March 14, 2013. Scientists were able to identify some of the particles are hiding deep in the Earth's mantle, which can tell us how much heat is generated, our planet, and to confirm that it is indeed formed from the solar material.
These particles are called geoneutrinos — antiparticles of neutrinos (exotic fundamental particles that can penetrate through the planet), formed deep within the earth's mantle. The data about the discovery scientists were published on March 11 this year.
The giant engine
In the time of the formation of the Earth's radioactive elements thorium and uranium were distributed in its crust and mantle uneven. As they decay inside the planet, they gave warmth and subatomic particles formed geoneutrinos, says study co-author, a physicist at the Gran Sasso National Laboratory in Italy, Aldo Ianni.
The heat from this decay is, in fact, the engine that drives the viscous fluid matter component of the Earth's mantle. This in turn may actuate the tectonic plates, causing earthquakes. Although scientists have models which predict how much heat is generated inside the Earth, its precise measurement is very difficult. And it is here that can help geoneutrinos.
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To accomplish this, researchers from the Gran Sasso underground laboratory, which lies at a depth of more than a kilometer beneath the mountains of Italy, followed the signals in a huge pool of special liquid that flickers when the particles pass through it, such as protons. When geoneutrinos pass through the shimmering liquid, they are faced with the protons and emit positrons and neutrons, creating a well-detectable signal.
Many of the particles initially identified by scientists actually came from nuclear reactors of nuclear power plants. But measuring the neutrino energy levels, they were able to identify 30 percent of which come from the earth's mantle, says Ianni.
Geoneutrinos formed by the radioactive decay of thorium and uranium in the reaction, giving an accurately known amount of heat. As a result, the number of detected particles can give a clue about the amount of radioactive elements in the Earth's mantle, and as a consequence — of how much heat they generate. This may help scientists improve knowledge about earth plate tectonics, says Ianni.
But it also may confirm the theory that the earth was formed out of the solar material. Ancient meteorites from the early history of the solar system times contain certain ratio of uranium and thorium, which is very closely reflects the composition of the surface of the Sun. Comparing this with the performance of the inner layers of the Earth, scientists can confirm that the Earth is descended from the Sun.