Alignment and girder system experience Mathieu Duquenne Helene

Alignment and girder system experience Mathieu Duquenne, Helene Mainaud Durand, Mateusz Sosin, Vivien Rude.

• Misalignment of SAS because problems of production, ü SAS 1 : Max error 91 µm (after oven) before 52 µm, ü SAS 2 : Max error 62 µm, AS<15 µm Brasage 2 AS • The fiducials fall off (gluing is not enough), • When we move a girder the second one moves too (MB/DB), Drive Beam Variation X (mm) Variation Y (mm) Main Beam • Difference between MAD-X and the reality for the lengths and the longitudinal positions of the components, • The visibility is difficult on the DB line, • The electronic of the radial actuators failed several times – under investigation now, • The link between girder and cradles is lost due to the difference of materials (thermal expansion coefficient)

• Difficult to access to the space under the girder, • SU support : used by other systems which have no support – unknown impact for eg. for vibration behaviour as done at the last moment as «bricolage» . Should be designed during CLEX area integration, • Grounding paths for sensors and actuators is very important. Each actuator chassis shall be grounded at the module level (minimize actuator noise impact). , • Low noise (2 µm CLEX vs 10 µm Lab), thanks to low noise NI acquisition modules and actuators-sensors cables separation,

• Heavy tripod constantly in the CLEX for measurement, • Double longitudinal adjustment device implemented by ZTS made girder overconstrained what caused damage of one of it. Non necessary piece was dismounted, • Fiducialisation not included in the schedules, had to be carried out at the last minute less accurate, • The fixation between BPM and DBQ was not fixed (BPM turn) Fiducialisation redone.