RIKEN Facility Office at RAL

RIKEN has constructed the RIKEN-RAL Muon Facility at Rutherford Appleton Laboratory in the UK, and has been promoting various kinds of science researches by applying unique characters of muon. Muon is created by decay of pion. Dr. Hideki Yukawa theoretically predicted the pion in 1935, and Dr. Yoshio Nishina observed the muon in cosmic rays in 1937. Muon is classified to electron family, and the lifetime is 2.2 μ second. The muon mass is 1/9 of proton and 207 times of electron. Muon has 100% spin polarization to the motion axis at the decay of pion. We stop polarized muons in materials, and observe the time evolution of muon spin to measure the local field and the fluctuation at the muon stopping site. This method is called "muon spin relaxation, rotation and resonance (μSR) method", and enables us to study the properties of condensed matters and molecules. In order to apply the μSR method to magnetism studies at surface and interface of functional materials, the development of ultra low energy muon beam has been in progress. Negative muon introduces spontaneous d-t fusions in D2 and T2 mixtures. This process is called gmuon catalyzed fusionh, and the elementary process has been studied toward realization of energy production.

Research Subjects

• Condensed matter and molecular science by muon spin relaxation method
• Ultra low energy muon beam generation and the applications to surface scienece
• Muon catalyzed d-t fusion
• Technical development of muon experiment apparatus

Publications

1. M. Iwasaki and K. Ishida,:
   "Development of new muon source for muon g-2 measurement and muon magnetic Microscope"
   Journal of Physics: Conference Series 225, 012005 (2010)
2. D. Tomono, T. M. Kojima, K. Ishida, T. Ikeda, Y. Iwai, M. Tokuda, Y. Kanazawa, Y. Matsuda, T. Matsuzaki, M. Iwasaki, and Y. Yamazaki,:
   "Focusing Effect of MeV Muon Beam with a Tapered Capillary Method"
   J. Phys. Soc. Jpn. 80, 044501 (2011)
3. O. A. Louchev, P. Bakule, N. Saito, S. Wada, K. Yokoyama, K. Ishida, and M. Iwasaki,:
   "Mechanism and computational model for Lyman-α-radiation generation by high-intensity-laser four-wave mixing in Kr-Ar gas"
   Physical Review A 84, 033842 (2011)
4. 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)
5. 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-T_c Cuprates: Review Based on the Hole Trapping by Ni"
   Phys. Rev. B 83, 144521-1-6 (2011)
6. T. Suzuki, M. Yamada, Y. Ishii, I. Watanabe, T. Goto, H. Tanaka, and K. Kubo,:
   "Change in Magnetic Ground States in Nonmagnetic-Impurity-Doped Spin-Gap Systems TlCu₁-_xMg_xCl₃ Proved by Muon Spin Relaxation"
   Phys. Rev. B 83, 174436-1-5 (2011)
7. F.L. Pratt, P.J. Baker, S.J. Blundell, T. Lancaster, S. Ohira-Kawamura, C. Baines, Y. Shimizu, K. Kanoda, and I. Watanabe,:
   "Magnetic-Field-Induced Quantum-Phase-Transition in the Spin-Liquid Phase of a Frustrated Magnet"
   Nature 471, 612-616 (2011)
8. K. Ohishi, Y. Ishii, K. Miyazawa, H. Fukazawa, I. Watanabe, Y. Kohori, P. M. Shirage, H. Kito, A. Iyo, and H. Eisaki,:
   "Fast Spin Fluctuation Viewed by Muon Spin Relaxation in Optimally Doped and Overdoped Iron-Based Oxypnictide Superconductors LaFeAsO₁-_xF_x"
   J. Soc. Phys. Jpn. 80, 024703-1-5 (2011)
9. J. Sugiyama, H. Nozaki, M. Harada, K. Kamazawa, O. Ofer, M. Mansson, J. H. Brewer, E. J. Ansaldo, K. H. Chow, Y. Ikedo, Y. Miyake, K. Ohishi, I. Watanabe, G. Kobayashi, and R. Kanno,:
   "Magnetic and diffusive nature of LiFePO₄ investigated by muon spin rotation and relaxation"
   Phys. Rev. B 84, 054430/1-9 (2011)
10. F. L. Pratt, P. J. Baker, S. J. Blundell, T. Lancaster, S. Ohira-Kawamura, C. Baines, Y. Shimizu, K. Kanoda, I. Watanabe and G. Saito,:
    "Magnetic and non-magnetic phases of a quantum spin liquid "
    Nature 471, 612 (2011)