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

CLIC Module WG 20/07/2009 H. MAINAUD DURAND BE-ABP/SU 2 SUMMARY Introduction: the pre-alignment strategy Feasibility around 4 key points: o A straight reference known and stable o Submicrometric sensors with a known zero and no drift o Module compatibility  Integration of the pre-alignment systems  Integration of the repositioning solutions  Installation sequences o Simulations Conclusion

3 Overlapping straight references Propagation network  a few microns over more than 200m Proximity network  a few microns over m. PRE-ALIGNMENT STRATEGY CLIC Module WG 20/07/2009 H. MAINAUD DURAND BE-ABP/SU

4 Baseline: straight reference = stretched wire. propagation network : WPS sensors proximity network: WPS sensors PRE-ALIGNMENT STRATEGY Accelerating structures PETS + DB quad on independent girders MB quad pre-aligned independently CLIC Module WG 20/07/2009 H. MAINAUD DURAND BE-ABP/SU

5 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 >

6 Baseline concerning the repositioning systems MB quad pre-aligned with 5+1 DOF PRE-ALIGNMENT STRATEGY Courtesy of F. Lackner CLIC Module WG 20/07/2009 H. MAINAUD DURAND BE-ABP/SU

7 Alternative: propagation network = laser beam under vacuum or stretched wire proximity network = RASNIK PRE-ALIGNMENT STRATEGY CLIC Module WG 20/07/2009 H. MAINAUD DURAND BE-ABP/SU

8 1 st key point: a straight reference, known and stable Issues:long term stability of a wire effects of temperature, humidity creeping effects effects of the air currents  Modelization of the wire using HLS systems but only in the vertical direction but 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 vacuum Inter-comparison of different types of wires and technologies  on short distances (50 m) this autumn at SLAC  on long distances (500m) at CERN CLIC Module WG 20/07/2009 H. MAINAUD DURAND BE-ABP/SU

9 2 nd key point: sub-micrometric sensors Issues:WPS sensor fulfilling the requirements: « absolute measurements » (known zero w.r.t mechanical interface) no drift sub micrometric measurements  Upgrade of the existing WPS sensor better mechanical interface better absolute calibration drift, CEM to be studied in further details  Development of a new WPS sensor 3 microns accuracy and precision to be controlled  Validation in the frame of an inter-comparison with SLAC CLIC Module WG 20/07/2009 H. MAINAUD DURAND BE-ABP/SU

10 3 rd key point: module compatibility Issue: integration of the pre-alignment systems HLS system (horizontal) Proximity sensors (RASNIK), mechanically linked to each cradle WPS system (follows the slope)

11 3 rd key point: module compatibility Issue: 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 load  a complete study of the concept will be undertaken by EN/MME  ZTS 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: o a cam based solution is studied by Friedrich o ZTS 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)

12 Pre-alignment mock-up Objectives: Validation of the mechanical concept Possibility of micrometric displacements with waveguides and interconnections Validation 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. 3 rd key point: module compatibility

13 3 rd key point: module compatibility Issue: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 network Metrological plate The metrological network consists of overlapping stretched wires and metrological plates (every 100 m if the wire length is 200 m)

14 3 rd key point: module compatibility Issue: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

15 Issue: simulations close to the reality Objectives: Find the best strategy and configuration of alignment systems for the pre-alignment Model 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 reality The 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. 4 st key point: beam studies compatibility

16 CONCLUSION A 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 20/07/2009 H. MAINAUD DURAND BE-ABP/SU

17 Astro-Geodetic Zenith Camera System of the ETH Zürich : DIADEM Each starry night, we perform astro-geodetic measurements thanks to a zenith camera system. If you are interested in participating, do not hesitate to contact us.