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RIKEN Facility Office at RAL

Philip KINGD.Sci.
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Research Areas

Our core activities are based on the RIKEN-RAL Muon Facility located at the Rutherford Appleton Laboratory (UK), which provides intense pulsed-muon beam. Muons have their own spins with 100% polarization, and can detect very precisely local magnetic fields and their fluctuations at muon stopping sites. The method to study characteristic of materials by observing time dependent changes of muon spin polarization is called "Muon Spin Rotation, Relaxation and Resonance (muSR method), and is applied to studies of electro-magnetic properties of insulating, metallic, magnetic, superconducting systems. Muons reveal static and dynamic properties of electronic state of materials in the zero-field condition which is the ideal magnetic condition for researches on the magnetism. muSR is applied to insulating, metallic, magnetic, superconducting systems. We have carried out muSR investigations on frustrated organic system which has a triangular spin network. We found the one dimensional properties of the spin-spin correlations in the system. This proves the first example which has the one-dimensional resonating spin state in real materials.

Positive muon beam with thermal energy has been produced by laser ionization of muoniums (bound system of mu+ and electron) emitted from hot tungsten surface with stopping surface muon beam at Port-3. The ultra-slow muon beam can be stopped in thin foils, multi-layered materials and artificial lattices and we can apply the muSR techniques to surface and interface science. The development of ultra-slow muon beam is also very important as the source of ultra-cold (pencil-like small emittance) muon beam for muon g-2 measurement. We have been developing muonium generators to create more muoniums in vacuum even at room temperature. Very recently, we demonstrated tremendous increase of the muonium emission efficiency by fabricating fine laser drill-holes on the surface of silica aerogel. We also developed a high power Lyman-alpha laser in collaboration with laser group at RIKEN. The new laser will ionize muoniums 100 times more efficiently for slow muon beam generation.

Research Subject

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

List of Selected Publications

  1. K. Mukai, Y. Aoki, D. Andraica, A. Amato, I. Watanabe, S.R. Giblin, and J. Sugiyama.:
    "Thermally Activated Spin Fluctuations in Stoichiometric LaCoO2"
    Phys. Rev. B 89, 094406 (2014)
  2. H. Guo, K. Matsuhira, I. Kawasaki, M. Wakeshima, Y. Hinatsu, I. Watanabe, and Z. Xu.:
    "Magnetic Order in Pyrochlore Iridate Nd2Ir2O7 Probed by Muon Spin Relaxation"
    Phys. Rev. B 88, 060441(R)-1-5(2013)
  3. I. Kawasaki, I. Watanabe, H. Amitsuka, H. Tanida, and Y. Ohnuki.:
    "Superconducting Properties of Noncentrosymmetric Superconductor LaPt3Si Studied by Muon Spin Spectroscopy"
    J. Phys. Soc. Jpn. 82, 084713-1-6 (2013)
  4. S. Wenner, R. Holmestad, K. Matsuda, K. Nishimura, T. Matsuzaki, D. Tomono, F.L. Pratt, and C.D. Marioara.:
    "Probing Defects in Al-Mg-Si Alloys Using Muon Spin Relaxation"
    Phys. Rev. B 86, 104201-1-7 (2012)
  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-Tc Cuprates: Review Based on the Hole Trapping by Ni"
    Phys. Rev. B 83, 144521-1-6 (2011)
  6. 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)
  7. G. A. Beer, et al.:
    "Enhancement of Muonium Emission Rate from Silica Aerogel with a Laser-Ablated Surface"
    Prog. Theor. Exp. Phys. 2014, 091C01
  8. P. Bakule, et al.:
    "Measurement of muonium emission from silica aerogel"
    Prog. Theor. Exp. Phys. 2013, 103C01
  9. P. Bakule, O. Sukhorukov, K. Ishida, F.L. Pratt, D. Fleming, T. Momose, Y. Matsuda, and E. Torikai.:
    "First Accurate Experimental Study of Mu Reactivity from a State-Selected Reactant in the Gas Phase: the Mu + H2{1} Reaction Rate at 300 K"
    J. Phys. B (At. Mol. Opt.) 48, 045204 (2015)
  10. 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 studie"
    Nuclear Instruments and Methods in Physical Research B 266, 335-346 (2008)


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