INR RAS - international collaborations

• Particle physics - accelerators experiments
• Particle physics - nonaccelerator experiments
• Fundamental nuclear physics
• Research and design for charge particle accelerators
• Neutrino astrophysics, cosmic rays physics
• CERN

Neutrino astrophysics, cosmic rays physics

Russia-USA Gallium-Germanium Experiment  SAGE
(Los-Alamos National Laboratory, Universities, USA )

Deep Underwater Stationary Neutrino Telescopes on the Baikal Lake. One of the main directions of research activities is the development of methods for deep underwater elementary particles detection and construction of detectors using vast bulks of water of natural reservoirs as target and working substances. At the Baikal Neutrino Station a unique large telescope NT-200 is now being constructed for deep underwater neutrino research with an effective detection area 2-11 thousand square meters (for atmospheric muons) and controlled water bulk of about 200 thousand cubic meters. The construction of this many-purpose setup will allow one to search for new elementary particles and rare processes and fulfill a large-scale experimental research program in the field of high-energy cosmic ray physics.

Search for the neutrino fluxes and research in the Underground Laboratory Gran Sasso LVD (National Laboratory Gran Sasso, National Institute of Nuclear Physics (INFN), Italy)

The Telescope Array is a large scale experiment located in Utah, USA. It is designed for registration of cosmic rays with energies greater than 10¹⁸ eV. The experiment consists of the array of 512 surface detector covering 700 km² and three fluorescence telescope stations on a 30 km triangle.
The low energy extension (TALE) deployed now will extend the energy region down to 3x10¹⁶ eV by adding 10 new high elevation angle telescopes and infill array of scintillator detectors. The experiment's goal is to understand an origin of the highest energy cosmic rays.
The project is an international collaboration of institutions in Japan, USA, South Korea, Russia and Belgium. Russia is represented by a group from INR RAS, including Vadim Kuzmin, one of the authors of the renown Greisen-Zatsepin-Kuzmin (GZK) cut-off.
The contribution of INR group includes the surface detector data reconstruction, the primary spectrum confirming the GZK effect, the strongest in the Northern hemisphere limit on the flux of ultrahigh energy photons, the analysis of the cosmic ray propagation and correlations of the observed arrival directions with the positions of potential sources.
(The University of Utah, The National Science Foundation, USA)

International project LHAASO - Large High Altitude Air Shower Observatory - is the next generation ground-based gamma-ray astronomy and cosmic ray experiment. It is situated in Sichuan province in (China) at altitude of 4410 m. Several arrays joined by LHAASO have record parameters and can measure all EAS components: Cherenkov light, muons, electrons and gammas. There were no hadronic detectors envisaged in the original project and INR RAS proposed to add the ENDA (Electron-Neutron Detector Array) consisting of 400 electron-neutron detectors (en-detectors elaborated in INR, recording electron and hadronic EAS components over whole array area) deployed on surface as a 5-m grid over 100 x 100 m² total area. This could improve the LHAASO performances to measure mass composition and energy spectrum of cosmic rays in PeV region. The ENDA could serve as a giant hadronic calorimeter of 10⁴m², which could be expanded later unlimitedly. The proposal had been accepted.
The LHAASO has obtained and published in 2021 outstanding results in gamma-ray astrophysics - there were discovered new sources of ultra-high energy gamma-rays in our Galaxy - PeVatrons. Moreover, coordinates of the sources have been found with unprecedented angular accuracy 0.05° and a conclusion is made that the highest energy gammas were highly likely originated from pion decays, i. e. along with electron accelerator there also should exist hadron accelerator. The latter means the Galactic sources should accelerate cosmic rays up to at least 10-15 PeV.

Experiment TUNKA (Republic of Buryatia)