Finally, the ghost is in the machine: For the first time, scientists create neutrinos in a particle collider.
These abundant and mysterious subatomic particles are so far removed from the rest of matter that they slide through it like a spectrum, earning them the name “ghost particles”.
Researchers say this work marks the first direct observation of a neutrino collider and will help us understand how these particles formed, what their properties are, and their role in the evolution of the universe.
Results achieved using the FASERnu detector at the Large Hadron Collider, has been shown At the 57th Rencontres de Moriond Conference on Electroweak Interactions and Unified Theory in Italy.
“We’ve discovered neutrinos from a completely new source – particle colliders – where you have two beams of particles colliding together at very high energies,” says particle physicist Jonathan Feng from the University of California, Irvine.
Neutrinos are one of the most abundant subatomic particles in the universe, second only to photons. But they have no electric charge, their mass is close to zero, and they barely interact with any other particles they encounter. Hundreds of billions of neutrinos are flowing through your body right now.
Neutrinos are produced under energetic conditions, such as nuclear fusion that occurs inside stars, or supernova explosions. And while we may not see them every day, physicists believe that their mass – however small – can influence the gravitational pull of the universe (although most neutrinos do). Reflects as dark matter).
Although their interaction with matter is negligible, it is not completely absent; Every now and then, cosmic neutrinos collide with other particles, producing very faint bursts of light.
Underground detectors, isolated from other radiation sources, can detect these explosions. it is batu in Antarctica, Super Kamiokande in Japan and mini wheels Fermilab in Illinois has three such reagents.
However, physicists have long sought to generate neutrinos in particle colliders because the high energies used have not been studied as well as the lower energy neutrinos.
“They can tell us about outer space in ways we can’t study,” said particle physicist Jamie Boyd of CERN. “These high-energy neutrinos at the LHC are important for understanding very exciting observations in particle astrophysics.”
FASERnu is a file emulsion detector It consists of millimeter-thick tungsten plates alternating with layers of an emulsion film. Tungsten was chosen because of its high density, which increases the probability of neutrino interactions; The detector consists of 730 emulsion films with a total mass of about 1 ton tungsten.
During particle experiments at the LHC, neutrinos were able to collide with the core of a tungsten sheet, producing particles that left traces in an emulsion layer, much like the way ionizing radiation makes prints in cloud space.
Like photographic film, these panels need to be developed before physicists can analyze a particle’s trajectory to see what produced it.
Six candidate neutrinos have been identified and published again in 2021. Now, researchers have confirmed their findings, using data from the third round of the LHC boost that began last year, with a significance level of 16 sigma.
This means that the probability of generating a signal by random chance is very low to zero; The 5 sigma level of significance adequately qualifies as a discovery in particle physics.
The FASER team is still hard at work analyzing the data collected by the detector, and it is likely that more neutrino detections will follow. The LHC’s third run is expected to continue Until 2026Continuous data collection and analysis.
By 2021, physicist David Casper of the University of California, Irvine, predicts that the race will generate around 10,000 neutrino interactions, meaning we’ve barely scratched the surface of what FASERnu has to offer.
“Neutrinos are the only known particles that could not be detected directly by the much larger experiments at the Large Hadron Collider.” He saidSo the successful FASER observation means that the full physical potential of the collider is finally being exploited.
Team results Presented at the 57th Congress Rencontres de Moriond Electroweak Interactions and Unified Theories.
