| Project/Area Number |
17540275
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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 |
Particle/Nuclear/Cosmic ray/Astro physics
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| Research Institution | National Astronomical Observatory of Japan |
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Principal Investigator |
KAJINO Toshitaka National Astronomical Observatory of Japan, Division of Theoretical Astronomy, Associate Professor (20169444)
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| Co-Investigator(Kenkyū-buntansha) |
AOKI Wako National Astronomical Observatory of Japan, Division of Optical and Infrared Astronomy, Research Associate (20321581)
NOMOTO Ken-ichi University of Tokyo, Graduate School of Science, Professor (90110676)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,630,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥330,000)
Fiscal Year 2007: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2006: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2005: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Keywords | astrophysics / nuclear physics / neutrinos / supernova / nucleosynthesis |
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| Research Abstract |
We studied the supernova (SN) neutrino-process for the production of light-to-heavy mass elements and tried to establish a new astronomical method to determine the unknown neutrino oscillation parameters such as the 13-mixing angle and the mass hierarchy from the parameter dependence of the abundance ratios for the nuclei, i.e. Li7/B11, Li7/La138, and La138/11a180. The results are summarized as follows.
(1) Li7, B11, La138, and Ta180 among many light-to-heavy mass elements produced in SN nucleosynthesis are the typical nuclei which are strongly affected by the SN neutrino-process. It is known from the Galactic chemical evolution (GCE) studies of the light elements that the observed metallicity dependence of B10 and B11 yields can strongly constrain the neutrino temperatures ejected from the core-collapse SN explosions. We combined the GCE and SN nucleosynthesis studies in order to establish a unique method to determine the temperatures of mu- and tau-type neutrinos and their anti-partic
… More
les. We have already studied that the r-process nucleosynthesis in SNe can limit the temperatures of electron- and antielectron-type neutrinos. From these comprehensive theoretical studies, we have established a method to constrain the temperatures of all flavored light-neutrino families in terms of nucleosynthetic studies.
(2) The absolute yields of Li7 and B11, which are produced from the SN neutrino-process, depend on the neutrino-induced spoliation cross sections of He4 and C12. There remains a huge uncertainty therefore in the neutrino-spallation cross sections calculated by using even the best Hamiltonians for the description of the nuclear structure of He4 and C12. We found that the uncertainty due to the Hamiltonians cancel with each other in the abundance ratio of Li7/B11, which is almost free from the assumed Hamiltonian.
(3) In the case of normal mass hierarchy, our proposed indicator of the neutrino oscillation Li7/B11 varies largely for the 13-mixing angles 10^<-4><sin^22θ_13< 10^2 through the high-density resonance in the MSW effect. This sensitivity is superior to any ongoing long-baseline neutrino experiments which are proposed in the world particle physics community.
In order to determine the absolute mass of neutrinos, we have to study the cosmological neutrinos of all flavors simultaneously. We studied therefore the neutrino effects on the cosmic microwave background (CMB) anisotropies and polarization, and large scale structure (LSS) formation. It is now under way to extensively study the Big-Bang nucleosynthesis, CMB, and LSS as well as SN neutrino-process nucleosynthesis by using a unified set of the neutrino oscillation parameters for both cosmological and SN neutrinos in order to constrain the absolute mass of neutrinos. Less
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