Irwin (UC Irwin) An international research team led by physicists at the University of California, Berkeley, has succeeded in finding the first signs of neutrinos inside a particle accelerator. These tiny particles, known as ghost particles, were discovered during a test run of a new miniature detector installed on the Large Hadron Accelerator (LHC) at the European Institute of Particle Physics (CERN) near Geneva, Switzerland.

This is the first time neutrinos have been detected inside a man-made particle accelerator. This discovery is significant because it opens a new window for scientists to explore the subatomic world. The study, which looked at the reaction of six neutrinos during a test run, was published in the November 24 issue of the Physical Review D, an international journal published by the American Physical Society.

“Prior to this project, no traces of neutrinos were found on particle accelerators,” said Dr. John H. Snyder, professor of physics at UC Irvine and co – author of the study. Jonathan Feng said. This is the first step in understanding the role in depth. They are playing. “

Neutrinos, one of the basic building blocks of the universe, are called ‘ghost particles’ because they rarely interact with other particles and pass through most matter. However, neutrinos are always around us because they come from fusion reactions in the sun, supernova explosions, cosmic rays, radiation decay, and decomposition reactions in nuclear power plants.

Installs a compact emulsion detector on the LHC

About 100 billion neutrinos pass through our body every 1 cm. However, neutrinos are difficult to detect because they have no charge, low mass, and rarely interact with other types of matter.

However, the fact that they are difficult to detect does not mean that neutrinos cannot be detected. In famous neutrino detection experiments such as Japan’s Super Cameo Cond,, miniboon at the Fer American National Accelerator Laboratory in the US, and Ice Cube in Antarctica, Cherenkov indirectly detected neutrinos indirectly produced by the sun.

This is because particles moving faster than light can emit a faint blue light as they pass through a light-reducing medium such as water, just as a plane faster than a sonic plane causes a sonic boom. By detecting light, scientists can detect traces of particle by-products left by neutrinos.

FASER is located 480m away from LHC’s ATLAS IP. © CERN

However, although such an experiment can detect signals from neutrinos flowing from the Sun to Earth, it is difficult to detect high-energy neutrinos that occur when particles collide inside a particle accelerator. To detect such neutrinos, CERN’s Forward Search Test (FASER) project team installed a small emulsion detector at LHC in 2018.

This pilot device contains alternate lead, tungsten plates, and emulsion layers. During particle collisions in the LHC, some neutrinos break up the nuclei of the dense metal, passing through the emulsion layer and forming particles that leave visible marks.

The researchers were able to identify which of the three types of neutrinos they discovered: tau neutrinos, muon neutrinos, and electron neutrinos.

A study of the differences between neutrinos and anti-neutrinos

The FASER team of 76 physicists from 21 institutions in 9 countries integrates the new detector ‘FASERnu’ with the FASER device. The current Pilot Small Detector weighs approximately 29 kilograms, while the FASERnu device is expected to weigh more than 1,088 kilograms.

The researchers claim that the new detector is not only more sensitive to detect neutrinos, but also to distinguish between neutrinos and their antimatter, known as antineutrinos.

When LHC reopens next year, researchers plan to use FASERnu to study in depth the neutrinos generated inside the particle accelerator.

“Given the performance of the new detector and its key position at CERN, we expect more than 10,000 neutrino interactions to be recorded in the LHC’s next run from 2022,” said Dr. John H. Snyder, co-author of the study at UC. David Caspar said. Irwin “We will find the highest energy neutrinos made by man-made devices.”

But the new detector is not the only one detecting neutrinos. Researchers say they are preparing experiments to find ‘dark photons’, which physicists believe are closely related to dark matter, which makes up about 85 percent of the universe’s mass.

(2395)