| Co-Investigator(Kenkyū-buntansha) |
BREWER J. H. UBC, Canada : Prof., 教授
KIEFL R. TRIUMF, Canada : Scientist, 研究員
OUTA Haruhiko INS, Univ. of Tokyo : Res. Ass, 原子核研究所, 助手 (60221818)
MATSUOKA Nobuyuki RCNP, Osaka Univ. : Res. Ass, 核物理研究センター, 助手 (10030032)
HAYANO Ryugo Faculty of Science, Univ. of Tokyo : Ass. Prof., 理学部, 助教授 (30126148)
TAMURA Hirokazu Faculty of Science, Univ. of Tokyo : Res. Ass, 理学部, 助手 (10192642)
FUKUDA Tomokazu INS, Univ. of Tokyo : Ass. Prof., 原子核研究所, 助教授 (50116092)
IKEHATA Seiichiro Faculty of Science, Univ. of Tokyo : Ass. Prof., 理学部, 助教授 (30107685)
KIENLE P. GSI, Germany : Director, Prof., 教授 所長
RADVANYI P. CEN, Saslay, France : Director, Prof., 教授 所長
KITAZAWA Hideaki Dept. of Magnetic Materials, RIKEN : Res., 磁性, 研究員 (00195257)
KADONO Ryousuke Dept. of Metal Physics, RIKEN : Res., 金属物理, 研究員 (10194870)
IWASAKI Masahiko Faculty of Science, Univ. of Tokyo : Res. Ass, 理学部, 助手 (60183745)
AZUMA Toshiyuki College of Arts and Sciences, Univ. of Tokyo : Res. Ass, 教養学部, 助手 (70212529)
MIYAKE Yasuhiro Faculty of Science, Univ. of Tokyo : Res. Ass, 理学部, 助手 (80209882)
NISHIYAMA Kusuo Faculty of Science, Univ. of Tokyo : Ass, Prof., 理学部, 助教授 (50164611)
TORIKAI Eiko Faculty of Engineering, Yamanashi Univ. : Prof., 工学部, 教授 (20188832)
NISHIDA Nobuhiko Faculty of Science, Tokyo Inst. of Technology : Ass. Prof., 理学部, 助教授 (50126140)
YAMAZAKI Yasunori College of Arts and Sciences, Univ. of Tokyo : Ass. Prof., 教養学部, 助教授 (30114903)
NAGAMINE Kanetada Faculty of Science, Univ. of Tokyo : Prof., 理学部, 教授 (50010947)
ERICSON T. CERN, Switzerland : Senior Scientist, 上級研究員
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| Research Abstract |
In 1988 a new slow and D. C. negative muon channel was completed by the cooperative work between UTMSL (The University of Tokyo, Meson Science Laboratory) and TRIUMF (Tri-University Meson Facility, Vanconver, Canada) with the help of the Grant-in-Aid for special Project Research on Meson Science from Mombusho. Now, this channel located in the meson area of TRIUMF gives an opportunity for Japanese and international researchers to use the world strongest negative muon beam.
With support of the present "KOKUSAI-GAKUJTYUTSU-KENKYU", many important muon experiments have been carried out by using this new negative muon channel.
The importance of the oxygen in the high Tc superconducting materials have been emphasized by many theoreticians and also by many experimentalists, for which there exist a few proper probes. The negative muon captured at the oxygen nucleus is one of the most efficient microscopic probe which can detect the local electric and magnetic fields at the oxygen site.
The joint
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group of UTMSL-RIKEN-Yamanashi University has found two different negative muon signals corresponding to different oxygen sites, using the very pure single srystal of LaSrCuO. The paramagnetic shift and the relaxation rate are studied for the various concentrations of the doped impurities. There temperature dependence as well as crystal axes dependences are obtained. The parts of this experiment have been reported at the 5th International Conference of muSR (Oxford, 1990) and International Conference on High Tc (Kanazawa, 1991).
Also to the other group of high Tc materials YBzCuO, negative muon study was applied. There, rather small amplitude of mu^-SR signal was found for the sample which shows superconductivity but a fairly large signal was obtained for the sample which shows antiferromagnetic ordering. In order to obtain the general understanding of the negative muon behavior in the magnetic oxides a systematic study are carried out on the various 3d-metal oxides.
On the other hands, the positive muon has been established as a unique and proper microscopic probes to detect antiferromagnetic ordering or weak magnetic local field, which is very difficult to be observed with another method. With this reason mu^+SR has intensively been applied on studiesof high Tc superconductors. The study was extended to new high Tc superconducting materials Bi_2Sr_2YCuO_y, Bi_2(Sr_<1-x>, La_x)_2Cuo_y, YBa(Cu_<1-x>, Cu_x)O, PrCuO, GdCeCuO etc. Another achievement is the success of mu^+SR measurement for the the high Tc material located inside the thick walled chamber for high pressure studies up to 0.6Gp.
The study of Peierls instability transition has been performed for one dimensional polymers polyacetylene, using a negative muon captured at carbon forming a substitutional boron-like impurity.
The interaction of slow muon and the thin foils was studied by detecting the distribution of secondary electron numbers. From the average number distribution of emitted electrons, charge asymmetric effect was obtained. The charge symmetric effect [n(mu^+)-n(mu^-)]/[n(mu^+)+n(mu^-)] called the Barkas effect (asymmetric effect in stopping power) was obtained for the momentum region 5 Mev/c - 12 Mev/c.
New exploratory experiments on meson production have been carried out at TRIUMF, CERN, GSI and Saclay. The most exciting result is also the observation of delayed antiproton annihilation in helium medium. Less
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