Cooperation

Experiment K2K (National Laboratory for High Energy Physics, (KEK, - Super-Kamiokande, Japan).
The evidence of the neutrino oscillations was discovered by the study of atmospheric neutrinos in 1998. In 1999, an accelerator based experiment was started to study this phenomena. This experiment is called the KEK to Kamioka long baseline neutrino oscillation experiment (K2K). The neutrinos are artificially generated by using the proton accelerator at KEK and observed in the Super-Kamiokande detector located 250km away from KEK.

This experiment was completed in Nov. 2004. As a result, 112 neutrino events are observed in Super-Kamiokande, while the expected number of events without oscillations is 158. The probability to observe the deficit without neutrino oscillations is estimated to be 0.0015% and this deficit confirms the prediction of the neutrino oscillation discovered by the observation of atmospheric neutrinos.

T2K is a neutrino experiment designed to investigate how neutrinos change from one flavour to another as they travel (neutrino oscillations). An intense beam of muon neutrinos is generated at the J-PARC (Japan Proton Accelerator Research Complex)nuclear physics site on the East coast of Japan and directed across the country to the Super-Kamiokande neutrino detector in the mountains of western Japan.

The beam is measured once before it leaves the J-PARC site, using the near detector ND280, and again at Super-K: the change in the measured intensity and composition of the beam is used to provide information on the properties of neutrinos.
Science Goals of T2K

•the discovery of ν_μ → ν_e ( i.e. the confirmation that θ₁₃ > 0 )

•precision measurements of oscillation parameters in ν_μ disappearance

•a search for sterile components in ν_μ disappearance by observation of neutral-current events

•world-leading contributions to neutrino-nucleus cross-section measurements

Emulsion detector for searching for neutrino oscillations in the Gran Sasso laboratory - Oscillation Project with Emulsion-tRacking Apparatus - the OPERA experiment was created for the international project CNGS (CERN neutrinos to Gran Sasso). It is aimed at studying the properties of neutrinos and is of fundamental importance for particle physics, astrophysics and cosmology. In the underground laboratory of Gran Sasso, Italy, at a depth of about 1.4 km underground, a detector was built, consisting of two independent supermodules, which include target blocks and muon spectrometers.

 A beam of muon neutrinos is formed due to the interaction of protons accelerated at the accelerator at CERN (energy about 400 GeV) with nucleons of graphite target nuclei, then the produced particles (pions and kaons) are focused by a system of magnets in the indicated direction - in the direction of Gran Sasso. Pions and kaons are short-lived particles that decay on the fly in a vacuum tunnel about 1 km long at very high energies. The products of such decay are muons and neutrinos.

The goal of the E929 NOvA experiment (Enrico Fermi National Accelerator Laboratory - FNAL, USA) is to study νμ → νe neutrino oscillations. The experimental program includes measuring the number of events caused by the interaction of electron (anti)neutrinos that can appear in beams of muon (anti)neutrinos as a result of νμ → νe oscillations. This makes it possible to measure the probability of such transitions, the mixing angle θ13 and the phase of violation of CP invariance in the lepton sector, as well as determine the hierarchy of masses of neutrino states.

The observation of CP violation in the lepton sector, which in itself is a discovery, would be the experimental basis for the fundamental idea of leptogenesis, which explains the baryon asymmetry of the Universe. This experiment will also determine other oscillation parameters with high accuracy, which will make it possible to understand the difference between the mixing of quarks and leptons. Currently, the Institute’s employees take part in the installation and adjustment of the near detector, as well as on duty at the NOvA neutrino detectors. They study the background from the penetrating component of cosmic rays and develop methods for its suppression. The main activities are related to the reconstruction, identification and analysis of neutrino events at the near and far NOvA detectors and calculations of (anti)neutrino fluxes in the NuMI off-axis beam.

The purpose of the E938 MINERvA experiment (Enrico Fermi National Accelerator Laboratory - FNAL, USA) is the study of neutrino scattering on nuclei.

The experimental program includes measuring cross sections for the interaction of neutrinos with various nuclear targets in the energy range of quasi-elastic scattering, resonance production and deep inelastic scattering.

The relevance of these studies is due, first of all, to the fact that uncertainties in the cross sections for quasi-elastic and resonant interactions of neutrinos with nuclei are one of the main sources of systematic errors in accelerator oscillation experiments with distant neutrinos.

Institute employees take part in duties at the detector, process and analyze data on exclusive quasi-elastic events, as well as determine the differential cross section of this process and the axial shape factor of the nucleon.

The main objective of the E949 experiment at BNL (Brookhaven National Laboratory, USA) is to measure the rare decay of K+ -> p + νν, which occurs due to neutral currents with a change in flavor. The sensitivity of the experiment to this decay is about 10-11, which is an order of magnitude greater than the prediction of the Standard Model. As a result, the matrix element of the SCM matrix |Vtd| can be determined with an accuracy of better than 25%.

The main goal of the E246 experiment at KEK (National High Energy Physics Laboratory, Japan) is to search for violation of T-invariance in the decay K+ -> m + p0ν. The discovery of such an effect would be a manifestation of new physics beyond the Standard Model and would mean the existence of mechanisms of CP violation through the exchange of Higgs bosons.