Atomic Physics Laboratory

Distinguished Senior Scientist

Yasunori Yamazaki

  • D.Eng.
  • Yasunori Yamazaki
  • Brief resume
    D.Eng., Department of Applied Physics, Osaka University
    Research Associate, Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology
    Associate Professor, College of Arts and Sciences, University of Tokyo
    Professor, College of Arts and Sciences, University of Tokyo
    Professor, Graduate School of Arts and Sciences, University of Tokyo
    Chief Scientist, Atomic Physics Laboratory, RIKEN
    Distinguished Senior Scientist, Atomic Physics Laboratory, RIKEN (-current)
    Project Professor, Graduate School of Arts and Sciences, University of Tokyo (-current)


Atomic Physics Laboratory

Developments of antimatter science with antihydrogen atoms: qualitatively new techniques are developed to produce spin-polarized antihydrogen beams, which allow for the first time the CPT symmetry of nature to be tested with high precision. To realize this, we have invented and developed a so-called cusp trap scheme. The cusp trap consists of superconducting anti-Helmholtz coils and a multi-ring trap. Actually, we succeeded in synthesizing a large number of antihydrogen atoms in 2010, i.e., we are really at the entrance of antihydrogen spectroscopy. The guiding principle of our research is “listen to the whisper of nature.” In addition, we are interested in the formation processes of antiprotonic atoms under single collision conditions.

Interdisciplinary research of particle-matter interaction: based on the knowledge of atomic physics and atomic collision physics, we develop interdisciplinary research fields involving radiation biology, surface science, and non-neutral plasma physics. We pay particular attention to particle-insulator interactions, where we have found various unexpected phenomena like beam-induced insulator-metal transitions. We have also developed a technique to inject micron-sized ions to an arbitrary position in liquid, which allows, e.g., selective bombardment of cellular structures under a microscope.

Recent Research Topic

Listen to the whisper of nature with ultra cold antimatter

Symmetry between hydrogen and antihydrogen
Fig. 1 Symmetry between hydrogen and antihydrogen

We believe that our universe started with an extremely high-density cloud of photons: the big bang. At the same time, it is known that CPT (Charge, Parity, Time) symmetry is conserved for various physical quantities. Actually, fundamental theories are usually constructed so that the CPT symmetry is conserved. Considering the facts above, it is straightforwardly concluded that the same amount of matter and antimatter were synthesized in the big bang. On the other hand, it is also known from astronomical observations that our universe is filled with matter, i.e., the matter-antimatter symmetry affears to be violated. This mystery of “disappeared antimatter” has been discussed from various points of view, and one attractive assumption is CPT violation. As the CPT symmetry claims that matter and the corresponding antimatter must have the same physical properties — mass, charge, magnetic moment, and lifetime — the first step is to investigate any differences between matter and antimatter. As this subject is the fundamental test of fundamental physical law, it is in itself quite interesting and important. It is also noted that P and CP symmetries have been found to be broken, and the last one still left is the CPT symmetry. Practically speaking, any CPT asymmetries are expected to be quite tiny, if any, and so experimental schemes to challenge such asymmetries should have high sensitivity and precision. In other words, a long observation time is necessary and the antimatter to be examined should be at rest (and cold). Antihydrogen is the best candidate to fulfill the above conditions because it is stable under vacuum, i.e., it in principle allows for infinitely precise measurements, and hydrogen — the counterpart of antihydrogen — is one of the best studied with respect to its spectroscopic properties (14 digits and 12 digits for 1S-2S and hyperfine transitions, respectively).

We have invented and developed a conceptually new scheme to synthesize ultra-cold spin-polarized antihydrogen beams, a cusp trap scheme. Fig. 2 schematically shows the cusp trap scheme, which consists of the cusp trap (superconducting anti-Helmholtz coils and multi-ring electrodes), a microwave cavity to induce spin-flip transitions, and a sextupole magnet. We plan to realize microwave spectroscopy with a precision of 6-7 digits, which improves the known magnetic moment of antiprotons by 3-4 digits, and provides information on the internal structure of antiprotons.

