Antimatter, the equivalent of light atomic nuclei, can travel long distances through the Milky Way before being absorbed, a new discovery reveals.
As these particles move, they can act as ‘messengers’ for dark matter, so the discovery could help astronomers search for dark matter. dark matterA mysterious substance that makes up about 85% of the total mass of the universe, but is invisible because it does not interact with light.
Scientists in the ALICE collaboration arrived at their discovery using anti-helium nuclei. antimatter Equivalent to helium nuclei, heavy nuclei Large Hadron Collider (LHC).
“Our results, based on direct absorption measurements, show for the first time that anti-helium-3 nuclei coming from the galactic center can reach close to Earth,” said Andrea Dainese, physics coordinator at ALICE. rice field. statement (opens in new tab).
Related: 10 Mysteries of the Universe that the Large Hadron Collider Can Solve
This form of antimatter can be created in particle accelerators like the LHC, but the LHC has no natural source of antimatter or “antinuclear”. earthBut these antiparticles are naturally produced elsewhere on Earth. milky wayscientists favor two possible origins.
The first proposed source of antinuclear is the interaction between high-energy cosmic radiation, which originates from outside the Earth. solar systemwith atoms in the interstellar medium that fill the so-called interstellar space.
Another suggested cause of the antinuclear is the annihilation of dark matter particles spread across the Earth. galaxyScientists know very little about dark matter, but it certainly isn’t made up of particles like protons and neutrons that make up the everyday matter that forms stars, planets, and us. , scientists believe dark matter is made up of different particles with colorful names like WIMPs (Weakly Interacting Massive Particles) and MACHOs (Large Compact Halo Objects). One scenario suggests that dark matter particles collide and annihilate into particles, which then decay into light matter and antimatter particles, such as the electron and its antimatter counterpart, the positron. If the disappearance of dark matter is indeed the source of antimatter in the universe, scientists hope that antimatter could point the way to dark matter.
The quest to learn more about dark matter has prompted the development of space-based missions such as the space-borne Alpha Magnetic Spectrometer (AMS). international space station (ISS). AMS was designed at CERN, home of the LHC, to search the universe for light antimatter nuclei that could indicate the presence of mysterious dark matter.
However, to determine whether dark matter is the source of antinucleons, scientists conducting AMS and similar experiments will first speculate that antimatter, also known as antiparticle “flux,” is in the Milky Way. We need to know how much light can pass through the galaxy and reach closer to Earth. .”
This flux depends on several factors, including the antimatter source, the rate at which it produces antinuclei, and the rate at which the antinuclei die as they travel from the galactic center to Earth. This disappearance occurs when antimatter particles meet particles of conventional matter. Either both annihilate or antimatter is absorbed into matter.
The ALICE collaboration investigated the disappearance of antimatter by bombarding it with ionized or electron-stripped lead atoms using the LHC. Physicists then measured how the anti-helium 3 nuclei produced by these collisions interacted with ordinary matter in the form of the ALICE detector. This experiment reveals for the first time the rate at which anti-helium 3 nuclei annihilate when they encounter ordinary matter.
The researchers then used a computer program to simulate the propagation of antiparticles through the galaxy and introduced the ALICE-measured annihilation rates into this model. This model allowed the researchers to extrapolate the results to the entire galaxy and examine his two proposed mechanisms of antinucleation. One model postulated that antimatter arose from cosmic ray collisions with interstellar matter, and another he postulated that it came from antimatter. It transforms into a hypothetical form of dark matter called Weakly Interacting Massive Particles (WIMPs).
For each of these mechanisms, the ALICE team estimated the transparency of the Milky Way to anti-helium 3 nuclei. That is, the distance an anti-helium 3 nucleus is free to travel before being destroyed or absorbed. The models revealed a transparency of about 50% in the dark matter model and a transparency ranging from 25% to 90% in the cosmic ray impact model, depending on the energy of the antinuclear produced.
These values indicate that anti-helium 3 nuclei originating from either process can travel long distances. Up to a few kiloparsecs, one kiloparsec equals approximately 3,300 light years. (The width of the Milky Way is about 30 kiloparsecs. According to NASA.)
This result counts how many antinuclei arrive around the Earth and with what energy to determine whether the origin of these antiparticles is due to cosmic ray collisions or the annihilation of dark matter. may be important in future experiments to
ALICE spokesperson Luciano Musa said in the same statement, “Our findings show that searching for light antimatter nuclei from outer space is a powerful way to search for dark matter.
This research paper (opens in new tab) Published in the journal on Monday (December 12) natural physics (opens in new tab).
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