• M. Tobiyama, J.W. Flanagan, T.M. Mitsuhashi, T. Obina, M. Tadano, R. Takai
  KEK, Ibaraki

A transverse bunch by bunch feedback system using iGp feedback processors has been tested at the KEK-PF. The system consists of a bunch position detection system using 1.5 GHz components of the beam (3 x fRF), iGp feedback signal processors, and a transverse feedback kicker with a high power amplifier. It shows sufficient performance to suppress instabilities completely up to a beam current of 450mA. Results of the mode analysis of the instabilities using the grow-damp function of the iGp are also shown.

• A. Toyoda, A. Agari, E. Hirose, M. Ieiri, Y. Katoh, A. Kiyomichi, M. Minakawa, T.M. Mitsuhashi, R. Muto, M. Naruki, Y. Sato, S. Sawada, Y. Shirakabe, Y. Suzuki, H. Takahashi, M. Takasaki, K.H. Tanaka, H. Watanabe, Y. Yamanoi
  KEK, Tsukuba
• H. Noumi
  RCNP, Osaka

We have continuously developed the Optical Transition Radiation (OTR) monitor with optics system based on the Newtonian telescope to measure a profile for a high intensity proton beamline. Now we installed the OTR monitors of production version on the J-PARC hadron beamline, and successfully observed a first OTR light. This led to the establishment of high S/N profile measurement with minimum beam disturbance. At this commissioning stage, a beam intensity is as small as 1.2 KW, but expected to increase up to 750 kW, so that maintenance work becomes important. To improve ease of maintenance, we plan to replace the focusing lens system with reflective mirror system with higher resistance to radiation. A result of beam profile measurement, an estimation of dependence of an OTR background on a beam loss, and a future plan for an upgrade of our optics system will be presented.

• K.R. Ye, J. Chen, Y.B. Leng, J. Yu, G.B. Zhao, W.M. Zhou
  SINAP, Shanghai
• T.M. Mitsuhashi
  KEK, Ibaraki

SR monitor for the measurements of beam profile, sizes, and bunch length has been designed and constructed at the Shanghai synchrotron radiation Facility (SSRF). A water-cooled beryllium mirror is installed to extract the visible SR. This beryllium mirror was designed via thermal analysis based on ANSYS. The extracted visible SR is relayed to dark room by three mirrors. The measurement system includes, imaging system, SR interferometers (SRI), streak camera and fast-gated camera etc are set in the dark room. Both the horizontal and the vertical beam sizes are monitored by SRI, and bunch length and temporal profile of the beam are measured by streak camera. The existed system suffers with dynamic problem for beam physics studies. The commissioning of synchrotron radiation monitor system has been performed in SSRF since December, 2007. The results obtained at SSRF will be presented.