Searching for cavities of various densities in the Earth's crust with a low-energy electron-antineutrino beta-beam

TL;DR

This paper proposes a novel method using low-energy electron-antineutrino beta-beams to detect underground cavities of varying densities, achieving high confidence levels and reconstructing cavity properties with improved accuracy.

Contribution

It introduces a new underground cavity detection technique using neutrino disappearance experiments with enhanced luminosity, capable of identifying cavities with high confidence and reconstructing their properties.

Findings

Detection confidence exceeds 3σ in 3 months and 5σ in 1.5 years.

Able to reconstruct cavity density, width, and position with reasonable accuracy.

Method can identify cavities with densities below 1 g/cm³ or above 5 g/cm³.

Abstract

We propose searching for deep underground cavities of different densities in the Earth's crust using a long-baseline electron-antineutrino disappearance experiment, realized through a low-energy beta-beam with highly-enhanced luminosity. We focus on four cases: cavities with densities close to that of water, iron-banded formations, heavier mineral deposits, and regions of abnormal charge accumulation that have been posited to appear prior to the occurrence of an intense earthquake. The sensitivity to identify cavities attains confidence levels higher than $3\sigma$ and $5\sigma$ for exposures times of 3 months and 1.5 years, respectively, and cavity densities below 1 g cm$^{-3}$ or above 5 g cm$^{-3}$, with widths greater than 200 km. We reconstruct the cavity density, width, and position, assuming one of them known while keeping the other two free. We obtain large allowed regions that improve as the cavity density differs more from the Earth's mean density. Furthermore, we demonstrate that knowledge of the cavity density is important to obtain O(10%) error on the width. Finally, we introduce an observable to quantify the presence of a cavity by changing the orientation of the electron-antineutrino beam, with which we are able to identify the presence of a cavity at the $2\sigma$ to $5\sigma$ C.L.