Monday , December 6 2021

Neutrino reveals the internal structure of the Earth



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Collisions between cosmic rays and atmospheric nuclei form a permanent neutrino surface shower. Small neutrals are rarely interacting with other substances that make them aware of it. But rarely, it has never been: if neutrinos with energy, which is at least some TEV, go through something as tight as Earth, there is a small but insignificant probability that it will be absorbed. The idea of ​​analyzing absorption to find out about the inner structure of the planet was first proposed more than 40 years ago. But until recently, neutrino detectors were not large enough to observe sufficient particles for such a study.

Neutral through the interior of the earth

IceCube neutralized the Observatory, which includes ice cubic meters near the South Pole, 2011-2012. They collected their first data during the year. Sergio Palomares-Ruiz and Andrea Donini Corpuscular Physics Institute (Spanish National Research Council and Valencia University) and Jordi Salvado Institute of Cosmos Sciences (University of Barcelona) have now used public data from the initial launch to investigate Earth's radial density. They considered atmospheric neutrinos, the number and distribution of which is known, and discovered how much neutrinos made it through the Earth at the detector. Neutrino crossed the density of another density at each set point, as shown in the figure above. The researchers used the probability of neutrino absorption, which depends on both the length and density of the road to form a one-way radial density profile.

The number of atmospheric neutrinos with energies above 5 TeV passing through the center of the Earth was about half what researchers could expect if nobody sucks. The attenuation decreased, reducing energy and road lengths until it became invaluable. The researchers used neutrino reduction to determine the average density of each layer in the picture. Although neutrino-based measurements have a high degree of uncertainty, the calculated mass of the Earth's mass is in good agreement with the current value, as shown below the left-hand side of the diagram with a red dotted line. The researchers also found a larger part of the Earth's mass, which is in the nucleus shown in the right-hand scale than 33%, calculated from the geophysical density models (with a red dotted line). However, the previously accepted value falls within a 68% confidence interval, so the difference is not statistically significant.

Earth and core mass estimates

The Earth's internal structures neutralize the tomography provides an independent measure of its makeup that can be used in conjunction with seismological data. This method demonstrates the first measurement of the mass of the Earth using weak force, not gravitational force. Neutrino also provides additional information on the Earth's kernel: slightly seismic waves cross the nucleus, but the longest neutrino path. The measurements are expected to improve as the IceCube and the next kilometer-wide KM3NeT detector will be available from the Mediterranean floor. (A. Donini, S. Palomares-Ruiz, J. Salvado, Nat Fiz, 2018, doi: 10.1038 / s41567-018-0139-1.)

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