• S. Hashimoto, S. Miyamoto
  NewSUBARU/SPring-8, Laboratory of Advanced Science and Technology for Industry (LASTI), Hyogo
• K. Kawata, Y. Minagawa, T. Shinomoto
  JASRI/SPring-8, Hyogo-ken

The periodic fluctuations and drifts in the radiation intensity have been observed at the NewSUBARU synchrotron radiation facility. To clarify the cause of this problem we have measured temperatures of air, cooling water, equipments and building with the network-distributed data logger. And we found that temperature fluctuations in both air in the shielded tunnel and the cooling water mainly affect the stabilities of electron beam orbit and optical axis. To maintain a constant temperature, the large doors for carrying equipment at the experimental hall were covered with insulated curtains, and we optimized PID parameters of temperature controllers for air and water. As results, the periodic fluctuations almost disappeared, but some drifts were still remained, which are due to slow variations of equipment temperature. By realizing the automatic COD correction, the drift in electron beam position could be suppressed and the fluctuations of radiation intensity observed at beam-lines became smaller than they used to be. For further stabilization, we recently introduced a XBPM upstream in a beamline to measure the vertical position of radiation axis precisely.