Scientists from the Borexino collaboration working on a neutrino detector in Italy have published a report in Physical Review D about the discovery of 53 geoneutrinos, elusive neutral particles originating from the depths of the Earth.
The Borexino underground particle detector, operating at the Gran Sasso National Laboratory (Laboratori Nazionali del Gran Sasso) near the Italian city of L'Aquila, is one of two detectors in the world capable of observing geoneutrino particles generated by the decay of radioactive nuclei in the interior of the Earth.
These elusive "ghost particles" do not interact with matter, making them difficult to detect. However, every second, about a million neutrinos penetrate every square centimeter of our planet's surface.
"Geoneutrinos are the only direct traces of radioactive decay taking place inside the Earth, the contribution of which to the total energy governing all the dynamics of our planet is still unknown," - quoted in a press release of the collaboration, the words of Livia Ludhova, one of the two scientific coordinators of the Borexino experiment and the head of the neutrino group at the Institute of Nuclear Physics (IKP) of the Helmholtz Association (Germany).
Researchers have been using the Borexino detector to collect neutrino data since 2007. By 2019, thanks to a technical update, they were able to register twice as many events as at the time of the last analysis in 2015, and reduce the measurement uncertainty from 27 to 18 percent, which is also associated with new analysis methods.
The new results more accurately point to the origin of the observed geoneutrino flux, showing that about half of the detected particles originate from the Earth's mantle, and the rest from the crust.
An intense magnetic field, continuous volcanic activity, tectonic plate movements and mantle convection: the conditions inside the Earth are in many ways unique across the entire solar system. Scientists have been debating where the Earth's internal heat comes from for over 200 years.
It is believed that more than half of the internal heat is generated by the processes of radioactive decay inside the Earth, while the other half is associated with the cooling of the mantle.
New data on measurements of neutrino fluxes received from the depths of the planet will help to clarify the models of the structure of the Earth and the processes occurring in its interior.
General scheme of the experiment. Geoneutrinos from the Earth's interior are measured with a Borexino spectrometric detector, after which the energy spectra are formed, shown in the lower left corner of the figure. The X-axis shows the charge (number of photoelectrons) of the signal, which is a measure of the energy stored in the detector, and the Y-axis shows the number of events measured.
A great contribution to the creation of the Borexino detector and the acquisition of experimental data on it was made by Russian scientists from the Institute of Nuclear Physics of the Moscow State University, the National Research Center "Kurchatov Institute" and JINR.
"A serious challenge for physicists today remains a more accurate measurement of the flow of geoneutrinos from the mantle. For this, it is likely that several detectors located at different points of the Earth will be used," one of the Russian authors of the study, a senior researcher at the Institute of Nuclear Physics, quoted in a press release from Moscow State University. Alexander Chepurnova Moscow State University - There is a project to create a geoneutrino detector in Russia, at the Baksan Neutrino Observatory. terms ".
The publication presents not only new results, but also details of the experiment carried out, which provide valuable information for scientists who will work on new generation liquid scintillation detectors aimed at measuring geoneutrino fluxes.