Spectral characteristics of electron fluxes at L < 2 under the Radiation Belts

The paper presents the analysis of experimental data on electron fluxes with energies 10 keV–10 MeV. Data were obtained during 1978–2005 years in different space experiments (COSMOS-900, MIR Space Station, ACTIVE, SAMPEX, CORONAS-I, CORONAS-F, NOAA POES-17, TATYANA and others). Two areas of electron flux enhancements are studied in the paper: the near-equatorial (L < 1.2) zone and the middle-latitude (1.2 < L < 1.9) zone. It is shown that electron flux enhancements are regularly registered at L < 2 and the observed formations have some typical features. Electron peaks at L < 1.2 appear sporadically while peaks at 1.2 < L < 1.9 are observed regularly. The approximations of spectra by several functions including kappa-function are presented.     

Direct dark matter searches with CDMS and XENON

The cryogenic dark matter search (CDMS) and XENON experiments aim to directly detect dark matter in the form of weakly interacting massive particles (WIMPs) via their elastic scattering on the target nuclei. The experiments use different techniques to suppress background event rates to the minimum, and at the same time, to achieve a high WIMP detection rate. The operation of cryogenic Ge and Si crystals of the CDMS-II experiment in the Soudan mine reported spectrum-weighted exposures of 34 (12) kg-d for the Ge (Si) targets after cuts, over the recoil energies 10–100 keV for a WIMP mass of 60 GeV/c². It gives an upper limit (90% C.L.) of spin-independent WIMP-nucleon cross-section at 1.6 × 10⁻⁴³ cm² for a WIMP mass of 60 GeV/c², starting to constrain predications in supersymmetry models. The two-phase xenon detector of the XENON10 experiment is currently taking data in the Gran Sasso underground lab and promising preliminary results were recently reported. Both experiments are expected to increase their WIMP sensitivity by a one order of magnitude in the scheduled science runs for 2007.     

HIRDES – The High-Resolution Double-Echelle Spectrograph for the World Space Observatory Ultraviolet (WSO/UV)

The World Space Observatory Ultraviolet (WSO/UV) is a multi-national project grown out of the needs of the astronomical community to have future access to the UV range. WSO/UV consists of a single UV telescope with a primary mirror of 1.7 m diameter feeding the UV spectrometer and UV imagers. The spectrometer comprises three different spectrographs, two high-resolution echelle spectrographs (the High-Resolution Double-Echelle Spectrograph, HIRDES) and a low-dispersion long-slit instrument. Within HIRDES the 102–310 nm spectral band is split to feed two echelle spectrographs covering the UV range 174–310 nm and the vacuum-UV range 102–176 nm with high spectral resolution (R > 50,000). The technical concept is based on the heritage of two previous ORFEUS SPAS missions. The phase-B1 development activities are described in this paper considering performance aspects, design drivers, related trade-offs (mechanical concepts, material selection etc.) and a critical functional and environmental test verification approach. The current state of other WSO/UV scientific instruments (imagers) is also described.     

Experiment VARIANT – first results from Wave Probe instrument

The international experiment VARIANT was carried out onboard Ukrainian remote sensing satellite SICH-1M launched 2004, December 24. In spite of other than planned satellite orbit and onboard systems failure about 11 telemetric files from VARIANT payload were obtained. Due to episodic and random payload switching the main goal of VARIANT experiment - study of field aligned currents and monitoring of electromagnetic state of the ionosphere – was not possible to realize. However the data analysis from VARIANT instrumentation allowed us to obtain for the first time a reliable confirmation of proper operation in ionospheric plasma of a new device developed for wave activity study – Wave Probe, which consists of compact combination of Split Langmuir Probe working at floating potential and search-coil magnetic field sensor. Such a probe can simultaneously measure variations of one component of spatial current density and a perpendicular component of magnetic field with a spectral sensitivity threshold up to 0.1 pA/(cm² Hz^1/2) and 0.03 pT/Hz^1/2, respectively.     

IONOSAT – Ionospheric satellite cluster

The IONOSAT project (from IONOspheric SATellites) is proposed by National Space Agency of Ukraine for First European Space Program as a part of Space Weather (SW) Program. As it is commonly accepted, Space Weather means the changes of the conditions on the Sun, in solar wind, magnetosphere and ionosphere which may affect the operation and reliability of on-board and ground technological systems and threaten human health. In this chain ionosphere is specific and integral part of SW formation. Moreover, namely in the ionosphere main part of the energy absorption of Sun-activated sporadic corpuscular and radiation fluxes takes places. The excitation of ionosphere by falling fluxes produces its “luminescence” in wide frequency band – from ULF waves till ultraviolet – and by this ionosphere works as an efficient “screen” or SW indicator.A goal of the proposed project is long-term spatial–temporal monitoring of main field and plasma parameters of ionosphere with aim to further develop fundamental conceptions of solar-terrestrial connections physics, nowcasting and forecast of SW, and diagnostics of natural and technogenic hazards with the help of scientific payload installed on-board a cluster of 3 low-Earth orbit (LEO) microsatellites (tentative launch date – 2012 year).The state of the project proposal and realization plans are discussed.     

