Research on layout of datum plane in equipment fiducialisation of particle accelerator

In the equipment fiducialisation of partical accelerator, the deviation for motion mechanism in wire scanner and stripper foil changer relative to the fiducialisation plane might be needed to non-contact measure by optical instrument indirectly, so it's necessary to lay out the datum accurately by laser tracker, and provide the reference points for locating the optical instrument. The layout error and its effect were analyzed in this paper, and the effect could be reduced effectively by using hold level best-fit and choosing the reasonable position for the reference points. This method improves the alignment accuracy, provides a guidance for the similar equipment fiducialisation in actual work, guarantees the good performance of the accelerator equipment and has an important significance in accelerator alignment field. (authors)