2023-06-20 11:15:48
It is believed that only 5% of the universe is made up of visible matter (atoms that are part of things we can see with the naked eye or with instruments) and that the remaining 95% is a combination of dark matter and dark energy, known together as the “dark sector”. Hypothetical particles such as axions, sterile neutrinos and others could be the identity, or part of it, of the dark sector.
The existence of axions could also solve an old problem in the Standard Model of physics. This model outlines the known behavior of the subatomic world. Axions, sometimes called the “fossils” of the universe, are thought to have originated just a second after the Big Bang. If they were really created then, they could tell us a lot about the Big Bang and what happened immediately after.
Since the existence of axions was first predicted theoretically nearly half a century ago, researchers have searched for evidence of the existence of these elusive particles, which are most likely not part of the visible universe but rather the dark sector. But how can you find particles that you can’t see? Early physical results from the Coherent CAPTAIN-Mills experiment at Los Alamos National Laboratory in the United States suggest that a particle accelerator with a liquid argon-based detector and other equipment initially designed to search for similar hypothetical particles, such as sterile neutrinos, They can also be used to search for axions.
That is the conclusion reached after the analysis of the results, carried out by an international team headed by Alexis Aguilar-Arevalo, from the National Autonomous University of Mexico.
The Coherent CAPTAIN-Mills experiment equipment centers on a 10-ton detector of supercooled liquid argon. (CAPTAIN stands for Cryogenic Apparatus for Precision Tests of Argon Reactions with Neutrinos).
High-intensity 800-megaelectronvolt protons generated by the LANSCE particle accelerator strike a tungsten target in the section of Los Alamos National Laboratory known as the Lujan Center, then travel 23 meters through extensive steel shielding and concrete to the detector, where they interact with the liquid argon.
The interior walls of the prototype detector are lined with 120 sensitive photomultiplier tubes measuring about 20 centimeters that detect the flashes of light (specifically single photons) produced when a normal particle shakes an atom in the tank of liquid argon, or, in theory , when a particle from the dark sector does.
Sector inside one of the detectors that could capture the passage of axions. (Image: Los Alamos National Laboratory / Coherent CAPTAIN-Mills experiment)
A coating of special material on the inner walls converts the light emission from the argon into visible light that can be detected by the photomultiplier tubes. Special measures prevent interference from unwanted background particles such as neutrons, cosmic rays and gamma rays from radioactive decay.
“Confirmation of the existence of particles from the dark sector would have a profound impact on the understanding of the Standard Model of particle physics, as well as on knowledge of the origin and evolution of the universe,” stresses physicist Richard Van de Water, from the Laboratory Nacional de Los Álamos and co-author of the analysis of the results of the aforementioned experiment.
Aguilar-Arevalo, Van de Water and their colleagues present the technical details of this analysis in the academic journal Physical Review D, under the title “Prospects for detecting axionlike particles at the Coherent CAPTAIN-Mills experiment”. (Source: NCYT from Amazings)
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