Baby Oil and Benzene Provide Look at Earth's Radioactivity
By DENNIS OVERBYE
Published: July 28, 2005
Using a telescope made of 1,000 tons of baby oil and benzene in a stainless steel tank, scientists have measured the total radioactivity of Earth for the first time, they are reporting today.
The telescope they used was designed to detect subatomic particles from nuclear reactors. The researchers simply pointed it downward, in effect, toward the center of Earth. Physicists and geologists said the measurement, which agrees roughly with geologists' calculations, was the start of a new era of being able to see inside Earth. Their findings, they said, would lead to a better understanding of what keeps the planet warm, volcanoes burbling, continents drifting, magnetic field churning - all things that contribute to enabling life.
Until now, scientists have had to rely on the reverberations from earthquakes to get a handle on what is going on down there.
The baby oil and benzene detector lies two-thirds of a mile below the Japanese island of Honshu in the Kamioka zinc mine. It recorded flashes caused by ghostly particles called neutrinos, which were produced by the radioactive decay of uranium and thorium deep in the heart of the Earth as they shot up through the ground and the detector.
According to the measurements of these "geoneutrinos," Earth's radioactivity generates about 19 billion kilowatts of heat, about half of the estimated 30 billion to 44 billion kilowatts that the planet produces. By comparison, all the world's nuclear power plants collectively generate about 1 billion kilowatts....
(NOTE: A team of 87 physicists from 4 countries, led by Stanford's Giorgio Gratta and Atsuto Suzuki from Japan's Tohoku University, are reporting this today in the journal Nature.)
http://www.nytimes.com/2005/07/28/science/28neutrino.html
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