Propagation and origin of ultra high-energy cosmic rays

Propagation of UHE protons through CMB radiation leaves the imprint on energy spectrum in the form of Greisen–Zatsepin–Kuzmin (GZK) cutoff, bump (pile-up protons) and dip. The dip is a feature in energy range 1 × 10¹⁸–4 × 10¹⁹ eV, caused by electron–positron pair production on CMB photons. Calculated for power-law generation spectrum with index γ_g = 2.7, the shape of the dip is confirmed with high accuracy by data of Akeno-AGASA, HiRes, Yakutsk and Fly’s Eye detectors. The predicted shape of the dip is robust: it is valid for the rectilinear and diffusive propagation, for different discreteness in the source distribution, for local source overdensity, deficit, etc. This property of the dip allows us to use it for energy calibration of the detectors. The energy shift λ for each detector is determined by minimum χ² in comparison of observed and calculated dip. After this energy calibration the absolute fluxes, measured by AGASA, HiRes and Yakutsk detectors remarkably coincide in energy region 1 × 10¹⁸–1 × 10²⁰ eV. Below the characteristic energy E_c ≈ 1 × 10¹⁸ eV the spectrum of the dip flattens for both diffusive and rectilinear propagation, and more steep galactic spectrum becomes dominant at E < E_c. The energy of transition E_tr < E_c approximately coincides with the position of the second knee E_2kn, observed in the cosmic ray spectrum. The dip-induced transition from galactic to extragalactic cosmic rays at the second knee is compared with traditional model of transition at ankle, the feature observed at energy 1 × 10¹⁹ eV.     

Rapid variability of 10–140 keV X-rays from Cygnus X-1

On five occasions in 1977 and 1978, Cygnus X-1 was observed using the Low-Energy Detectors of the UCSD/MIT Hard X-Ray and Low-Energy Gamma-Ray Experiment on the HEAO-1 satellite. Rapid (0.08 s ≤ t ≤ 1000 s) variability was found in the 10 – 140 keV band. The power spectrum was “white” for 10⁻³ Hz < f ≤ 5 × 10⁻² Hz and was proportional to f⁻¹ for 5 × 10⁻² Hz ≤ f < 3 Hz, indicating correlations on all time scales < 20 s. If the emission is produced by Comptonization of a soft photon flux in a hot cloud, the heating of the cloud cannot be constant; it must vary on time scales up to 20 seconds. A variable accretion rate could cause the observed effects.     

On possible genesis of fractal dimensions in the turbulent pulsations of cosmic plasma – galactic cosmic rays – turbulent pulsation in planetary atmosphere system

The spectrum of turbulent pulsations induced in the atmosphere by the galactic cosmic rays is defined. A possible manifestation of genesis of fractal dimensions in the system of “spectrum of turbulent pulsations of cosmic plasma – galactic cosmic rays’ spectrum – spectrum of atmospheric turbulent pulsations” is analyzed.     

Surface elements and landing strategies for small bodies missions – Philae and beyond

The investigation of small bodies, comets and asteroids, can contribute substantially to our understanding of the formation and history of the Solar System. In-situ observations by Landers play a prominent role in this field.The Rosetta Lander – Philae – is currently on its way to comet 67P/Churyumov–Gerasimenko. It will land in November 2014 and perform numerous experiments with a suite of 10 scientific instruments.Philae has been designed to cope with a wide range of possible comet properties. The considerations taken during its development are relevant for future Lander missions to small bodies in the Solar System.In addition the paper provides a review of alternative concepts, studied or developed for various missions like Phobos, Hayabusa/Minerva or Géocroiseur/Leonard.Various missions to small bodies in the Solar System, including Landers, are currently studied (e.g., Marco Polo). The paper will address the mission options and compare applicable technologies with the solutions chosen for Philae.     

Launch and commissioning of the PAMELA experiment on board the Resurs-DK1 satellite

PAMELA is a satellite borne experiment designed to study with great accuracy cosmic rays of galactic, solar, and trapped nature in a wide energy range (protons: 80 MeV–700 GeV, electrons 50 MeV–400 GeV). Main objective is the study of the antimatter component: antiprotons (80 MeV–190 GeV), positrons (50 MeV–270 GeV) and search for antimatter (with a precision of the order of 10⁻⁸). The experiment, housed on board the Russian Resurs-DK1 satellite, was launched on June, 15th 2006 in a 350 × 600 km orbit with an inclination of 70°. The detector consists of a permanent magnet spectrometer core to provide rigidity and charge sign information, a Time-of-Flight system for velocity and charge information, a silicon–tungsten calorimeter and a neutron detector for lepton/hadron identification. An anticounter system is used off-line to reject false triggers coming from the satellite. In self-trigger mode the calorimeter, the neutron detector and a shower tail catcher are capable of an independent measure of the lepton (e⁺ + e⁻) component up to 2 TeV. In this work we focus on the first months of operations of the experiment during the commissioning phase.     

