KAMLAND

An international team of physicists completed construction on the KAMLAND detector—short for Kamioka Liquid-scintillator Anti-Neutrino Detector—in 1997 on the Japanese island of Honshu. KAMLAND detects antineutrinos, the antimatter opposites of neutrinos, which signal the latter's presence. The detector uses a telescope made of 1,000 tons of mineral oil and benzene in a stainless steel tank two thirds of a mile below the Earth's surface to measure antineutrinos issuing from nuclear power reactors and natural nuclear reactions. In July 2005, KAMLAND scientists measured the Earth's total radioactivity for the first time. Their findings will allow them to better understand what keeps the planet warm, the volcanoes active, the continents drifting, the magnetic field churning—all things that enable life. Until this discovery, geologists relied on the reverberations from earthquakes to estimate the planet's radioactivity.

Source: http://www.pbs.org/wgbh/nova/neutrino/dete-02.html