Locating the Core-Mantle Boundary using Oscillations of Atmospheric Neutrinos

TL;DR

This paper explores how atmospheric neutrino oscillations can be used to locate the Earth's core-mantle boundary, demonstrating the potential of neutrino detectors like ICAL to measure this boundary with high precision.

Contribution

The study shows that atmospheric neutrino oscillations can effectively determine the Earth's core-mantle boundary location using neutrino detectors, providing a novel geophysical probing method.

Findings

ICAL can measure the CMB location with about 250 km precision in a flexible model.

Using the PREM profile, the precision is approximately 350 km.

Charge identification capability enhances the measurement accuracy.

Abstract

Atmospheric neutrinos provide a unique avenue to explore the internal structure of Earth based on weak interactions, which is complementary to seismic studies and gravitational measurements. In this work, we demonstrate that the atmospheric neutrino oscillations in the presence of Earth matter can serve as an important tool to locate the core-mantle boundary (CMB). An atmospheric neutrino detector like the proposed 50 kt magnetized ICAL at INO can observe the core-passing neutrinos efficiently. These neutrinos would have experienced the MSW resonance and the parametric or neutrino oscillation length resonance. The net effect of these resonances on neutrino flavor conversions depends upon the location of CMB and the density jump at that radius. We quantify the capability of ICAL to measure the location of CMB in the context of multiple three-layered models of Earth. For the model where the density and the radius of core are kept flexible while the mass and radius of Earth as well as the densities of outer and inner mantle are fixed, ICAL can determine the location of CMB with a 1$\sigma$ precision of about 250 km with an exposure of 1000 kt$\cdot$yr. With the 81-layered PREM profile, this $1\sigma$ precision would be about 350 km. The charge identification capability of ICAL plays an important role in achieving this precision.