Exploring Layered Structure Inside Earth Using Atmospheric Neutrino Oscillation at IceCube DeepCore

TL;DR

This work investigates whether atmospheric neutrino oscillations observed by IceCube DeepCore can reveal Earth's layered interior. By comparing a 12-layer PREM density profile to a homogeneous density model using multi-GeV atmospheric neutrinos, the study employs MC reweighting to oscillation probabilities and a likelihood analysis that frees $\theta_{23}$ and $\Delta m_{31}^2$ while incorporating relevant systematics. The analysis yields a $1.4\sigma$ improvement for the layered PREM over the homogeneous case, with a $92.4\%$ CL to reject the uniform hypothesis, demonstrating the viability of neutrino oscillation tomography for Earth interior studies. The results highlight the potential of IceCube DeepCore, and future upgrades, to enhance sensitivity to Earth's matter profile through atmospheric neutrinos.

Abstract

The IceCube detector, using its densely instrumented center, called DeepCore, can detect multi-GeV atmospheric neutrinos. The oscillation pattern of neutrinos is altered due to interactions with ambient electrons as they pass through Earth. The changes in these patterns are influenced by the amount of matter and its specific arrangement. As neutrinos propagate, they retain information about the densities they encounter. Our study demonstrates that IceCube DeepCore can utilize the Earth's matter effects to distinguish between a homogeneous matter density profile and a layered structure density profile of Earth. In this contribution, we present that IceCube DeepCore data equivalent to 9.3 years of observation can reject the homogeneous matter density profile with a confidence level of 1.4$σ$.

Figures (1)

• Figure 1: Left: Sensitivity to reject Uniform hypothesis as a function of true choices of $\sin^2\theta_{23}$ calculated using Asimov-method (curves), and median sensitivity calculated using the frequentist method at few choices of $\sin^2\theta_{23}$ (markers). The error bars on the frequentist points represent the standard error. The red (blue) color corresponds to the assumption of normal (inverted) neutrino mass ordering. Right: Distributions of metric (true PREM and true Uniform) are calculated from the pseudo-experiments, which are generated with the best-fit parameters from the hypotheses PREM (green) and Uniform (red). The vertical black line represents the observed experimental value of the metric.