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MDI alignment progress The pre-alignment of the QD0 ’ s

MDI alignment progress The pre-alignment of the QD0 ’ s. Niels van Bakel, Bram Bouwens, Hubert Gerwig, Lau Gatignon, Harry van der Graaf, Henk Groenstege, Joris van Heijningen, Jan Koopstra, Helene Mainaud Durand,, Richard Rosing, Vivien Rude CERN, Nikhef. IWAA 2012 Fermilab,

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MDI alignment progress The pre-alignment of the QD0 ’ s

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  1. MDI alignment progress The pre-alignment of the QD0’s Niels van Bakel, Bram Bouwens, Hubert Gerwig, Lau Gatignon, Harry van der Graaf, Henk Groenstege, Joris van Heijningen, Jan Koopstra, Helene Mainaud Durand,, Richard Rosing, Vivien Rude CERN, Nikhef IWAA 2012 Fermilab, Sept 13, 2012

  2. Alignment of two objects: • omit Z • omit rotZ Y Y Y X X X • Measure: • translation X • translation Y • - rotX • rotY • Equivalent to • 4 points (X,Y)

  3. Momentum Measurement of charged particles in the L3 experiment: Chamber Position Monitoring Detector Detector Detector Muon Particle Track • Lorentz Force: • Track Curvature measurement

  4. Direct measurement: two anti // Rasniks: lens light source + image sensor … would only require path of sight of 20 mm2…. …. along beampipe…..!

  5. Instead: use space away from beam tube, • at larger R: • alignment in two steps: • Reference Rings • via Radial Spokes • (double) anti // Rasniks

  6. Monitor X,Y of (both) QD0 end ref’s with respect to RR (with Rasniks) to be calibrated on 3D measuring machine

  7. Rasnik Lines-of Sight spokes

  8. Reference Ring RR

  9. Spoke • length 3.5 m; • has only one function: to transfer radial position better than 1 μm • Material: Zerodur: thermal expansion coefficient < 0.2 x 10-6

  10. Alignment is NOT influented by: • (common) deformation of RRs (sag, spoke load) • temperature of individual RR • (common) deformation of spoke wheel (spoke weight compression) • temperature of individual spoke wheel

  11. Steel ball Zerodur rod (6 mm x 6 mm x 3500 mm Spoke tip on RR side: contact definition < 0.1 μm spoke support tube: flexo suspension

  12. Outer spoke detail Inner spoke detail Precision ring QD0 support tube

  13. Volume reserved for support plate of Rasnik/Rasdif Radial retraction for endcap opening

  14. 1983: 4QD Red Alignment System Nikhef (Rasnik) 1993: CCD Rasnik 2003: RasDif: long distance

  15. Comparison Stretched Wire System versus RasDif (TT1) RasChain: interconnected Rasnik systems for basic CLIC units of 2010 mm • - new (green) semiconductor lasers • shielding • image analysis software MDI/QD0 alignment: vibrations

  16. diffraction plate simulated measured Thermal shielding of light path

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