Tobiyama, M.

Paper	Title	Page
MOPC061	Progress in R&D Efforts on the Energy Recovery Linac in Japan	205
	S. Sakanaka, T. A. Agoh, A. Enomoto, S. Fukuda, K. Furukawa, T. Furuya, K. Haga, K. Harada, S. Hiramatsu, T. Honda, Y. Honda, K. Hosoyama, M. Izawa, E. Kako, T. Kasuga, H. Kawata, M. Kikuchi, H. Kobayakawa, Y. Kobayashi, T. Matsumoto, S. Michizono, T. Mitsuhashi, T. Miura, T. Miyajima, T. Muto, S. Nagahashi, T. Naito, T. Nogami, S. Noguchi, T. Obina, S. Ohsawa, T. Ozaki, H. Sasaki, S. Sasaki, K. Satoh, M. Satoh, M. Shimada, T. Shioya, T. Shishido, T. Suwada, T. Takahashi, Y. Tanimoto, M. Tawada, M. Tobiyama, K. Tsuchiya, T. Uchiyama, K. Umemori, S. Yamamoto KEK, Ibaraki R. Hajima, H. Iijima, N. Kikuzawa, E. J. Minehara, R. Nagai, N. Nishimori, M. Sawamura JAEA/ERL, Ibaraki H. Hanaki JASRI/SPring-8, Hyogo-ken A. Ishii, I. Ito, T. Kawasaki, H. Kudo, N. Nakamura, H. Sakai, S. Shibuya, K. Shinoe, T. Shiraga, H. Takaki ISSP/SRL, Chiba M. Katoh UVSOR, Okazaki Y. Kobayashi, K. Torizuka, D. Yoshitomi AIST, Tsukuba M. Kuriki HU/AdSM, Higashi-Hiroshima
	The future synchrotron light sources, based on the energy recovery linacs (ERL), are expected to be capable of producing super-brilliant and/or ultra-short pulses of synchrotron radiation. The ERL-based light sources are under development at such institutes as the Cornell University, the Daresbury Laboratory, the Advanced Photon Source, and KEK/JAEA. The Japanese collaboration team, including KEK, JAEA, ISSP, and UVSOR, is working to realize the key technologies for the ERLs. Our R&D program includes the developments of ultra-low-emittance photocathode DC guns and of superconducting cavities, as well as proofs of accelerator-physics issues at a small test ERL (the Compact ERL). A 250-kV, 50-mA photo-cathode DC gun is under construction at JAEA. Two single-cell niobium cavities have been tested under high electric fields at KEK. The conceptual design of the Compact ERL has been carried out. We report recent progress in our R&D efforts.
TUOBG01	Observations of Beam-beam Tune Spectrum and Measurement of Coherent Tune Shift at KEKB	962
	T. Ieiri, Y. Ohnishi, M. Tobiyama, S. Uehara KEK, Ibaraki
	KEKB is a double-ring electron/positron collider with a horizontal crossing angle. The crab cavities installed in 2007 achieved an effective head-on collision and gained a higher specific luminosity. Under the new crabbing collision as well as the horizontal crossing collision, tune spectra of a colliding bunch were observed on a spectrum analyzer to study beam-beam effects. The beam-beam spectrum showed strong nonlinear resonant phenomena. Considering the nonlinearity, the coherent beam-beam tune shift was measured as a function of the bunch current. It was confirmed that the vertical beam-beam parameter estimated from the coherent beam-beam tune shift agreed with a value obtained from a bunch-by-bunch luminosity monitor. The estimated vertical beam-beam parameter was saturated on a level of about 0.04, which is called a beam-beam limit. We found that the bunch current corresponding to the beam-beam limit was far below the bunch current used in the usual operation.
	Slides
TUPC040	Measurements of Beam-beam Kick using a Gated Beam-position Monitor under Crabbing Collision at KEKB	1143
	T. Ieiri, H. Fukuma, Y. Funakoshi, M. Masuzawa, K. Ohmi, M. Tobiyama KEK, Ibaraki
	KEKB is a double-ring electron/positron collider with a horizontal crossing-angle. The crab cavities installed in 2007 achieved an effective head-on collision and gained a higher specific luminosity. A gated beam-position monitor is a tool to measure the beam-beam effects. A beam-beam kick curve was measured by comparing the beam position between colliding and non-colliding bunches, while shifting the beam orbit at the interaction point (IP). An effective horizontal beam size at the IP was obtained from a linear part of the beam-beam kick around the central orbit. The estimated beam size agreed with a calculated value including the dynamic effects. It was confirmed that the effective horizontal beam size was reduced by the crabbing collision, as expected from a calculation with a rigid Gaussian model. When a horizontal orbit offset was larger than a beam size, however, we found that the measured beam-beam kick curve deviated from calculated values using the Gaussian model. The result suggests that the beam profile might enlarge horizontally in the peripheral part.
MOPP059	Study for ILC Damping Ring at KEKB	676
	K. Ohmi, J. W. Flanagan, H. Fukuma, K.-I. Kanazawa, H. Koiso, M. Masuzawa, Y. Ohnishi, K. Oide, Y. Suetsugu, M. Tobiyama KEK, Ibaraki M. T.F. Pivi SLAC, Menlo Park, California
	ILC damping ring consists of very low emittance electron and positron storage rings. It is necessary for ILC damping ring to study electron cloud effects in such low emittance positron ring. We propose a low emittance operation of KEKB to study the effects.
THPC116	Commissioning of the iGp Feedback System at DAΦNE	3251
	A. Drago INFN/LNF, Frascati (Roma) J. D. Fox SLAC, Menlo Park, California D. Teytelman Dimtel, San Jose M. Tobiyama KEK, Ibaraki
	The iGp (Integrated Gigasample Processor) is an innovative digital bunch-by-bunch feedback system developed by a KEK/SLAC/INFN-LNF joint collaboration. The processing unit can sample at 500 MHz and compute the bunch-by-bunch output signal for up to 5000 bunches. The feedback firmware code is implemented inside just one FPGA (Field Programmable Gate Array) chip, a Xilinx Virtex-II. The FPGA implements two 16 taps FIR (Finite Impulse Response) filter that are realtime programmable through the operator interface. At DAΦNE, the Frascati PHI-Factory, two iGp units have been commissioned in the April 2007. The iGp systems have plugged in the previous betatron feedback systems. This insertion has been very fast and has shown no problems involving just a substitution of the old, less flexible, digital unit, letting unchanged the baseband analog frontend and the analog backend. The commissioning has been very simple, due to the complete and powerful EPICS operator interface, working well in local and remote operations. The software includes also tools for analyzing post processor data. A description of the commissioning with the operations done to find the best feedback setup are reported.