[S17-1] Outer core structure and dynamics (Oral contributions)

[S17-1-03] Neutrino oscillations and electron density distribution of the Earth's core

^○Akimichi Taketa¹, Carsten Rott² (1.Earthquake Research Institute, University of Tokyo, Tokyo, Japan, 2.SungKungKwan University, Suwon, Korea)

Neutrinos, a kind of elementary particle, and consist of three species, electron neutrino, muon neutrino, and tau neutrino. They have unique property. A neutrino can change its specie to another kind of species as it pass thorough space. This phenomena called as neutrino oscillation. The probability of oscillation depends on the electron density of the media which is passed through neutrinos, so neutrino oscillation can be used as a probe to measure the electron density of the media.

Neutrinos are naturally produced in the atmosphere (atmospheric neutrino), the Sun (solar neutrino), and so on. The arrival direction distribution of the atmospheric neutrino is isotropic, so 1D electron density distribution can be measured by a single detector. The arrival direction distribution of the solar neutrino is point source, but we know the relative geometry of the Sun, the Earth, and the detector. And the Earth is rotating and revolving, so we can also measure 1D electron density distribution along solar trajectory, like CT scan. If we have several neutrino detectors which have enough sensitivity, 3D electron density distribution of the Earth also can be measured.

The matter density distribution of the Earth is already measured by using seismic data. The ratio of the matter density to the electron density is equal to the ratio of atomic weight to atomic number, i.e. the average chemical composition. By combining the matter density distribution and the electron density distribution, we can measure the average chemical composition distribution of the Earth.

We demonstrate the capability to apply the neutrino oscillation to geo-physics.