CFSS and ES electrical screening for SPD Harness RB24-RB26

1. CFSS and ES electrical screening for SPD Harness RB24-RB26 Electrical screening of the carbon fiber support structures (CFSS and ES) for the SPD. Considering the tests results of the D0 vertex detector http://lhc-electronics-workshop.web.cern.ch/lhc-electronics-workshop/2002/Plenary/P42.pdf (Grounding and shielding Techniques for Large Scale Experiments; M. Johnson Fermilab; M. Quinn talk at the Vertex02 conference: Carbon Fiber Grounding Issues in the DØ Run IIb Silicon Detector Design. We made some tests on a small sample of CFSS evaporating a thin aluminum film to short circuit the carbon fibres embedded in the epoxy resin and than we tested at different frequencies the same D0 results. Then we need an electricall screening for: CFSS ES Beam Pipe? SPD CFSS screening/Harness RB24-RB26 /ALICE Week A. Pepato – INFN PD

2. Suggested solutions: CFSS: we suppose to sputter a thin film (Th=0.15 mm) of Titanium (other solutions: Aluminum, Copper, Silver but..) with a rectangular shape of 20x50 mm to short circuit all carbon fibres. Screening surfaces The electrical connections is done by means of metallic washers crimped onto the CFSS. A thin copper foil will connect the CFSS to the ES obtaining two grounding connections/CFSS. External Screen (ES): we suppose to sputter a thin film of aluminum (Th=0.15 mm) all over the internal skin of the cylinder. This was already foreseen for the thermal decoupling of the ES to the SDD. Mechanical connections of the copper foils is also provided at the CFSS fixation points. A global grounding line is then routed through the services cones to the service patch panels where we suppose to have the general grounding of the different parts. Beam Pipe (BP): we have to define if the BP protection against liquid drops could be used also for an electrical screening (if we assume it is needed). SPD CFSS screening/Harness RB24-RB26 /ALICE Week A. Pepato – INFN PD

3. The complete Military Standard Codes for Composites is available, The evaporation of the aluminum film was performed in the LNL with a small sample of the CFSS (the evaporation vessel does not fit with the SPD CFSS dimensions. The evaporation tests and the final treatments on the CFSS will be done at CERN (MME TS group – S. Calatroni): They should deliver the piece mid April 04). Their sputtering unit can also fit with the cylinder dimensions, while not for the external cones (it is not needed for the grounding of the system). Beam Pipe screening: possible solution A cylinder gloove made by a carbon fibre tissue (min. 60 mm thick) cocured to a Kapton foil of about 25 mm thick. Material budget problems? SPD CFSS screening/Harness RB24-RB26 /ALICE Week A. Pepato – INFN PD

4. RB24 and RB26 Harness. SPD CFSS screening/Harness RB24-RB26 /ALICE Week A. Pepato – INFN PD

5. RB24 side Movable service channels SPD CFSS screening/Harness RB24-RB26 /ALICE Week A. Pepato – INFN PD

6. Transveral section of the SPD ten sectors at the CFSS endcaps. SPD CFSS screening/Harness RB24-RB26 /ALICE Week A. Pepato – INFN PD

7. LV cables MCM & bus lines Capillar tubes CuNi 1.5/1.8 mm Optical fibers: 18 fibers/sector Service harness @ RB24 SPD CFSS screening/Harness RB24-RB26 /ALICE Week A. Pepato – INFN PD

8. SPD CFSS screening/Harness RB24-RB26 /ALICE Week A. Pepato – INFN PD

9. RB26 side: service patch panels Assembly sequence: MCM cables (1) Bus cables (2) Cooling line (C4F10) (3) Air ducts (two ducts) (4) Optical fibers.(5) 5 3 4 2 1 SPD CFSS screening/Harness RB24-RB26 /ALICE Week A. Pepato – INFN PD

10. Services dimensions at RB26. SPD CFSS screening/Harness RB24-RB26 /ALICE Week A. Pepato – INFN PD