[en] Recent remarkable results of μSR experiments on condensed matter studies at the pulsed muon facility of UT-MSL/KEK are reviewed. Special emphasis are given on the μSR studies for artificial magnetic superlattice, LaSrCuO high T_c superconductor and the μSR and photon luminescence combined studies on alkali halides, etc. Future directions of the UT-MSL facility is also given

[en] The muon is 200 times heavier than the electron and penetrates matters well since it is an electromagnetic-interaction particle being not a strong-interaction particle. Thus it can be used in radiographies of large objects such as a human body or larger matters. Methods which have been employed for the investigation of volcanoes and the inspection of the inside of blast furnace using cosmic muons will be further developed at the muon facility in J-PARC where the beam cooling or re-acceleration of muons will be possible. The principle and the present status of the cosmic-ray radiography are described. Future prospects of researches using muon at J-PARC are also given. (K.Y.)

[en] Meson/Muon science research program under planning at the future high intensity proton accelerator of the Japan Hadron Project is reviewed. Main subjects will be μSR studies on condensed matter, muon catalyzed fusion and fundamental physics, etc. Possible future development of new muon beam concept is also described. (author)

[en] It has been considered very difficult to produce an intense slow negative muon (μ^-) beam because of some difficulties. The study focuses on a basic process of the muon catalyzed fusion (μCF) in a high density D-T mixture, where μ^- injection, muonic atom (μd) and (μt) formation, (μd) to (μt) transfer, (dtμ) molecule formation, fusion inside molecule, and μ^- libration occur cyclically, and considers a situation where a MeV μ^- is stopped in a thin layer of condensed D₂/T₂ in which 10 keV μ^- is successively generated during the μCF processes up to 150 times on the average during the μ^- life-time. Right after this 10 keV μ source, an electrostatic extraction system combined with electrostatic lens optics or a large acceptance magnetic optics system may be placed to transport the resultant μ^- efficiently onto an experimental target. The 10 keV energy can be further accelerated or decelerated down to the hundreds eV region. The proposed method for slow μ^- production could also be applied to a (ddμ) system. There are some ideas as to how to upgrade the proposed μ^- beam. (N.K.)

[en] Low temperature (or normal temperature) nuclear fusion is one of the phenomena causing nuclear fusion without requiring high temperature. In thermal nuclear fusion, the Coulomb barrier is overcome with the help of thermal energy, but in the low temperature nuclear fusion, the Coulomb barrier is neutralized by the introduction of the particles having larger mass than electrons and negative charges, at this time, if two nuclei can approach to the distance of 10^-13 cm in the neutral state, the occurrence of nuclear fusion reaction is expected. As the mass of the particles is heavier, the neutral region is smaller, and nuclear fusion is easy to occur. The particles to meet this purpose are the electrons within substances and muons. The research on muon nuclear fusion became suddenly active in the latter half of 1970s, the cause of which was the discovery of the fact that the formation of muons occurs resonantly rapidly in D-T and D-D systems. Muons are the unstable elementary particles having the life of 2.2 μs, and they can have positive and negative charges. In the muon catalyzed fusion, the muons with negative charge take part. The principle of the muon catalyzed fusion, its present status and future perspective, and the present status of low temperature nuclear fusion are reported. (K.I.)

[en] Spin-polarized muons, naturally available from the decay of accelerator-producing pions, with the help of anisotropic emission of energetic positrons/electrons, can be used to probe quite sensitively both the static and dynamic behaviors of the microscopic magnetic properties of various types of condensed matter. After historical developments, during the past 25 years, the following significant progress has been recently marked based upon mainly developments of advanced muon beams: (1) a consistent study of the magnetic phase diagram of high-T_c superconductors has revealed the existence of an anomalous anti-ferromagnetic phase in underdoped LaSrCuO; (2) the successful generation of a sub-keV μ⁺ beam has brought us the capability of spin-dynamics studies of various surface magnetism; (3) the electron brought by the μ⁺ during the slowing-down process was found to be useful for studies of electron transfer in proteins

