N. S. Khaerdinov

Modernization of the Carpet-2 array of the Baksan Neutrino Observatory

The state of the art and the project of modernization of the extensive-air-shower array Carpet-2 of the Baksan Neutrino Observatory of the Institute for Nuclear Research, Russian Academy of Sciences are described. The modernized array will allow the performance of detailed study of variations in the cosmic ray intensity, the energy spectra and composition of primary cosmic rays in the energy range 1013–1016 eV, and the anisotropy of primary cosmic rays with energies above 1013 eV.

Experimental search for gamma-ray bursts from evaporating primordial black holes

The energy spectra and temporal characteristics of high-energy gamma-ray bursts from evaporating primordial black holes have been calculated using various evaporation models. The currently existing theoretical uncertainties in the shape of the evaporated photon spectrum are discussed. The data from the Andyrchy and Carpet-2 arrays of the Baksan Neutrino Observatory (Institute for Nuclear Research, Russian Academy of Sciences) obtained in the mode of detection of a single cosmic-ray component are used to search for cosmic gamma-ray bursts with a primary photon energy of about 8 GeV. New upper limits have been obtained for the number density of evaporating black holes in a local region of space with a characteristic size of ∼10−3 pc for various evaporation models.

Strong variations of cosmic ray muons during thunderstorms

Experimental data about a strong decrease of the intensity of cosmic ray muons are presented. The event occurred during a thunderstorm on September 24, 2007 in Baksan Valley (North Caucasus). The threshold energy of muons is 100 MeV. In comparison with other events of this type detected previously, this event is remarkable by a longer duration (more than an hour and a half) and by the fact that well-pronounced correlations with lightning strokes are observed for the first time.

Dynamics of cosmic rays in the atmospheric electrostatic field and production of particles by thunderclouds

Acceleration of particles in the atmospheric electrostatic field is considered taking into account multiple elastic scattering. The critical field strength necessary for implementing runaway effect of charged particles under different initial conditions is analytically obtained. The process of cyclic particle production in strong thunderstorm fields is considered. It is shown that this mechanism can be used to describe the strong increases (sometimes with exponential segments) observed during thunderstorms in the intensity of the soft component.

Effect of the Near-Earth Electric Field on the Intensity of the Soft Component of Cosmic Rays

The transformation of the energy spectrum of the electron-positron component of cosmic rays in the energy range 10–100 MeV in the near-Earth electric field of thunderstorm atmosphere has been estimated analytically by solving the kinetic equation for secondary cosmic rays in the one-dimensional case. The solution obtained adequately describes the observed variations in the soft component in moderate electric fields (±7 kV m−1).

Variations in cosmic rays during thunderstorms and new geophysical effects

Processes that occur during thunderstorms accompanied by anomalous disturbances in cosmic rays are comprehensively investigated using the Carpet air shower array at the Baksan Neutrino Observatory. The data collected so far indicate the discovery of a new type of electric discharge: runaway electron break-down in the near-threshold regime. A glow in the stratosphere corresponding to this discharge is detected, as is stabilization of geomagnetic micro-pulsations. Both are demonstrated using one event as an example.

Comprehensive study of energetic particle processes in thunderclouds

In the course of an experiment studying variations of cosmic rays during thunderstorms at the Baksan Neutrino Observatory evidence has been obtained in favor of existence of a new type of large-scale electric discharge in thunderstorm atmosphere: a slow runaway electron breakdown in the near-threshold regime. Continuous glow of the stratosphere region above thunderclouds is discovered, correlating with anomalous disturbances in intensity of secondary cosmic rays detected on the ground.

Limiting Transformation of the Equilibrium Spectrum of Electrons and Photons in Strong Electric Fields of Thunderclouds

The upper limit of transformation of the equilibrium electron-photon spectrum (E > 10 MeV) is obtained for the case of strong fields by solving the one-dimensional kinetic equation. Comparison with the experimental data from the Carpet array at the Baksan Neutrino Observatory (Institute for Nuclear Research, Russian Academy of Sciences) shows that variations in the intensity of the electron-photon component are observed during thunderstorms, which cannot be explained only by transformation of the spectrum in strong thunderstorm fields. One has to hypothesize some process of particle production in the energy range below ∼30 MeV.

Thunderstorm effects according to data from a comprehensive study of variations in secondary cosmic ray particles

Thunderstorms have been studied at the Baksan Neutrino Observatory (Institute for Nuclear Research, Russian Academy of Sciences) since the summer of 2013 using a measuring instrumentation complex. During the period of observation, three events of continuous night-sky airglow correlating with the disturbances in the flux of energetic particles have been recorded during thunderstorms. It is established that there is interaction between a thunderstorm’s front and the precipitation of protons from the Earth’s radiation belt into the atmosphere due to seismic activity.

A method of determining basic thunderstorm field parameters from variations of cosmic ray muons detected by a horizontal array

An array of scintillators tightly packed in the horizontal plane and designed for recording secondary particles produced by cosmic rays is capable of probing the angular dependence of intensity disturbances caused by electric fields of a thunderstorm atmosphere. The basic parameters of thunderstorm activity are estimated using a specific example of variation in intensity in different ranges of energy release in the detectors. These parameters include the characteristic radius of the active region (5 km), its total charge (30 C), the accumulated electric field energy (6 GJ), and the potential difference in the stratosphere above the active thunderstorm region (375 MV).