Long term ground movement of TRISTAN synchrotron

The long term ground movement is estimated through the geological survey before a big accelerator is planned. For the case of TRISTAN-MR (main ring), its site was surveyed to reflect the underground information to the building prior to the construction. The movement of the synchrotron magnet mainly results from the structure of the tunnel. If an individual movement of the magnet exceeds a certain threshold limit, it gives a significant effect on the particle behavior in a synchrotron. Height of the quadrupole magnets were observed periodically during past two years at the TRISTAN-MR and their height differences along the 3 km circumference of the accelerator ring were decomposed into the Fourier components depicting the causes of the movements. Results shows the movement of the tunnel foundation which was also observed by the simultaneous measurement of both magnets and fiducial marks on the tunnel wall. The long term movement of the magnets is summarized with the geological survey prior to construction. 1 ref., 6 figs., 1 tab