Frequency spectrum of Cherenkov radiation and radioastronomical method for measuring the flux of ultrahigh-energy cosmic particles

The frequency spectrum of a radio pulse generated by a cascade shower in the Moon’s regolith has been calculated with the inclusion of the transverse sizes of the shower and the inhomogeneous distribution of excess electrons over the disc radius. The character of the spectrum differs significantly from the previous results that were obtained by E. Zas et al., Phys. Rev. D 45, 362 (1992), and J. Alvarez-Muñis et al., astro-ph/0003315, and were more recently used by T. H. Hankins et al., Mon. Not. R. Astron. Soc. 283, 1027 (1996); P. W. Gorham et al., astro-ph/9906504; and P. W. Gorham et al., astro-ph/0310232. The maximum-intensity region lies in a range of 500–600 MHz. In a frequency range of 1.5–2 GHz, the radiation intensity decreases by several orders of magnitude. This seems to be one of the causes of the absence of events in experimental works of T. H. Hankins et al., Mon. Not. R. Astron. Soc. 283, 1027 (1996); P. W. Gorham et al., astro-ph/9906504; and P. W. Gorham et al., astro-ph/0310232, which closed Z-burst models.     

Unstable superheavy relic particles as a source of neutrinos responsible for ultrahigh-energy cosmic rays

Decays of superheavy relic particles may produce extremely energetic neutrinos. Their annihilations on the relic neutrinos can be the origin of the cosmic rays with energies beyond the Greisen-Zatsepin-Kuzmin cutoff. The redshift acts as a cosmological filter selecting the sources at some particular value z(e)+/-deltaz, for which the present neutrino energy is close to the Z pole of the annihilation cross section. We predict no directional correlation of the ultrahigh-energy cosmic rays with the galactic halo. At the same time, there can be some directional correlations in the data, reflecting the distribution of matter at redshift z = z(e)+/-deltaz. Both of these features are manifest in the existing data. Our scenario is consistent with the neutrino mass reported by super-Kamiokande and requires no lepton asymmetry or clustering of the background neutrinos.     

Plasma wakefield acceleration for ultrahigh-energy cosmic rays

A cosmic acceleration mechanism is introduced which is based on the wakefields excited by the Alfvén shocks in a relativistically flowing plasma. We show that there exists a threshold condition for transparency below which the accelerating particle is collision-free and suffers little energy loss in the plasma medium. The stochastic encounters of the random accelerating-decelerating phases results in a power-law energy spectrum: f(epsilon) proportional, variant 1/epsilon(2). As an example, we discuss the possible production in the atmosphere of gamma ray bursts of ultrahigh-energy cosmic rays (UHECR) exceeding the Greisen-Zatsepin-Kuzmin cutoff. The estimated event rate in our model agrees with that from UHECR observations.     

Search for anisotropy in arrival directions of ultrahigh-energy cosmic rays by using the marr wavelet on the equatorial sphere

The arrival direction distribution of cosmic rays for energies E>10¹⁸ eV detected at the Yakutsk EAS array is analyzed using the Marr wavelet. Deviation from the isotropic distribution of 361 showers above 10¹⁹ eV is found at a significance level of 0.007, which corroborates previous evidence of the cosmic ray anisotropy in this energy range. In contrast to the previous methods, the wavelet analysis makes it possible to localize both a celestial-sphere domain containing a supposed source of excess cosmic ray flux and the scale parameter of the two-dimensional wavelet.     

Investigation of the properties of the flux and interaction of ultrahigh-energy cosmic rays by the method of local-muon-density spectra

A new method for studying extensive air showers is considered. The method is based on the phenomenology of the localmuon density. It is shown that measurement ofmuon-density spectra at various zenith angles makes it possible to obtain information about the energy spectrum, mass composition, and interaction of cosmic rays over a broad range of energies (10¹⁵–10¹⁸ eV) by using a single array of comparatively small size. The results obtained from a comparison of experimental data on muon bundles from the DECOR coordinate detector with the results of simulation performed under various assumptions on the properties of the primary flux and for various hadron-interaction models are presented, and possible versions of the interpretation of these results are discussed.     

Possible galactic sources of ultrahigh-energy cosmic rays and a strategy for their detection via gravitational lensing

If decays of superheavy relic particles in the galactic halo are responsible for ultrahigh-energy cosmic rays, these particles must be clustered to account for small-scale anisotropy in the AGASA data. We show that the masses of such clusters are large enough for them to gravitationally lens stars and galaxies in the background. We propose a general strategy that can be used to detect such clusters via gravitational lensing, or to rule out the hypothesis of decaying relic particles as the origin of highest energy cosmic rays.     

Radio emission of extensive air showers as a method for detecting ultra-high energy cosmic rays

Recording radio emission from extensive air showers (EASs) is considered now as a new promising method for detecting ultra-high energy (E ₀ > 5 × 10¹⁶ eV) cosmic rays. The results of calculation of EAS radio emission at frequencies from 40 to 80 MHz in the EAS energy range E ₀ = 10¹⁴–10¹⁷ eV are reported here, and the possibilities of determining EAS parameters from the radio emission lateral distribution are discussed.     

