2005 Fiscal Year Final Research Report Summary
Study of Neutrino Mass and Mixing by Long Baseline Neutrino Oscillations : from K2K to a Next-Generation Experiment
| Project/Area Number |
15204023
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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 |
Particle/Nuclear/Cosmic ray/Astro physics
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| Research Institution | High Energy Accelerator Research Organization (KEK) (2004-2005)
The High Energy Accelerator Research Organization (2003) |
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Principal Investigator |
NAKAMURA Kenzo KEK, Institute of Particle and Nuclear Studies, Prof., 素粒子原子核研究所, 教授 (10011735)
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| Co-Investigator(Kenkyū-buntansha) |
TAKASAKI Minoru KEK, Institute of Particle and Nuclear Studies, Prof., 素粒子原子核研究所, 教授 (70044782)
KOBAYASHI Takashi KEK, Institute of Particle and Nuclear Studies, Assoc.Prof., 素粒子原子核研究所, 助教授 (70291317)
ICHIKAWA Atsuko KEK, Institute of Particle and Nuclear Studies, Res.Associate, 素粒子原子核研究所, 助手 (50353371)
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| Project Period (FY) |
2003 – 2005
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| Keywords | neutrino / neutrino oscillation / long baseline neutrino oscillation / K2K / J-PARC / T2K / high intensity proton accelerator / magnetic horn |
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| Research Abstract |
One of the purposes of the present research project is to conduct the K2K experiment. The K2K experiment is the first accelerator long baseline neutrino oscillation experiment. The purpose of the experiment is to confirm the Super-Kamiokande's discovery of atmospheric neutrino oscillation by using artificially produced muon neutrino beams. In total,112 neutrino events are observed in Super-Kamiokande ; we expect 158.1(+9.2-8.6) events if ν_μ does not oscillate. The neutrino energy spectrum distortion caused by ν_μ oscillation is also seen. The probability that we would observe these results due to statistical fluctuation even if there is no neutrino oscillation is 0.0015%. The corresponding significance is 4.3σ. A two-flavor neutrino oscillation analysis, with ν_μ disappearance, is performed. The best-fit oscillation parameters obtained are (Δm^2,sin^22θ)=(2.8×10^<-3> eV^2,1.0) in the physical region. This results is consistent with the Super-Kamiokande's atmospheric neutrino oscillation analysis. Therefore the purpose of the K2K experiment has been successfully accomplished.
Another important purpose of the present research project is R & D of the T2K neutrino beam line, in particular, that of triplet magnetic horns which are the most important beam line elements to obtain high intensity neutrino beams. T2K is the next Japanese accelerator long baseline neutrino oscillation experiment from J-PARC to Super-Kamiokande. The main objective of R & D is the first horn which should operate under very severe radiation and thermal loads. We have made extensive analyses of electrical and thermal shocks, and through these studies we have optimized the structure and size of the horn. To verify the endurance of thus designed horn against the shocks due to high intensity beams, a prototype has been constructed. Initial testing has shown expected performances.
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Research Products
(52 results)
