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Deployment of the deep-sea neutrino telescope Baikal-GVD continues in Lake Baikal. By April 2022, ten telescope clusters, which include 2880 optical modules, were put into operation. One of the ...urgent tasks of the Baikal project is to study the possibility of increasing the detection efficiency of the detector based on the experience of its operation and the results obtained with other neutrino telescopes in recent years. In this paper, the authors consider a variant of optimizing the telescope configuration by installing an additional string of optical modules between the detector clusters (external string). An experimental version of the external garland was installed in Lake Baikal in April 2022. The paper presents the results from calculations of the efficiency of registration of neutrino events for a new setup configuration, the technical implementation of the system for recording and collecting data from the external garland, and the first results of its full-scale tests in Lake Baikal.
In TAIGA Observatory (Tunka Advanced Instrument for cosmic ray physics and Gamma-ray Astronomy) we are commissioning the first Imaging Atmospheric Cherenkov Telescope (IACT). The telescope has an ...alt-azimuth mount and 17-bit shaft encoder for each axis, stepper motors are used for axis control. For the pointing calibration of the telescope a CCD-camera is installed on the dish of the telescope and its position allows to capture simultaneously both the Cherenkov camera with LEDs and the sky with observed source. Since October 2017, the telescope has been operating in tracking mode. In this work the TAIGAIACT telescope pointing calibration approach and first results of the tracking operations are described.
Abstract
Objectives of the TAIGA Astrophysical complex include the study of the flux of charged cosmic rays and diffuse gamma rays with energies above 100 TeV. This complex is located in the Tunka ...Valley about 50 km from Lake Baikal at the site of the Tunka-133 Cherenkov facility. TAIGA includes the TAIGA-HiSCORE wide-angle Cherenkov array, the network of Imaging Atmospheric Cherenkov Telescopes (TAIGA-IACT), the Tunka-Grande and TAIGA-Muon scintillation arrays. In this work, we present the results of an analysis of the joint events of the Tunka-Grande scintillation array and TAIGA-HiSCORE and Tunka-133 Cherenkov facilities. The results verify sufficient accuracy of the scintillation experiment for the hybrid study of mass composition of cosmic rays and gamma-hadron separation.
Diversity of the oil-degrading microbial strains isolated from the water and sediments of the Gulf of Finland (Baltic Sea) in winter and in summer was studied. Substrate specificity of the isolates ...for aliphatic and aromatic hydrocarbons was studied. The isolates belonged to 32 genera of the types Proteobacteria (alpha-, beta-, and gammaproteobacteria),
Actinobacteria,
Firmicutes
, and
Bacteroidetes
. Seasonal variations of the oil-degrading microbial communities was revealed. The presence of the known genes responsible for the degradation of oil aliphatic and aromatic hydrocarbons was determined. The alkB sequence of the alkane hydroxylase gene was found in ~16% of the studied strains. The sequence of the
phnAc
phenanthrene 3,4- dioxygenase was found in
Sphingobacterium
sp. and
Arthrobacter
sp. isolates retrieved in winter and summer. In five Pseudomonas sp. strains from winter samples, the classical operons of naphthalene degradation (
nah
) were localized in catabolic plasmids, of which three belonged to IncР-9, one, to IncР-7, and two to an unidentified incompatibility group.
Burkholderia
and
Delftia
strains contained the operons for naphthalene degradation via salicylate and gentisate (nag). The presence of
nag
genes has not been previously reported for Delftia spp. strains. The sequences of the nagG salicylate 5-hydroxylase gene were also found in
Achromobacter
,
Sphingobacterium
, and
Stenotrophomonas
strains.
