Oscillation tomografy study of Earth's composition and density with atmospheric neutrinos

TL;DR

This study explores how atmospheric neutrino oscillations can be used to perform Earth's interior tomography, providing insights into density and composition variations in the core and mantle beyond traditional geophysical methods.

Contribution

It demonstrates the potential of neutrino oscillation measurements to reveal Earth's internal composition and density, focusing on the outer core, mantle, and D'' layer, using Monte Carlo simulations.

Findings

Neutrino oscillation data can distinguish density variations in Earth's outer core and mantle.

The analysis shows potential for detectors like ORCA to resolve compositional differences.

Variations consistent with Earth's mass and inertia constraints can be detected with statistical significance.

Abstract

Knowledge of the composition of the Earth's interior is highly relevant to many geophysical and geochemical problems. Neutrino oscillations are modified in a non-trivial way by the matter effects and can provide valuable and unique information not only on the density but also on the chemical and isotopic composition of the deep regions of the planet. In this paper, we re-examine the possibility of performing an oscillation tomography of the Earth with atmospheric neutrinos and antineutrinos to obtain information on the composition and density of the outer core and the mantle, complementary to that obtained by geophysical methods. Particular attention is paid to the D$^{\prime \prime}$ layer just above the core-mantle boundary and to the water (hydrogen) content in the mantle transition zone. Our analysis is based on a Monte-Carlo simulation of the energy and azimuthal angle distribution of $\mu$-like events generated by neutrinos. Taking as reference a model of the Earth consisting of 55 concentric layers with constant densities determined from the PREM, we evaluate the effect on the number of events due to changes in the composition and density of the outer core and the mantle. To examine the capacity of a detector like ORCA to resolve such variations, we construct regions in planes of two of these quantities where the statistical significance of the discrepancies between the reference and the modified Earth are less than $1\sigma$. The variations are implemented in such a way that the constraint imposed by both the total mass of the Earth and its moment of inertia are verified.