Alignment Work in TT2 and PS During the Shut-down 2006-2007

CLIC Module WG 20/07/2009H. MAINAUD DURAND, BE-ABP/SUPre-alignment system and impact on module design CLIC Module WG 20/07/2009H. MAINAUD DURAND BE-ABP/SU2

SUMMARY

Introduction: the pre-alignment strategy

Feasibility around 4 key points: A straight reference known and stable Submicrometric sensors with a known zero and no drift Module compatibility Integration of the pre-alignment systems Integration of the repositioning solutions Installation sequences Simulations

Conclusion3

Overlapping straight references Propagation network a few microns over more than 200m Proximity network a few microns over 10-15 m.PRE-ALIGNMENT STRATEGYCLIC Module WG 20/07/2009H. MAINAUD DURAND BE-ABP/SU4

Baseline: straight reference = stretched wire. propagation network : WPS sensors proximity network: WPS sensorsPRE-ALIGNMENT STRATEGY

Accelerating structuresPETS + DB quadon independent girdersMB quad pre-aligned independentlyCLIC Module WG 20/07/2009H. MAINAUD DURAND BE-ABP/SU5

Baseline concerning the repositioning systems DB and MB girders pre-aligned with 3+1 DOF (snake system) Natural smoothing 3 motorized DOF (cost advantage) mechanics tested and validated in CTF2

PRE-ALIGNMENT STRATEGY

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Baseline concerning the repositioning systems MB quad pre-aligned with 5+1 DOF

PRE-ALIGNMENT STRATEGY

Courtesy of F. LacknerCLIC Module WG 20/07/2009H. MAINAUD DURAND BE-ABP/SU7

Alternative: propagation network = laser beam under vacuum or stretched wire proximity network = RASNIKPRE-ALIGNMENT STRATEGY

CLIC Module WG 20/07/2009H. MAINAUD DURAND BE-ABP/SU8

1st key point: a straight reference, known and stableIssues:long term stability of a wire effects of temperature, humidity creeping effects effects of the air currents

Modelization of the wire using HLS systemsbut only in the vertical directionbut HLS system follows the geoid which needs then to be known

Is a stretched wire really straight (top view)?First idea: comparison with a laser beam under vacuumInter-comparison of different types of wires and technologies on short distances (50 m) this autumn at SLAC on long distances (500m) at CERNCLIC Module WG 20/07/2009H. MAINAUD DURAND BE-ABP/SU9

2nd key point: sub-micrometric sensorsIssues:WPS sensor fulfilling the requirements: absolute measurements (known zero w.r.t mechanical interface) no drift sub micrometric measurements

Upgrade of the existing WPS sensorbetter mechanical interfacebetter absolute calibrationdrift, CEM to be studied in further details

Development of a new WPS sensor3 microns accuracy and precision to be controlledValidation in the frame of an inter-comparison with SLACCLIC Module WG 20/07/2009H. MAINAUD DURAND BE-ABP/SU10

3rd key point: module compatibilityIssue: integration of the pre-alignment systems

HLS system (horizontal)Proximity sensors (RASNIK), mechanically linked to each cradle

WPS system (follows the slope)

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3rd key point: module compatibilityIssue: design and integration of the positioning systems

Case of the DB and MB girders:Concept of snake system validated in CTF2, but with a load 10 times lower.Friedrich raised some questions concerning that concept: 8 contact points providing friction in case of higher loada complete study of the concept will be undertaken by EN/MMEZTS proposes a prototype of linear actuator with the following characteristics: load of 500 kg precision better than 0.5 micron (resolution: 0.17/5 micron) length: ~ 350 mm Diameter: ~ 130 mm (but can be decreased to 100 mm easily)

Case of the MB quad: a cam based solution is studied by FriedrichZTS proposed another solution: a two dimensional linear actuator allowing the alignment of a load of 500kg, with a precision of 0.5 micron (height: 421 mm, base dimensions: 755 x 350 mm)

12Pre-alignment mock-upObjectives:Validation of the mechanical conceptPossibility of micrometric displacements with waveguides and interconnectionsValidation of the stability of the components on the girders: The pre-alignment of the CAS (or PETS + quad) on the girder stays within the micron after 25 km of transport.The fiducialisation of the components on the girder stays within the micron after thermal cycles.

3rd key point: module compatibility

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3rd key point: module compatibilityIssue:installation considerations

The propagation network must be installed and determined at the beginning, once the geodetic network is known. (to allow a positioning of actuators and sensors within their range)

Geodetic networkMetrological plateThe metrological network consists of overlapping stretched wires and metrological plates (every 100 m if the wire length is 200 m)14

3rd key point: module compatibilityIssue:installation considerations

For each module, and adjustable plate with the actuators will be installed and pre-aligned w.r.t this metrological network

Once the module (or MB quad) is in place, its relative alignment is performed w.r.t the metrological network the joining of the interconnection is possible

Once all the modules in a sector (pit to pit) are installed, the positions of the elements are computed pre-alignment of the modules (and MB quads)

Once no more access in the tunnel, implementation of the active pre-alignment

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Issue: simulations close to the reality

Objectives:Find the best strategy and configuration of alignment systems for the pre-alignmentModel the impact of the pre-alignment errors on the beam emittance growth

First results:The pre-alignment tolerance could be achieved with wires longer than 425m.Beam simulations, based on these data showed that 400m wires were able to limit the long distance emittances.

Next steps implementation of a new model, closer to the realityThe requirements were defined in collaboration with Daniel These steps are now mathematically defined The algorithms will have to be implemented and tested on the TT1 configuration (validation of the model on 150m) Development of a software allowing the modeling on the whole CLIC.

4st key point: beam studies compatibility16

CONCLUSIONA strategy is being followed actively concerning the CLIC pre-alignment studies.

One last question dealing with the BDS and experimental area:It will be possible to pre-align all the components along each linac within a few microns, but then what are the position requirements concerning one BDS with respect to the other?Based on the experience of the LHC, it will be very difficult to determine their relative position at better than 0.1 mm (1 sigma).

CLIC Module WG 20/07/2009H. MAINAUD DURAND BE-ABP/SU17

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