Centers & Labs

RIKEN Nishina Center for Accelerator-Based Science

Meson Science Laboratory

Group Director: Masahiko Iwasaki (D.Sci.)
Masahiko  Iwasaki(D.Sci.)

Particles like muons, pions, and kaons have finite life times, so they do not exist in natural nuclei or matters. In our research, we introduce different kind of impurities into nuclei/matters, and study new states of matter, new phenomena, or the object properties.
Implanting these particles into nuclei/matters, exotic phenomena in varieties of objects can be studied from a new point of view. Kaon is a second lightest meson which has strange-quark as a constituent quark. It is expected that if one embed a kaon into nuclei, the sizes of the nuclei become smaller and forms a high-density object beyond the normal nuclear density. Study of this object could lead better understanding of the origin of the mass of the matter, and may reveal the quark degree of freedom beyond the quark-confinement. Those properties can be studied by precise heavy pionic atom research in different angle. The other example is the weak interaction in nuclear matter. It can only be studied by the weak decay of hypernuclei, which have Lambda particle in the nuclei.
Muon provides even wider variety of study from nuclear reaction to magnetism in matter. For instance, stopping positively charged muon in a material, we obtain information on the magnetic properties or the local field at the trapped-site (muon-spin-relaxation method). Ultra-slow muon beam can be used for the material surface studies and also as a source of ultra-cold muon beam for precise muon g-2 measurement.

Main Research Field

Interdisciplinary science and engineering

Related Research Fields

Complex systems


  • Meson
  • muon
  • hadron
  • mass

Selected Publications

  1. M. Iwasaki, H. Bhang, J. Chiba, Choi Seonho, Y. Fukuda, T. Hanaki, R.S. Hayano, M. Iio, T. Ishikawa, S. Ishimoto, T. Ishiwatari, K. Itahashi, M. Iwai, P. Kienle, J.H. Kim, Y. Matsuda, H. Ohnishi, S. Okada, H. Outa, M. Sato, S. Suzuki, T. Suzuki, D. Tomono.:
    "Search for strange tribaryon states in the inclusive He-4 (K-(stopped), p) reaction"
    Nucl. Phys. A804, 186-196 (2008)
  2. S. Okada, G. Beer, H. Bhang, M. Cargnelli, J. Chiba, Seonho Choi, C. Curceanu, Y. Fukuda, T. Hanaki, R.S. Hayano, M. Iio, T. Ishikawa, S. Ishimoto, T. Ishiwatari, K. Itahashi, M. Iwai, M. Iwasaki, B. Juhasz, P. Kienle, J. Marton, Y. Matsuda, H. Ohnishi, H.:
    "Precision measurement of the 3d ---> 2p x-ray energy in kaonic He-4"
    Physics Letters B 653, 387-391 (2007).
  3. T. Suzuki, H. Bhang, J. Chiba, S. Choi, Y. Fukuda, T. Hanaki, R. S. Hayano, M. Iio, T. Ishikawa, S. Ishimoto, T. Ishiwatari, K. Itahashi, M. Iwai, M. Iwasaki, P. Kienle, J. H. Kim, Y. Matsuda, H. Ohnishi, S. Okada, H. Outa, M. Sato, S. Suzuki, D. Tomono.:
    "Lambda d correlation from He-4(stopped K-, d) reaction"
    Physicl Review C76, 068202 (2007)
  4. Y. Tanabe, T. Adachi, K. Suzuki, Y. Koike, T. Kawamata1, Risdiana, T. Suzuki1, and I. Watanabe.:
    "Similarity between Ni- and Zn-Impurity Effects on the Superconductivity and Cu-spin Correlation in La-214 High-TC Cuprates: Review Based on the Hole Trapping by Ni"
    Phys. Rev. B 83, 144521-1-6 (2011)
  5. F.L. Pratt, P.J. Baker, S.J. Blundell, T. Lancaster, S. Ohira-Kawamura, C. Baines, Y. Shimizu, K. Kanoda, and I. Watanabe.:
    "Magnatic-Field-Induced Quantum-Phase-Transition in the Spin-Liquid Phase of a Frustrated Magnet"
    Nature 471, 612-616 (2011)
  6. T. Lancaster, F.L. Pratt, S.J. Blundell, A.J. Steele, P.J. Baker, J.D. Wright, I. Watanabe, R.S. Fishman, and J.S. Miller.:
    "Local Magnetism in the Molecule-Based Metamagnet [Ru2(O2CMe)4]3[Cr(CN)6] Probed with Implanted Muons"
    Phys. Rev. B 84, 092405-1-4 (2011)
  7. Imao, H., Ishida, K., Kawamura, N., Matsuzaki, T., Matsuda, Y., Toyoda, A., Strasser, P., Iwasaki, M. and Nagamine, K.:
    "Density effect in d-d muon-catalyzed fusion with ortho- and para-enriched D2"
    Phys. Lett. B 658, 120-124 (2008)
  8. P. Bakule, D.G. Fleming, O. Sukhorukov, K. Ishida, F. Pratt, T. Momose, E. Torikai, B.G. garrett, K.A. Peterson, G.C. Schatz and D.G. Truhlar:
    "State-selected reaction of muonium with vibrationally excited H2"
    J. Phys. Chem. Lett. 3, 2755-2760 (2012)
  9. Bakule, P., Matsuda, Y., Miyake, Y., Nagamine, K., Iwasaki, M., Ikedo, Y., Shimomura, K., Strasser, P., and Makimura, S.:
    "Pulsed source of ultra low energy positive muons for near-surface mSR studies"
    Nuclear Instruments and Methods in Physical Research B 266, 335-346 (2008)
  10. T.Hashimoto et al.:
    "Search for the deeply bound K−pp state from the semi-inclusive forward-neutron spectrum in the in-flight K− reaction on helium-3"
    Prog. Theor. Exp. Phys. (2015) 061D01.

Lab Members

Principal Investigator

Masahiko Iwasaki
Group Director

Core Members

Katsuhiko Ishida
Vice Chief Scientist
Isao Watanabe
Senior Research Scientist
Kenta Itahashi
Senior Research Scientist
Fuminori Sakuma
Senior Research Scientist
Haruhiko Outa
Senior Research Scientist
Yue Ma
Senior Research Scientist
Hidemitsu Asano
Special Postdoctoral Researcher
Sohtaro Kanda
Special Postdoctoral Researcher
Shu Aikawa
Junior Research Associate
Dita Puspita Sari
Junior Research Associate
Retno Asih
Junior Research Associate
Fahmi Astuti
Junior Research Associate
Shintaro Tanaka
Junior Research Associate
Julia Angel
Junior Research Associate
Sungwon Yoon
International Program Associate
Harison Binti Rozak
International Program Associate
Redo Muhammad Ramadhan
International Program Associate
Suti Winarsih
International Program Associate

Contact information

2-1 Hirosawa,
Wako, Saitama
351-0198, Japan

Email: advanced_meson [at]

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