Magnet alignment of the SPring-8 storage ring

Wide area of the storage ring of SPring-8 is put on the hard rock, however the ground of other area was improved. The 21 monuments for the magnet alignment of the storage ring were surveyed before building construction. After tunnel construction the 88 monuments were surveyed again and these positions were determined. After setting girders and magnets, the girders were surveyed with a laser tracker by making network. After the smoothing the relative displacements were within ±0.04 mm. A laser and CCD camera system is used for a precise alignment of quadrupole and sextupole magnets on a girder and now this alignment has finished about half ring. The target shift from the 5m-straight line can be measured to an accuracy less than 10 μm. The misalignment of them are estimated to be less than the tolerance. For these alignment some convenient instruments have been made, for example a target stage with ball cage etc. (author)