An interpretation of SPring-8 ground elevation by the empirical ATL-law approach

Abstract

Starting in 1996, the coordinates of the accelerator components on the SPring-8 storage ring were continuously surveyed for over two decades. The dispersion of the elevation changes of the ground motion ⟨ dz 2⟩ analyzed from the aspect of the empirical ATL-law which has been intensively researched since 1990s. With the ATL-law, ⟨ dz 2⟩ can be expressed as products of a ground diffusion coefficient A, temporal survey spans T, and spatial scales L. The coefficient A is well known to depend on the local geology and is evaluated as (7.6 ± 1.4) × 10−6 μm2/s/m for the SPring-8 storage ring. In this paper, a transition of survey methods in the SPring-8 storage ring is reviewd and survey results both in horizontal and vertical directions are presented. Furthermore, the relevance of the ATL-law approach for the ground elevation dispersion are discussed.