Alignment of DB and MB quadrupoles

Hélène MAINAUD DURAND

17/11/2011

With a lot of input from Sylvain GRIFFET

Outline

Actual plan

Case of MB quad and DB quad

Means

Proposals and questions

3

Main linac alignment requirements

Problem

Within +/- 0.1 mm (1s)

Active pre-alignment Beam based alignment

Beam based feedbacksWithin a few microns

Active pre-alignment

=Determination of the position of the components in a

general coordinate system thanks to alignment systems

Re-adjustment thanks to actuators+

The zero of each component will be included in a cylinder with a radius of a few microns:

14 μm / 17 μm for main linac components 1 µm

Adjustment required: step size below 1 µm, 5 DOF

Mechanical pre-alignment

PRE-ALIGNMENT (beam off)

Tolerances

5

Alignment strategy

Solution proposed (for all area of CLIC)

Installation and determination of the Survey network

Transfer of reference into tunnel

Installation and determination of the tunnel network

Combination of 3D triangulation and trilateration coupled with measurements of on vertical plumb wires

Methods validated on an LHC pit in 2010 (depth of 65 m): precision of 0.1 mm and accuracy of 0.5 mm

Hypothesis considered for CLIC: absolute position at the bottom of each pit: ± 2 mm (depth > 100 m)

Distance < 2.5 km

6

BDS: strategy

Solution proposed Absolute alignment of the elements

Relative alignment of the elements

Metrological Reference Network

Installed w.r.t the tunnel network

Overlapping stretched wires propagating the precision over long distances

Simulations in 2009: o Precision at the bottom of the shaft of ± 2 mmo Calibration of metrological plates: ± 5 μmo Distance between pits: 3.5 kmo Wires: 400m long

Std deviation of 3.6 μm over 200m of sliding window

Propagation network simulations

7

Alignment strategy

Solution proposed Absolute alignment of the elements

Relative alignment of the elements

All the components or the supports on which are pre-aligned the components will be aligned w.r.t Metrological Reference Network (overlapping stretched wires)

All the components must be pre-aligned on their supports within a micrometric precision and accuracy

As the requirements of alignment concern the zero of each component, the position of each zero of component must be known within a micrometric precision and accuracy w.r.t the sensor interface.

Laser tracker: AT 401

cWPS mechanical interface

8

Alignment strategy

Summary of the configuration

9

Alignment strategy

Summary of the fiducialisation steps for DB quad:

• Determination of each zero of component w.r.t fiducials (external alignment references): BPM, DB quad

• Assembly and measurement of the assembly of components w.r.t their fiducials (DB quad and BPM)

• Alignment of components on supports (DB quad + BPM on girders) and determination of their position in the support coordinate system

• Determination of the supports coordinate system w.r.t sensors interface

Best solution for accuracy : to group the determination of the zero of the components w.r.t sensors interface!

Zero of component to be precised.

10

Alignment strategy

Summary of the fiducialisation steps for MB quad:

• Determination of each zero of component w.r.t fiducials (external alignment references): BPM, MB quad

• Assembly and measurement of the assembly of components w.r.t their fiducials (MB quad and BPM)

• Alignment of components on supports (MB quad + BPM on common support) and determination of their position in the support coordinate system, for a given position of micro positioning adjustment system (stabilization)

• Determination of the supports coordinate system w.r.t sensors interface

Best solution for accuracy : to group the determination of the zero of the components w.r.t sensors interface!

11

Alignment strategy

2 solutions concerning the location of sensors:

• Sensors directly on the components

• Lever arm effect towards alignment reference (stretched wire) important

• Heavy load on BPM

• Sensors mounted on the common support:

• The position of micro positioning adjustment system must be taken into account

• Determination of the position of BPM not direct

Means

Means

Means

15

Means and strategy

Fiducialisation and dimensional control of objects < 1.2 m: CMM measurements (Tolerances of measurement of Leitz Infinity: 0.3 μm + 1 ppm)

For objects > 1.2 m or as control after transport: Combination of « mobile » means:

Laser tracker: AT 401

Micro triangulation

Instrument

Standard deviation between instruments and CMM measurements

AT401 < 5 μm

Micro triangulation

< 5 μm

Romer arm < 10 μm

Romer arm

16

Some ideas…

Objective: the most precise and accurate measurement between the zero of the component and the sensors interfaces.

Perform the measurement of the magnetic axis of DB quad and MB quad in a CMM

If a “vibrating stretched wire” technique is used to perform the magnetic measurements, measure the position of this wire thanks to oWPS and cWPS. Then their mechanical interfaces and the mechanical interfaces of the alignment sensors can be determined through very accurate CMM measurements.

For the DB quad, use WPS mounted on supports installed on the V-shaped supports.

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Some questions…

Definition of the zero of the components

Case of the MB quad: according to the requirements, the position of BPM should be known more precisely and accurately than the MB quad: 2 configurations to be studied

Clear definition of the tolerances needed:

what does “quadrupole offsets: 20 µm” mean?

Kinematic pitch problem raised by Kurt:

For the type 1: for a pitch with vertical delta of 1 mm, φ=0.38°

- longitudinal displacement of the center of ~ 2.5 mm

- vertical displacement ~ 8 µm

Thank you very much!