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Description
The Siam Photon Source II (SPS-II) is Thailand's next-generation 3 GeV synchrotron light source currently under construction, comprising a 270 MeV linear accelerator, a 3 GeV booster synchrotron, a 3 GeV storage ring, and beamline facilities. Achieving the designed electron beam emittance below 1 nm·rad requires precise component placement and long-term positional stability, making a robust alignment network essential for establishing a reliable reference frame for installation, verification, and future realignment. This paper presents the design of the SPS-II alignment network developed to support the installation and maintenance of the accelerator complex. The proposed system comprises a three-level hierarchical reference network: the Ground Control Network, the Primary Network, and the Alignment Network, established using floor and wall monuments distributed throughout the accelerator tunnels and experimental areas to satisfy the required positioning accuracy of ± 0.1 mm. The network geometry was designed to provide sufficient redundancy, visibility, and measurement reliability. A Laser Tracker system is used as the primary metrology instrument for three-dimensional coordinate measurements, and the network is adjusted using the Unified Spatial Metrology Network (USMN) algorithm in Spatial Analyzer (SA) software to establish a consistent and reliable coordinate system. The proposed network supports the complete installation process, including pedestal placement, girder–magnet assembly installation, alignment, and periodic verification. It also serves as a reference frame for integrating survey data throughout installation, commissioning, and future maintenance, supporting the required accuracy and long-term operational stability.
