Vol 83, No 5 (2019)

Results are presented for the first time from the PAMELA orbital experiment of 2006–2014. Observations record ²H isotopes with energies above ~50 MeV/nucleon and ³He isotopes with energies above ~90 MeV/nucleon in solar flares. Time-of-flight analysis of nuclei that have rigidities known from orbital experiments with the scintillation telescope of the PAMELA magnetic spectrometer is used for isotope selection, along with data on their ionization losses in the strip detectors of the tracker. The spectra of ¹Н and ⁴Не in solar cosmic rays are used in GEANT4 simulation of the ²H and ³Не nuclei generation in solar matter to assess the spatial scale of the region of isotope generation. Additional acceleration of the ²H and ³Не nuclei during flares is likely revealed.

Based on a study of two-dimensional solar flare distributions according to the intensity of soft X‑ray burst peaks and solar proton peaks, it is concluded that the heliolongitudinal dependence of solar proton peak intensity varies with solar cycles. GOES spacecraft data on X-ray bursts in the wavelength range of 0.1–0.8 nm and data on solar proton events with proton energies above 30 MeV are used. It is found that the heliolongitudinal reduction in the peak intensity of proton events in different cycles can differ by an order of magnitude. The reduction in the peak intensities of proton events after flares in the heliolongitudinal interval of 0–30 E relative to the peak intensities of proton events from flares on the western hemisphere of the Sun’s disk is 30 for solar cycle 23 and only 3 for solar cycle 22. The variation in the longitudinal dependence of solar proton peak intensities with solar cycles must be considered in all statistical studies of proton events.

The solar proton events of September 6 and 10, 2017, are studied using means developed earlier by the author. The results are compared to those obtained for events of January 27 and May 17, 2012. The start of microwave emission at 15.4 GHz is chosen as zero time for each parent solar flare. Intensities of protons (GOES) and electrons (SOHO EPHIN) are considered, relative to these zero times, along with the count rate of the anti-coincidence system of the spectrometer on board the INTEGRAL space platform (ACS SPI). The ACS SPI is used as a detector of hard X-ray (HXR) emission and relativistic protons. Electrons accelerated in the impulsive first phase of flares on September 6 and 10, 2017, were detected before protons. Protons and electrons, apparently accelerated in the second phase of the flare and later, are detected simultaneously in all of the events.

The global survey approach developed at the Institute of Cosmophysical Research and Aeronomy in 1960s allows us to use the worldwide network of neutron monitors as a common multidirectional device that enables us to obtain information on the distribution of cosmic rays (CRs) in interplanetary space for each measured moment in time. In analogy with this approach, this work presents a version of a new way of using measurement data from the worldwide network of muon telescope stations in Hobart, Kuwait, Nagoya, São Martinho, and Yakutsk. The reception characteristics of these stations are calculated with allowance for particle trajectories, the directional patterns of the devices, coupling coefficients, and the energy spectrum of hypothetical variations in CRs. At a later stage, the use and improvement of the approach will allow us to obtain new information about the dynamics of the CR distribution in distant regions of the heliosphere.

The influence of the global heliospheric current sheet on the heliospheric characteristics important for GCR propagation is considered, particularly the strong dependence of the solar wind velocity on the distance from the current sheet. A simple model of the solar wind velocity is proposed that, after estimating the parameters from observations, can be used for theoretical studies of GCR modulation. The choice of the GCR propagation model to be used for periods of low and medium sunspot activity is discussed.

Results are presented from an analysis of changes in the muon flux of cosmic rays during Forbush effects, recorded by the URAGAN muon hodoscope in the period 2012–2017 and the scintillation muon hodoscope in 2016–2017. Characteristics of the Forbush effects for this period are analyzed. The obtained characteristics of muon flux variations are compared to different parameters of the near heliosphere during the Forbush effects for the 11-year cycle of solar activity.

At the beginning of September 2017, the Sun was characterized by anomalously high solar activity (SA), which was unusual for the region of the minimum of the 11-year cycle. A great many powerful flares of the M- and X-classes were observed; these were accompanied by powerful coronal mass ejections (CMEs). These events caused strong magnetic storms on the Earth (the Kp index was as high as 8; the Dst index was <−140 nT). In this work, the effect these ejections had on the flux of cosmic rays (CRs) is considered using data from the URAGAN muon hodoscope at the Moscow Engineering Physics Institute. The study is based on an analysis of variations in the cosmic ray muon flux. Results are presented from processing flux intensity via flicker-noise spectroscopy in order to identify geoeffective disturbances of the Earth’s magnetosphere. A predictor that precedes by more than one day the emergence in near-Earth space of disturbances related to CME propagation is obtained.

The PAMELA and ARINA spectrometers installed on board the Resurs-DK1 spacecraft measure different components of the cosmic ray flux in a broad range of energies, including the interval from 30 MeV to tens of GeV, with high resolution during the period of June, 2006, to January, 2016. The results from these measurements allow us to obtain new information on the characteristics of variations in Galactic cosmic rays (GCRs), including their period, amplitude, and dependence on particle energy. This work presents the first preliminary results of this investigation, obtained via wavelet analysis of a temporal series of proton and helium nucleus fluxes.

The results are presented from an analysis of proton fluxes in the inner radiation belt (RB), obtained with the ARINA spectrometer. The ARINA satellite experiment was performed on board the Russian low-orbit spacecraft Resurs-DK1 (altitude 350–600 km; inclination 70°; duration, 2006–2016). The spectrometer registered high-energy protons (30–100 MeV) with an energy resolution of 10% and an angular resolution of 7°. The geographical and pitch-angle distribution of proton flux in the inner radiation belt (1.15 < L < 2.0) were analyzed during the waning phase of the 23rd solar cycle and main part of the 24th cycle. It is shown that the proton flux intensity depends on the phase of the solar cycle (the minimum intensity is observed in the period of the solar activity maximum and vice versa) and varies by 2–7 times for different L‑shells.

