Search

Work is currently under way in the Tunka Valley, 50 km from Lake Baikal, to create the TAIGA gamma observatory for studying gamma radiation and cosmic ray fluxes in the 1013–1018 eV range of energies. To detect gamma rays with energies above tens of TeV, a hybrid method of detecting showers is implemented. It is based on data obtained by the TAIGA Imaging Atmospheric Cherenkov Telescope (IACT) and the wide-angle TAIGA-HiSCORE array. The preliminary results from processing the telescope’s data for the low-energy region (>2–3 TeV) are presented. Joint events with energy more than 50 TeV are analyzed and compared to Monte Carlo calculations.

The TAIGA (Tunka Advanced Instrument for cosmic ray physics and Gamma-ray Astronomy) experiment aims at observing gamma-rays in the energy range from 1 TeV to several 100 TeV. The operation of the observatory is based on a new hybrid approach that combines imaging air Cherenkov telescopes (IACTs) and wide-angle Cherenkov detectors (TAIGA-HiSCORE) for measuring times of extensive air shower (EAS) light front arrival. Monte Carlo simulations are compared to real data to determine the performance of the detector setup. Dedicated software and algorithms are described, model parameters are given, and an overview of the current status of model-based performance studies is presented.

The relevance and benefits of the new TAIGA gamma observatory complex in the Tunka Valley (50 km from Lake Baikal) are discussed. The main aim of the TAIGA installation is to study high-energy gamma radiation and search for cosmic pevatrons. The first series of gamma stations was commissioned in 2019 and covers an area of 1 km2. Its expected integral gamma radiation sensitivity at an energy of 100 TeV over 300 h of source monitoring is (2–5) × 10−13 TeV cm−2 s−1. It is planned to expand the effective area of TAIGA gamma observation to 10 km2 in the future.

The Tunka-133 Cherenkov complex for recording extensive air showers (EAS) collected data over seven winters from 2009 to 2017. The differential energy spectra of all particles was acquired in the 6 × 1015–3 × 1018 eV range of energies over 2175 h. The TAIGA-HiSCORE complex is continually being expanded and upgraded. Data acquired by 30 first-line stations over 35 days during the period 2017–2018 is analyzed in this work. As at the Tunka-133 setup, the primary particle energies above 1015 eV are measured using the density of the Cherenkov light flux at a distance of 200 m from a shower’s axis. Data on lower energies are collected by determining the energy of the light flux near a shower’s axis. This results in a spectrum of 2 × 1014–1017 eV. The combined spectrum for the two systems covers a range of 2 × 1014–2 × 1018 eV.

A new knee-like approximation of the lateral distribution function (LDF) of EAS Cherenkov light in the 30–3000 TeV energy range was proposed and tested with simulated showers in our earlier studies. This approximation fits the LDFs of individual showers accurately for all types of primary particles gamma-rays, protons, and nuclei) and is suitable for reconstructing the shower core, determining the energy, and separating gamma-induced showers from hadron-induced ones. In the present study, the knee-like fitting function is used to determine the parameters of real showers detected by TAIGA-HiSCORE. It is demonstrated that this approximation characterizes properly all types of individual LDFs of experimental events in the 300–1000 TeV range. The accuracy of fit is governed by fluctuations intrinsic to the process of measurement of the Cherenkov photon density. The probability density function of these fluctuations was reconstructed and introduced into simulations. Certain useful methodical applications of the knee-like approximation are con-sidered, and the possibility of shower sorting into nuclei groups is examined. The extensive statistical coverage and detailed LDF measurement data of HiSCORE have provided the first opportunity to examine in depth the LDF of Cherenkov radiation in the 300–1000 TeV range.

