Another expedition to build Baikal-GVD Deep Underwater Neutrino Telescope of cubic kilometer scale completed on Lake Baikal
The annual expedition to build a neutrino telescope on Lake Baikal has been completed. Participants in the Baikal-GVD project deployed the 15th and 16th clusters of the telescope in an eight-string configuration. The configuration of the last three clusters (14th, 15th, and 16th) included three external strings with calibration lasers. Maintenance and upgrade were performed on clusters 6 and 10, as well as on the prototype string for the next-generation neutrino telescope deployed jointly with the Institute of High Energy Physics (IHEP, Beijing). Furthermore, a full-scale string of optical modules based on 20-inch photomultipliers was put into operation during the expedition. A bottom cable was laid during the expedition to supply power and transmit data for two clusters. Thus, the underwater structure comprises just under 4,900 optical modules.
In accordance with the joint work plan, colleagues from Irkutsk State University and the Limnological Institute of the Siberian Branch of the Russian Academy of Sciences carried out a series of hydrology experiments during the 2026 winter expedition.
Work at the Ice Сamp ended several days earlier than usual due to a lack of snow on the ice surface during the second half of the expedition. Bright sunshine and warm weather drastically changed the ice structure, reducing its bearing capacity.
Nevertheless, almost all plans for the expedition were implemented. More than 70 people from institutes and scientific organizations participating in the Baikal-GVD collaboration took part in the expedition.
The Baikal-GVD telescope is the largest in the Northern Hemisphere and the second largest in the world. To date, 16 clusters, located at a distance of 250—300 m, have been put into operation. Since 6 April 2026, they have been working in data acquisition mode. Each cluster is an independent detector consisting of 8 vertical strings on which optical modules are installed (36 on each string). According to the project, the installation volume should be about 1 km³ by 2028.
“This year, the ice cover on Lake Baikal was almost perfectly flat and more than 60 centimeters thick by the time the first team arrived. The beginning of the expedition was marked by cold weather (daytime temperatures hovered around -20°C) during the first two weeks, but despite such harsh conditions, installation began on the third day after the arrival of the first group. This was facilitated by careful preparation for the work and newly introduced technological solutions for deploying the facility.
The absence of snowfall and strong winds for almost the entire period of ice work contributed to rapid deployment on the one hand, but on the other hand, it meant that the ‘ice’ team of the expedition had no rest. However, the main team demonstrated strong willpower, and following their example, the new expedition members performed excellently. In the end, almost all plans were completed, and a record number of new optical modules were installed in a single season – 756, or 21 strings without the ‘Chinese’ ones,” notes I. A. Belolaptikov, head of the expedition, head of the Baikal-GVD facility at the Dzhelepov Laboratory of Nuclear Problems of the Joint Institute for Nuclear Research, and deputy head of the Baikal-GVD collaboration, Igor Anatolyevich Belolaptikov.
"Since 2015, The Baikal-GVD neutrino telescope has been successfully deployed primarily due to the modular structure of the telescope's detecting system, which is formed from functionally independent clusters of photodetectors. This detector configuration made it possible to study natural neutrino fluxes at a high level of sensitivity already in the early stages of its construction. As a result of analyzing experimental data accumulated over the period 2018–2023 by various telescope configurations, a diffuse flux of cosmic neutrinos was detected, which was the first independent confirmation of the results of the IceCube experiment; a flux of neutrinos with energies above 200 TeV from our Galaxy was detected; a limit was set on the flux of cosmogenic neutrinos in the energy range above 10 PeV; and a number of indications of the existence of local neutrino sources both in our Galaxy and beyond have been obtained. Completion of the construction of the neutrino telescope in the next 2–3 years and its subsequent operation in the design configuration with a volume of one cubic kilometer will provide unique results in the study of our Universe using neutrinos," says Zh.-A. M. Dzhilkibaev, doctor of sciences (physics and mathematics), head of the Laboratory of High-Energy Neutrino Astrophysics at the Institute for Nuclear Research of the Russian Academy of Sciences, and head of the Baikal-GVD collaboration.
For reference
The Baikal Neutrino Telescope is a neutrino detector located in Lake Baikal 3.6 km offshore at a depth of about 1300 m. This unique scientific facility is an important tool for multi-messenger astronomy, a new advanced method of studying the Universe. Baikal-GVD is one of three operating neutrino telescopes in the world, and, along with IceCube at the South Pole and KM3Net in the Mediterranean Sea, it is included in the Global Neutrino Network (GNN).
The Baikal-GVD neutrino telescope is designed to detect and study ultra-high-energy neutrino fluxes of astrophysical origin. Using the telescope, scientists plan to study not only processes with enormous energy releases that occurred in the distant past, but also the evolution of galaxies, the formation of supermassive black holes, and the mechanisms of particle acceleration.
The Baikal neutrino telescope is being built by international collaboration, with leading roles played by the Institute for Nuclear Research of the RAS (Moscow), the founder of the experiment and field “high-energy neutrino astronomy” in the world, and the Joint Institute for Nuclear Research (Dubna). More than 70 scientists and engineers from nine research centres of Russia, Czech Republic, Slovakia, and Kazakhstan take part in the project.
Photographs by Bair Shaybonov
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