The Baikal Neutrino Telescope Baikal-GVD detects high- and ultrahigh-energy neutrinos.
A neutrino is an elementary particle. It has exceptional properties: no charge and almost no mass. Neutrinos travel through enormous cosmic distances, without deflecting from their path and very rarely interacting with matter. This property distinguishes them from photons and nuclei of matter, which make up the main flux of cosmic rays reaching the Earth.
Because of their unique properties, neutrinos are difficult to detect. Scientists search for these particles by rare signals of their interaction with matter. A neutrino interacts with a water atom, and relativistic charged particles are produced generating flashes of light (Cherenkov radiation). These flashes are detected by photodetectors (optical modules).
The large instrumental volume of the facility in a natural body of water solves the problem of rare interactions of neutrinos. The larger the volume, the greater the probability of detecting the interaction. Cherenkov radiation (which propagates in the form of a cone) triggers several optical modules on one or several strings of one or several clusters.
The response time of electronics, when detecting Cherenkov photons, the position of triggered modules, and the amount of detected light enable determining the energy of neutrinos and the direction from which they arrived.
Data from optical modules are transmitted first to the Cluster Centre, then via a bottom cable to the Shore Centre, and after that to Dubna, to the Joint Institute for Nuclear Research.
Potential sources of high-energy neutrinos can be cosmic objects (active galactic nuclei, quasars, blazars, supernovae, etc.), as well as various processes in our Galaxy and beyond (mergers of black holes, mergers of neutron stars, etc.). Neutrinos do not interact with anything and therefore carry direct information on how different regions of cosmic objects interact with each other.
Thanks to high-energy neutrinos, scientists will be able to study properties of neutrino sources, mechanisms of particle acceleration in cosmic objects, galaxy formation and evolution. Today, high- and ultrahigh-energy neutrino physics is terra incognita. It has just started to reveal its secrets. Discoveries in this area will significantly expand our understanding of the world.