Vol 87, No 7 (2023)

Using PAMELA flight data for 2006–2014 on the rigidity of detected nuclei and their velocity (time-of-flight analysis and ionization losses in the multilayer calorimeter of the device), a new analysis of the isotopic composition of Li and Be nuclei in the rigidity range 1–5 GV (nuclear energies 0.1–1.5 GeV/nucleon) was carried out. The new PAMELA data expand the energy range of previous measurements, are consistent with the few existing measurements, and indicate correlated deviations of Li and Be isotope ratios from the GALPROP data for GCRs, which can be interpreted as evidence of the observation of contributions from several nearby local sources against the GCR background. The analysis of precision AMS-02 data on the spectra of positrons, antiprotons, secondary nuclei Li, Be, and B, also carried out in this work, indicates correlated increases in intensity at rigidities of ~50–1000 GV, which could be associated with local sources as well. We estimate the contribution of local sources against the GCR background at the level of tens of percent for rigidities of 1–5 GV and at the level of a few percent for rigidities of 50–1000 GV.

During the processing of the data obtained in the space experiment NUCLEON, results were obtained that were of significant astrophysical importance. Using the GALPROP package, the inverse problem of the propagation of cosmic rays from the source (close Supernovae) to the observer was solved, a component spectrum was calculated at the source. It was shown that a systematic change in the power index (slope of the spectrum) was observed at the source, which can be interpreted as incomplete ionization of cosmic rays now of acceleration at the front of the supernova shock wave. Magnetic rigidity spectra analysis was applied for nitrogen nuclei fluxes and the total spectrum of rare nuclei with odd charges from 9 to 19 (F, Na, Al, P, Cl, K). Ratios of odd and even nuclei fluxes are calculated. It turned out that the spectrum of rare, odd nuclei is more rigid than the spectrum of abundant even nuclei (Z = 10–20) at the magnetic rigidity area 300–10 000 GV.

We discuss new scenario of the formation of the observed spectra of electrons/positrons and nuclei of ultrahigh-energy cosmic rays in the framework of the nonclassical (superdiffusion) model of particles propagation in a highly inhomogeneous interstellar and intergalactic media. It is shown that the proposed scenario provides a consistent description of the experimental data of precision satellite measurements, ground-based hybrid EAS arrays and Cherenkov telescopes on the spectra of leptons and nuclei, as well as the mass composition of cosmic rays in the range of super-high and ultrahigh energies.

We studied how the process of self-modulation of cosmic rays, occurring upon their penetration into dense molecular clouds, affects the total gamma-ray emission of the Galaxy. We estimated how the self-modulation modifies the emission from each individual cloud and integrate the results along the line of sight for a given area in the sky. Our calculations show that the self-modulation reduces the total intensity of gamma-ray emission below 1 GeV by about 10–30%. Even though the magnitude of the effect is not large, it still can substantially affect the background gamma-ray emission at low energies.

The Tunka-Grande scintillation array is described. The scientific results obtained during the first 5 years of its operation are presented. The prospects for studying cosmic rays in the energy range 10¹⁶–10¹⁸ eV are discussed.

We studied the spectrum of gamma-rays from the Crab Nebula in the energy range of 4–100 TeV, obtained from the data of two atmospheric Cherenkov telescopes, as part of the TAIGA complex. We described a technique for selection and reconstruction of gamma-rays energy, including a procedure for reconstruction the energy spectrum.

Results of measurements of the energy characteristics of muon bundles in inclined extensive air showers in the NEVOD-DECOR experiment are presented. Estimates of the average energy of muons in the bundles in the energy range of primary particles from 10 to 1000 PeV were obtained and compared with the calculated expected values for various assumptions about the composition of cosmic radiation and models of hadronic interactions. An excess of experimental values of the average muon energy in comparison with calculations for high local densities corresponding to energies of primary particles above 100 PeV was found.

The main goal of the Baikal-GVD deep-sea neutrino telescope is to detect high-energy neutrinos of astrophysical origin by reconstruction of muon tracks or showers of particles generated in interactions of neutrino with water. Since September 2020, Baikal-GVD has been monitoring IceCube telescope alerts about detection of neutrinos with the energy over 100 TeV. When follow-up analysis is carried out in real time, the delay between an IceCube notification and Baikal-GVD analysis does not exceed three minutes. The fast follow-up is complemented by an offline search for coincidences in time intervals of ±1 and ±12 h with refinement of event’s reconstruction. In the absence of a coincidence or in a case of a single coincidence, the value of expected background is calculated and upper limits on the neutrino flux are set.

