Variations in the cosmic-ray rigidity spectrum during events of January 2005

Variations in the cosmic-ray (CR) rigidity spectrum during events of January 2005 have been investigated on the basis of the ground-based observations of the CR intensity performed at the world network of stations using spectrographic global survey. The parameters of the CR rigidity spectrum reflecting the electromagnetic characteristics of heliospheric fields during the events under study have been determined in the combined analysis of ground-based and satellite measurements of protons with energies from several megaelectronvolts to several tens of gigoelectronvolts. The CR variations in a wide energy range are explained on the basis of the analysis performed.     

Effect of primary nuclei composition on the response functions for cosmic-ray muons

Summary The integral response functions for cosmic-ray muons, at different muon threshold energies, are calculated by taking into account the nuclear composition of the primary cosmic radiation, and showing their contribution also at large zenith angles.

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Riassunto Sono state calcolate le funzioni di risposta dei muoni della radiazione cosmica per differenti energie di soglia, introducendo la composizione nucleare della radiazione cosmica primaria e valutando il suo contributo anche a grandi angoli zenitali.

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Резуме Вычисллутся функции интегрального отклика для муонов космического излучения при различных пороговых энергиях муонов, учитывая ядерний состав первичного космического излучения и оценивая их вклад при вольших зенитных углах.

     

Effect of limiting polarization in the Jovian inner magnetosphere

Jovian decameter emission is known to exhibit almost total polarization. We consider the elliptical polarization to be a consequence of linear-mode coupling in the Jovian magnetosphere outside the source region. We determine conditions of emission propagation along the ray path that are necessary for self-consistent explanatation of the polarization observations and show that the ellipticity (axial ratio of the polarization ellipse) is determined by the magnetospheric plasma density n_e in a small region a distance of about half the Jovian radius from the radiation source. The plasma density in the region is quite low, n_e<0.4 cm⁻³, and the geometrical-optics approximation of emssion propagation in front of the region converts to the vacuum approximation behind it. The latter means that the linear-mode coupling in the Jovian inner magnetosphere is manifested as the effect of limiting polarization. Sources of decameter emission emitting at different frequencies f are located at heights corresponding to gyrofrequency levels f _Be ≅f and at magnetic-force lines that belong to L-shells passing through the satellite Io. The location of the transitional region in the Jovian magnetosphere varies depending on the emission frequency and the time. For each given decameter radio emission storm occupying some region in frequencytime space, we have a number of transitional regions located in a certain region of the Jovian magnetosphere—the interaction region of the magnetosphere (IRM) for the given emission storm. The distribution of magnetospheric plasma in an IRM is found from data of observations of the polarization ellipiicity of the given decameter radio emission storm. By matching the calculated ellipticity of emission with the observed ellipticity at every point of frequency-time space of the emission dynamic spectrum one finds a recurrent relation between the local values of the magnetospheric plasma density N_c and the planetary magnetic field B in the IRM, which allows evaluation of the distribution of plasma density if a definite model of the Jovian magnetic field has been adopted. Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia; Space Research Institute, Austrian Academy of Sciences, Austria. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 41, No. 2, pp. 177–193, February, 1998.     

Dark matter,neutrino mass,cutoff for cosmic-ray neutrino,and the Higgs boson invisible decay from a neutrino portal interaction

