Kamioka Liquid Scintillator Antineutrino Detector

Kamioka Liquid Scintillator Antineutrino Detector

The Kamioka Liquid Scintillator Antineutrino Detector (KamLAND) is an experiment at the Kamioka Observatory, an underground neutrino observatory near Toyama, Japan. It was built to detect electron antineutrinos. The experiment is situated in the old Kamiokande cavity in a horizontal mine drift in the Japanese Alps. The site is surrounded by 53 Japanese commercial power reactors. Nuclear reactors produce electron antineutrinos (ν
e) in the decays of radioactive fission products in the nuclear fuel. Like the intensity of light from a light bulb or a distant star, the isotropically emitted ν
e flux decreases as 1/R2 for increasing distance R from the reactor. The experiment is sensitive to the estimated ~25% of antineutrinos from nuclear reactors that exceed the threshold energy of 1.8 MeV and thus produce a signal in the detector.

If neutrinos have mass, they may "oscillate" into flavors that an experiment may not be able to detect, leading to a further dimming, or "disappearance", of the electron antineutrinos (see neutrino oscillation). KamLAND is at a flux weighted average distance of ~180 km from the reactors which makes the experiment sensitive to the neutrino mixing associated with the large mixing angle (LMA) solution to the solar neutrino problem.