Engineering survey planning for the alignment of a particle accelerator: part II. Design of a reference network and measurement strategy

• Published in: Measurement science & technology 2018-03, Vol.29 (3), p.34007
• Main Authors: Junqueira Leão, Rodrigo, Baldo, Crhistian Raffaelo, Collucci da Costa Reis, Maria Luisa, Alves Trabanco, Jorge Luiz
• Format: Article
• Language: English
• Subjects: large-scale dimensional metrology; laser trackers; length metrology; precision positioning; synchrotron light sources
• ISSN: 0957-0233; 1361-6501
• DOI: 10.1088/1361-6501/aa9dc3

The building blocks of particle accelerators are magnets responsible for keeping beams of charged particles at a desired trajectory. Magnets are commonly grouped in support structures named girders, which are mounted on vertical and horizontal stages. The performance of this type of machine is highly dependent on the relative alignment between its main components. The length of particle accelerators ranges from small machines to large-scale national or international facilities, with typical lengths of hundreds of meters to a few kilometers. This relatively large volume together with micrometric positioning tolerances make the alignment activity a classical large-scale dimensional metrology problem. The alignment concept relies on networks of fixed monuments installed on the building structure to which all accelerator components are referred. In this work, the Sirius accelerator is taken as a case study, and an alignment network is optimized via computational methods in terms of geometry, densification, and surveying procedure. Laser trackers are employed to guide the installation and measure the girders' positions, using the optimized network as a reference and applying the metric developed in part I of this paper. Simulations demonstrate the feasibility of aligning the 220 girders of the Sirius synchrotron to better than 0.080 mm, at a coverage probability of 95%.