We study an effective theory beyond the standard model(SM) where either of the two additional gauge singlets, a Majorana fermion and a real scalar, constitutes all or some fraction of dark matter. In particular, we focus on the masses of the two singlets in the range of O(10) MeV-O(10) GeV with a neutrino portal interaction, which plays an important role not only in particle physics but also in cosmology and astronomy. We point out that the thermal dark matter abundance can be explained by(co-)annihilation, where the dark matter with a mass greater than 2 GeV can be tested in future lepton colliders, CEPC, ILC, FCC-ee and CLIC, in the light of the Higgs boson invisible decay. When the gauge singlets are lighter than O(100) MeV, the interaction can affect the neutrino propagation in the universe due to its annihilation with cosmic background neutrino into the gauge singlets. Although in this case it can not be the dominant dark matter, the singlets are produced by the invisible decay of the Higgs boson at such a rate which is fully within reach of future lepton colliders. In particular, a high energy cutoff of cosmic-ray neutrino,which may account for the non-detection of Greisen-Zatsepin-Kuzmin(GZK) neutrino or the non-observation of the Glashow resonance, can be set. Interestingly, given the cutoff and the mass(range) of WIMPs, a neutrino mass can be"measured" kinematically.     

Effect of upflowing field-aligned electron beams on the electron cyclotron waves in the auroral magnetosphere

The role of low density upflowing field-aligned electron beams (FEBs) on the growth rate of the electron cyclotron waves at the frequencies ω _r < Ω_e, propagating downward in the direction of the Earth’s magnetic field, has been analysed in the auroral region at ω _e/Ω_e < 1 where ω _e is the plasma frequency and Ω_e is the gyrofrequency. The FEBs with low to high energy (E _b) but with low temperature (T _‖b) have no effect on these waves. The FEBs with E _b < 1 keV and T _‖b (> 1.5 keV) have been found to have significant effect on the growth rate. Analysis has revealed that it is mainly the T _‖b which inhibits the growth rate (magnitude) and the range of frequency (bandwidth) of the instability mainly in the higher frequency spectrum. The inhibition in the growth rate and bandwidth increases with increase in T _‖b. The FEBs with less E _b (giving drift velocity) reduce growth rate more than the beams with larger E _b. The inhibition of growth rate increases with the increase in the ratio ω _e/Ω_e indicating that the beams are more effective at higher altitudes.      

Effect of solar activity and cosmic-ray variations on the position of the Arctic front in the North Atlantic

The long-period variations in the climatic position of the Arctic front in the North Atlantic have been investigated. It is found that oscillations of the Arctic front latitude near Greenland occur with main periods of ～80, ～44, and ～22 years; this finding indicates possible relationship of these oscillations with the solar activity and variations in galactic cosmic rays. It is shown that the secular oscillations of the Arctic front latitude can be responsible for the amplitude modulation of the 11-year harmonic in sea-level pressure variations in the North Atlantic.     

Variations in the geomagnetic cutoff rigidity of CR in the period of magnetospheric disturbances of May 2005: Their correlation with interplanetary parameters

The correlation between the rigidities of a geomagnetic cutoff, obtained using the global spectrographic survey method, and by trajectory tracing of CR particles in the magnetic field of the Ts03 Tsyganenko magnetosphere model (2001–2003) and the Dst variation and interplanetary parameters, was studied for the May 15–19, 2005, period of interplanetary and geomagnetic disturbances.     

Electrohydrodynamics of the pulsar magnetosphere

The dispersion relations for weak waves in a cold, charge-separated plasma (due to a strong rotating magnetic field) show that radio waves, and even low frequency waves can propagate through a (one-component) pulsar magnetosphere.     

Effect of space charge on subnanosecond current cutoff in powerful semiconductor diodes

High-density current cutoff in an SOS diode is studied with a physicomathematical model including the space-charge effect. If the depth of the p-n junction exceeds 180 µm, the forward pumping time is less than 60 ns, and the backward pumping time is shorter than 20 ns, the subnanosecond cutoff of current with a density of several kiloamperes per square centimeter takes place. The cutoff mechanism is associated with the origination of three high-field zones at the stage of current cutoff: two zones on the p-side, which expand with a velocity close to the saturation value, and one on the n-side, which expands slowly. Taking the space charge into account reduces the role of avalanche multiplication and, as a consequence, improves the switching properties of the diode. It is found that a set of conditions for the electric circuit parameters that specify the pumping current duration and density and for the dopant profile in the semiconductor must be met for subnanosecond current cutoff to occur. The results are compared with experimental data and a model using a quasi-neutral approximation.     

