Combined mechanisms of solar cosmic ray acceleration

Spectra of solar cosmic rays on the Sun’s surface at a flare site and near Earth are modeled using the Monte Carlo method. Two of the most important mechanisms of energy accumulation by the particles are considered simultaneously: the regular acceleration of ions by the impulsive electric field of the current sheet and stochastic acceleration by the Alfvenic turbulence. This leads to substantial variations in the particle spectra in the low-energy region.     

Passive longitudes of solar cosmic ray sources

Solar proton events during the period from 1956 to 2012 are considered. Fluences of protons of various energies in these events are computed. On the basis of these data, the inhomogeneity observed in our earlier studies of the distribution of their sources on the Sun along the Carrington longitude is confirmed. Special attention is given to the extensive interval of passive longitudes discovered between ≈90°–170° over the period of observations. The summed proton fluence of the events whose sources lie in this interval of Carrington longitudes is considerably lower than the summed proton fluences of events in other heliolongitude intervals. Of the 60 most powerful solar proton events observed during the period of observations, no more than 1 event originated from this interval of passive longitudes.     

On the characteristics of solar activity and galactic cosmic ray intensity at the solar cycle maximum and inflection points

The correlation between the characteristics (sunspot area and galactic cosmic ray intensity) at inflection points and at the solar cycle maximum is discussed. Probable characteristics in the forthcoming maximum of cycle 24 are considered.     

Ultimate ground level enhancements of solar cosmic ray intensity

Possible values of ground level enhancements (GLEs) of the intensity of solar cosmic rays (SCRs) that can be recorded by neutron monitors (NMs) are estimated in two different ways for the ultimate spectra of solar protons. The first approach uses the statistical dependence between the maximum values of the integral proton flux >100 МeV and the GLE recorded by an NM. The second is to calculate the expected effect for the ultimate spectrum at a particular NM with known couple coefficients, atmospheric depth, and the threshold of the geomagnetic cutoff. Estimates using the first method vary from 9600 to 160000% for high-latitude NMs; estimates using the second method, from 1200 to 750000%. The obtained lower limits approximately correspond to GLE values observed earlier, and the upper limits are two orders of magnitude higher. Studies of the possible impact of solar proton events with spectra close to ultimate on the Earth’s atmosphere and biosphere should be continued.     

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.     

Decay phase of energetic electrons and protons in solar cosmic ray events

The decay phase of solar energetic particle (proton and electron) events is considered. The propagation mechanisms for particles of different kind may differ in the same events, which should manifest itself in the pecularities of their decay phases. To compare the propagation parameters of protons and electrons, we used the data of simultaneous measurements of few-MeV proton and few-hundred-keV electron fluxes from IMP-8 CPME and SOHO COSTEP. Nearly half of clear-shaped simultaneously measured electron and proton decays have similar character (exponential or power-law), suggesting that at least in a part of events electrons can be subjected to the same propagation mechanisms as protons.     

Induction mechanism of cosmic ray production and kinks in the cosmic ray spectrum

Two kinks are observed in the energy spectrum of galactic cosmic rays. It is shown that the entire spectrum can be described, to a good approximation, by a single formula obtained on the basis of the hypothesis that the particles are produced and accelerated in plasma pinches by an induction mechanism under the assumption that three hierarchical groups of currents are present—interstellar, galactic, and metagalactic. Pis’ma Zh. éksp. Teor. Fiz. 64, No. 4, 225–230 (25 August 1996)     

On the formation of spot and magnetic cycles in the galactic cosmic ray intensity in the minima of solar activity

The problems of the determination and separation of variations in the galactic cosmic ray intensity, caused by the spot-forming activity and polarity of high-latitude solar magnetic fields, are discussed. Based on the solution of the boundary-value problem, some features in the intensity formation at solar cycle minima are formulated.     

宇宙射线和α放射线的地质作用

对采集到的矿物样品结合理论计算结果进行了详细分析.阐明了矿物样品上的菱形腐蚀坑,可能是宇宙射线粒子和天然放射线中的α粒子与矿物晶格碰撞后,在晶格中留下的损伤经过地层中腐蚀性液体长期腐蚀扩大形成的.讨论了这些腐蚀坑对地质作用的影响.指出这些射线对地质作用的影响,应当是地质作用研究中不可忽视的因素.     

Primary cosmic ray flux

We discuss the primary cosmic ray flux from the point of view of particle interactions and production of atmospheric neutrinos. The overall normalization of the cosmic ray flux and its time variations and site dependence are major ingredients of the atmospheric neutrino predictions and the basis for the derivation of the neutrino oscillation parameters.     

