卷 89, 编号 6 (2025)

We presented the results of modeling background events in the Large Volume Detector – LVD (Gran Sasso Laboratory, Italy) from natural radioactivity of the rock and detector construction materials. Contributions to the overall background of events from various sources are calculated and compared with experimental data.

Temporal variations of nuclei decay parameters are actively searched now; their detection may be a signal of new physical effects of cosmic origin. Correlations of intensity of ⁶⁰Co, ⁵⁴Mn and ⁵⁵Fe weak decay parameters with solar activity, with solar flares, were observed. In our work, correlations of X-class solar flares with ⁶⁰Co and ⁵⁵Fe decay rate variations measured via decay γ-ray detection by semiconductor detectors. For ⁵⁵Fe decay the significant deviations of decay counting rate from the expected rate observed at the level -0.2% correlated with solar flares. For ⁶⁰Co decay four similar events were detected with deviations at a level of ~0.4%. All decay rate deviations start from 30 to 155 hours before solar flare moments at confidence level of 90%.

In the Experimental complex NEVOD (MEPhI, Moscow), the "Neutron" and PRISMA-36 facilities, consisting of unshielded neutron detectors, are being operated. The results of the analysis of two most powerful Forbush decreases detected at these facilities in the first half of 2024 are presented and compared with the Moscow neutron monitor data. The obtained dependence of the disturbance amplitude on the thickness of the substance above the detector is presented.

Theoretical estimates of the acceleration times of solar electrons and protons during the process of “magnetic detonation” — the development of eruptive flares — are made. The relationship between the acceleration rate and the energy of the first protons arriving in the Earth’s orbit is studied using the example of observations of four events in May–June 2024. Eruptive flares (proton and non-proton) can be classified by the electric field strength (by the time of electron acceleration to 100 keV and the moment of arrival of the first protons) and the duration of observation of electron radiation above 100 keV (the time available for proton acceleration >100 MeV).

We presented the results of observations of electrons of solar cosmic rays and hard X-ray radiation from solar flares in the first half of 2024 in experiments on CubeSat satellites with a low polar orbit (LEO, altitude ~550 km and inclination ~98°) using scientific instruments created at the SINP MSU.

We presented a brief overview of publications dedicated to observations of the Sun and other objects in the Universe in the submillimeter range of the electromagnetic spectrum. The main objective is to estimate the expected fluxes of solar flares in the terahertz range and to determine the classes of celestial bodies that could be potential sources of submillimeter waves. This data is necessary for developing scientific equipment that records spectral fluxes of terahertz radiation from astrophysical objects, with the aim of studying the mechanisms of energy release and acceleration of charged particles in the conditions of cosmic plasma.

The Baksan underground scintillation telescope is the sole detector in Russia dedicated to the observation of neutrinos from core-collapse supernovae. Candidates for neutrino events within the detector are identified as single triggers from individual counters. The background rate of single triggers from the internal planes is measured at 0.02 s^–1. A methodology is proposed for investigating the background of penetrating atmospheric single muons, which is based on the development of a geometric model of the detector.

The integral local muon density spectra (LMDS) of EAS at large zenith angles were reconstructed on the basis of the DECOR experimental data on muon bundles detected in a long-term measurement series from 03.05.2012 to 04.07.2023. The results were obtained for two threshold muon density values of 0.015 and 0.068 particles/m², corresponding to the detection of bundles with a multiplicity of at least 3 and at least 5 muons in the detector. At zenith angles less than 80°, the zenith-angle dependence of LMDS is well described by a power function of the zenith angle cosine. However, with a further increase in the zenith angle, this dependence changes significantly, and at angles of 87–88°, the measured values exceed the specified simple extrapolation by about an order of magnitude. This is due to the inapplicability of the flat atmosphere approximation at such angles. A simple formula has been obtained that takes into account the curvature of the Earth's atmosphere.

We discussed possible locations for the deployment of the TAIGA-100 gamma-ray observatory with a hybrid detector system on an area of about 100 km₂, which will make a significant contribution to solving many fundamental problems of cosmic ray physics and gamma-ray astronomy.

