Speaker
Description
Alignment of SuperKEKB, whose nano-beam optics demand sub-millimetre magnet positioning, relies on laser-tracker surveys that have proven highly accurate — the surveyed ring circumference was confirmed directly by the beam during commissioning. The survey is, however, performed intermittently, while the tunnel and the interaction region move on daily, seasonal and long-term scales, and the continuous monitoring (hydrostatic levelling, gap sensors and a GPS network) is handled by separate systems rather than in a single adjustment. This motivates evaluating a rigorous, unified three-dimensional framework. We report the first application of LGC2 (Logiciel Général de Compensation), the least-squares network-adjustment software developed and maintained at CERN, to SuperKEKB main-ring survey data. For the present analysis, the ring is divided into nine sections following the existing naming convention — the Tsukuba, Oho, Fuji and Nikko regions, each split into left and right halves, plus the interaction region; these boundaries are introduced solely for the analysis and do not correspond to any change in the survey. The full data set is brought into a common machine frame with LGC2. The reconstruction is validated by comparing reference monuments measured at each section boundary. The good agreement between adjacent sections confirms the consistency of the reconstructed network and demonstrates that LGC2 is a suitable platform for integrating periodic surveys with continuous HLS and future frequency-scanning interferometry (FSI) monitoring at SuperKEKB.
