The origin and nature of extreme energy cosmic rays (EECRs), which have energies above the
5
⋅
10
19
eV
—the Greisen-Zatsepin-Kuzmin (GZK) energy limit, is one of the most interesting and complicated ...problems in modern cosmic-ray physics. Existing ground-based detectors have helped to obtain remarkable results in studying cosmic rays before and after the GZK limit, but have also produced some contradictions in our understanding of cosmic ray mass composition. Moreover, each of these detectors covers only a part of the celestial sphere, which poses problems for studying the arrival directions of EECRs and identifying their sources. As a new generation of EECR space detectors, TUS (Tracking Ultraviolet Set-up), KLYPVE and JEM-EUSO, are intended to study the most energetic cosmic-ray particles, providing larger, uniform exposures of the entire celestial sphere. The TUS detector, launched on board the Lomonosov satellite on April 28, 2016 from Vostochny Cosmodrome in Russia, is the first of these. It employs a single-mirror optical system and a photomultiplier tube matrix as a photo-detector and will test the fluorescent method of measuring EECRs from space. Utilizing the Earth’s atmosphere as a huge calorimeter, it is expected to detect EECRs with energies above
10
20
eV
.
It will also be able to register slower atmospheric transient events: atmospheric fluorescence in electrical discharges of various types including precipitating electrons escaping the magnetosphere and from the radiation of meteors passing through the atmosphere. We describe the design of the TUS detector and present results of different ground-based tests and simulations.
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•Evolution of Graphene/Ni system due to intercalation with Fe and Si is studied.•Graphene strongly interacts with the topmost atoms of the intercalated fcc Fe film.•The in-plane ...ferromagnetic ordering of the film arises after intercalation of 5ML Fe.•Fe-Si solid solution and Fe3Si surface silicide are formed after intercalation of Si.•The capping graphene layer is weakly electronically coupled to the silicide phase.
A new method for synthesis of graphene-protected iron silicides has been tested, which consists in formation of graphene on Ni(111) followed by two-step intercalation of the system with Fe and Si. Characterization of the samples was performed in situ by low-energy electron diffraction, angular-resolved photoelectron spectroscopy, core-level photoelectron spectroscopy with synchrotron radiation and magnetic linear dichroism in photoemission of Fe 3p electrons. It is shown, that at 400°C the intercalation of graphene/Ni(111) with iron occurs in a range up to 14ML. The graphene layer strongly interacts with the topmost Fe atoms and stabilizes the fcc structure of the film. The in-plane ferromagnetic ordering of the film has a threshold nature and arises after the intercalation of 5ML Fe due to the thickness-driven spin reorientation transition. Subsequent intercalation of graphene/Fe/Ni(111) with Si leads to the formation of the inhomogeneous system consisted of intercalated and nonintercalated areas. The intercalated islands coalesce at 2ML Si when a Fe-Si solid solution covered with the Fe3Si surface silicide is formed. The Fe3Si silicide is ferromagnetic and has an ordered (√3×√3)R30° structure. The graphene layer is weakly electronically coupled to the silicide phase keeping its remarkable properties ready for use.
Some results of studies of cosmic rays obtained during the NUCLEON space experiment in 2015–2017 are presented. This experiment was intended for direct measurements of the energy spectra and chemical ...composition of cosmic rays (
Z
= 1−30) in the energy range 2–500 TeV. Results presented include energy spectra for various abundant nuclei measured using the new Kinematic Lightweight Energy Meter (KLEM). The primary energies are established using the spatial densities of secondary particles produced in inelastic interactions with a carbon target.
•Formation of Co2FeSi alloy films on the CaF2/Si(111) substrate is studied in situ.•5nm CaF2 layer inhibits the diffusion of the alloy components into a substrate.•Annealing of deposited Co/Fe/Si ...layers at 200°C leads to formation of the alloy.•The alloy is characterized by the mode with energy of 99.01eV in Si 2p spectra.•2nm Co2FeSi film is ferromagnetic and stable at temperatures below 450°C.
Ultrathin (∼2nm) films of Co2FeSi ferromagnetic alloy were formed on silicon by solid-phase epitaxy and studied in situ. Experiments were carried out in an ultrahigh vacuum (UHV) using substrates of Si(111) single crystals covered with a 5nm thick CaF2 barrier layer. The elemental and phase composition as well as the magnetic properties of the synthesized films were analyzed by photoelectron spectroscopy using synchrotron radiation and by magnetic linear dichroism in photoemission of Fe 3p and Co 3p electrons. The study shows that the synthesis of the Co2FeSi ferromagnetic alloy occurs in the temperature range of 200–400°C. At higher temperatures, the films become island-like and lose their ferromagnetic properties, as the CaF2 barrier layer is unable to prevent a mass transfer between the film and the Si substrate, which violates the stoichiometry of the alloy.
—The fruits of
Trapa natans
L. s.l. (Trapaceae) (disappeared from the territory of Saratov oblast), collected in floodplain lakes of the Khoper River at the territory of Voronezh oblast ...(Novokhoporskii district), were sown in autumn 2019 and spring 2020 into the Khoper and Volga rivers on the territory of Saratov oblast. In autumn 2020, germinated rosettes of water caltrop were noted in 17 sowing places; moreover, there were fewer germinated rosettes than the number of fruits sown in most of these places. Only in three artificial plantings was the number of rosettes equal to or more than the number of fruits sown. According to morphometric parameters of the vegetative sphere, five artificial plantings (nos. 6, 7, 9, 15, 21) from the Khoper River are close to the donor populations; by potential and real seed productivity, only two artificial plantings (nos. 7 and 9) from the Khoper River. Reintroduction of
T. natans
is more promising in the Khoper River, while reintroduction is complicated in the Volga River (at least in the seeding region) due to sharp changes in the water level during the season.
As part of the preparation of the TAIGA gamma ray observatory (Republic of Buryatia, Russian Federation) and the TUS space experiment on the Mikhailo Lomonosov satellite, 1400 PMTs of XP1911 type, ...1020 PMTs of XP1911/UV type, and 290 PMTs of R1463 type were tested for their main and additional specifications (nominal (operating) voltage, dark current at nominal voltage, quantum efficiency of the photocathode at a wavelength of 480 nm, cathode chamber resistivity, and quality parameters of the dynode system). The number of PMTs that did not meet the selection criteria is 3.9% for XP1911, 15.8% for XP1911/UV, and 4.8% for R1463 of the corresponding number of PMTs of this type. The parameters of 856 PMTs of XP1911/UV type, which successfully passed the selection criteria and turned out to be ready for use in the TAIGA experiment, were compared with the corresponding parameters of the new 1250 PMTs of R7877 type (Hamamatsu) previously measured for the ATLAS hadron scintillation calorimeter at the LHC (CERN, Geneva, Switzerland).
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