RasClic Quadrupole Alignment

1. RasClicQuadrupole Alignment 12-07-2011 Cern

2. Alignment of Quadrupoles 3m Optical path through these tubes Zerodur spokes within these tubes

3. Alignment of Quadrupoles • Path of the bundle can not be used for alignment purposes, as this would reduce the amount of time available for the experiment. • Use of external reference (ground) would introduce additional errors => transfer Quadrupole position to outside of magnets.

4. Alignment of LHC - Alignment of pipe sections Low CTE spokes Thin, vulnerable spokes. RasClic components at spoke end • Large amount of spoke bending requires support with aluminum/ carbon fibre tubes

5. Reference Rings • Zerodurrefence rings All dof constraint Vertical dof constraint

7. RasClic at end of spokes

8. Meeting the requirements • Temperature range in Quadrupole Structure: 15 – 25oC • => Spoke-to-spoke deviation in expansion << 1um.

9. PropertiesZerodur: • r = 2.53g/cm^3 = 25300 kg/m^3 • E20oC=90.3GPa,n=0.243 • afe – 3 categories: • Class 0: 0+/- 0.02x10-6/K • Class 1: 0+/- 0.05x10-6/K • Class 2: 0+/- 0.10x10-6/K • Company: Schott • Rods of 6mm x 6mm square cross-section with a maximum length of 200mm. Goal: 3m • => Requires gluing of several sections of rod.

10. Quadrupole Reference Ring

11. Quadrupole Reference Ring - deformation • Deformation under its own weight – 1.3um deformation. • Not absolute deformation, but ring-to-ring variation is important.

12. Spoke test structure Rubber flexo Zerodur spoke Al tube

15. Press-fit Spoke is pressed against flat reference block, which has been orderedRequirement: well-defined force and therefore deformation Or Demand:Within 0.1 um reproducable

16. Guiding spoke in tubes

17. Guiding spoke in tubes - 2

18. Flexo - Mesh

19. Flexo F

20. Flexo flexible enough – hand calculation Say:

21. Thermal expansion of AL tube w.r.tZerodur spoke • CTEZerodur