Team finds neutrinos emitted from Earth

07/28/2005

The Asahi Shimbun

KAMIOKA, Gifu Prefecture--Neutrinos, the ghostly particles that could hold the key to unlocking the mysteries of the universe, have been detected for the first time emitting from Earth, a research team in Japan said Wednesday.

The KamLAND (Kamioka Liquid scintillator Anti-Neutrino Detector) facility here detected the neutrinos from the energy source that triggers volcanic activities and geological movements, the team said.

The international team of researchers, led by Atsuto Suzuki, a physics professor at Tohoku University, says the discovery will help scientists understand the thermal energy and components at the Earth's interior.

The findings will be published in the magazine Nature.

Neutrinos, which do not carry electrical charges and can pass through great distances of matter, are considered one of the fundamental particles that make up the universe.

Previous studies detected neutrinos only from space.

The Earth's crust and mantle are believed to have high temperatures because of heat emitted when radioactive elements, such as uranium and thorium, break down and transform.

In theory, neutrinos are emitted during this process. But previous devices failed to detect such neutrinos.

For example, the KamLAND's predecessor, the Kamiokande, collected light emitted from neutrinos as they fell from the universe. The facility was developed by Masatoshi Koshiba, professor emeritus at the University of Tokyo who won the Nobel Prize in Physics in 2002.

The Kamiokande used huge amounts of water for detection. But the KamLAND facility, operated by Tohoku University, uses a special oil that can detect low-energy neutrinos that escaped its predecessor.

Suzuki's group weeded out the "false signal" neutrinos, and concluded that five to 54 neutrinos derived from Earth were among 152 observed at the KamLAND facility between May 2002 and October 2004.

The KamLAND started operating in 2002 and is located at a depth of about 1,000 meters.(IHT/Asahi: July 28,2005)

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