Fig. 3 (a) shows the cross-section of the cusp trap overlapped with magnetic field lines. Fig. 3 (b) gives a typical potential distribution to synthesize antihydrogen atoms. In this case, the positron cloud is centered around z=100 mm, and the antiproton cloud oscillates around the positron cloud. In 2010, we succeeded in synthesizing a large number of antihydrogen atoms by storing positrons in the cusp trap and injecting a bunch of pulsed ultra-slow antiprotons. No one had ever succeeded in synthesizing antihydrogen atoms in a non-uniform magnetic field before this experiment. The next step is to extract an antihydrogen beam and to optimize the extraction conditions. After this, we can at last start high-resolution microwave spectroscopy of antihydrogen atoms for the first time.

The cusp trap scheme
Fig. 2 The cusp trap scheme
Antiprotons and positrons, the ingredients of antihydrogen atoms, are injected from the left side, stored, cooled, and eventually synthesized into antihydrogen atoms. Antihydrogen atoms are extracted from the right side.
The structure of the cusp trap
Fig. 3 The structure of the cusp trap
(a) A cross-section of the cusp trap part and the magnetic field lines. The bore tube around the central multi ring electrodes are cooled below 10 K. (b) A typical potential distribution for antihydrogen sysnthesis.

Selected Publications

  1. N. Okabayashi, K. Komaki, Y. Yamazaki, Enhanced Sputtering from the F/Si(100) Surface with Extraction of the Surface Bond Direction, Phys. Rev. Lett. 2011, 107, 113201.
  2. Y. Enomoto, et al. Synthesis of Cold Antihydrogen in a Cusp Trap, Phys. Rev. Lett. 2010, 105, 243401.
  3. G. B. Andresen, et al. Trapped antihydrogen, Nature 2010, 468, 673.
  4. H. Knudsen, et al. Target Structure Induced Suppression of the Ionization Cross Section for Very Low Energy Antiproton-Hydrogen Collisions, Phys. Rev. Lett. 2010, 105, 213201.
  5. N. Kuroda, et al. Radial compression of antiproton cloud for production of intense antiproton beams, Phys. Rev. Lett. 2008, 100, 203402.
  6. T. Iwai, et al. Ion irradiation in liquid of mm3 region for cell surgery, Appl. Phys. Lett. 2008, 92, 023509.
  7. T. Ikeda, et al. Production of a microbeam of slow highly charged ions with a tapered glass capillary, Appl. Phys. Lett. 2006, 89, 163502.
  8. T. Azuma, et al. Anisotropic X-Ray Emission from Heliumlike Fe24+ Ions Aligned by Resonant Coherent Excitation with a Periodic Crystal Potential, Phys. Rev. Lett. 2006, 97, 145502.
  9. N. Kuroda, et al. Confinement of a large number of antiprotons and production of an ultra-slow antiproton beam, Phys. Rev. Lett. 2005, 94, 023401.
  10. N. Oshima, et al. A new positron accumulation scheme in ultra high vacuum, Phys. Rev. Lett. 2004, 93, 195001.
  11. S. Ninomiya, et al. Stabilized hollow ions extracted in vacuum, Phys. Rev. Lett. 1997, 78, 4557.

Core Members

Principal Investigator add delete
Yasunori Yamazaki Distinguished Senior Scientist    
Staff Scientist add delete
Yasuyuki Kanai Senior Research Scientist    
Takao Kojima Senior Research Scientist    
Tokihiro Ikeda Senior Research Scientist    
Tomohiro Kobayashi Senior Research Scientist    
Manabu Hamagaki Senior Technical Scientist    
Postdoctoral Fellow add delete
Daniel James Murtagh Foreign Postdoctoral Researcher    
Volkhard Maeckel Postdoctoral Researcher    
Simon Hendrik Celine Van Gorp Postdoctoral Researcher    
Student Trainee add delete
Technical Assistant add delete
Administrative Assistant add delete
Hitomi Wada Assistant    
Visiting Research Staff add delete
Walter Meissl Visiting Scientist    
Other Staff add delete
Isao Shimamura Research Consultant    
Tsutomu Watanabe Research Consultant    
Ken-ichirou Komaki Research Consultant    
Akihiro Mohri Research Consultant    
Kiyoshi Ogiwara Part-timer1    
Yugo Nagata Part-timer1    
Machiko Izawa Part-timer2    
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