tilt meter

fiducial

Guide rail

AbstractThis poster covers the survey and alignment techniques selected for installation of the SPIRAL2 accelerator devices.

To determine the best technique for aligning any equipment, it is essential to know the precision required for the six degrees of freedom, and to understand the reasons for the requested precision. An object is “located” by its fiducial marks. High quality of mechanical connection to these marks is important in the final precision of the location of the object.

Survey and Alignment Concept for Construction of SPIRAL2 Accelerator

Tacheometer TDA 5005

3D measuring portable arm

Level NA3003Digital CCD System

connected to the Alignment Telescope

Journées Accélérateurs de la SFP Roscoff, 12-14 octobre 2009

1. Surveying instruments

Final survey

The solution adopted to support the linac components, is a welded-frame structure equipped with guide rails. One advantage of this solution is the possibility of bringing a component into a laboratory together with its support in order to do, for example, a realignment of the cavities inside the cryostat then to put it back on the beam line under the same conditions, using the guide rails.

4. The Superconducting Linac

R. Beunard, A. Lefevre, F. Legruel, GANIL, B.P. 55027 14076 CAEN, CEDEX 5, France Alignment/Instrumentation Group/Physics Technical Department

Thanks to all members of the GANIL design offices, as well as the colleagues from the other laboratories involved in this project, particularly from IPN Orsay and the DAPNIA Saclay

3. The injector beamlines

Magnets Fiducialization

As opposed to surveying with a theodolite, the use of a laser tracker will thus avoid dismounting certain equipment such as vacuum pumps or beam diagnostic devices during the shutdown period to permit alignment.

Dipole

The tolerated maximum static errors for the global alignment of the quadrupole and dipole magnets are:

• displacement (mm): ± 0.1

• rotations (X,Y) (deg): ± Qr Qr=d/L with d the displacement and L the length of the element

• rotations (Z) (deg): ± Qz Qz=d/R with d the displacement and R the radius of the element

The tolerated maximum static error for the global alignment of the diagnostic devices is: ± 0.2 mm

The tolerated maximum static errors for the global alignment of the quadrupole and dipole magnets are:

• displacement (mm): ± 0.1

• rotations (X,Y) (deg): ± Qr Qr=d/L with d the displacement and L the length of the element

• rotations (Z) (deg): ± Qz Qz=d/R with d the displacement and R the radius of the element

The tolerated maximum static error for the global alignment of the diagnostic devices is: ± 0.2 mm

Diagnostic boxes Fiducialization

Laser Tracker

35 m

Cryomodule A = 0.06 Cryomodule B

= 0.12

Tacheometer T3000A

Reflector

coded invar rod

2. The RFQ

RFQ FiducializationThe localization of the RFQ requires fiducial points transferred on the top of the vacuum vessel by adjustable plates equipped with a conical centering-surface for a Taylor-Hobson-Sphere. These spheres are the only reference points which will be accessible. Their spatial coordinates will be given in the reference system of the object.

Network measurement for metrological control of the vanes

and the fiducial pointsThe network measurement will be made with a laser tracker. The reference network will consist of approximately 6 pillars (green), 6 floor monuments (blue) and 4 laser tracker stations. Two sets of angles and 8 interferometer distances will be observed from each tracker station to all points.

Estimated global error: 60 m (RMS at 2).

The fiducials are the points located on the magnet with respect to the theoretical beam trajectory. Each beam line magnet will be fiducialized with a reference socket cup (CERN - type) installed on the plate during the process of alignment.

fiducial

tilt

The tolerated maximum static errors for the global alignment are: • ± 0.1 mm for the displacement of the quadrupoles• ± 0.03 deg for the rotations (X,Y) of the quadrupoles• ± 0.1 deg for the rotations (Z) of the quadrupoles• ± 1.0 mm for the displacement of the cavities• ± 0.3 deg for the rotations (X,Y) of the cavities.

The tolerated maximum static errors for the global alignment are: • ± 0.1 mm for the displacement of the quadrupoles• ± 0.03 deg for the rotations (X,Y) of the quadrupoles• ± 0.1 deg for the rotations (Z) of the quadrupoles• ± 1.0 mm for the displacement of the cavities• ± 0.3 deg for the rotations (X,Y) of the cavities.

Cryomodule B: Transfer methodology of the cavities beam axis

During assembly process, once the cryomodule is closed, the interior of the superconducting cavities cannot be accessed outside a clean room. As a result, the cavities are equipped with optical targets “Taylor and Hobson” mounted on an arm in order to facilitate its adjustment inside the cryostat. The optical targets fixed on the helium tank are adjusted to be parallel to the cavity axis.

The transfer was carried out by means of inter-dependent tools in the two beam tubes. The axis defined by the two beam tubes and the nut drift tube is also measured in order to define an average axis between the three cylinders.

The adjustment was performed with an error on the reported axis position of the order of 0.1 mm.

Cryomodule A: Transfer

methodology of the cavities

beam axisOnce the cryomodule is closed, it is no longer possible to change the cavity position with respect to the vacuum tank. External references of the cavity position will allow the alignment of one cryomodule cavity with respect to the other ones. Previous measurements of the cavity beam axis displacement during cool-down will be necessary to check the calculation. This will be made using a bare cavity.

Qualifying cryomodule B: Measurement of the cavities displacements during vacuum tests and cooling down

The measurement campaign was conducted in two stages because stability to 4K is obtained only after 2 to 3 days. The first campaign concerns the impact due to the vacuum and the second due to the cooling down. The technical principles include an optical method by using a Taylor and Hobson telescope. The displacements were measured on the optical targets inserted into the arms outside cavities.

fiducial

Alignment concept component fiducialization

As the components cannot be aligned through the beam tube, the solution adopted is to transfer new axes outside the object, i.e. to the sides of their supports by adjustable target boxes (fiducials). The three-dimensional coordinate measurements of these fiducials would be given in the reference system of the accelerating tubes of the cavities and the mechanical axis of the poles for the magnets. The measurements will be done by means of a portable-arm coordinate-measuring machine.

The measuring accuracy given by this system is ± 0.06 mm (at 2 ).

Transfer beam axis

Beam axis

Transfer beam axis

0.5malignment

target

Survey reflector

Tilt-meter plate

Wall monument

Floor monument

1 m

Fiducial nest

QWR (beta =0.07) 1 cavity

QWR (beta =0.12) 2 cavities

View of cryomodule installed on the bench for

measuring

Location of the measured points

reflector

Bench for component fiducialization