2002 Fiscal Year Final Research Report Summary
Study of Extremely High Energy Cosmic Rays beyond Greisen Cut off (10^<20>eV)
| Project/Area Number |
12304012
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
素粒子・核・宇宙線
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| Research Institution | Institute for Cosmic Ray Research, The University of Tokyo |
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Principal Investigator |
HAYASHIDA Naoaki Institute for Cosmic Ray Research, The University of Tokyo, Research Associate, 宇宙線研究所, 助手 (50114616)
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| Co-Investigator(Kenkyū-buntansha) |
YOSHIDA Shigeru Faculty of Science, Chiba University, Associate Professor, 理学部, 助教授 (00272518)
TAKITA Masato Institute for Cosmic Ray Research, The University of Tokyo, Associate Professor, 宇宙線研究所, 助教授 (20202161)
FUKUSHIMA Masaki Institute for Cosmic Ray Research, The University of Tokyo, Professor, 宇宙線研究所, 教授 (30241227)
CHIKAWA Michiyuki Science and Technology, Kinki University, Associate Professor, 理工学部, 助教授 (50179941)
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| Project Period (FY) |
2000 – 2002
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| Keywords | Cosmic ray / Cherenkov light / Fluorescence light / LIDAR system |
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| Research Abstract |
The Akeno Giant Air Shower Array (AGASA) has been operated for 12 years, then Extremely High Energy (EHE) cosmic ray events(11events) above Greisen cut off energy of 10^<20> eV were observed. Cosmic ray protons is believed to lose their energy by the pion production through the interaction with 2.7K microwave background radiation. EHE cosmic rays observed by AGASA clearly exceed this critical energy and is really interesting in its nature. In this project, to confirm the energy determination of AGASA, we have built air fluorescence imaging detector (CRIS ―― Cosmic Ray Imaging System) at the center of the Akeno Observatory.
In 2000 and 2001, we have build CRIS detector which cover 2 steradian around zenith and LIDAR system to monitor atmospheric transparency. The Lidar system has been successfully in operation since the winter of 2001, and the atmospheric monitoring at near UV region for cosmic ray measurement purpose was established. This result was already published in the journal, Nuclear Instrument and Method. In 2002, very intensive observation of 300 hrs in cherenkov mode was carried out, then we have observed more than 10,000 of high energy cosmic rays and studied the cosmic ray energy spectrum around the knee region (10^<14〜>10^<16>eV).
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