHEF-6 Hans de Vries Secondary vacuum box (detail)

November 29, 2002 NIKHEF-7 Hans de Vries Material data: Material:AlMg3 Young's modulus: MPa Poisons ratio:0.33 Shear Modulus:27.3 GPa Yield Strength: MPa Ultimate Strength: MPa Electrical conductivity:1.9x10 7 ohm -1 m -1 (almost 50% of pure Al) Weldable!

November 29, 2002 NIKHEF-8 Hans de Vries Production of RF foil –Hot gas forming Deform at 350° Formation speed –Superplastic deformation Deform at 520° –One cycle, p  10 barCrystal growth, melting, Vacuum leaks Methods investigated: –Cold formation Press- anneal at 420° (or 350 °) - cool- press … –More than 15 cycles, 2 – 100 bar –Two or more moldsTime consuming –Explosive formation Uncontrolled

November 29, 2002 NIKHEF-9 Hans de Vries Full size foil Full size rf foil with reinforcement ribs

November 29, 2002 NIKHEF-10 Hans de Vries 3D measurement set-up Exploded view

November 29, 2002 NIKHEF-11 Hans de Vries Measurement of one slot 20 x 5 measurement points

November 29, 2002 NIKHEF-12 Hans de Vries 3D result for one slot

November 29, 2002 NIKHEF-13 Hans de Vries Projection for one slot Variation in depth of one slot ± 0.1 mm

November 29, 2002 NIKHEF-14 Hans de Vries Minimum depth along foil

November 29, 2002 NIKHEF-15 Hans de Vries Minima enlarged Variation in depth for all slots: ± 0.2 mm

November 29, 2002 NIKHEF-16 Hans de Vries Close-up minima Position of slots along foil: 0.1 mm

November 29, 2002 NIKHEF-17 Hans de Vries Thickness measurements Along central beam line: mm mm Largest curvature point: 0.15 mm

November 29, 2002 NIKHEF-18 Hans de Vries FEM analysis: input Input model for the FEM calculations

November 29, 2002 NIKHEF-19 Hans de Vries FEM analysis: down 10 mbar over pressure in primary vacuum Maximum deflection 0.88 mm in “floppy part” of foil

November 29, 2002 NIKHEF-20 Hans de Vries FEM analysis: up 10 mbar over pressure in secundary vacuum Maximum deflection 1.04 mm in “floppy part” of foil

November 29, 2002 NIKHEF-21 Hans de Vries Deflection measurement

November 29, 2002 NIKHEF-22 Hans de Vries FEA for full box (1)

November 29, 2002 NIKHEF-23 Hans de Vries FEA for full box (2)

November 29, 2002 NIKHEF-24 Hans de Vries FEA for full box (3)

November 29, 2002 NIKHEF-25 Hans de Vries FEA for full box (4)

November 29, 2002 NIKHEF-26 Hans de Vries RF pick-up (1) Foil thickness 30  m Al; Power level in the 50 ohm coaxial line: 10 Watts at 40MHz. The Si detector was 5 mm from the foil outside conductor of the coax. In this condition there was no influence on the noise background.

November 29, 2002 NIKHEF-27 Hans de Vries RF pick-up (2) Cut a hole in the foil and put the silicon strip just 5 mm in front of this hole. The power level in this coax line was still 10 watt at 40MHz. The fieldlevels from this radiator are much higher then we can obtain with the beam through the RF foil. The result was that we do not see influence on the working of the silicon in combination with the electronics of the test setup at NIKHEF in febr

November 29, 2002 NIKHEF-28 Hans de Vries RF shielding Frans Kroes has produced a note on Attenuation of an EM field by AlMg4 screen of 0.2 mm Conclusion: Assuming a conductivity of 0.33 of pure Al: At 1 mm distance to the rf screen: x V/m

November 29, 2002 NIKHEF-29 Hans de Vries Conductivity  Pure Al = 37 x 10 6 Ohm -1 m -1 Measured (10%) conductivity of 1 m long 1 cm wide strips of AlMg3:  undeformed = 17 x 10 6 Ohm -1 m -1  deformed = 11 x 10 6 Ohm -1 m -1 45% for undeformed 30% for deformed material

November 29, 2002 NIKHEF-30 Hans de Vries Coating The extreme deformation might result in tiny leaks in the material. Also a protective layer might be used at the inside of the detector box. Apply poly-amide-imide coating –Solution in N-Methyl-2-Pyrrolidone (NMP) –Drying and polymerization at 60º, 150º, 260º and 315º C –Properties like Kapton and Torlon –Good electric insulation –Radiation resistant 30 MGy, strength not changed Outgassing properties have been studied

November 29, 2002 NIKHEF-31 Hans de Vries Final solution A thin layer of poly-amide-imide is air brushed on the inside of the foil for electrical protection and to increase vacuum tightness Effect of the layer: Leak detection With Helium BeforeAfter 1.2e-33.2e-7 1.2e-57.2e-7 3.6e-55.2e-7 3.8e-52.4e-6 1.2e-63.2e-7

November 29, 2002 NIKHEF-32 Hans de Vries Cabling Cables inside vacuum: Heat production Signal shielding Kapton with 3 Cu layers: = 25 micron kapton outside layer micron Cu (foil) = 75 micron kapton micron lines (100 micron width) = 75 micron kapton micron Cu (foil) = 25 micron kapton outside layer

November 29, 2002 NIKHEF-33 Hans de Vries Outgassing (1) Outgassing poly-amide-imide coating

November 29, 2002 NIKHEF-34 Hans de Vries Outgassing (2) Poly-amide-imide coating:1.5 m 2 Kapton cables:20 m 2

November 29, 2002 NIKHEF-35 Hans de Vries RF foil and Silicons

November 29, 2002 NIKHEF-36 Hans de Vries RF foil and Silicons- reinforcements

November 29, 2002 NIKHEF-37 Hans de Vries Summary Full size RF/vacuum foil has been obtained –Material: 300  m Al with 3% Mg –Minimal radius 8 mm –Deviations measured: ± 0.3 mm –FEM analysis has been performed –Variations measured for 10 mbar overpressure –Electrical properties measured –Application of poly-amide-imide –Kapton cables with 3 Cu layers