We live on the surface of the Earth, yet what lies beneath its crust can be just as enigmatic as faraway things in space. Neutrinos, fortunately, provide a glimpse into the unknown beneath our feet.

Neutrinos are perhaps the ultimate communicators of the cosmos, as they are unaffected by magnetic or mass in their passage. The particles, once discovered, point back to their origins, providing scientists with information about areas they couldn’t see otherwise. Investigating these neutrinos reveals information about the particles as well as their unknown origins.

Because we know that neutrinos are produced by particle decay, the number of geoneutrinos, or neutrinos that originate from within the Earth, can inform researchers how much radioactive material (such as thorium and uranium) is present below. This knowledge can help geophysicists learn more about our planet’s makeup, how it developed in our solar system, and what the future holds for it. Geoneutrinos for geophysical research is still in its early stages, but it bears promise for the future.

Geoneutrinos are low-energy electron antineutrinos, which necessitate the employment of massive detectors to detect them. This helps them to understand more about our planet’s composition without having to delve miles beneath the surface. Our globe generates trillions of watts of heat, but scientists aren’t sure how much of it originates from radioactive decay or how it’s distributed. This heat is responsible for everything from the formation of the molten iron core that generates Earth’s magnetic field to the spread of the sea floor and the movement of continents, and scientists want to know how it works.

Geoneutrinos have been studied by scientists at the KamLAND experiment in Japan and the Borexino detector in Italy, but not exclusively. Because neutrinos are so elusive, just a few events are captured each year. Additional scintillator detectors, which catch light produced by neutrino interactions, have been proposed for a better view of the Earth’s interior.

When an antineutrino collides with the material in a detector, a phenomenon known as inverse beta decay occurs, revealing geoneutrinos. It converts a proton into a neutron and a positron, which is the antimatter equivalent of an electron. The positron annihilates swiftly with an electron inside the detector, resulting in light flashes that are recorded. When the neutron is grabbed by a neighboring proton, a new signal appears. Scientists can clear out unwanted background noise and confirm the neutrino interaction with great accuracy by looking for the twin signals.