[en] The collaboration with late Prof. K. Sugimoto was begun in 1974 at Berkley on muon experiments. Since then, the author has been involved in the construction and utilization of the facilities at KEK booster, TRIUMPF-M9 muon channel, RIKEN RAL muon facility and J-PARC MUSE. In this note, however, only the matters related to the fundamental physics of nuclei and elementary particles are reviewed. In section (2), 'Binding effects of negative muons' are taken up and general properties of negative muons are summarized. Then, in 2.1) magnetic moment data in the groundbreaking years of the collaborative research and recent data, in 2.2) re-polarization of the muonic atoms, and in 2.3) decay electron spectra are described. In section (3) of 'Negative muon nuclear absorption reactions', two urgent problems of 3.1.1) preparation and applications of radioactive ⁹⁹Tc and 3.1.2) confirmation of the transmutation of the nuclear reactor waste are mentioned. In section (4) of 'Ultra-fine spectroscopic elementary particle physics of muon atomic levels', 4.1) laser spectroscopy of the negative muon hydrogen atoms, and 4.2) atomic spectroscopy of the positive muon antiproton atoms and CPT theorem are pointed out. In section (5) of 'Frontier measurements of muon fundamental physics', 5.1) ultra-low velocity positive muons and positive muon anomalous magnetic moment, and 5.2) ultra-low velocity highly polarized negative muons and negative muon anomalous magnetic moment are mentioned. In section (6) of 'Toward the new developments of the muon nuclear fusion', 6.1) Present status of research with two subsections and realization of the break even by strongly correlated muon catalyzed fusion, and 6.2) realization of break even by the strongly correlated muon catalyzed nuclear fusion are discussed. In section 7, other muon nuclear science, internal exploration and imaging radiography are picked up. Finally, three agenda are described not only for himself but for the coming generation. (S. Funahashi)

[en] The status of experimental and theoretical studies on the muon catalyzed nuclear fusion is reviewed. Subjects covered are 1) the most recent experimental results on the mesonolecule formation done at Dubna, LAMPF, and SIN, 2) recent theoretical works on the mesomolecular formation, and 3) muon production and usage efficiency. (author)

[en] The research of muon-catalyzed nuclear fusion has a long history initiated by the work of Sakharov and Frank in 1947. The present rush of research activities has been triggered by the discovery of resonant formation process in (ddμ) and (dtμ) carried out by Russian group. The main interest of this muoncatalyzed nuclear fusion study is the physical interest associated with a Coulomb few body problem and a possibility in the application to real energy production. The principle of muoncatalyzed nuclear fusion is explained for the case of negative muons injected into a mixture of D₂ and T₂. In the nuclear fusion process of (dtμ), high temperature is not required at all, and the fusion process proceeds at low temperature by the aid of negative muon screening of d-t Coulomb interaction. The rate constant in d-t muon-catalyzed nuclear fusion, further details of d-t muon-catalyzed nuclear fusion towards energy production and enhanced energy production by laser muon catalyzed nuclear fusion are discussed. The future experimental research is shown. (Kako, I.)

[en] The third method of controlled nuclear fusion is studied. Unlike the confinement under high temperature condition, by using the muons created with an accelerator as the catalyst, the nuclear fusion reaction of deuterium-tritium is to be caused. The present status of its rapidly developing basic research and the perspective toward its practical use are reported. Muon-catalyzed fusion (μCF) became a topic about 40 years ago as nuclear fusion which does not require high temperature and does not run away. Its research progresses very rapidly, and the international conference is opened somewhere once every a half year. Muons are the unstable elementary particles having average life of 2.2 μsec, and there are μ⁺ and μ^- having positive and negative charge. Those appearing in μCF are only μ^-. The generation of μ^- and its catalytic action in μCF are explained. The slow rate of muon molecule formation was improved by the concept of resonance molecule formation by Ponomarev et al. The representative problems in μCF are the rate of muon molecule formation, the process of loss of α attachment and others, the necessity of extending experimental condition and so on. The possibility of the practical use of μCF for energy production is discussed. (Kako, I.)