Drift of beam orbit at NewSUBARU storage ring

The orbit stability of an electron beam in a storage ring is one of the most important issues in synchrotron radiation facilities. In the NewSUBARU storage ring, various efforts have been performed to stabilize the beam orbit. However, the slow orbit drift of 40 micron with the period of about 20 minutes is still observed. Then we investigated the cause of the periodic drift. We have constructed a data acquisition system to measure both beam positions and temperature of air, cooling water, chambers, magnets, floor and so on. The measurement results show that air-conditioners in the storage ring tunnel greatly influence the beam orbit. Using the same system, we also measured the shift of beam orbit and betatron tunes during the energy ramping from 1.0 to 1.5 GeV. It gave information on the beam loss mechanism in this period. (author)