International Collaboration FASER at CERN Detects First Neutrinos Made by Particle Collider
“We’ve discovered neutrinos from a brand-new source, from particle colliders, where you have two beams of particles smashing together at extremely high energy to make the neutrinos,” said Jonathan Feng, particle physicist at UC Irvine and Co-Spokesperson of the FASER Collaboration which now includes over 80 researchers at 22 institutions, including JINR.
Brian Petersen, a particle physicist at CERN, announced the results on behalf of the FASER Collaboration on Sunday at the 57th Rencontres de Moriond Electroweak and Unified Theories Conference in Italy.
“Neutrinos are particles that we know exist,” said Jamie Boyd, a particle physicist at CERN and a Co-Spokesperson of FASER alongside Feng. “They’ve been known for several decades, and were very important for establishing the standard model of particle physics. But previously, no neutrino produced at a collider had ever been detected by an experiment.”
It’s the latest result to come from the Forward Search Experiment (FASER), a particle detector designed and built by an international group of physicists and installed at the European Organization for Nuclear Research (CERN) in Geneva, Switzerland. There, FASER detects particles that are produced by CERN’s Large Hadron Collider (LHC).
JINR scientists’ contribution to neutrino physics takes its start from works by Bruno Pontecorvo. Till now the majority of neutrinos studied by physicists have been relatively low-energy neutrinos. But the neutrinos detected by FASER are the highest energy ever produced in a lab, and are similar to the neutrinos found when deep-space particles trigger extensive particle showers in our atmosphere.
“They can tell us about deep space that we can’t learn in other ways,” said Boyd. “These very high-energy neutrinos at the LHC are important for understanding really exciting observations in particle astrophysics.”
FASER itself is brand-new and unique among particle-detecting experiments. Compared to other detectors at CERN like ATLAS, which is several stories tall and weighs thousands of tons, FASER is only about one ton and fits neatly into a small side-tunnel at CERN. Therefore, it took only a few years to design and construct it using spare parts from other experiments.
Beyond neutrinos, one of FASER’s other chief objectives is to help identify the particles that make up dark matter which physicists think comprises most of the matter in the universe, but which they’ve never directly observed before.
FASER has yet to find signs of dark matter, but with the LHC set to begin a new round of particle collisions in a few months, the detector stands ready to record them, should they appear.
“We’re hoping to see some exciting signals,” said Boyd.
Previously, the FASER Collaboration have already reported on a few collider neutrinos registered by its nuclear emulsion detector. The new result is based on large statistics of detected very high energy neutrinos at the FASER electronic detector, its statistical significance exceeds 16 sigmas.
“JINR participants in the FASER experiment are DLNP researchers who have a great experience in neutrino physics experiments, in particular the OPERA experiment where nuclear photoemulsion was used for neutrino detection. FASER also has a photoemulsion subdetector, FASERnu, aimed at neutrino detection at the LHC. The JINR group is involved in signal simulation, reconstruction and analysis of photoemulsion data, design and development of the cooling system with the possibility of controlling and stabilizing temperature for the FASERnu,” explained Svetlana Vasina, researcher from the Sector of Experimental Neutrino Physics, the JINR participant in the FASER collaboration.
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