on behalf of the CLIC active pre-alignment team BDS alignment H. MAINAUD DURAND on behalf of the CLIC active pre-alignment team Alignment strategy, status and next steps BDS MDI area

BDS: objective of pre-alignment PRE-ALIGNMENT (beam off) Mechanical pre-alignment Active pre-alignment Beam based alignment Beam based feedbacks Within +/- 0.1 mm (1s) Within a few microns Determination of the position of the components in a general coordinate system thanks to alignment systems = Active pre-alignment + Re-adjustment thanks to actuators The zero of each component will be included in a cylinder with a radius of a few microns: 10 µm (BDS components) OVER 500 m (14 μm/17 μm for main linac components over 200 m) Adjustment required: step size below 1 µm, 5 DOF

BDS: strategy Determination of the geodetic network on surface Transfer of reference into tunnel Determination of the geodetic network in the tunnel Absolute alignment of the elements Fiducialisation Relative alignment of the elements Active prealignment Control and maintenance of the alignment

BDS: strategy Next steps No further studies needed between 2012-2016 Determination of the geodetic network on surface Transfer of reference into tunnel Determination of the geodetic network in tunnel Distance < 2.5 km Combination of 3D triangulation and trilateration coupled with measurements of on vertical plumb wires Methods validated on an LHC pit in 2010 (depth of 65 m): precision of 0.1 mm and accuracy of 0.5 mm Hypothesis considered for CLIC: absolute position at the bottom of each pit: ± 2 mm (depth > 100 m) Next steps No further studies needed between 2012-2016

BDS: strategy Metrological Reference Network (MRN) Absolute alignment of the elements Metrological Reference Network (MRN) Propagation network simulations: max deviation along the linac below 1 mm Installed w.r.t the tunnel network Overlapping stretched wires propagating the precision over long distances Simulations in 2009: Precision at the bottom of the shaft of ± 2 mm Calibration of metrological plates: ± 5 μm Distance between pits: 3.5 km Wires: 400m long Deviation along 200m according to wire length ~ 3 to 5 μm

BDS: strategy (MRN) TT1 facility Absolute alignment of the elements (MRN) TT1 facility Precision on a 140 m wire: better than 2 microns over 33 days Accuracy: 11 microns in vertical, 17 microns in radial. Can be improved!

BDS: strategy Fiducialisation at the micron level Fiducialisation and dimensional control of objects < 2m: CMM measurements (Tolerances of measurement of Leitz Infinity: 0.3 μm + 1 ppm) For objects > 2m or as control after transport or during specific tests: combination of « mobile » means: Instrument Standard deviation between instruments and CMM measurements AT401 < 5 μm Micro triangulation Romer arm < 10 μm Romer arm Laser tracker: AT 401 Micro triangulation

BDS: strategy Support Pre-alignment Network (SPN) Relative alignment of the elements Support Pre-alignment Network (SPN) Sensors that are part to the component Micrometric measurements between zero of the component and sensors interfaces Summary: Next steps Improve accuracy of stretched wire solution (better calibration of sensors, relative determination of the deflection of vertical, more accurate and precise biaxial inclinometers) Go on with fiducialisation studies concerning objects with a length > 2m Update network propagation simulations performed in 2009 Better knowledge of wires stretched over 500 m (TZ32 tunnel)

BDS: strategy Determination of the position Adjustment with cam movers Active prealignment Adjustment with cam movers Next steps Validation of the algorithms of repositioning Adapt design to BDS components (weight and size?) Improve the stiffness of the solution

MDI area Determination of the position of QD0 w.r.t other components of the BDS (1) Requirements: Position of the zero of QD0 w.r.t ideal straight line of the 500 last meters of BDS: ± 10 μm rms (including fiducialisation) Longitudinal relative position between QD0 and QF1: ± 20 μm rms Solutions: Main difference concerns the MRN network (due to lack of space): No overlapping of stretched wires in the last 250 m No HLS system needed for the modeling of the sag, which will be extrapolated on the last 250 m.

MDI area Determination of the position of QD0 w.r.t other components of the BDS (2) Longitudinal monitoring of QD0 w.r.t QF1: capacitive sensors coupled to each component measuring w.r.t targets of a common carbon bar Capacitive sensor QD0 QF1 Carbon bar with targets on both extremities Development of special mechanics and sensors to displace the stretching device when QD0 is removed. Development of « opened » WPS sensors Fixed part of stretched wire will have to displaced remotely, radially (get out the WPS installed on QD0) and longitudinally (get out the support tube of QD0). Can not be removed as it gives an alignment reference for all the BDS components over the last 500m. Next steps Propose a design for these solutions and integrate them Validate prototypes on dedicated mock-ups 11

MDI area Left side w.r.t right side Next steps Requirements: Determination of left reference line w.r.t right reference line : within ± 0.1 mm rms Monitoring of left reference line w.r.t right reference line : within a few microns Monitoring of the position of left QD0 / right QD0 within ± 5 μm rms Solutions: Determination of left reference line w.r.t right reference line &monitoring of one BDS w.r.t other: link stretched wires on both side by a common reference (as in the LHC), using the survey galleries Next steps No further studies needed between 2012-2016 12

MDI area Left side w.r.t right side Monitoring of the position of left QD0 /right QD0: Concept 4 Reference Rings (RR) located at each extremity of QD0, supported from outer tube 6 radial spokes per RR In two steps: A monitoring of the position of QD0 w.r.t RR thanks to proximity sensors. (initial calibration of their position performed on a CMM) A transfer of the position of RR thanks to 6 spokes to alignment systems. By combination of redundant information, the position of the center of 4 RR is computed. RR spoke Line of sight for alignment systems See next presentation by Harry van der Graaf Next steps Validation of spokes design and alignment systems at NIKHEF (2011-2012) Validation of the concept on a mock-up at CERN (2012-2013) 13

Summary Same strategy of pre-alignment concerning BDS than for main linac But tighter requirements in the determination of position, in the adjustment, which will require dedicated prototypes and mock-ups, especially for the MDI area. Improve accuracy of stretched wire solution Go on with fiducialisation studies for objects longer than 2 m Update propagation network simulations performed in 2009 Use TZ32 tunnel to have a better knowledge of wires stretched over 500 m. Cam movers: adapt the design of MB quad to the BDS and MDI components (weight & size of the components, loads not centered, 6 motorized DOF) Special solutions required concerning longitudinal monitoring of final focus, and stretched wire around QD0 Collaboration with NIKHEF concerning the monitoring of QD0 through the detectors Concept proposed Validation of spokes and alignment systems under progress @ NIKHEF Validation of the whole concept foreseen @ CERN in 2012-2013.

Thank you very much for your attention! 15