the Depths of our planet emit 47 terawatts of heat. Judging by the content of radioactive elements in the earth’s crust, their decay provides from 7 to 10 terawatts. Where does the rest of it?
the debate about this continues. Some experts say that our Earth was born hot, and not less than half the present heat flow from its interior — is the energy stored at the time of formation. Others believe that the planet formed as cold, and warms it basically friction from sinking to the center of the Earth with heavy rocks and Bob up to the surface of the lungs.
do Not forget that radioactive substances are certainly not only in the cortex but also in the mantle (at the core of their planet, according to geophysicists, is negligible). But how many of them there? To the mantle, in contrast to the cortex, it is impossible to reach the drill. Therefore, it remains unclear which part of the underground heat is formed during radioactive decay. Estimates range from 15% to 50%.
the Answer to the burning question gives a scientific article published in the journal Physical Review D international group, which includes Russian scientists.
Physicists have measured the neutrino flux coming from the bowels of the earth. Neutrinos are very light particles that are formed including the radioactive decay of uranium-238 and thorium-232. Knowing the intensity of the neutrino flux, you can determine how many of these elements decays per second in the depths of the Earth.
Researchers worked with the Borexino detector started in 2007. They have processed the data accumulated from December 2007 to April 2019. Note that in the creation of this tool and retrieving the great contribution made by scientists from the Institute of nuclear physics, Moscow state University, National research center “Kurchatov Institute” and the joint Institute for nuclear research.
Only this time, the detector has recorded 53 of the particle. Do not be deceived: every second, every square centimeter of the earth’s surface penetrate millions of neutrinos, born in the bowels of the planet. But this capricious particle athonor never interacts with matter, including with matter of the detector.
the number of registered neutrinos, the authors calculated their full flow and counted it in the number decaying in the depths of the Earth uranium and thorium.
on the Basis of the known radioactivity of the earth’s crust, physicists have calculated the contribution of the mantle. They took into account that 18% of radiogenic heat accounts for the decay of potassium-40 and uranium and thorium provide the remaining 82%.
According to the calculations of researchers, the radioactive mantle material provide from 14 to 36 terawatt underground heat. The most probable value is 25 terawatts. That is, the amount of radioactive substances of the crust and mantle gives about 70% of the underground heat.
for More specific numbers can be called when the neutrino flux from the mantle to be measured more accurately.
“a Serious challenge for physicists today is still more accurate measurement of the flow of geoneutrinos from the mantle. For this purpose, possibly, will be used by several detectors located in different points of the Earth. There is a project to create geoneutrino detector in Russia, Baksan neutrino Observatory. Another project is the JUNO detector, currently under construction in China, which is 70 times more “Borexino” mass that will allow you to achieve more precision of measurements over shorter time” — sums up the senior researcher of the Institute of nuclear physics of Moscow state University Alexander Chepurnov.
By the way, earlier “Conduct.Science” wrote about the contribution of the mantle in the generation of the magnetic field of our planet.