Model of cosmic ray generation

It is shown that the two bends observed in the cosmic ray energy spectrum can be well approximated by equations derived by assuming that cosmic rays can be generated and accelerated in plasma pinches. Zh. éksp. Teor. Fiz. 111, 385–403 (February 1997)     

Long-period variations in the characteristics of frontal zones in the north Atlantic and their relation to solar activity and cosmic ray variations

The oscillations of the temperature gradients with the periods of ～10 and ～22 years have been detected in the Arctic frontal zone near the Greenland coasts. It has been shown that geomagnetic activity and the rate of variations in the GCR flux in the 11-year solar cycle are the main factors affecting the temperature contrasts in the frontal zone. It has been noted that the detected variations in the frontal zone temperature characteristics are important for the formation of the solar activity effects on the intensity of extratropical cyclogenesis.     

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.     

宇宙线研究进展评述与展望

近年来,宇宙线探测技术发展迅速,天基和地基宇宙线实验均取得了多项重要成果,打破了宇宙线研究领域多年来的沉寂．多手段复合观测是精确测量宇宙线能谱和成分的必要途径,甚高能伽玛射线天文学成为探索宇宙线起源这一世纪之谜的最有效手段．高海拔宇宙线观测站(LHAASO)计划将以最高的超高能伽玛射线探测灵敏度和甚高能伽玛射线巡天灵敏度以及最宽的宇宙线能量覆盖范围探索领域的基本问题．     

宇宙线研究进展评述与展望

近年来,宇宙线探测技术发展迅速,天基和地基宇宙线实验均取得了多项重要成果,打破了宇宙线研究领域多年来的沉寂.多手段复合观测是精确测量宇宙线能谱和成分的必要途径,甚高能伽玛射线天文学成为探索宇宙线起源这一世纪之谜的最有效手段.高海拔宇宙线观测站(LHAASO)计划将以最高的超高能伽玛射线探测灵敏度和甚高能伽玛射线巡天灵敏度以及最宽的宇宙线能量覆盖范围探索领域的基本问题.     

Stationary cosmic jets as accelerators of ultrarelativistic cosmic ray particles

A model of a cosmic jet working in the mode of a magnetohydrodynamic nozzle and unipolar inductor is considered. It is shown that the “solid-state” rotation of screw magnetic field lines leads to acceleration of small fractions of plasma particles up to ultrarelativistic energies with the spectrum dq/d? ～ ? ^?n , the exponent n being close to the experimental value.     

Multiscaling of galactic cosmic ray flux

Multiscaling analysis of the differential flux dissipation rate of galactic cosmic rays (carbon nuclei) is performed in the energy ranges 56.3-73.4 MeV/nucleon and 183.1-198.7 MeV/nucleon, using the data collected by the ACE/CRIS spacecraft instrument for the year 2000. The analysis reveals strong (turbulencelike) intermittency of the flux dissipation rate for short-term intervals: 1-30 h. It is also found that the type of intermittency can be different in different energy ranges.     

Identification of the primary cosmic ray

The nature of the primary particle giving rise to an atmospheric shower may be, to some extent, inferred from the observable properties: longitudinal profile (especially position of the maximum of the number of charged particles) or shape at ground level (lateral distribution, curvature and thickness of the shower front, muonic component). Distinguishing different nuclei cannot be performed unambiguously on a single shower, because of the random fluctuations in the first steps of the cascade; however, it is possible to study the composition of the incident flux on a statistical basis: showers from heavier nuclei have a faster development, and contain more muons. The uncertainties on the hadronic interactions at the highest energies limit the reliability of the identification. Other primaries, if they exist, could be easier to distinguish. Photons would give a slower development than protons, especially at highest energies, and a very reduced muonic component; neutrinos would be characterized by deep interactions in the atmosphere, or even within the Earth, giving almost horizontal showers with a large electromagnetic component, clearly different from the muonic tail of showers induced in the upper atmosphere by nuclei. Such ‘exotic’ primaries have not yet been observed. To cite this article: P. Billoir, P. Sommers, C. R. Physique 5 (2004).     

Application of student’s criterion for detecting ground level enhancements of solar cosmic ray intensity

Student’s criterion is used to detect ground level enhancements of solar cosmic ray intensity at middle latitudes. Application of this test to the data recorded by Alma-Ata high-altitude neutron monitor made it possible to detect the arrival of solar-origin relativistic particles on November 6, 1997 and August 24, 1998.