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Pre-alignment status

MDI meeting, 16/03/2012. Pre-alignment status. SUMMARY Pre-alignment of the BDS components Latest news from other studies. Active pre-alignment of the components. Requirements.

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Pre-alignment status

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  1. MDI meeting, 16/03/2012 Pre-alignment status H. MAINAUD DURAND on behalf of the CLIC active pre-alignement team

  2. SUMMARY • Pre-alignment of the BDS components • Latest news from other studies

  3. Active pre-alignment of the components Requirements 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. • 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.

  4. 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 Magnet Straight reference Sensor referential frame WPS Mechanical support WPS Step 2 Step 1

  5. Active pre-alignment of the components Determination of the zero of the object: status and next steps Step 1 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.

  6. 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 μm • Faults/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,…

  7. SUMMARY • Pre-alignment of the BDS • Latest news from other studies

  8. Study of cam movers The 5 DOF mock-up is ready Program of study

  9. 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 performed • Repeatability < 0.1μm • 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.

  10. 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.

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