2004 Fiscal Year Final Research Report Summary
Study of High-energy Cosmic Gamma Rays and Cosmic Rays in Tibet.
| Project/Area Number |
14340070
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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 |
素粒子・核・宇宙線
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| Research Institution | The University of Tokyo (2003-2004)
Nagoya University (2002) |
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Principal Investigator |
YUDA Toshinori The University of Tokyo, Institute for Cosmic Ray Research, Professor Emeritus, 宇宙線研究所, 名誉教授 (60092368)
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| Co-Investigator(Kenkyū-buntansha) |
TAKITA Masato The University of Tokyo, Institute for Cosmic Ray Research, Associate Professor, 宇宙線研究所, 助教授 (20202161)
OHNISHI Munehiro The University of Tokyo, Institute for Cosmic Ray Research, Research Associate, 宇宙線研究所, 助手 (10260514)
YAMAMOTO Yoshiaki Konan University, Faculty of Science and Technology, Professor, 理工学部, 教授 (70068112)
HOTTA Naoki Utsunomiya University, Faculty of Education, Professor, 教育学部, 教授 (60157039)
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| Project Period (FY) |
2002 – 2004
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| Keywords | Tibet / air shower array / knee energy region / emulsion chamber / burst detector / cosmic-ray acceleration / cosmic-ray anisotropy / supernova remnant |
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| Research Abstract |
We study high-energy cosmic gamma rays and cosmic rays with an air shower array (Tibet-II and Tibet-III) in Tibet as a joint research with China. The main research purpose is to study the origin and acceleration mechanism of high-energy cosmic rays by the observation of high-energy primary cosmic-ray energy spectrum and by observation/search of celestial high-energy cosmic gamma-ray point sources
From 1996 to 1999, we set up 80 m^2 emulsion chambers and burst detectors at the center of Tibet-II and studied the energy spectrum of primary cosmic-ray protons in the knee energy region. We obtained the energy spectrum of protons above 10^<15> eV for the first time in the world, by analyzing the emulsion chamber data. The measured energy spectrum showed steepening of the spectral index in the power-law spectrum compared with that below 10^<14> eV, suggesting the acceleration scenario of cosmic rays in the shock wave in a supernova remnant. For this pupose, we developed an automatic analysis device of X-ray films based on a commercial image scanner which enabled us to process X-ray film data. We also did R&D studies of a burst detector array (1000 m^2) for selectively detecting heavy nuclei in the knee energy region, in cooperation with Tibet-III. Four test detectors with a plastic scintillator and optical fibers were setup and in operation in the Tibet-III.
We also successfully observed the energy dependence of the apparent anisotropy in multi-TeV galactic cosmic-ray intensitiy due to the terrestrial orbital motion around the Sun for the first time in the world. We obtained a new result on the cosmic-ray anisotropy at the sidereal time frame as well.
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