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RIKEN SPring-8 Center Accelerator System Operation Research Group

Group Director: Toru Hara (D.Sc.)

Research Summary

Toru Hara

The Accelerator System Operation Research Group advances the performance improvement and upgrade projects of SPring-8 and SACLA. We are working on SPring-8-II, which is a next-generation synchrotron radiation source adopting Multi-Bend Achromat (MBA), and the SACLA upgrade plan aiming at a kHz repetition XFEL with a normal conducting accelerator technology. We also proactively develop and introduce Machine Learning methods in accelerator operation and tuning. Our goal is not only to enhance the light source performance but also to achieve a green facility.

Main Research Fields

  • Interdisciplinary Science & Engineering

Related Research Fields

  • Engineering
  • Mathematical & Physical Sciences
  • Quantum Beam Science
  • Applied Physics


  • Electron Accelerator
  • X-ray Free-Electron Laser
  • Synchrotron Radiation
  • Machine Learning
  • Beam Physics

Selected Publications

  • 1. Iwai E., Inoue I, Maesaka H., Inagaki T., Yabashi M., Hara T. and Tanaka H.:
    "Spectral-brightness optimization of an X-ray free-electron laser by machine-learning-based tuning"
    J. Synchrotron Rad. 30, 1048 (2023).
  • 2. Hiraiwa T., Soutome K., and Tanaka H.:
    "Suppression of Emittance Variation in Extremely Low Emittance Light Source Storage Rings"
    Phys. Rev. Accel. Beams 25, 040703 (2022).
  • 3. Hara T. et al.:
    "Low-emittance beam injection for a synchrotron radiation source using an X-ray free-electron laser linear accelerator"
    Phys. Rev. Accel. Beams, vol. 24, 110702 (2021).
  • 4. Tono K., Hara T., Yabashi M. and Tanaka H.:
    "Multiple-beamline operation of SACLA"
    J. Synchrotron Rad. 26, 595 (2019).
  • 5. Inoue I. et al.:
    "Generation of narrow-band X-ray free-electron laser via reflection self-seeding"
    Nature Photon. 13, 319 (2019).
  • 6. Maesaka H., Hara T., Togawa K., Inagaki T. and Tanaka H.:
    "Brightness analysis of an electron beam with a complex profile"
    Phys. Rev. Accel. Beams 21, 050703 (2018).
  • 7. Bizen T. et al.:
    "Radiation-induced magnetization reversal causing a large flux loss in undulator permanent magnets"
    Sci. Rep. 6, 37937 (2016).
  • 8. Tanaka T.:
    "Proposal to generate an isolated monocycle X-ray pulse by counteracting the slippage effect in free-electron lasers"
    Phys. Rev. Lett. 114, 044801 (2015).
  • 9. Hara T. et al.:
    "Two-colour hard X-ray free-electron laser with wide tunability"
    Nature Commun. 4, 2919 (2013).
  • 10. Ishikawa T. et al.:
    "A compact X-ray free-electron laser emitting in the sub-angstrom region"
    Nature Photon. 6, 540 (2012).

Recent Research Results


Related Links

Lab Members

Principal investigator

Toru Hara
Group Director

Core members

Sunao Takahashi
Senior Technical Scientist
Hirokazu Maesaka
Senior Research Scientist
Kouichi Soutome
Research Scientist
Toshihiko Hiraiwa
Research Scientist
Takahiro Inagaki
Research Scientist

Contact Information

1-1-1 Kouto, Sayo-cho
Sayo-gun, Hyogo
679-5148 Japan
Email: toru [at] spring8.or.jp


Advanced Beam Dynamics Team
Toru Hara (D.Sc.)
FEL Physics Team
Takashi Tanaka (D.Eng.)