Global magnetohydrodynamic simulations of the magnetosphere

The authors demonstrate the use of a global MHD (magnetohydrodynamic) simulations to study the magnetospheric configuration by reviewing some of the results obtained from the Ogino model. The authors start by considering the steady-state configuration of the magnetosphere in the absence of an IMF (interplanetary magnetic field), and then demonstrate how that configuration is changed when a northward or southward IMF is introduced. It is noted that the magnetosphere is very dynamic and since global MHD simulations are intrinsically time-dependent, they offer the possibility of modeling the time-sequence of events in the magnetosphere. Finally results of a calculation in which a magnetospheric substorm is modeled are presented     

The effect of wind on cosmic-ray muon asymmetry

Summary We investigate the effect of horizontal density and pressure gradients (i.e. atmospheric wind) on the muon asymmetry measured with crossed telescopes. By using the model of Judge and Nash (1965) for muon production and the geostrophic approximation for atmospheric dynamics, we obtain theoretical estimates which agree well with experimental results. The effect of wind sometimes exceeds 0.5%. Winds above the 100 mbar pressure level, which affect the primary proton spectrum, have the strongest influence on the observed asymmetry. The magnitude and variation of the local wind field should also be taken into account in accurate anisotropy measurements.

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Riassunto Si studia l'effetto, dei gradienti orrizontali di densità e pressione (cioè vento atmosferico) sull'asimmetria muonica misurata con telescopi incrociati. Usando il modello di Jadge e Nash (1965) per la produzione, di muoni e l'approssimazione geostrofica per la dinamica atmosferica, si ottengono valori teorici che sono in buon accordo con i risultati sperimentali. L'effetto del vento qualche volta supera lo 0.5%. I venti al di sopra del livello di pressione di 100 mbar, che influenzano lo spettro protonico primario, hanno l'influenza più forte sull'asimmetria osservata. In misurazioni accurate dell'anisotropia dovrebbero anche essere prese in considerazione la grandezza e la variazione del campo del vento locale.

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Резуме Мы исследуем влияние горизонтальной плотности и градиентов давления (т.е. атмосферного ветра) на асимметрию мюонов, измеренную с помощью скрещенных телескопов. Используя модель Джудза и нэше для образования мюонов и геострофическое приближение для атмосферной динамики, мы получаем теоретические оценки, которые согласуются с экспериментальными результатами. Эффект ветра превышает 0.5%. Ветры, возникающие при давлении выше 100 мбар, которые влияют на спектр первичных протонов, оказывают очень сильное воздействие на наблюденную асимметрию. Величина и вариация локального поля ветров также должны учитываться при точных измерениях анизотропии.

     

Effect of pressure on the electronic structure of cuprates with strongly correlated electrons

For cuprates of the n and p types, the effect of pressure on the electronic structure of a CuO₂ layer is studied. In the calculations performed, a generalized tight-binding method is used taking into account the influence of strong electronic correlations on the electronic structure of cuprates. The results obtained demonstrate the unusual effect of pressure on the nature of quasiparticle states at the top of the valence band in p-type cuprates. As the pressure increases, the hole states in these materials cease to be Zhang-Rice singlets and become combined singlet-triplet states.     

