For the first time, physicists have created and detected high-energy “ghost particles” inside the world’s largest atom crusher. The findings could help reveal the secrets of how stars go supernova.
Small particles, known as neutrinosby the FASER neutrino detector at the Large Hadron Collider (LHC) – the world’s largest particle accelerator, located at the European Organization for Nuclear Research (CERN) near Geneva, Switzerland.
Neutrinos earn their spectral moniker because their non-existent electrical charge and almost zero mass mean they hardly interact with other types of matter. True to the ghostly moniker, neutrinos fly through ordinary matter at nearly the speed of light. Physicists They presented their results (Opens in a new tab) At the 57th Congress of Electroweak Interactions and Unified Theories Rencontres de Moriond in La Thuile, Italy on March 19.
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“We’ve discovered neutrinos from a completely new source – particle colliders – where you have two beams of particles colliding together at extremely high energy,” Jonathan Feng (Opens in a new tab)a physicist at the University of California, Irvine and spokesperson for the FASER Collaboration, he said in a statement (Opens in a new tab).
Every second, about 100 billion neutrinos pass through every square centimeter of your body. Tiny particles are everywhere – produced in the nuclear flames of stars, in massive supernova explosions, by cosmic rays and radioactive decay, and in particle accelerators and nuclear reactors on Earth. In fact, neutrinos, which were first detected ejecting from a nuclear reactor in 1956, are second only to photons as the most abundant subatomic particle in the universe.
But despite their ubiquity, the interactions of chargeless, near-mass particles with other matter make them extremely difficult to detect. Despite many famous neutrino detection experiments—such as Japan’s Super-Kamiokande detector, Fermilab’s MiniBooNE, and IceCube’s south pole detector— I managed to detect solar-generated neutrinos.
But the neutrinos that reach us from the sun are just one tiny slice of the ghost particles out there. On the other end of the energy spectrum are the high-energy neutrinos produced in giant supernova explosions and in particle showers when deep-space particles collide with Earth’s atmosphere. These high-energy ghosts have remained a mystery to scientists until now.
“These high-energy neutrinos at the LHC are important for understanding really exciting observations in particle astrophysics,” Jimmy Boyd (Opens in a new tab), a CERN particle physicist and co-spokesperson for FASER, said in the statement. The new discoveries could help explain how stars burn and explode, and how high-energy neutrino interactions lead to the production of other particles in space.
To capture the subatomic spectra, physicists built a Beaver particle detector: dense metal sheets of lead and tungsten trap multiple layers of a sticky, light-detecting substance called an emulsion. When bundles of high-energy protons collide with each other inside the Large Hadron Collider, they produce a shower of byproduct particles, a small part of which are neutrinos, that enter Sable. The neutrinos from these collisions then hit the atomic nuclei in the dense metal sheets and decay into other particles. The layers of emulsion work in a similar way to old photographic film, interacting with neutrino byproducts to imprint the particle’s traceable outlines as it passes through it.
By “developing” this film-like emulsion and analyzing the trajectories of the particles, the physicists discovered that some of the marks were caused by jets of particles made by neutrinos passing through the plates; They can even identify which of the three particle “flavors” of neutrinos – tau, muon or electron – they have detected.
The six neutrinos detected by this experiment were first identified in 2021. It took physicists two years to gather enough data to be sure they were real. Now, they expect to find more, and they think they can use them to explore environments throughout the universe where high-energy ghost particles form.
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