Positioning the SPring-8 magnets with the laser tracker

The storage ring of third-generation synchrotron radiation source is much sensitive to magnet misalignment, especially quadrupole misalignment. To reduce this sensitivity, the magnet alignment for the SPring-8 storage ring is divided into two stages. Alignment of SPring-8 storage ring magnets is composed of monument survey and magnet survey and alignment. 10 monuments are set outside the storage ring and 88 monuments are buried at the intersection points of the side straight lines of the bending magnet. The magnets are surveyed and aligned with the laser tracker SMART 310, a 3-dimension measurement system. This system is for the first time employed in the measurement of storage ring networks. Many factors may influence measurement accuracy of the laser tracker. To realize the accuracy it can achieve, the laser tracker was checked under various conditions. The laser tracker was found to have a distance accuracy of 0.001 + 0.2 ppm x L (mm) and an angular accuracy of ca. 10 μrad, which is four times the error of theodolite T3000. Using Smart for network survey, the precision is restricted by the angular resolutions of the encoders. Although the Smart 310 has a large angle measurement error which is not match for its distance accuracy, it is also can be successfully used in network survey for positioning magnets as long as take its strong point and avoid its short coming. (M.N.)