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For the first time ever, physicists have detected signs of neutrinos at the Large Hadron Collider

Teach First at CERN Facility Preview for the upcoming 3-year research campaign.

The international Forward Search Experiment team, led by physicists at the University of California, Irvine, has made the first-ever detection of a candidate neutrino produced by the Large Hadron Collider at

CERN
Established in 1954 and headquartered in Geneva, Switzerland, CERN is a European research organization that operates the Large Hadron Collider, the largest particle physics laboratory in the world. Its full name is the European Organization for Nuclear Research (French: Organisation européenne pour la recherche nucléaire) and the CERN acronym comes from the French Conseil Européen pour la Recherche Nucléaire.

“>CERN Facility near Geneva, Switzerland.

In a research paper published in the journal on November 24, 2021 physical review dIn 2018, the researchers describe how they observed six neutrino interactions during an experimental run of a pressurized emulsion detector installed at the LHC in 2018.

“Prior to this project, there was no sign of neutrinos in the particle collider,” said co-author Jonathan Feng, UCI Distinguished Professor of Physics and Astronomy and co-leader of the FASER Collaboration. “This important breakthrough is a step toward developing a deeper understanding of these elusive particles and the role they play in the universe.”

He said the discovery made during the pilot gave his team two important pieces of information.

The CERN-approved FASER particle detector to be installed at the Large Hadron Collider in 2019 was recently enhanced with a neutrino detector. The UCI-led FASER team used a smaller detector of the same type in 2018 to make the first observations of the elusive particles generated at the collider. The researchers said the new instrument will be able to detect thousands of neutrino interactions over the next three years. Image source: CERN

“First, verify that the forward position of the ATLAS interaction point in the LHC is the correct location for detecting collider neutrinos,” Feng said. “Second, our efforts demonstrated the effectiveness of using an emulsion detector to monitor these types of neutrino interactions.”

The experimental instrument was composed of lead and tungsten plates alternating with layers of emulsion. During particle collisions in the LHC, some neutrinos caused the dense metal cores to break apart, creating particles that travel through the layers of the emulsion and create visible marks after processing. These inscriptions provide clues about the particle’s energies and flavours – tau, muon or electron – and whether they are neutrinos or antineutrinos.

According to Feng, the emulsion works in a similar way to photography in the pre-digital camera era. When 35 mm film is exposed to light, the photons leave trails that appear as patterns as the film is developed. The FASER researchers were also able to see neutrino interactions after the emulsion layers in the detector were removed and developed.

“After verifying the effectiveness of the emulsion detector approach in observing the interactions of neutrinos generated by the particle collider, the FASER team is now setting up a new series of experiments with a complete instrument that is much larger and significantly more sensitive,” said Feng.

FASER Experience Map

The FASER experiment is located 480 meters from the Atlas interaction point at the Large Hadron Collider. According to Jonathan Feng, UCI Distinguished Professor of Physics and Astronomy and co-leader of the FASER collaboration, this is a good site for detecting neutrinos from particle collisions at the facility. Image source: CERN

Since 2019, he and his colleagues have been preparing to conduct an experiment using the FASER instruments to examine the LHC’s dark matter. They hope to discover dark photons, which will give researchers an initial glimpse into how dark matter interacts with natural atoms and other matter in the universe through forces other than gravity.

With the success of their neutrino work over the past few years, the FASER team – made up of 76 physicists from 21 institutions in nine countries – is combining a new emulsion detector with the FASER instrument. While the experimental detector weighs about 64 pounds, the FASERnu instrument will be more than 2,400 pounds, and will be more reactive and able to distinguish between types of neutrinos.

said co-author David Kasper, co-project FASER-leader and associate professor of physics and astronomy at UCI. “We will discover the highest-energy neutrinos that have been produced from a man-made source.”

What makes FASERnu unique, he said, is that while other experiments have been able to distinguish between one or two types of neutrinos, they will be able to observe all three flavors as well as their antineutrino counterparts. Casper said there have only been about 10 observations of tau neutrinos in all of human history, but he expects his team will be able to double or triple that number within the next three years.

“This is an incredibly wonderful connection to the tradition in the physics department here at UCI,” Feng said, as it continues the legacy of Frederick Raines, a founding faculty member at UCI who won the Nobel Prize in Physics for being the first to discover neutrinos. “

“We have produced a world-class experiment in the world’s premier particle physics lab in record time and with very unconventional resources,” Kasper said. “We owe a huge debt of gratitude to the Heising-Simons Foundation and the Simons Foundation, as well as the Japan Society for the Promotion of Science and CERN, who have generously supported us.”

Reference: “The first candidates for the neutrino interaction in the LHC” by Henso Abreu et al. (FASER Collaboration), November 24, 2021, Available here. physical review d.
DOI: 10.1103 / PhysRevD.104.L091101

Savannah Shivley and Jason Arakawa, Ph.D. from UCLA. Physics and astronomy students, also contributed to the research.

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