High-energy cosmic-ray research via the detection of Cherenkov radiation from extensive air showers was begun in the Tunka valley (50 km to the west from the southern extremity of Lake Baikal) in the ...early 1990s. A series of large arrays combined into the TAIGA (Tunka Advanced Instrument for cosmic-ray physics and Gamma Astronomy) astrophysical facility and designed to study gamma rays and charged cosmic rays have been created in the elapsed time. Descriptions of the facility arrays and the main results obtained while investigating high-energy cosmic rays are presented. Plans for a further development of the astrophysical facility are discussed.
We consider the possibilities for prediction of liquid densities under pressure based on the inverse reduced fluctuations parameter, which is directly connected with the isothermal compressibility. ...This quantity can be determined based on the thermodynamic properties of the saturated liquid, and it consists of only two constant parameters within a relatively wide region close to the melting points. It is confirmed by the comparison with the experimental data on
n
-alkanes that the derived expression is a quite reasonable estimator without a necessity to fit data along some parts of isotherms for different temperatures. At the same time, the obtained formula (i) can be reduced to the form of the Tait equation and (ii) the resulting Tait parameters in this representation have a clear physical meaning as functions of the excess entropy, which determines the mentioned reduced fluctuations.
The mechanisms of transport of substances in the brain parenchyma have been a hot topic in scientific discussion in the past decade. This discussion was triggered by the proposed glymphatic ...hypothesis, which assumes a directed flow of cerebral fluid within the parenchyma, in contrast to the previous notion that diffusion is the main mechanism. However, when discussing the issue of “diffusion or non-diffusion”, much less attention was given to the question that diffusion itself can have a different character. In our opinion, some of the recently published results do not fit into the traditional understanding of diffusion. In this regard, we outline the relevant new theoretical approaches on transport processes in complex random media such as concepts of diffusive diffusivity and time-dependent homogenization, which expands the understanding of the forms of transport of substances based on diffusion.
In this paper we propose a ‘knee-like’ approximation of the lateral distribution of the Cherenkov light from extensive air showers in the energy range 30–3000 TeV and study a possibility of its ...practical application in high energy ground-based gamma-ray astronomy experiments (in particular, in TAIGA-HiSCORE). The approximation has a very good accuracy for individual showers and can be easily simplified for practical application in the HiSCORE wide angle timing array in the condition of a limited number of triggered stations.
We analyse the inverse reduced fluctuations (inverse ratio of relative volume fluctuation to its value in the hypothetical case where the substance acts as an ideal gas for the same ...temperature-volume parameters) for simple liquids from experimental acoustic and thermophysical data along a coexistence line for both liquid and vapour phases. It has been determined that this quantity has a universal exponential character within the region close to the melting point. This behaviour satisfies the predictions of the mean-field (grand canonical ensemble) lattice fluid model and relates to the constant average structure of a fluid, i.e. redistribution of the free volume complementary to a number of vapour particles. The interconnection between experiment-based fluctuational parameters and self-diffusion characteristics is discussed. These results may suggest experimental methods for determination of self-diffusion and structural properties of real substances.
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The paper is devoted to the modeling and analysis of data detected by the TAIGA-IACT installation in the stereo mode. Five Imaging Atmospheric Cherenkov Telescopes (IACT) with a viewing angle of ...9.6° are expected to be included in the installation. Today there are three telescopes spaced far apart (from 320 to 500 m) in the installation. The effective area of the installation is as large as 0.6 km
2
; therefore, it is possible to conduct statistically significant measurements of weak γ-ray sources in the energy range above 10 TeV over a reasonable observation time (300–400 h). The Monte Carlo procedure for simulating the hadrons and γ-rays detected by the telescopes is described as is the procedure for reconstructing the parameters of extensive air showers, such as the arrival direction of an event, the axis position, the depth of the maximum of shower development (
X
max
), and the primary-particle energy. In order to solve the problem of γ-hadron separation, the criteria for selecting γ-rays detected in the stereo mode have been optimized and the effective area of the installation has been calculated.
Main Results from the TUNKA-GRANDE Experiment Monkhoev, R. D.; Astapov, I. I.; Bezyazeekov, P. A. ...
Bulletin of the Russian Academy of Sciences. Physics,
07/2023, Letnik:
87, Številka:
7
Journal Article
Recenzirano
The Tunka-Grande scintillation array is described. Scientific results obtained over the first five years of its operation are presented. Prospects for studying cosmic rays in the 10
16
–10
18
eV ...range of energies are discussed.
The more correct recalculation from the measured Cherenkov light fluxes at distances of 200 (Q200) and 100 (Q100) m from the Extensive Air Shower (EAS) core to the energy of the primary particle has ...been developed using the results of M-C simulation by the CORSIKA code, assuming a light primary composition of cosmic rays. Using the new conversion expressions, a differential energy spectrum was obtained according to the data of the Tunka-133 array for 7 years of operation and the TAIGA-HiSCORE array for 2 years of operation.
A wide-angle Cerenkov array TAIGA-HiSCORE (FOV
0.6 sr), was originally created as a part of TAIGA installation for high-energy gamma-ray astronomy and cosmic ray physics. Array now consist on nearly ...100 optical stations on the area of 1 km
. Due to high accuracy and stability (
1 ns) of time synchronization of the optical stations the accuracy of EAS arrival direction reconstruction is reached 0.1
. It was proven that the array can also be used to search for nanosecond events of the optical range. The report discusses the method of searching for optical transients using the HiSCORE array and demonstrates its performance on a real example of detecting signals from an artificial Earth satellite. The search for this short flares in the HiSCORE data of the winter season 2018–2019 is carried out. One candidate for double repeater has been detected, but the estimated probability of random simulation of such a transient by background EAS events is not less than 10
, which does not allow us to say that the detected candidate corresponds to a real astrophysical transient. An upper bound on the frequency of optical spikes with flux density of more than
and a duration of more than 5 ns is established as
events/sr/h.
An analysis is performed of the spectrum of gamma rays from the Crab Nebula in the 4–100 TeV range of energies, obtained using data from two Atmospheric Cherenkov Telescopes that are part of the ...TAIGA complex. A way of selecting and restoring the energy of gamma rays is described that includes a procedure for restoring the energy spectrum.
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