THE LINEAR COLLIDER ALIGNMENT AND SURVEY ( LiCAS ) PROJECT

For the next generation of Linear Colliders (LC) the precision alignment of accelerator components will be critical. The DESY applied geodesy group has developed the concept of an automated ”survey train”. The train runs along the accelerator wall measuring the 3D position of a set of equispaced reference markers. This reference structure is then used to align the accelerator components. The LiCAS group is developing a measurement system for the survey train. It will use a combination of Laser Straightness Monitors (SM) and Frequency Scanning Interferometry (FSI). FSI is an interferometric length measurement technique originally developed for the online alignment of the ATLAS Inner Detector. This novel combination of optical techniques is expected to overcome the limitations of traditional open air survey. The authors describe the LiCAS project, the measurement systems and their integration into the survey train. The technical parameters and constraints will be mentioned. There will also be brief discussion of the second phase of the project to allow on-line monitoring of the LC alignment.