1. Pre-alignment of quadrupoles 1 CLIC stabilization day, 18.03.08 STARTSLIDE PRE-ALIGNMENT OF THE MAIN BEAM QUADRUPOLES Hélène MAINAUD DURAND

2. Pre-alignment of quadrupoles 2 CLIC stabilization day, 18.03.08 INTRODUCTION 1.Concept oWorking hypotheses concerning the pre-alignment oDetermination of the position of the components oRepositioning oOur proposal concerning the mechanical support 2.Test and results 3.Future plans Overview

3. Pre-alignment of quadrupoles 3 CLIC stabilization day, 18.03.08 INTRODUCTION Concept Working hypotheses concerning the pre-alignment Transverse position of the CLIC linac components: 10 microns (3  ) over a sliding window of 200m, along the whole length of the linacs. The pre-alignment must be accurate enough to allow the sending of a pilot beam and the implementation of the beam based alignment. The pre-alignment is carried out in an active loop: determination of the position of the components repositioning of the components Main beam quadrupole independent from the girder Pre-alignment of the main beam quadrupole according to 5 degrees of freedom (longitudinal direction not critical).

4. Pre-alignment of quadrupoles 4 CLIC stabilization day, 18.03.08 INTRODUCTION Concept Determination of the position of the components The straight reference line between the two ends of the linac is obtained through overlapping reference lines Simplification of the alignment by linking adjacent girders by a common articulation point Current strategy: Association of a « proximity network » to each articulation point

5. Pre-alignment of quadrupoles 5 CLIC stabilization day, 18.03.08 INTRODUCTION Concept Determination of the position of the components At the scale of the module: Association of a propagation network every « x « articulation point Drive beam (PETS + quad on the same girder) Main beam (cavities on girder, quad independent)

7. Pre-alignment of quadrupoles 7 CLIC stabilization day, 18.03.08 INTRODUCTION Concept Repositioning One horizontal plate supported by 3 vertical stepper motors One vertical part linked to 2 horizontal stepper motors Stepper motors equipped with two end swivels, working as an expanding link rod  almost frictionless, no introduction of stresses Always precise displacement without hysteresis under load Movers validated in CTF2 concerning the repositioning Support not optimized against structural resonances (S. Redaelli).

8. Pre-alignment of quadrupoles 8 CLIC stabilization day, 18.03.08 INTRODUCTION Concept Our proposal concerning the main beam mechanical support ( from F. Lackner). Keep the support concept from the CTF2 experience and optimize it against structural resonances Update the design and stepper motor system to the actual state of technology Take into account the quadrupole weight, and the space limitations Perform a market research in order to find adequate stepper motors There are various acceptable products providing the requirements in order to build a stepper based pre- alignment system with an accuracy to align to better than 10 microns. There is a real issue concerning the cost of the stepper motors, knowing that more than 150 000 would be needed for girders and quadrupoles.

9. Pre-alignment of quadrupoles 9 CLIC stabilization day, 18.03.08 INTRODUCTION Test and results A R&D program has been proposed and accepted, and is followed concerning the determination of the position of the components. (see presentation in the CLIC workshop) A market survey has been undertaken concerning the stepper motors Some first ideas have been proposed by Friedrich Lackner concerning a solution which would combine final alignment and stabilization.

10. Pre-alignment of quadrupoles 10 CLIC stabilization day, 18.03.08 INTRODUCTION Future plans What remains to do from the pre-alignment point of view… To redesign a support (or 4 types of supports), taking into account the space available, the new size and weight of girders and quadrupoles, the compatibility with the stabilization system,… to define the technical requirements concerning the stepper motors and order them to check the stepper motors To align the quadrupoles and BPM on the support within a few microns To fiducialize the quadrupoles to define the interfaces for the alignment sensors to measure within a few microns the link between the beam line (or mechanical reference of the quadrupole) and the pre-alignment sensor. To validate the 10 microns pre-alignment of the quadrupole: to perform tests in lab with the stepper motors, support and sensors to perform tests in a real environment to test the compatibility with the stabilization solution.