11-year and 22-year variations in the anisotropy of galactic cosmic rays

An 11-year modulation of the electric drift anisotropy directed across the force lines of the interplanetary magnetic field and a 22-year modulation of the magnetic drift anisotropy along the interplanetary magnetic field have been found on the basis of the data of the Yakutsk underground complex of muon telescopes. Some specific features of the anisotropy during the pole reversal of the total solar magnetic field are discussed.     

Studying semidiurnal variations in galactic cosmic rays

Seasonal changes in the semidiurnal variation of cosmic rays and their changes with the level of solar activity are discovered as a result of the long-term recording of cosmic rays by the spectrograph in Yakutsk (62°01′ N, 129°43′ E) and multidirectional muon telescope at Nagoya (35°10′ N, 136°58′ E). Seasonal changes are simulated using mechanisms proposed earlier by the authors.     

New method for estimating the absolute flux and energy spectrum of solar cosmic rays based on neutron-monitor data

A new method is described for estimating the absolute flux of solar cosmic rays based on the data from a single neutron monitor. The method is capable of yielding the energy spectrum at the isotropic phase of a solar flare using the available data from the currently operable worldwide network of cosmic-ray stations. The method is based on the determination of the effective momentum or energy for which the particle flux derived from the neutron-monitor count rate is weakly sensitive to small variations in the exponent of the power-law spectrum. A comparison of the calculations with direct space-borne measurements and calculations by other authors based on the data from the neutron-monitor network shows their satisfactory agreement for the last ground-level enhancement of solar cosmic rays observed on December 13, 2006.     

Energy Dissipation in a Medium with Turbulent Viscosity and the Hill Vortex

Doklady Physics - A new approach to calculation of the dissipation of mechanical energy in a medium with turbulent viscosity based on determination of the velocity-shear modulus is proposed. As an...     

Beam of Ultrarelativistic Particles and Cherenkov Resonance

Earlier, we reported on registration of three sequential events with energies greater than 10¹⁹ eV with two installations of EAS (Yakutsk and Telescope Arrays) for one day. Here we take into account that a moving relativistic source creates a particle beam due to the Cherenkov effect. In this case, with a certain orientation of the direction of movement of the source relative to the observer and direction of the interstellar magnetic field, there is a mechanism that allows to explain the observed sequence of the recorded events.

     

Variation of the cosmic ray intensity in an 11-yr solar activity cycle: Experiment and theory

To study long-term variations of the cosmic ray intensity in a wide energy range, a basic model of the modulation of cosmic rays in the heliosphere has been developed at the Institute of Cosmophysical Research and Aeronomy, Siberian Branch, Russian Academy of Sciences. The model involves only one free modulation parameter, the ratio of the regular magnetic field to the turbulent field. It can be used to describe variations of the cosmic ray intensity in a wide energy range of 0.1 to 100 GeV. Attempts have been made to most correctly describe the features of the behavior of the cosmic ray intensity in several solar activity cycles.     

Heliospheric modulation of high-energy cosmic rays: II. Deformation of the neutral surface

Analysis of neutron monitor data in the periods of negative and positive polarities of the general solar magnetic field has revealed a dependence of the long-term cosmic-ray modulation on both deformation of the neutral surface of the interplanetary magnetic field and solar activity level. The effects of solar activity and neutral surface deformation dominate at positive and negative polarities, respectively. The magnetic drift of cosmic rays with different trajectories in the epochs of positive and negative polarities is responsible for this behavior of the 11-year and annual density modulations.     

Heliospheric modulation of high-energy cosmic rays: I. Basic model of cosmic-ray modulation with solar cycle

We have constructed a greatly simplified theory for the heliospheric modulation of high-energy cosmic rays in which no adjustable parameters are used. The only parameter k, which characterizes the degree of regularity of the interplanetary magnetic field, varies in the model in a definite way with solar cycle phase. The approximations used lead to solutions expressed in terms of elementary functions. The role of the magnetic drift of particles has been revealed. Quantitative agreement with the observed cosmic-ray variations has been achieved.