The PAMELA data reveals considerable flux differences between electrons and positrons trapped in the radiation belt. The ratio of fluxes of positrons and electrons in the inner radiation belt is found to diminish at lower energies. This contradicts models based on the interaction between cosmic radiation and residual atmospheric nuclei. The residual atmosphere density in the trapping region at L ~ 1.15−1.25 is estimated separately for electrons and positrons by simulating the trajectories of trapped particles in the magnetosphere of the Earth. Calculations show that the processes of interaction between trapped electrons and positrons and residual atmospheric nuclei, which result in the production of δ-electrons, contribute appreciably to the fluxes of these particles.

Soft gamma radiation that appears in the atmosphere as part of secondary cosmic rays has so far been studied very poorly. Observations with a gamma-ray detector designed at the Polar Geophysical Institute began in 2010 at cosmic-ray stations in Apatity and Barentsburg (in the Spitsbergen Archipelago). Observations are now being made at six stations. Two types of variation, annual and daily, are reliably observed in the data obtained with the detectors. The annual variation is associated with the formation of a stable snow cover during the cold season. The daily variation has a specific feature: the positions of its maximum and minimum differ from the analogous quantities in neutron monitors and muon detectors.

Several detectors have been integrated into a single system for monitoring the electromagnetic component of secondary cosmic rays (SCRs) at the Cosmic Ray Laboratory of the Polar Geophysical Institute (Apatity). The system includes a differential gamma-ray spectrum detector based on a NaI(Tl) crystal. One gamma-ray spectrum is collected in 30 min. The energy range is 0.2–8 MeV. It should be noted that like other detectors, the spectrometer was precalibrated using known lines. Background gamma radiation increases during precipitation. More than 1500 such events have been detected since the detector became operational. A number of long-term measurements have been made thus far, which make it possible to study in detail the energy parameters of increase events. The main aim of the study is to compare the characteristics between the spectra in clear weather and under different types of precipitation. Particular attention is given to radiation analysis of samples collected during the rain. The results show there is no pollution of water with radionuclides. It is concluded that the observed effect is due to purely atmospheric effects. A preliminary interpretation of the phenomenon is the creation of a model for the acceleration of charged particles of SCRs in the electromagnetic fields of nonthunderstorm rain clouds. The results from calculations are presented, and their consistency with the experimental data is shown.

A hardware and software system created at the Lebedev Physical Institute and featuring neutron detectors based on SNM-18 neutron counters is described. Its characteristics and the results from a preliminary analysis of data obtained in terrestrial measurements of neutron fluxes in the period 2015–2018 are presented.

Temperature coefficients for muons in the atmosphere are estimated from results from continuous observations of muon intensity, recorded at sea level at different zenith angles, and aerologic sounding data. Obtained results are compared with ones from theoretical calculations performed earlier.

The GAMMA-400 space project is one of the new generation of space observatories designed to search for signs of dark matter in the cosmic gamma emission, and to measure the characteristics of diffuse gamma-ray emission and gamma-rays from the Sun during periods of solar activity; gamma-ray bursts; extended and point gamma-ray sources; and electron, positron, and cosmic-ray nuclei fluxes with energies in the TeV ranges. The GAMMA-400 γ-ray telescope constitutes the core of the scientific instrumentation. The nature of the intended experiments imposes stringent requirements on the gamma telescope’s system of trigger signal formation, now being developed using the state-of-the-art logic devices and fast data links. The design concept of the system is discussed, along with the chosen engineering solutions and some experimental results obtained during the operation of the system prototype using a positron beam with energies of 100–300 MeV from the PAKHRA S-25R synchrotron at the Lebedev Physical Institute.

The mass composition of primary cosmic rays remains an unresolved problem of physics in the region of energies above the knee. Results from different experiments are contradictory in assessments of the mean mass number and its variation as the primary energy grows. The PRISMA project is designed to study the energy spectrum and mass composition of cosmic rays at energies of 10¹⁵–10¹⁷ eV. The project is based on a detector capable of simultaneously detecting the electromagnetic and hadron components of a shower. The results are presented from measurements with the PRISMA-YBJ prototype located at 4300 m a.s.l., made over 3.5 years of operation. A new way of estimating the average mass composition from the electron/neutron ratio is tested.

The aims and scientific tasks of the space High-Energy Ray Observatory experiment are determined. The design of the scientific equipment is described. It is characterized by an unprecedently high geometric factor (~20 m² sr) and fairly high accuracy of measurement. The performance of the equipment allows precise study of cosmic rays in a wide range of energies, including the completely unstudied region of 10¹⁵–10¹⁶ eV. The current status of the space experiment is determined.

The Baksan Underground Scintillation Telescope (BUST) is located in the North Caucasus in an underground laboratory at an effective depth of 850 m.w.e. The BUST began working in 1977, and the installation is still in operation. The successful design of the BUST allows it to be used to solve a number of problems in astrophysics and particle physics. The new data acquisition system is designed to record and analyze experimental data with greatly improved measurement characteristics of digital and analog signals. The data acquisition system is based on the VME interface and provides complete compatibility with existing low-level BUST recording electronics. The hodoscope of pulse channels was completely redeveloped and implemented on field-programmed gate array (FPGA) and LVDS chips.

A way of eliminating diurnal variations in muon fluxes for matrix observations of the URAGAN hodoscope (MEPhI) is proposed, based on a matrix digital two-dimensional low-pass filter. Its structure is developed on the basis of matrix elementwise multiplications. Diurnal variations in the muon fluxes for the sequence of matrix observations of the Uragan hodoscope are eliminated.