Researchers have discovered a particle that is suitable for the role of dark matter

This is what the place looks like, where, in all probability, one of the universe’s greatest mysteries is solved. And it is located in Russia. These are Kabardino-Balkaria, Baksan Gorge, Mount Andyrchi. At its foot, in Soviet times, lay a village with the telling name Neutrino. Physicists live there with their families. Under this mountain there are tunnels with a total length of almost four kilometers, and the Baksan Neutrino Observatory operates in this dungeon. Only many kilometers of rock provide reliable protection against cosmic rays that bombard the earth, in the current of which it is impossible to observe neutrinos.

What is a neutrino

The name neutrino (in Italian – “neutron”) was given to the world by the physicist Enrico Fermi, the creator of the world’s first nuclear reactor. He chose this word because neutrino also has no electrical charge, it is also neutral. These particles are constantly formed during the course of nuclear reactions (first of all, of course, in the interior of the stars) and rush freely through space, because they interact very, very little with other particles. Every moment an unimaginable amount of neutrons permeates us and our entire planet, but this has absolutely no effect on us.

Their existence was suspected as early as 1930, first registered in 1956, and since then it has been discovered that they exist in at least three variants. They have been called electron, muon and tau neutrons: they arise from the interaction between just such particles.

Mysterious invisible particles

Myriads of electron neutrinos are formed in the solar core, but as measurements have shown, they pass through the earth two to three times smaller than they should. It turned out that this is because many electron neutrons are transformed into others along the way. These spontaneous reincarnations are scientifically called neutrinoscillations, which translated into human language means that neutrinos are “werewolves”. Before that it was thought that they – just like photons – had no mass at all, but weightless particles could not be transformed into each other in this way. So they have a lot.

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But one day in 1995, during an experiment at the Los Alamos laboratory, it turned out that some “neutrons” do not just change clothes in a jump – they disappear completely. Like falling into a parallel universe. That is, all known neutrinos participate, even if they are in weak nuclear interaction. Thanks to this only noticeable property, they can be detected, but nothing at all. Silence.

And so it dawned on physicists: what if these “pants” turn into particles that do not interact at all, but only gravity? What if there is a fourth type of neutrino, we just do not see it? And these hypothetical invisible particles were called sterile neutrinos. Now they are being hunted all over the world: a particle that has a mass and nothing else is just an ideal candidate for dark matter.

Briefly about dark matter

We remind you of the direction of forces in the universe: everything we see (galaxies, stars, planets) is 4%, another 20% is just invisible dark matter, and everything else is something even more mysterious, namely dark energy, which makes everything collide and thus expands the universe faster and faster.

Why should there be dark matter? Scientists have calculated that, say, in our Milky Way galaxy, there are too few stars and everything else for this entire spiral structure to be kept intact, it should have decayed a long time ago. And it’s the same with all other galaxies. They are held by an invisible mass, which is five times larger than the visible one.

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In search of a sterile neutrino

So, in the Elbrus region, under Mount Andyrchi, Russian physicists organized the following experiment: they took a large tank, poured 50 tons of light gallium metal into it, and placed a container with a radioactive isotope of chromium inside. The atoms in this chromium constantly decompose, that is, a nuclear reaction takes place, and during this reaction neutrons fly from there in a continuous stream. Electronic neutrinos, ie the same as those thrown out of the sun. Of course, physicists know in advance that “neutrons” will “hooligan”, that is, transform. But all three known incarnations of neutrinos, at least, sometimes, but will interact with gallium atoms and turn them into the nuclei of a completely different substance – germanium. And this is an indicator of their presence.

What did the researchers do? They divided the gallium tank into two zones – inner and outer. And then they started counting how many kernels of germanium are obtained here and there. The calculation was as follows: when neutrinos reach the outer zone, some of them will have time to disappear completely, that is, they will turn into sterile. And sterile will not affect gallium at all. This means that if sterile neutrinos do exist, less germanium will form in the outer part of the barrel of germanium nuclei.

And the situation is such that this calculation was justified. It actually turned out that there is less germanium in the outer zone. Of course, the scientific approach requires that one continues to doubt the latter and that the same experience is repeated. But scientists are experiencing cosmic inspiration. Now they want to measure the mass of these invisible. They know how heavy such particles must be in order to completely shift the responsibility for the existence of dark matter to them. If they turn out to be brighter, well, then they form part of this dark matter. It’s not bad either.

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