J-GLOBAL         Last updated: May 2, 2013 at 16:37
High Energy Accelerator Research Organization
Accelerator Laboratory
Job title
Dr. of Science(Hiroshima University), Master of Science(Hiroshima University)


In a storage ring which stores many bunches at high beam current, especially in particle-factory machines, such as KEKB, it is very likely that many strong coupled-bunch instabilities occur in both the transverse and longitudinal planes. Reduction of the impedances in the ring is essential to suppress the instabilities. However, we have observed strong transverse coupled-bunch instabilities in both rings of KEKB. How we suppress and analyze the instabilities holds the key to achieving the designed qualities of the accelerators.
To cure these instabilities, we are now operating beam feedback systems with a bunch-by-bunch scheme. My main theme of study is to develop, improve and maintain the feedback systems. Also I am working to develop the monitor systems to analyse unknown beam instabilities.

Research Interests


Research Areas


Academic & Professional Experience

Apr 2012
Professor, Accelerator Laboratory, High Energy Accelerator Research Organization (KEK)
Apr 2008
Mar 2012
Associate Professor, Accelerator Laboratory, High Energy Accelerator Research Organization (KEK)
Apr 1997
Mar 2008
Research Associates, Accelerator Laboratory, High Energy Accelerator Research Organization (KEK)
May 1993
Mar 1997
Research Associates, Accelerator Department, National Laboratory for High Energy Physics (KEK)
Apr 1988
Apr 1993
Research Associates, Department of Materials Science, Faculty of Science, Hiroshima University


Graduate School, Division of Natural Science, Hiroshima University
Faculty of Science, Hiroshima University


M.Tobiyama, J.W.Flanagan, H.Fukuma, S.Kurokawa, K.Ohmi and S.S.Win
Physical Review Special Topics - Accelerators and Beams   9(1) 012801   2006
Physical Review Special Topics - Accelerators and Beams   8,094401    2005
T.Ieiri, Y.Ohnishi, M.Tobiyama, S.Uehara
Physical Review Special Topics - Accelerator and Beams   12 064401   2009
T.Ieiri, K.Akai, H.Fukuma and M.Tobiyama
Nuclear Instruments and Methods in Physics Research A   606(3) 248-256   2009
Y.Funakoshi, M.Masuzawa, K.Oid, J.Flanagan, M.Tawada, T.Ieiri, M.Tejima, M.Tobiyama, K.Ohmi and H.Koiso
Physical Review Special Topics - Accelerator and Beams   10 101001   2007

Books etc

Beam Feedback Systems
AIP Conference Proceedings   2002   
Analysis of increase in impurity in single bunch mode for electron storage ring
Report on Grant-in-Aid for Scientific Research(C)   1993   
Measurement of bunch time-structure in KEK-PF
Proceedings of the 1993 IEEE Particle Accelerator Conference   1993   
Suppression of Longitudinal Coupled-Bunch Instability in Small Storage Ring for SR
Proceedings of the Fifth Japan-China Joint Symposium on Accelerator for Nuclear Science and Their Applications   1993   
Influence of External Magnetic Field on Beam DCCT
Proceedings of the 9th Symposium on Accelerator Science and Technology   1993   


Suppression of Longitudinal Coupled-bunch Instabilities by means of Decoupling Method
1990 - 1992
Design study for HiSOR accerelator system
1986 - 1992
Study of pulser for electron gun for linear accelerator
1991 - 1992
Development of feedback system for B-Facotory
Improvement of high frequency response on button-type electrode

Research Grants & Projects

Development of the digital feedback system for the B-Factory
Development of General purpose digital filter system for bunch by bunch feedback systems
International Collaboration
Project Year: 2002   
Study of beam instability and its cure for high intensity proton accelerator
Project Year: 2007