Pre-alignment status

H. MAINAUD DURAND

on behalf of the CLIC active pre-alignement team

Pre-alignment status

MDI meeting, 16/03/2012

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SUMMARY

Pre-alignment of the BDS components

Latest news from other studies

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Active pre-alignment of the components

Requirements

Because of the very tight tolerances, taking into consideration the temperature effects, ground movements,… and the number of components to be pre-aligned such a pre-alignment must be active:- Determination of the position

by sensors- Adjustment by movers.

The radius of the cylinder corresponds to the total error budget in the determination of the position of components.In the BDS area, this radius equals to 10 μm rms for all the components over 500 m.

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Active pre-alignment of the components

What does this mean?

The determination of the position of the component can be divided (as an approximation) into two steps:

Determination of the “zero” of the component • In the referential frame of its mechanical support• In the referential frame of the sensor

Determination of the position of the referential frame of the sensor coupled to the component w.r.t a stretched considered as a straight reference

Step 1

Step 2

Step 2Step 1

Magnet

Mechanical support

Sensor referential frame

Straight reference

WPS

WPS

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Active pre-alignment of the components

Determination of the zero of the object: status and next steps

Zero = mechanical axis of the component best solution = CMM if the length of the components and their support is not too long

Zero = magnetic axis best solution = CMM

Measurement of this magnetic axis using a vibrating wire, in a CMM, with the support, the quadrupole and the sensors interfaces.

Next step: development of a mock-up to be tested in the Leitz CMM.

Step 1

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Active pre-alignment of the components

Determination of the zero of the object: status and next steps Step 2

Vertical rms error of 11 μm

Radial rms error of 17 μmFaults/problems identified and solved:

• Linearity problem on the sensors (calibration bench)

• Ceramic spheres unglued

But not enough sensors available new sensors ordered (delivery foreseen mid May)reinstallation in TT1 not before August).

Other improvements identified: determination of the deviation of vertical, correction of lunar/solar tides,…

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SUMMARY

Pre-alignment of the BDS

Latest news from other studies

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Study of cam movers

The 5 DOF mock-up is ready

Program of study

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Monitoring of QD0

Latest results : status

First tests concern the assembly of 1m long zerodur rods

Tests of repeatability during the dismounting/mounting spokes and on temperature effects performedo Repeatability < 0.1μmo Temperature effects coherent with expansion coefficient of granite table on

which the spokes are fixed. Next steps foreseen on relative displacement of the 3 spokes.

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SUMMARY

Pre-alignment of the BDS components:

We work in parallel on two steps, trying to gain microns:• Determination of the zero of the component w.r.t the reference frame of

the support and the sensor• Determination of the reference frame of the support w.r.t. stretched wire,

considered as the straight reference of alignment.Results foreseen this summer.Please keep the components as small as possible!

Cam movers: the facility is now operational

Latest news from NIKHEF: repeatability on the contact between the end of the spoke and the reference ring below 0.1 μm, which was the target.