Physical and model interpretation of HF radio propagation on the St. Petersburg–Longyearbyen (Svalbard) path

HF radio wave observations have been carried out with an oblique ionospheric sounding (OIS) method on the radio path from St. Petersburg to Longyearbyen (Svalbard), and experimental ionograms were obtained for December 2001. These ionograms have been analysed to investigate the impact of the main ionospheric trough (MIT) and magnetic disturbances on the signals on this path. The observations during weakly disturbed (K_р = 2) magnetic conditions on 14–15 December 2001 were compared with predictions from ray-tracing through a numerical model of the ionosphere. The ray-tracing computer program synthesizes the OIS ionograms by means of the “shooting method”. This method calculates trajectories of HF radio waves for different values of elevation angle and transmission frequency. There was a variety of calculated trajectories, from which we choose those which reach the receiver, and the selected paths provide a synthesis of the oblique ionograms. To simulate HF radio wave propagation, we apply a three-dimensional distribution of the electron density calculated with the mathematical model of the high-latitude ionosphere developed in the Polar Geophysical Institute (PGI). These numerical simulations permit us to interpret specific peculiarities of the OIS data such as abnormal propagation modes, increased delays of signals, enhanced MOF (maximum observed frequency) values etc. New results of the study are summarised as follows. (1) An unusual feature of the propagation along the path is the change of propagation mechanism during substorms on entering a path midpoint (or 1-hop reflection point) to the MIT. (2) Even weak substorms, having the distinguished intensities, lead to the appearance of different types of irregularities observed by the CUTLASS radar and therefore to the different propagation modes and F2MOF values. (3) The PGI model of the ionosphere was first used for ray-tracing at high latitudes. The model results are basically in a good qualitative agreement with experimental observations. This model provides the satisfactory agreement between the calculated and experimental F2MOF values while not correctly representing the fine structure of the experimental OIS ionograms at night. An agreement between the calculated and experimental data is better for day and evening hours than at night.     

Studying the evolution of the hot universe with the X-ray evolving universe spectroscopy mission – XEUS

Europe is one of the major partners building the International Space Station (ISS) and European industry, together with ESA, is responsible for many station components including the Columbus Orbital Facility, the Automated Transport Vehicle, two connecting modules and the European Robotic Arm. Together with this impressive list of contributions there is a strong desire within the ESA Member States to benefit from this investment by utilizing the unique capabilities of the ISS to perform world-class science. XEUS is one of the astronomical applications being studied by ESA to utilize the capabilities of the ISS. XEUS will be a long-term X-ray observatory with an initial mirror area of 6 m² at 1 keV that will be expanded to 30 m² following a visit to the ISS. The 1 keV spatial resolution is expected to be 2–5″ half-energy-width. XEUS will consist of separate detector and mirror spacecraft (MSC) aligned by active control to provide a focal length of 50 m. A new detector spacecraft, complete with the next generation of instruments, will also be added after visiting the ISS. The limiting 0.1–2.5 keV sensitivity will then be 4 × 10⁻¹⁸ erg cm⁻² s⁻¹, around 200 times better than XMM-Newton, allowing XEUS to study the properties of the hot baryons and dark matter at high redshift.     

Model for induced ionization by galactic cosmic rays in the Earth atmosphere and ionosphere

The ionization profiles produced by galactic cosmic rays in the Earth atmosphere and ionosphere are obtained on the basis of Monte Carlo simulations. Cascade processes in the atmosphere are simulated using CORSIKA 6.52 code with FLUKA 2006 and QGSJET II hadronic interaction subroutines. Proton induced showers are considered using a realistic atmospheric model (US Standard Atmosphere). The energy deposit from different components is taken into account, namely electromagnetic, hadron and muon components. The curvature of the atmosphere is considered in the computer code. On the basis of the computed ionization yield function the ion pair production rate in the atmosphere is obtained for different conditions and locations. The model is applicable to the entire atmosphere, from ground level to upper atmosphere. Several applications of the obtained results are discussed. The Monte Carlo simulation model considers nuclear interactions below the altitude of 35 km. It is compared with analytical–numerical electron production rate model. The latter model which takes into account the electromagnetic interactions above altitudes of 35 km has two main regions of application: above 50 km (thin target model) and between 35 and 50 km (intermediate target model). A good agreement between the CORSIKA results and analytical–numerical model results is found above altitude of 35 km.     

