Determination of magnet realignment period based on smoothing analysis

A deformation measurement of the PLS storage ring tunnel shows that the settlement of the tunnel floor keeps going on about 3 mm (peak-to-valley) a year, and the lateral deformation is within the range of ±1 mm. The tunnel settlement of 3 mm results in the storage ring deformation of ±1.5 mm a year in vertical direction. Results of the case studies for the estimation of relative positional errors by a smoothing analysis from 1995 to 1997 are summarized as follows: a low filter method for the smoothing analysis was successfully employed, and the storage ring magnets are placed within 2σ (±0.3 mm) range from the smoothed curve. While the relative positional errors are well within the tolerance of 0.15 mm, the absolute positional tolerance that is the range of maximum deviations of magnets from the ideal beam path is extended to ±3 mm, which is derived from the experience of storage ring operation. Therefore, we estimate the period of magnet realignment of the PLS storage ring should be about 2 years. (author)