(ORDO NEWS) — The ghost is finally actually in the machine: scientists have created neutrinos for the first time in a particle collider.
These plentiful but mysterious subatomic particles are so far removed from the rest of the world because they slither through it like ghosts, earning them the nickname “ghost particles.”
The researchers say this work represents the first direct observation of collider neutrinos and will help us understand how these particles are formed, what their properties are, and their role in the evolution of the universe.
The results obtained with the FASERnu detector at the Large Hadron Collider were presented at the 57th Rencontres de Moriond Electroweak Interactions and Unified Theories conference in Italy.
“We have detected neutrinos from a completely new source – particle colliders – where two beams of particles collide with each other at extremely high energy,” says physicist Jonathan Feng of the University of California. Irwin.
Neutrinos are among the most abundant subatomic particles in the universe, second only to photons.
But they have no electrical charge, their mass is almost zero, and they have little to no interaction with other particles they encounter along the way. Right now, hundreds of billions of neutrinos are passing through your body.
Neutrinos are produced in energetic conditions such as nuclear fusion occurring inside stars or supernova explosions.
And while we may not notice them day in and day out, physicists believe that their mass, however small, likely influences the universe’s gravity (although neutrinos are virtually ruled out as dark matter).
Although their interaction with matter is small, it is not entirely absent; from time to time a cosmic neutrino collides with another particle, producing a very faint flash of light.
Underground detectors, isolated from other sources of radiation, can detect these flashes. IceCube in Antarctica, Super-Kamiokande in Japan, and MiniBooNE at Fermilab in Illinois are three such detectors.
However, neutrinos produced in particle colliders have long been sought after by physicists because the high energies involved are not that great. well studied as low energy neutrinos.
“They can tell us about deep space in ways we can’t know otherwise,” says particle physicist Jamie Boyd of CERN.
“These very high-energy neutrinos at the LHC are important for understanding really exciting observations in particle astrophysics.”
FASERnu is an emulsion detector consisting of millimeter-thick tungsten plates interleaved with layers of emulsion film.
Tungsten was chosen because of its high density, which increases the likelihood of neutrino interactions; The detector consists of 730 emulsion films and a total mass of tungsten of about 1 ton.
During particle experiments at the LHC, neutrinos can collide with nuclei in tungsten plates, forming particles that leave traces in emulsion layers, a bit like how ionization occurs. radiation leaves traces in the cloud chamber.
These plates must be developed like photographic film before physicists can analyze the particle trails to figure out what made them.
Six neutrino candidates have been identified and published as early as 2021. Now the researchers have confirmed their finding using data from the third run of the upgraded LHC, which began last year, at a 16 sigma significance level.
This means that the probability that the signals were generated randomly is so small that it is almost zero; a significance level of 5 sigma is sufficient to qualify as a discovery in particle physics.
The FASER team is still diligently analyzing the data collected by the detector, and it is likely that many more neutrino detections will follow. The third launch of the LHC is expected to last until 2026, and data collection and analysis continues.
Back in 2021, physicist David Kasper of the University of California, Irvine predicted that about 10,000 neutrino interactions would occur during a launch, which means we’ve barely scratched the surface of what FASERnu has to offer.
“Neutrinos are the only known particles that cannot be directly detected in the much larger experiments at the Large Hadron Collider,” he says, “so the successful observation of FASER means that the full physical potential of the collider is finally being used.”
The group’s results were presented at the 57th Rencontres de Moriond Electroweak Interactions and Unified Theories.
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