| Project/Area Number |
11694068
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Space and upper atmospheric physics
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| Research Institution | Shinshu University |
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Principal Investigator |
YASUE Shin-ichi Shinshu University, Faculty of Science, Physics Department, Lecturer, 理学部, 講師 (80020668)
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| Co-Investigator(Kenkyū-buntansha) |
FUJII Zenjiro Nagoya University, STE Lab., Assistant Professor, 太陽地球環境研究所, 助手 (10022724)
KATO Chihiro Shinshu University, Faculty of Science, Physics Department, Assistant Professor, 理学部, 助手 (50252060)
MUNAKATA Kazuoki Shinshu University, Faculty of Science, Physics Department, Professor, 理学部, 教授 (40221618)
TANAKA Takashi Communication Research Institute, Space Science Div., Head Researcher, 宇宙科学部, 主任研究員
WASHIMI Haruichi Shonan Institute of Technology, Faculty of Engineering, Professor, 工学部, 教授 (60023686)
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| Project Period (FY) |
1999 – 2000
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| Keywords | galacticcosmic ray modulation / sidereal anisotropy / cosmic ray transport inheliosphere / air shower observation / cosmic ray muon detector network |
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| Research Abstract |
Calculations of cosmic-ray orbits in a MHD model heliosphere showed that almost all particles with energy around 500GeV are arriving at the earth from the heliotail with their orbits significantly deflected at the magnetic wall formed in the region between the solar wind termination shock and heliopause. We also analyzed the sidereal daily variation of 10TeV cosmic-ray intensity observed by a high-count air shower ( AS ) experiment at Tibet and confirmed that the "Tail-in" component anisotropy doesn't exist in 10TeV region and diminishes with, increasing energy above 1TeV. The daily variation observed at Tibet was quite consistent with the result by the AS experiment at Mt. Norikura over 15 years, both were consistent with the "Loss-cone" component anisotropy. There was no significant energy dependence seen in the "Loss-cone" anisotropy. Tibet AS experiment also recorded a significant seasonal change in the magnitude of sidereal daily variation. This seasonal change, possibly due to earth's revolution suggests a influence of large scale solar magnetic field on cosmic-ray orbits.
Aiming to develop a new cosmic-ray muon detector, we constructed a narrow angle multidirectional telescope using 88 proportional counters in four layers and evaluated the performance. A new recording system, in which a computer determines the incident direction of every muon event, is confirmed to be enough useful for our network observation. We have also been collecting data of the stability of the system performance.
By installing a prototype multidirectional muon detector at Sao Martinho in Brazil, we extended the longitudinal coverage of the present network. The new network with the detector in Brazil, which covers a full range of pitch angle of primary cosmic-rays, is now observing precursors of geomagnetic storms.
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