CEPC survey and alignment

For CEPC such big size machine survey and alignment, several key issues need to be considered: the measurement and data processing method, error accumulation control, the global and relative accuracy, the measurement efficiency, component alignment method and the deformation problem. To these issues an overall survey and alignment scheme was made. The global datums will be established for the measurement and data reduction. A multi -level control network will be built for the global and relative position control, the establish method and measurement method are introduced and the accuracies are estimated. To the component alignment, the schemes of fiducialization, pre -alignment and tunnel alignment are introduced, the deformation problem was analysed and monitor equipment will be applied. To improve the measurement efficiency a new kind of instrument was designed, the prototype has been fabricated and some experiments has been carried out.