The status of the Baksan Large Neutrino Telescope project and some selective results of the first stage of the project, namely a prototype detector with a liquid scintillator mass of 0.5 tons are described. The results of the second stage of the project, a prototype with a liquid scintillator mass of 5 tons, and the prospects for the project are discussed.

The characteristics of Forbush decreases (FDs) and solar energetic particle (SEP) events driven by the same solar sources (i.e. coronal mass ejection and associated solar flare) are investigated. The part of the solar disk (E04–W35) was chosen in which most of the solar events lead both to an FD and SEP event at Earth. SEPs for different energies (E > 10, >100 MeV, and ground level enhancements) and with different flux thresholds were considered independently. The obtained results were compared with the control group of solar events that had solar sources within the same longitudinal zone but did not lead to any SEPs. It is shown that coronal mass ejections (CMEs) followed by SEPs have a very high probability to create a large FD in the Earth’s orbit and further to cause a geomagnetic storm. It is also obtained that the accelerative and modulating efficiencies of such driving solar events are well correlated; this can be explained mostly by high solar wind speeds of the corresponding CMEs.

We presented the preliminary results of the search for helium nuclei in solar energetic events measured in the PAMELA experiment in the rigidity range from 0.1 to 1 GV from 2006 to 2014. We constructed selection criteria for helium nuclei and estimated their efficiency. The spectra are approximated using a simple power-law function and functional form based on Ellison-Ramaty, consisting of a power-law spectrum modulated by an exponential.

The proton event of October 28, 2021, which was accompanied by the first in the current 25th cycle and the 73rd in the history of observations, a ground-based enhancement in the intensity of cosmic rays (GLE73), is considered. The development of the parent flare lasted more than 10 min against the background of the highest energy release simultaneously creating the conditions both for acceleration of the coronal mass ejection (CME) and acceleration of charged particles to relativistic energies. The similarity of time intensity profiles of relativistic electrons and protons in the Earth’s orbit indicates a stochastic mechanism of their acceleration. The X1.0 eruptive flare on October 28, 2021, is similar in hard X-ray emission to the M5.1 flare on May 17, 2012 (GLE71). The relatively late start of the increase in the fluxes of relativistic electrons and protons in the Earth’s orbit compared to the GLE71 event is explained by the location of the flare on October 28, 2021 (S26W05) and the southward launch of the CME.

To study the solar modulation of cosmic-ray fluxes below 1 GeV, machine learning methods allowed obtaining the flux ratios of positrons and electrons with energies from 100 to 500 MeV, and the fluxes of electrons and protons with 1–1.7 GV rigidities from the PAMELA experiment for 2006–2016. The observed features of the data obtained and its comparison with the AMS-02 experimental data enable researching the charge-sign dependence of the modulation around the solar minimum in 2009 and the maximum in 2015.

We presented a new method of the neutron monitors’ (NM’s) effective energy estimation based on the 27‑day galactic cosmic rays (GCR) variations: using AMS-02 measurements we study rigidity dependance of 27-day variations’ amplitude and calculate the energy value so that the variability of the GCR particles at this energy is equal to that of the NM’s count rate. We examined how NM’s effective energy depends on the geomagnetic cutoff rigidity using data of several NM.

In the LVD experiment (Gran Sasso, Italy), variations in the counting rate of detector background pulses associated with the injection of radon from the rock into the experimental hall are studied. We present dependences of changes in atmospheric pressure on the surface and in the experimental hall of the setup, as well as variations in the counting rate of LVD events associated with changes in radon concentration.

Based on the data from the global network of neutron monitors, by using the spectrographic global survey, we obtained the parameters of magnetospheric current systems in the 1998 May events. Within the axisymmetric model for the bounded Earth magnetosphere, we determined the DR (ring current) and DCF (magnetopause currents) parameters for the current systems, as well as their contribution to variations in the rigidity of the geomagnetic cutoff and to the Dst-index over the addressed period.