Effect of strongly coupled plasma on the doubly excited states of heliumlike ions

The effect of strongly coupled plasma occurring in astrophysical context has been studied for the first time to estimate the energy levels of the autoionizing states of highly stripped astrophysically important ions Al¹¹⁺, Si¹²⁺, P¹³⁺, S¹⁴⁺ and Cl¹⁵⁺ and also C⁴⁺ isoelectronic to helium. The transition energies corresponding to 1s ²:¹S^e → 2s ²:¹S^e, 2p ²:¹D^e, 2s2p:¹P^o, 2s3d:¹D^e and 2p3d:¹F^o are analyzed with respect to different plasma densities using the ion sphere (IS) model of strongly coupled plasma. Transition energies are obtained from the position of the poles of a variational functional based on frequency dependent perturbation calculation probing the collective oscillation modes of the plasma embedded two electron ions. For the free ions corresponding to zero plasma coupling our calculated data agree well with those obtained from spectroscopic data while for the plasma embedded ions the data are new but follow systematic trend. The work has been performed in the domain of linear response theory. The analytical wave function of the doubly excited states have been obtained and may be useful for calculating various transition properties of the plasma embedded ions and also for estimating the rate coefficients for dielectronic recombination processes which play a major role in maintaining equilibrium in high temperature astrophysical or laser produced plasmas.     

Effect of disorder on the conductivity of two-phase strongly inhomogeneous highly filled composites

The effect of the “stir” of a structure (small deviations from strict periodicity) on effective conductivity is considered. For determinate and random deviations, concentration and field dependences of the effective conductivity are found. Numerical experiments with determinate deviations are carried out for the cases of linear (with respect to the field) inclusions embedded in both a linear and nonlinear matrix. The numerical results are compared with the effective conductivity calculated analytically.     

Dependence of cosmic-ray transport on the orientation of the solar magnetic dipole

Summmary In this paper we discuss the dependence of cosmic-ray transport in the interplanetary space on the polarity configuration of the solar and interplanetary magnetic fields. The diffusion mechanism is not only related to the irregularities present in the interplanetary magnetic field, but also to its regular structure, because of the curvature and gradient drifts of the particles. Hence diffusion is affected by the polarity reversals of the interplanetary magnetic dipole which are related to the reversals of the solar dipole. As a consequence a phase reversal of both the annual and semi-annual variations in the cosmic-ray intensity occurs. This effect has been studied throughout the period 1954–1976, by analysing the Climax neutron monitor data. In addition, the latitudinal distribution of the average solar activity itself in this period changes simultaneously to the polarity reversals of the solar polar fields.

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Riassunto In questo lavoro esaminiamo come la configurazione del campo magnetico solare e del campo magnetico interplanetario influenzi il trasporto dei raggi cosmici nello spazio interplanetario. Il meccanismo di diffusione non è legato infatti solo alle irregolarità presenti nel campo magnetico interplanetario, ma anche alla sua struttura regolare, dalla cui curvatura e dal cui gradiente dipendono i, drift delle particelle. Pertanto, la diffusione risente della polarità del dipolo magnetico interplanetario, legata alla polarità del dipolo magnetico solare, che si inverte secondo il ciclo undecennale. Come conseguenza di queste inversioni di polarità, si manifesta un'inversione di fase tanto nella variazione annua dell'intensità dei raggi cosmici, che in quella semiannua. Questo effetto è stato studiato per il periodo 1954–1976, che copre due cicli solari. Si è inoltre trovata, per il medesimo periodo, una variazione della distribuzione in latitudine dell'attività solare in corrispondenza alle inversioni di polarità dei campi magnetici polari del Sole.

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Резюме В этой статре мы обсуждаем, зависимостъ переноса космических лучей в межплнетном пространстве от конфигирации полярности солнечного и межпланетного магнитных полей. Механизм диффузии связан не толъко с наличием иррегулярностей в межпланетном магнитном поле, а также с регууярной структурой этого поля. Следователъно, диффузия зависит от изменений направления полярности межпланетного магнитного диполя, которые связаны с обращениями солнечного диполя. В резулътате этого возникает фазовое обращение годичных и полугодичных вариаций интенсивности космических лрчей. Этот эффект изучался в течение 1954–1976 г. г., анализируя данные с нейтронных мониторов. Кроме того, широтное распределение средней солнечной активности в зтот период изменяется одновременно с обрашением полярности солнечных полей.