Analytical approach to cosmic ray ionization by nuclei with charge Z in the middle atmosphere – Distribution of galactic CR effects

The effects of galactic and solar cosmic rays (CR) in the middle atmosphere are considered in this work. A new analytical approach for CR ionization by protons and nuclei with charge Z in the lower ionosphere and middle atmosphere is developed in this paper. For this purpose the ionization losses (dE/dh) according to the Bohr–Bethe–Bloch formula for the energetic charged particles are approximated in three different energy intervals. More accurate expressions for energy decrease E(h) and electron production rate profiles q(h) are derived. The obtained formulas allow comparatively easy computer programming. The integrand in q(h) gives the possibility for application of adequate numerical methods – such as Romberg method or Gauss quadrature, for the solution of the mathematical problem. On this way the process of interaction of cosmic ray particles with the upper, middle and lower atmosphere will be described much more realistically. Computations for cosmic ray ionization in the middle atmosphere are made. The full CR composition is taken into account: protons, Helium (α-particles), light L, medium M, heavy H and very heavy VH group of nuclei.     

Development of a 2.8 μm film for scientific balloons

Development of a balloon to fly at higher altitudes is one of the most attractive challenges in scientific balloon technologies. After reaching the highest record setting balloon altitude of 53.0 km using the 3.4 μm film in 2002, we tried to make a thinner balloon film. In 2003, we developed a forming die and an air-ring and succeeded in forming a film with a thickness of 3.0 μm and a width of 220 cm. Using this film, we manufactured a balloon with a volume of 5000 m³ and succeeded in flying the balloon up to an altitude of 46.0 km. We then searched for a good combination of resins to make a thinner and wider film and obtained films with widths of 280 cm, and a thickness of 3.0 μm at first, and then 2.8 μm. In 2004, we performed balloon experiments making a 30,000 m³ balloon with the 3.0 μm film and a 5000 m³ balloon with the 2.8 μm film. Both balloons were well manufactured and reached the highest altitudes of 50.7 and 42.6 km, respectively.     

Even–odd cycle parity in complexity of hemispheric sunspot activity

We have used the Lempel–Ziv measure to describe the complexity in sunspot activity during the solar cycles 18–23. In particular, we examined the time series of daily sunspot numbers in the northern and southern hemispheres in each of the six cycles and calculated the Lempel–Ziv complexity (LZC) value for each time series. Our results indicate that in the even cycles, the LZC values of the sunspot numbers in the two hemispheres are very close to each other, whereas in the odd cycles they differ significantly between the two hemispheres. We also find that within each hemisphere the LZC varies from cycle to cycle. This even–odd cycle parity reflects the variations in inter-hemispheric strengths of the solar magnetic field leading to different temporal distributions of sunspots in the two hemispheres. The degree of complexity may influence the predictability of sunspot activity in the two hemispheres during the various cycles. Although the physical implication of the results is not clear, these results may stimulate new ideas into modeling the complex dynamics of the solar dynamo.     

Observations of 1–30 MeV gamma rays from the galactic center

Preliminary results are reported for gamma ray observations of the galactic center region made during a 15 hour balloon flight from Alice Springs, Australia on April 18, 1979. The observations were carried out with the UCR double-scatter gamma-ray telescope at energies of 1 to 30 MeV. The observations are compatible with a galactic source of approximately equal brightness along the region 300°<ℓII<60°. The energy distribution joins smoothly to previous spark chamber results at energies above 30 MeV and to scintillator results below 1 MeV. It appears to be a combination of nuclear gamma ray lines superimposed on a bremsstrahlung spectrum with a power law (1.3±.7) × 10⁻³ E⁻(^1.7±.2). The ¹²C* line at 4.4 MeV appears to be present with a significance of about 16σ. The flux in the line is (6±3) × 10⁻⁴photons cm⁻²s⁻¹rad⁻¹. The oxygen line at 6.1 MeV does not seem to appear significantly above background.     

A summary of the applications of a weighted average method determining times of solar cycle extrema

This paper is a summary of our recent researches on the applications of a weighted average method determining times of solar cycle extrema in the prediction of solar activity. Some correlation coefficients among the parameters in solar cycle according to this definition are higher than those according to the conventional definition. The descending time is found to be correlated (r = −0.77) with the ascending time 3 cycles earlier. The amplitude of solar cycle is found to be correlated (r = −0.77) with the max–max solar cycle length 2 cycles earlier. The ascending time is found to be correlated (r = −0.72) with the amplitude. A newly defined parameter called effective duration is found to be well correlated (r = 0.86) with the amplitude 5 cycles later. These correlations suggest that earlier cycles should influence later ones. The next (24th) solar cycle is estimated to start in March 2007 ± 7 months, reach its maximum in January 2011 ± 14 months, with a size of 150 ± 22, larger than those from some correlations according to the conventional definition.