For several upcoming years scientists will be able to solve one of the most important problems of physics of elementary particles, called “muon mystery”, it will help to better understand processes, going on in the Universe; a great contribution into these processes will be made by Russian specialists.

Cosmic particles in the Earth atmosphere go through a series of transformations, as the result of which there appear elementary particles – muons. Muons can reach the Earth surface and thus be observed by terrestrial detectors. Several years ago scientists’ attention was attracted to the fact that the number of registered muons is tens percent bigger than it should be according to existing theories. This phenomenon was called “muon mystery” by physicists.

For the first time a reference to “muon mystery” was obtained in 2002-2007 during a long series of experiments on DECOR facility. Later the existence of muon abundance was confirmed in experiments, conducted in a large observatory “Pierre Auger” in Argentina.

Employees of the Scientific educational centre NEVOD, which is a part of MEPhI Institute of Nuclear Physics and Technologies, study muons with the help of one and only in the world multi-purpose neutrino water detector, aimed at the research of all components of cosmic rays near the Earth surface. MEPhI specialists have told about the latest results of experiments on studying of cosmic rays with the help of the NEVOD complex at the All-Russian conference on cosmic rays, which was held in Dubna.

“For the last years we have increased experimental material 3-4 times and thus improved the accuracy of measuring. One of the directions of experimental research on the solution to the muon mystery is measuring not only of the muon quantity, but also their energy characteristics. We started the experiment on measuring of muon energies back in 2012 and we are still doing it. At first, with the help of the coordinate tracking detector DECOR we register a group of muons and then measure, what measuring effect they gave in the Cherenkov water detector NEVOD,” said chief research fellow of the NEVOD Centre Rostislav Kokoulin.

Scientists aim to find out if there is a change of muons’ average energy apart from their number excess.

“When it is experimentally shown that there is such energy excess, it will become clear, what kind of changes are required from a theoretical model. New facilities, which will work with new detectors DECOR and NEVOD, are currently being built in MEPhI. It will allow increase the set of observed characteristics and the precision of measuring.”

According to Kokoulin’s words, the solution to the “muon mystery” is a question of 3-5 years.

“The solution to the “muon mystery” will give us better understanding of the picture of the nuclear cascade process in the interaction of particles of superhigh energies. This understanding is necessary for the research of characteristics of our Universe, for studying processes, going on there,” says the scientist.