EDR - Mech. 2; December 16/17, 2002 Hans de Vries - 1

Status of Vertex at NIKHEF

• VELO Mechanics RF/vacuum foil

Rectangular bellow

RF measurements

Cabling

• Summary & Outlook

EDR - Mech. 2; December 16/17, 2002 Hans de Vries - 2

VELO Overview

EDR - Mech. 2; December 16/17, 2002 Hans de Vries - 3

Secondary vacuum box

EDR - Mech. 2; December 16/17, 2002 Hans de Vries - 4

Material data

Material: AlMg3Young's modulus: 70.000 MPaPoisons ratio: 0.33Shear Modulus: 27.3 GPaYield Strength: 80-180 MPaUltimate Strength: 180-260 MPaElectrical conductivity: 1.9x107 ohm-1 m-1

(almost 50% of pure Al)Weldable!

EDR - Mech. 2; December 16/17, 2002 Hans de Vries - 5

Full size foil

Vacuum tight foil from 300 µm AlMg3Buckling in the center toblerones is solvedRibs (2.5mm high) are added at the forward-end to increase the stiffness.

EDR - Mech. 2; December 16/17, 2002 Hans de Vries - 6

FEM analysis

ACP 5080, AlMg4.5Mn (Alimex)

EDR - Mech. 2; December 16/17, 2002 Hans de Vries - 7

FEM analysis: input

Input model for the FEMcalculations

EDR - Mech. 2; December 16/17, 2002 Hans de Vries - 8

FEM analysis: results

CONCLUSION:

The max stress (91 MPa) is 33% below the Yield Strength (130 MPa), so still elastic and safe.A max displacement of 0.3 mm is no problem.

EDR - Mech. 2; December 16/17, 2002 Hans de Vries - 9

RF foil and Silicons-reinforcements

EDR - Mech. 2; December 16/17, 2002 Hans de Vries - 10

Bellow

EDR - Mech. 2; December 16/17, 2002 Hans de Vries - 11

Rectangular Bellow

Sagging problems Vacuum leaks in corners

Parallel effort in edge-welding

EDR - Mech. 2; December 16/17, 2002 Hans de Vries - 12

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.

EDR - Mech. 2; December 16/17, 2002 Hans de Vries - 13

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 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. 2002.

The fieldlevels from this radiator are much higher then we can obtain with the beam through the RF foil.

EDR - Mech. 2; December 16/17, 2002 Hans de Vries - 14

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:

1.415 x 10-3 V/m

EDR - Mech. 2; December 16/17, 2002 Hans de Vries - 15

Conductivity

Pure Al = 37 x 106 Ohm-1 m-1

• Measured (accuracy 10%) conductivity of 1 m long 1 cm wide strips of AlMg3:

undeformed = 17 x 106 Ohm-1 m-1

deformed = 11 x 106 Ohm-1 m-1

•45% for undeformed•30% for deformed material

EDR - Mech. 2; December 16/17, 2002 Hans de Vries - 16

Cabling

Cables inside vacuum:• Heat production• Signal shielding

Kapton with 3 Cu layers:• = 25 micron kapton outside layer•--- 17 micron Cu (foil)•= 75 micron kapton•--- 17 micron lines (100 micron width)•= 75 micron kapton •---17 micron Cu (foil)•= 25 micron kapton outside layer

EDR - Mech. 2; December 16/17, 2002 Hans de Vries - 17

Outgassing (2)Contribution in the pressure of the secondary vacuum by out gassing

Seff=500l/s

1.E-08

1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

0 1 2 3 4 5 6 7 8 9 10

time [day]

P [

mb

ar]

Coating

Flat Cable

Poly-amide-imide coating: 1.5 m2

Kapton cables: 20 m2

EDR - Mech. 2; December 16/17, 2002 Hans de Vries - 18

Summary and outlook

• Bellow– Still under development

• RF measurements– 300 µm Al gives sufficient rf shielding– Side flaps not needed

• Outgassing– poly-amide-imide– Kapton cables with 3 Cu layers