Method for registration of solar cosmic rays by detecting neutrons

We consider a method of detecting the ionizing component of solar cosmic rays (SCRs) with energy from tens of MeV to tens of GeV by measuring the energy loss of SCR protons and light nuclei in scintillators and the multiplicity of the local neutron generation in a converter. Scintillation detectors based on stilbene, lithium glass, and solid-state photomultiplier tubes are capable of detecting fast neutrons with a temporal resolution of 10 ns and rejecting the gamma-ray background in the measuring system. The method will allow investigating the nucleon components of primary SCRs in circumterrestrial space.     

Iron oxide and iron carbide particles produced by the polyol method

Iron oxide (γ-Fe₂O₃) and iron carbide (Fe₃C) particles were produced by the polyol method. Ferrocene, which was employed as an iron source, was decomposed in a mixture of 1,2-hexadecandiol, oleylamine, and 1-octadecene. Particles were characterized using Mössbauer spectroscopy, X-ray diffraction, and transmission electron microscopy. It was found that oleylamine acted as a capping reagent, leading to uniform-sized (12-16 nm) particles consisting of γ-Fe ₂O₃. On the other hand, 1-octadecene acted as a non-coordinating solvent and a carbon source, which led to particles consisting of Fe₃C and α-Fe with various sizes.     

Channeling problem for charged particles produced by confining environment

Channeling problem produced by confining environment that leads to resonance scattering of charged particles via quasistationary states imbedded in the continuum is examined. Nonmonotonic dependence of physical parameters on collision energy and/or confining environment due to resonance transmission and total reflection effects is confirmed that can increase the rate of recombination processes. The reduction of the model for two identical charged ions to a boundary problem is considered together with the asymptotic behavior of the solution in the vicinity of pair-collision point and the results of R-matrix calculations. Tentative estimations of the enhancement factor and the total reflection effect are discussed. The text was submitted by the authors in English.     

Snow cover monitoring method by using HJ-1 satellite data

Environment and Disasters Monitoring Microsatellite Constellation with high spatial resolution,high temporal resolution and high spectral resolution characteristics was put forward by China.HJ-1B satellite,one of the first two small optical satellites,had a CCD camera and an infrared camera,which would provide an important new data source for snow monitoring.In the present paper,through analyzing the sensor and data characteristics of HJ-1B,we proposed a new infrared normalized difference snow index (INDSI) referring to the traditional normalized difference snow index (NDSI).The accuracy of these two automatic snow recognition methods was estimated based on a supervised classification method.The accuracy of the traditional NDSI method was 97.761 9％ while that of the new INDSI method was 98.617 1％.     

Processing of high-energy proton events using a new method for searching primary cosmic ray particles in X-ray emulsion chambers (according to the RUNJOB experiment data)

In the RUNJOB Russian-Japanese balloon experiment, tracks of primary singly charged particles are detected in approximately half the events related to the proton ones. During repeated processing of the experimental data obtained when exposing RUNJOB-3B, 6A, 11A, and 11B X-ray emulsion chambers (XRECs) using the new method for searching primary cosmic particles, approximately 50% of tracks of primary singly charged particles as before were not detected in the group of events related to the proton ones with primary particle energiesE ₀ > 20 TeV and zenith angle tan θ ≤ 5. In this paper,we present a new method for searching and tracing particles in the XREC; characteristics of processed events (the energy, zenith angle, and particle penetration depth in the XREC before the interaction) are given.     

Spectral changes produced by static scattering on a system of particles

A formula of considerable generality is derived for the spectrum of light produced by static scattering of polychromatic light on a system of particles. It applies to deterministic as well as to random distributions of monodispersed or polydispersed particles. We illustrate it by examples. It is suggested that spectral changes produced by scattering could be used for determining the structure of some scattering systems.     

A method of autonomous orbit determination for satellite using star sensor

1 Introduction Autonomous orbit determination of satellite means that orbit determination is solely finished on board, independent of the observation of ground system. Study on autono-mous orbit determination of satellite has been very hot in the field of orbit determination currently internationally due to its significance in application. There are two common ways of autonomous orbit determination internationally. One is autonomous orbit deter-mination based on navigation system, such as on-b…     

Fast calibration methods using cosmic rays for a neutron detection array

An overall irradiation and calibration technique was introduced and applied to a test scintillation detector array. An integral conversion method was used to reduce the nonlinearity of the time difference spectrum, and to improve the position determination especially for positions close to the two ends of a long scintillation bar. An overall position resolution of about 3.0 cm (FWHM) was extracted from the residual analysis method and verified by a direct measurement. Energy calibration was also realized by selecting cosmic rays at different incident angles. The bulk light attenuation lengths for the four test bars were also determined. It is demonstrated that these methods are especially efficient for calibrating large and complex detector arrays.