| Project/Area Number |
10640280
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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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 | Tokyo Metropolitan University |
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Principal Investigator |
YASUDA Osamu Tokyo Metropolitan Univ., Physics Dept., Assist.Prof., 理学研究科, 助手 (50183116)
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| Co-Investigator(Kenkyū-buntansha) |
KAJITA Takaaki Univ.of Tokyo, Inst.for Cosmic Ray Research, Prof., 宇宙線研究所, 教授 (40185773)
MINAKATA Hisakazu Tokyo Metropolitan Univ., Physics Dept., Prof., 理学研究科, 教授 (00112475)
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| Project Period (FY) |
1998 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2000: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1999: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1998: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | atmospheric neutrino / neutrino oscillation / neutrino mass / lepton flavor mixing |
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| Research Abstract |
Yasuda worked on analysis of the atmospheric neutrino data in the frameworks of two, three and four flavors, and showed that θ_<13> is small in the three flavor case, and that a large class of the hybrid oscillations with ν_μ【tautomer】ν_γ and ν_μ【tautomer】ν_s is still allowed. He also discussed phenomenology of long baseline experiments and neutrino factories and showed that CP violation can be enhanced due to matter effects and that signals of CP violation at neutrino factories are optimized for the baseline approximately 3000km and the muon energy 50 GeV.Minakata worked on implications of massive neutrinos to neutrinoless double beta decay experiments with Yasuda and found that a scheme with almost degenerate massive neutrinos suggested by the mixed dark matter scenario inevitably implies a positive signal in neutrinoless double beta decay experiments. He also examined the possibility of measuring CP violation in very low energy medium baseline experiments, and he worked on supernova neutrinos in the three flavor framework and showed that inverted and normal hierarchy patterns can be distinguished under a certain condition by neutrino conversion from supernovae. Kajita worked on observation of atmospheric neutrinos as a leader of the Super-Kamiokande group and they concluded that their data can be interpreted as evidence of neutrino oscillation. This work has caught a lot of attention not only from physicists but also from the media. Subsequently they gained more statistics of the data and they excluded the ν_μ【tautomer】ν_s scenario. On the other hand, the Super-Kamiokande group measured the solar neutrinos and they concluded that the large mixing angle MSW solution gives the best fit to the data. From our research results we have gained much more knowledge on neutrino oscillations coming from the mass squared difference of the atmospheric neutrinos.
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