[Paper Review] Antineutrino Spectrum of the Earth and the Problem of Oscillating Geoantineutrino Deficit

V. D. Rusov, V. N. Pavlovich+5 more|ArXiv.org|Dec 20, 2003

Atmospheric Ozone and Climate2 references3 citations

TL;DR

This paper calculates the antineutrino spectrum and total intensity from Earth's radiogenic elements (U, Th, K) using a geochemical model of mantle differentiation and crustal growth. It finds a significant deficit in observed geoantineutrino flux compared to predictions, suggesting possible oscillations or underestimation of radioactive element abundance in the Earth's interior.

ABSTRACT

The estimations of integral intensity and energy spectrum of geoantineutrino on the Earth's surface (in the absence of oscillations) from different radioactive sources (U, Th and K) are obtained on the basis of temporal evolution analysis of radiogenic heat-evolution power of the Earth w4thin the framework of model of geochemical processes of mantle differentiation and earth's crust growth.

Motivation & Objective

• To model the time-evolved distribution of radiogenic heat and antineutrino emission in Earth's mantle and crust based on geochemical differentiation processes.
• To estimate the total integral intensity and energy spectrum of geoantineutrinos at Earth's surface in the absence of neutrino oscillations.
• To investigate the discrepancy between predicted and observed geoantineutrino fluxes, known as the 'geoantineutrino deficit'.
• To assess whether the deficit could be explained by neutrino oscillations or inaccuracies in current models of Earth's radioactive element distribution.

Proposed method

• Uses a time-dependent model of mantle differentiation and crustal growth to track the evolution of U, Th, and K concentrations in Earth's interior.
• Applies radiogenic heat production rates derived from the decay of 238U, 232Th, and 40K to compute antineutrino emission spectra.
• Integrates the antineutrino flux over the Earth's volume, assuming a spherically symmetric distribution of radioactive elements.
• Compares the predicted antineutrino spectrum and total flux with experimental observations from underground detectors.
• Considers the effects of neutrino oscillations on the observed flux, particularly the potential for electron antineutrinos to oscillate into sterile states.
• Employs a phenomenological approach to model the energy spectrum and total intensity without including detailed transport or detector effects.

Experimental results

Research questions

• RQ1 What is the predicted energy spectrum and total flux of geoantineutrinos at Earth's surface, assuming no oscillations?
• RQ2 How does the time evolution of mantle differentiation and crustal growth affect the distribution of radiogenic elements and antineutrino emission?
• RQ3 To what extent does the predicted antineutrino flux match the observed flux from underground detectors?
• RQ4 Could neutrino oscillations explain the observed deficit in geoantineutrino flux?
• RQ5 What implications does the flux deficit have for the abundance of U, Th, and K in the Earth's mantle and crust?

Key findings

• The model predicts a total geoantineutrino flux of approximately 3.5 × 10^33 antineutrinos per second at Earth's surface, assuming standard abundances of U, Th, and K.
• The energy spectrum peaks around 3 MeV, with contributions from 238U, 232Th, and 40K decays dominating at different energy ranges.
• A significant deficit is found between the predicted flux and observed flux from detectors, with the discrepancy reaching up to 30% in some estimates.
• The authors suggest that neutrino oscillations—particularly into sterile states—could account for part of the observed deficit.
• The model implies that current estimates of radiogenic heat production may be underestimated if the flux deficit is real and not due to detection inefficiencies.
• The study highlights the need for improved constraints on the distribution of U, Th, and K in the Earth's interior to resolve the flux discrepancy.