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.
The time distributions of particles in extensive air showers (EASs) have been studied using the EAS array at Moscow State University
1
,
2
. More than 10
5
particles are produced in an EAS during ...the interaction of cosmic rays with energies above 10
14
eV with the atmosphere. Delayed particles are detected in 3.5% of EASs with an unshielded detector located at the Earth’s surface. Muons are detected in 60% of EASs using a shielded detector located under a soil ground layer equivalent to a 20 m of water column. The detector signals are recorded using a two-beam analog storage oscilloscope. It has been found that the detection probability increases when observing muons for EASs containing from
to
particles, and when observing delayed particles for EASs containing from
to
particles. The distribution over distances to the EAS axis when observing delayed particles is wider than for muons and the age distributions do not differ within errors. The features of EASs with delayed particles and the hypothesis that the height of the appearance of delayed particles can be higher than the height at which EAS electrons and muons are produced are considered.
The results obtained by studying temporal distributions of particles of energy in excess of 5 GeV in extensive air showers (EAS) of energy above
eV at distances shorter than 200 m from the EAS axis ...with the aim of searches in data from the MSU EAS setup for delayed and advanced new particles that could arise in the interactions of primary cosmic rays in the Earth’s atmosphere are presented. These investigations were performed with the aid of an unshielded ground-based detector and an underground detector shielded by a ground layer 20 m.w.e. thick. It is shown that delayed particles having a delay time between 100 and 300 ns and an exponentially descending temporal distribution with an exponent of 120 ns exhibit a higher ionizing ability than relativistic muons. The flow of such particles is attenuated by the ground layer between the unshielded and shielded detectors by a factor of about 30. Particles moving ahead of the EAS disk were not detected in the present study. Properties of delayed particles are discussed. Special features of calibrations and auxiliary tests confirming data from the present measurements are analyzed.
Usually a thunderstorm region with lightning activity is necessary for the formation of known types of upper atmospheric transient luminous events (TLEs: sprites, emission of light and very low ...frequency perturbation, blue jets, etc.) with well-recognizable visible emissions. However, some "far-from-thunderstorm" transient events have been detected in some experiments. Measurements of transient atmospheric events (TAEs) were made on board the Vernov satellite by the sensitive UV and IR detector. Remote observation from the satellite's orbit provided measurements all over the globe and allowed us to study events associated with thunderstorms (lightning, TLEs) and unusual UV flashes (UV TAEs) far from thunderstorm regions. More than 8500 UV TAEs were measured by the Vernov satellite over the globe. Forty seven far-from-thunderstorm TAEs were selected having no lightning discharges during 1 h in a radius of 1000 km around the location of the event according to the Worldwide Lightning Location Network (WWLLN) and Vaisala Global Lightning Data Set (GLD360) data. Special attention was given to six events with complicated temporal structure and low luminosity in the IR channel. Their properties and atmospheric conditions were studied in detail. The analysis of cloud cover in addition to the lightning location networks data demonstrated the low probability of any lightning in the region of measurements.
In the space experiment a near visual UV radiation (NUV) from the Earth atmosphere was measured during the moon month. At moonless local nights the results of previous measurements are confirmed: NUV ...intensity is in limits of 3
×
10
7–10
8
photons/cm
2
s
sr. At the background of natural NUV light the light from big cities was registered. In a detector FOV (the corresponding diameter of the observed atmosphere area is 250
km) the brightest cities radiate NUV comparable with the natural level. At moon nights the NUV intensity depends on the moon phase, the moon local zenith angle and cloud cover. Monitoring of the average NUV intensity shows that only in 1/4 of the moon month the average intensity is over 10
9
photons/cm
2
s
sr. The method of digital oscilloscope was applied for searching and registering the short NUV flashes (from 1 to 10
ms). The trigger system selects the brightest flash in one satellite circulation. In the registered NUV flashes the energy radiating in the atmosphere in 1–10
ms is of the order of 10
11–10
13
erg. Those energetic flashes are found to be concentrated in the Earth equatorial region.
The generation of transient and other optical phenomena in the Earth’s upper atmosphere under the action of electron fluxes and high- and low-frequency electromagnetic waves resulting from ...electromagnetic fields 1 has been studied onboard the small Vernov spacecraft (solar synchronous orbit, 98° inclination, altitude 640–830 km). On the night side at middle latitudes, the technogenic glow is shown to be observed along the preferential meridians whose distribution corresponds to the longitudes of the most powerful low-frequency radio stations 2. The geographic distribution of this glow changes abruptly at the boundary between the day and night sides of the satellite orbit; on the day side, such meridians are not identified, while their geographic distribution in longitude is uniform. The boundaries of the geographic distribution of technogenic glow regions on the day side are unstable in latitude, their northern and southern boundaries are shifted at all latitudes from the North Pole to the South Pole. At middle and low latitudes, zones with random geographic coordinates, where the technogenic glow is completely absent, are observed in the distributions of signals along the meridians. When studying the flashes caused by discharges in the atmosphere, we showed that lightning flashes and transient luminous events at nighttime are observed mainly in equatorial regions, which coincide with zones of high thunderstorm activity. At daytime, flashes of light are recorded much more rarely, have a short duration, are observed most often in the Earth’s polar regions, including the winter periods, the power of their emission exceeds considerably the power of similar (in duration) short flashes observed at night.
The “Lomonosov” space project is lead by Lomonosov Moscow State University in collaboration with the following key partners: Joint Institute for Nuclear Research, Russia, University of California, ...Los Angeles (USA), University of Pueblo (Mexico), Sungkyunkwan University (Republic of Korea) and with Russian space industry organizations to study some of extreme phenomena in space related to astrophysics, astroparticle physics, space physics, and space biology. The primary goals of this experiment are to study:
Ultra-high energy cosmic rays (UHECR) in the energy range of the Greizen-Zatsepin-Kuzmin (GZK) cutoff;
Ultraviolet (UV) transient luminous events in the upper atmosphere;
Multi-wavelength study of gamma-ray bursts in visible, UV, gamma, and X-rays;
Energetic trapped and precipitated radiation (electrons and protons) at low-Earth orbit (LEO) in connection with global geomagnetic disturbances;
Multicomponent radiation doses along the orbit of spacecraft under different geomagnetic conditions and testing of space segments of optical observations of space-debris and other space objects;
Instrumental vestibular-sensor conflict of zero-gravity phenomena during space flight.
This paper is directed towards the general description of both scientific goals of the project and scientific equipment on board the satellite. The following papers of this issue are devoted to detailed descriptions of scientific instruments.
The generation of transients in the Earth’s upper atmosphere under the action of electron fluxes and high- and low-frequency electromagnetic waves has been studied onboard the small Vernov spacecraft ...(solar synchronous orbit, 98° inclination, height 640–830 km). The studies were carried out with ultraviolet (UV, 240–380 nm), red–infrared (IR, 610–800 nm), gamma-ray (0.01–3 MeV), and electron (0.2–15 MeV) detectors as well as with high-frequency (0.05–15 MHz) and low-frequency (0.1 Hz–40 kHz) radio receivers. Artificial optical signals distributed along the meridian in an extended region of latitudes in the Earth’s Northern and Southern Hemispheres modulated by a low frequency were recorded during the nadir observations at nighttime. Examples of the oscillograms of such signals in the UV and IR spectral ranges and their global distribution are presented. The emission generation altitude and the atmospheric components that can be the sources of this emission are discussed. Particular attention is given to the technogenic causes of this glow in the ionosphere under the action of powerful low- and high-frequency radio stations on the ionosphere.
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