The Tunka-Grande and TAIGA-Muon arrays are the part of a single experimental complex, which also includes the Tunka-133 and TAIGA-HiSCORE (High Sensitivity COsmic Rays and gamma Explorer) wide-angle ...Cherenkov arrays, TAIGA-IACT array (Imaging Atmospheric Cherenkov Telescope) and Tunka-Rex radio antennas array (Tunka Radio Extension). This complex is located in the Tunka Valley (Buryatia Republic, Russia), 50 km from Lake Baikal. It is aimed at investigating the energy spectrum and mass composition of charged cosmic rays in the energy range 100 TeV - 1000 PeV, searching for diffuse gamma rays above 100 TeV and studying local sources of gamma rays with energies above 30 TeV. This report outlines 3 key points. The first is a description of the Tunka-Grande and TAIGA-Muon scintillation arrays. The second part presents preliminary results of the search for diffuse gamma rays with energies above 50 PeV according to the Tunka-Grande data. The third part is devoted to the prospects of the search for diffuse gamma rays with energies above 100 TeV using the TAIGA-Muon array.
The physical motivations and advantages of the new gamma-observatory TAIGA (Tunka Advanced Instrument for cosmic ray physics and Gamma Astronomy) is presented. The TAIGA array is a complex, hybrid ...detector for ground-based gamma-ray astronomy for energies from a few TeV to several PeV as well as for cosmic ray studies from 100 TeV to several EeV. The TAIGA will include the wide angle Cherenkov array TAIGA-HiSCORE with ~5 km2 area, a net of 16 I ACT telescopes (with FOV of about 10x10 degree), muon detectors with a total area of up to 2000-3000 m2 and the radio array Tunka-Rex.
Over the past few years, the TAIGA (Tunka Advanced Instrument for cosmic ray physics and Gamma-ray Astronomy) observatory has been being deployed in the Tunka Valley, Republic of Buryatia. It is ...designed for studying gamma rays of energy above 30 TeV and performing searches for sources of galactic cosmic rays with energies in the vicinity of 1 PeV, which is an energy region around the classic knee in the cosmic-ray energy spectrum. The first phase of the observatory will be situated at a distance of about 50 km from Lake Baikal at the site of the Tunka-133 array. The TAIGA gamma observatory will include a network of 500 wide-angle (0.6 sr) Cherenkov detectors (TAIGA-HiSCORE array) and up to 16 atmospheric Cherenkov telescopes (ACT) designed for analyzing the EAS images (imaging atmospheric Cherenkov telescopes, or IACT) and positioned within an area of 5 km
2
. The observatory will also include muon detectors of total area 2000 m
2
distributed over an area of 1 km
2
. Within the next three years, it is planned to enhance the area of the TAIGA-HiSCORE array by a factor of four—from 0.25 km
2
to 1 km
2
; to supplement the existing IACT with two new ones; and to deploy new muon detectors with a total coverage of 200 m
2
. The structure of the new observatory is described along with the data analysis techniques used. The most interesting physical results are presented, and the research program for the future is discussed.
Abstract
In the paper we present our simulation strategy of the Tunka-Grande, TAIGA-Muon, and TAIGA-HiSCORE arrays in the light of the problem of separation astrophysical high-energy gamma rays from ...the cosmic ray background. The paper contains a description of our simulation method, based on Geant4 and CORSIKA codes. We also present the prospect of future research with TAIGA (Tunka Advanced Instrument for cosmic rays and Gamma Astronomy) with using the simulation results.
The differential energy spectrum of cosmic rays in the energy range of 3 × 10
14
–3 × 10
18
eV and the corrected dependence of the mean depth of the maximum 〈
X
max
〉 of an extensive air shower (EAS) ...inside the wide energy range of 10
15
–3 × 10
17
eV have been obtained from the data of the Tunka-133 array for 7 years of operation (2009–2017) and the TAIGA-HiSCORE array for the 2019–2020 season of operation. At the extremely high energy, our results agree with the results of the Pierre Auger Observatory based on direct measurements of the maximum depth by the observation of fluorescent light from EAS. The recalculation from the 〈
X
max
〉 to the parameter
, which characterizes the average composition of the primary cosmic rays, is presented.
The main goal of the Baikal-GVD deep-sea neutrino telescope is to detect high-energy neutrinos of astrophysical origin by reconstructing muon tracks or showers of particles generated in interactions ...of neutrino with water. Since 2020, Baikal-GVD has been monitoring IceCube telescope alerts about detecting neutrinos with energies of more than 100 TeV. This work presents results from searching for matches between Baikal-GVD events and IceCube neutrino alerts from September 2020 to April 2022.
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