March 29, 2024

Particle Physics: Neutrinos Detected in a Particle Accelerator

An international research team has discovered for the first time neutrinos produced by a particle accelerator. These elementary particles are among the most common particles in the universe, but they are very difficult to study because they rarely interact with other matter. Therefore they are often referred to as “ghost particles”. A total of 85 researchers from CERN in Geneva and 21 universities around the world, including the Universities of Bern, Bonn and Mainz, took part in the study.

Co-authors announced this week that the discovery at CERN’s Large Hadron Collider (LHC) particle accelerator will help better understand neutrinos and, among other things, answer the question of why there is more matter than antimatter. The result was announced at a conference in Italy on Sunday. For the current study, 153 neutrino events were detected in collision data from the LHC recorded between July and November 2022. It is the beginning of a series of investigations that remain to be done.

How are neutrinos created and discovered?

So most of the neutrinos that physicists have studied so far have been low-energy. To date, no neutrinos have been detected created in a particle accelerator such as the LHC. High-energy particles are created there when two beams of extremely high-energy particles collide. However, it has not yet been detected because it escaped the large detectors without leaving any traces.

In the current project (FASER – this stands for “ForwArd Search ExpeRiment”), the researchers are using two special detectors: the “FASER detector”, which is specifically designed to search for new elementary particles as dark matter candidates, and the “FASERnu” neutrino detector, which studies collisions of particles that Speaking at the LHC’s ATLAS particle detector, this will allow the properties of all three different types of neutrinos — the electron, muon and tau — to be studied with unprecedented precision.

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The neutrinos detected in the current study interacted with a so-called emulsion detector with sheets of tungsten and were converted into other elementary particles, called muons. These were in turn detected by a FASER detector.