'Ghostly' neutrinos spotted inside the world's largest particle accelerator for the first time

Neutrino signatures, or phantom particles that infrequently communicate with one another, were inadvertently discovered in the LHC in 2021. Physicists have now established that they exist.

In the biggest atom smasher in the world, physicists have for the first time produced and identified high-energy "ghost particles." The discoveries might provide the key to understanding why stars go nuclear.

The FASER neutrino monitor at the Large Hadron Collider (LHC), the biggest particle accelerator in the world, which is housed at the European Organization for Nuclear Research (CERN) close to Geneva, Switzerland, discovered the neutrinos.

Because of their negligible electrical charge and almost zero mass, neutrinos scarcely interact with other kinds of matter, earning them the spectral moniker. Neutrinos move through ordinary matter at nearly the speed of light, living up to their spectral name. On March 19, scientists in La Thuile, Italy, gave a presentation of their findings at the 57th Rencontres de Moriond Electroweak Interactions and Unified Theories meeting.

Jonathan Feng, a physicist at the University of California Irvine and a co-spokesperson for the FASER Collaboration, said in a statement: "We've found neutrinos from a brand-new source — particle colliders — where you have two streams of particles crash together at extremely high energy" (opens in new tab).

Your body contains about 100 billion particles per square centimeter per second. The minuscule particles are created everywhere, including in particle accelerators and nuclear reactors on Earth. They are also created in the nuclear fire of stars, massive supernova blasts, cosmic radiation, and radioactive decay. In reality, neutrinos, which were first found bursting from a nuclear plant in 1956, are the universe's second-most prevalent subatomic particle after photons.

The chargeless and near massless particles are ubiquitous, but they are extremely hard to identify due to their weak interactions with other materials. Despite this, a number of well-known neutrino detection projects, including the Antarctic IceCube detector, Fermilab's MiniBooNE, and Japan's Super-Kamiokande detector, have been successful in detecting solar-generated neutrinos.

However, the phantom particles that exist are much more numerous than the neutrinos that come to us from the solar. High-energy neutrinos, which are generated in massive supernova explosions and in particle showers when deep-space particles collide with Earth's atmosphere, are at the other extreme of the energy spectrum. Scientists have been baffled by these energetic spirits up until this point.

The LHC's extremely high-energy neutrinos, according to FASER co-spokesperson Jamie Boyd(opens in new tab), are crucial for comprehending some extremely thrilling particle astrophysics data. The novel discoveries may shed light on how stars blaze and erupt as well as how extremely energetic neutrino interactions lead to the creation of other space-based particles.

The scientists created a particle-detecting s'more to capture the subatomic specters: Multiple layers of the light-detecting goo known as emulsion are sandwiched between dense metal slabs made of lead and tungsten. A tiny portion of the neutrinos produced by the collision of powerful protons inside the LHC penetrate the s'more as a result of the byproduct particle shower. The atomic atoms in the thick metal plates are struck by the neutrinos from these impacts, which then decay into other particles. Similar to traditional photographic film, the emulsion layers respond with neutrino byproducts to stamp the drawn contours of the particles as they fly through them.

The physicists discovered that some of the marks were caused by particle jets made by neutrinos passing through the plates by "developing" this film-like emulsion and examining the particle trails; they were even able to identify which of the three neutrino "flavors" — tau, muon, or electron — they had detected.

This operation discovered six neutrinos, which were first recognized in 2021. It took the scientists two years to gather enough evidence to prove they were genuine. They anticipate finding a lot more of them and believe they can use them to look for places throughout the cosmos where extremely energetic ghost particles are produced.