Institute of Experimental and Applied Physics

The neutrino underwater telescope, which is being developed by a scientific team from the Institute of Experimental and Applied Physics of the Czech Technical University (IEAP CTU) as part of the international KM3NeT project, has captured a neutrino with record-breaking energy. The results of the analysis of this unique phenomenon, which can advance neutrino astronomy and contribute to a better understanding of the Universe, have recently been published in the prestigious journal Nature.

 One of the two underwater neutrino telescopes KM3NeT, located 3.5 kilometers below the surface of the Mediterranean Sea off the coast of Sicily, detected a neutrino with the highest energy ever measured, about 220 peta-electron volts (PeV). This is an energy up to 30 thousand times greater than that achieved at the LHC accelerator at CERN. And also the first ever proof of the existence of neutrinos with such high energy in the cosmos.

Although the detection of the high-energy neutrino itself took place on February 13, 2023, it was only today, two years later, that the journal Nature published a  detailed report based on the analysis and interpretation of the data obtained. According to scientists of the international KM3NeT project, which operates the telescope, the capture of this unique particle could lead to a reassessment of our understanding of cosmic ray sources and expand our knowledge of the cosmos. 

The KM3NeT neutrino telescope is one of the devices whose purpose is to detect neutrinos coming from space. These are considered by scientists to be one of the most mysterious and difficult to capture elementary particles. They have no electric charge, almost no mass, and interact with matter so weakly that they are able to fly through the Earth. But thanks to these qualities, they can become a kind of "space postmen" who nothing can stop and who can bring us valuable information about its form and functioning from the depths of space.

The device was created as part of the KM3NeT project, a successful international collaboration in the field of neutrino physics, whose active participants are now France, Italy, the Netherlands, Germany and other countries, as well as the Czech Republic and Slovakia.

"The fact that we have been able to detect a neutrino with such high energy is the result of a huge joint effort by a number of international teams of scientists, engineers and technicians," says Miles Lindsey Clark of the French Institute Le Laboratoire Astroparticule et Cosmologie.

The Czech Republic is represented in KM3NeT by the Institute of Experimental and Applied Physics of the Czech Technical University (IEAP CTU), which has brought together scientists from the Czech Republic, Slovakia and the United Kingdom in its team. And to finance our participation in the project, he also received support from the Grant Agency of the Czech Republic. 

"Our institute is dedicated to the research of neutrinos in their extreme positions. In underground laboratories such as LSM Modane, in an environment where cosmic rays do not penetrate, we try to determine the mass of the neutrino. On the other hand, on an underwater telescope such as KM3NeT, we try to capture cosmic neutrinos with the maximum possible energy," explains Ivan Štekl, director of IEAP CTU. 

 In addition to the research of the "most mysterious" elementary particle, neutrino physics also brings technological development in the field of detector development, robotics and nuclear energy safety as a side effect. And recently, AI-related technologies have also been increasingly used to analyze data obtained from neutrino telescopes.

The KM3NeT underwater neutrino telescope is designed primarily for the study of high-energy neutrinos and their sources in space. It consists of digital optical modules, glass spheres with a diameter of approximately 40 cm, in the bowels of which photomultipliers and other necessary electronics are placed. The optical modules are then suspended on wire ropes and lowered to a depth of 3.5 kilometers, where they form 700-meter-long chains anchored to the seabed.

According to the scientists' assumptions, the high-energy particle captured by the neutrino telescope could have been created as a product of cataclysmic astrophysical phenomena such as the growth of supermassive black holes at the center of some galaxies, supernova explosions or gamma-ray bursts, of which we still have only a vague idea.

These sources of cosmic rays can also be thought of as super-powerful natural "accelerators" that create streams of particles. These then interact with matter or photons around the source to create, among other things, so-called cosmic neutrinos, which set off on their journey through space and some of which reach Earth. The detection of a neutrino with such high energy is therefore an exceptional event that can open a new chapter in neutrino astronomy and more generally in the understanding of the universe.

Website of the KM3NeT experiment:

www.km3net.org

Illustrations used: Copyright KM3NeT