Geoneutrino

A geoneutrino is an electron antineutrino produced by radioactive decay inside Earth. Its detection provides evidence about the planet’s internal radioactive heat sources.

Beta decay: A radioactive process in which a nucleus changes its composition by emitting an electron or positron and a neutrino or antineutrino. Beta-minus decays in uranium and thorium chains emit the antineutrinos measured as geoneutrinos.
Radioactive decay chain: A sequence of radioactive transformations in which unstable nuclei decay into daughter nuclei, eventually reaching stability. Geoneutrinos arise from beta decays within long-lived decay chains.
Radiogenic heat: Heat generated by radioactive decay within a planet or other body. Geoneutrino flux constrains how much of Earth’s heat comes from radioactive sources.
Georeactor: A hypothesized natural nuclear fission reactor operating near Earth’s core. A georeactor would add an antineutrino signal distinct from ordinary radioactive decay.
Inverse beta decay: A reaction in which an electron antineutrino interacts with a proton to produce a positron and a neutron. Liquid-scintillator experiments identify geoneutrinos through this characteristic reaction.
Uranium-238: A naturally occurring radioactive isotope of uranium with a half-life of about 4.5 billion years. Its decay chain produces a major share of Earth’s detectable geoneutrinos.
Bulk silicate Earth: The compositional model of Earth’s mantle and crust considered together, excluding the metallic core. Measured uranium and thorium signals test estimates of radioactive elements in the silicate Earth.
Earth’s heat budget: The accounting of heat entering, moving through, and leaving Earth. Geoneutrino results constrain the radiogenic contribution, while the total budget remains debated.
Liquid scintillator: A transparent liquid that emits light when charged particles deposit energy in it. Its light records the positron signal and, later, the neutron capture.
Uranium-235: A naturally occurring fissile uranium isotope with a half-life of about 704 million years. Its decay chain contributes geoneutrinos alongside uranium-238 and thorium-232.

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