The two most powerful extensive air showers (EAS) with energies of about 10²⁰ eV, registered at the Yakutsk EAS array during the entire observation period of 1974–2024, are considered. Both showers hit the array near the center and triggered all surface detectors and underground muon detectors with a threshold energy of E_u = 1.0 · cos θ GeV. These events have an abnormally high fraction of muons, which is beyond current model predictions. This may change our understanding of hadron interactions at ultra-high energy, but there is also a possibility that these showers were initiated by some exotic primary particles.

Assuming cosmic rays at ultra-high energies being of extragalactic origin we discuss propagation of cosmic iron nuclei with energies above 10¹⁹ eV from their sources to the Galaxy. In extragalactic space cosmic nuclei interact with background emissions and inevitably fragment. We analyze the fraction of iron nuclei reaching the Earth and its energy dependence on distances from cosmic ray sources. It is obtained that energies of iron nuclei can be used to find restriction on the distances from their sources.

At the MSU EAS array the temporal distributions of particles in extensive air showers (EAS) with energies greater than 10¹⁴ eV were studied. Delayed particles were registered in 3.5% of EAS. The flash in the frequency rate of registration of delayed particles from 1986 to 1990 with a maximum of the registration frequency in 1987 and the fine structure of which at the decline of the flash, consisted of a series of bursts of quasi-periodic fading oscillations with an oscillation period of approximately 4 days and a burst duration of about 32 days, is discussed. At the same time, the EAS frequency registration rate in limits of statistical errors was unchanged.

The AVS-F catalogue contains several tens of GRBs, the one of NATALYA-2M consists of 6 objects (maximum photon energy ∼150 and ∼60 MeV, respectively). The Fermi/LAT catalogue contains more than 200 bursts in the range E > 100 MeV. Different behavior of the prompt emission time profiles is observed in the high and low energy ranges during some events with the presence of a high-energy spectral component. When using the parameter Rt (the ratio of the arrival time of photon with maximum energy to the duration of the burst) that does not require taking into account cosmological duration dilation, the following groups are distinguished among long bursts: (1) for ∼25% of GRBs the duration of high-energy emission is shorter than that of low-energy range; (2) for the remaining ∼75% the opposite situation is observed, but the maximum energy γ is detected during the low-energy prompt emission (2a) or after its completion (2b). The characteristics of GRBs with γ in the sub-TeV region are similar to types 2a and 2b, there is no significant correlation between their maximum energy and redshift.

Proposals for a new approach to the development of scientific equipment for the study of galactic and solar cosmic ray fluxes in the solar modulation energy range (30–1000 MeV/nucleon) with elementary charge and mass resolution are considered. It is proposed to place the equipment on the Russian space station ROS (project "Modulation") and on the international scientific lunar station MNLS (project "Moon–Modulation"), if it is created. The projects assume the creation of a database of galactic and solar cosmic rays (SCR) for the entire solar activity cycle. Such a database is necessary to improve numerical models of the fluxes of energetic heliospheric particles in interplanetary and near-Earth space.

We calculate the characteristics of the anisotropy of galactic cosmic rays formed by an electromagnetic mechanism. The mechanism is based on the combined action of the induction electric field and the regular magnetic field of the moving solar wind. For cosmic rays with an energy of 10 GeV, the following results were obtained: 1) vector anisotropy of 0.4 – 0.6% is directed perpendicular to the Earth-Sun line from west to east; 2) tensor anisotropy has the form of a biaxial ellipsoid, the minor axis of which is directed along the interplanetary magnetic field. The calculations correspond to the measurements.

We proposed to use new inexpensive specialized scintillators optimized for different types of particles in experiments of detecting extensive air showers. The scintillators developed in our laboratory are based on locally produced phosphors immersed in a compound — optically transparent silicone rubber, so we called them "silicone rubber-based scintillators". Some of the first versions of such scintillators are already successfully used to register thermal neutrons and cascade particles in a number of Extensive Air Showers arrays created with our participation. We show here preliminary results of the development of specialized scintillators of this type to record different particles: fast neutrons, muons, electrons and gamma rays.