Atoms sometimes release alpha particles during radioactive decay.

What’s the News: An international team of researchers has completed the most precise measurement of the Earth’s radioactivity to date. By analyzing subatomic particles streaming out of the interior of the planet, the geologists and physicists discovered that the radioactive decay of several elements generates roughly half of the Earth’s total heat output. Their results were published recently in the journal Nature Geoscience.

What’s the Context:

Radioactive decay is a natural process where an unstable atom loses energy by emitting particles (thus decaying into smaller atoms). Radioactive decay can sometimes release neutrinos: tiny, electrically neutral, and nearly massless elementary particles that pass through most normal matter with little to no interaction. Because of their ability to phase through matter mostly unaffected, these ghostlike particles are very hard to detect.
Like all other particles, neutrinos have anti-siblings, called antineutrinos. A proton can sometimes capture an antineutrino, which then splits into a neutron plus a positron (an anti-electron). That positron will annihilate when it hits an electron, releasing energy that can be detected with very sensitive instruments, such as the Kamioka Liquid Scintillator Antineutrino Detector (KamLAND) deep in ...