One of the most informative methods of cosmic ray studies is the detection of Cherenkov light from extensive air showers (EAS). The primary energy reconstruction is possible by using the Earth’s atmosphere as a huge calorimeter . The EAS Cherenkov light array Tunka-133, with ∼ 3 km 2 geometrical area, is taking data since 2009. Tunka-133 is located in the Tunka Astrophysical Center at ∼ 50 km west of Lake Baikal. This array allows us to perform a detailed study of the energy spectrum and the mass composition in the energy range from 6 ⋅ 1 0 15 eV to 1 0 18 eV . Most of the ongoing efforts are focused on the construction of the first stage of the detector TAIGA (Tunka Advanced Instrument for cosmic ray physics and Gamma Astronomy). The latter is designed for the study of gamma rays and charged cosmic rays in the energy range of 1 0 13 eV – 1 0 18 eV . The TAIGA prototype will consist of ∼ 100 wide angle timing Cherenkov stations (TAIGA-HiSCORE) and three IACTs deployed over an area of ∼ 1 km 2 . The installation of the array is planned to be finished in 2019 while the data-taking can start already during the commissioning phase. The joint reconstruction of energy, direction, and core position of the imaging and non-imaging detectors will allow us to increase the distance between the IACTs up to 800 m, therefore providing a low-cost, highly sensitive detector. The relatively low cost together with the high sensitivity for energies ≥ 30–50 TeV make this pioneering technique very attractive for exploring galactic PeVatrons and cosmic rays. In addition to the Cherenkov light detectors we intend to deploy surface and underground muon detectors over an area of 1 km 2 with a total area of about 1000 m 2 . The results of the first season of coincident operation of the first ∼ 4 m diameter IACT with an aperture of ∼ 10°with 30 stations of TAIGA-HiSCORE will be presented.

The article presents the relevance and advantages of the new gamma observatory TAIGA (Tunka Advanced Instrument for cosmic ray physics and Gamma Astronomy), which is being constructed in the Tunka Valley 50 km from Lake Baikal. Various detectors of the six TAIGA gamma observatory arrays register the Cherenkov and radio radiation, as well as the electron and muon components of EAS. The primary objective of the TAIGA gamma observatory is to study the high-energy part of the gamma-ray spectrum, in particular, in order to search for Galactic PeVatrons. The energy, direction, and position of the EAS axis are reconstructed in the observatory based on the data of the wide-angle Cherenkov detectors of the TAIGA-HiSCORE experiment. Taking into account this information, the gamma quanta are distinguished from the hadron background using the data obtained by the muon detectors and telescopes that register the EAS image in the Cherenkov light. In this hybrid mode of operation, the atmospheric Cherenkov telescopes can operate in the mono-mode, and the distance between them can be increased to 800–1000 m, which makes it possible to construct an array with an area of 5 km2 and more at relatively low cost and in a short time. By 2019, the first stage of the gamma observatory with an area of 1 km2 will be constructed; its expected integral sensitivity for detecting the gamma radiation with an energy of 100 TeV at observation of the source for 300 hours will be approximately $$2 \times 5$$ 10–13 TeV cm–2s–1.

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 km2. The observatory will also include muon detectors of total area 2000 m2 distributed over an area of 1 km2. 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 km2 to 1 km2; to supplement the existing IACT with two new ones; and to deploy new muon detectors with a total coverage of 200 m2. 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.

The Tunka-Grande array is part of an experimental complex located in the Tunka Valley (Republic of Buryatia, Russia) about 50 km from Lake Baikal. This complex also contains the Tunka-133 and Tunka-Rex arrays. The aim of this complex is to study the primary cosmic ray energy spectrum and mass composition in the energy range of 1016–1018 eV, and to search for diffuse gamma rays in the energy range of 5 × 1016–5 × 1017 eV. The design of the Tunka-Grande array and the procedure for reconstructing the parameters of extensive air showers (EASes) are described, and preliminary results are presented from the search for diffuse gamma rays with energies of more than 5 × 1016 eV.

It is planned that new TAIGA-Muon detectors will complement the existing Tunka-GRANDE facility of scintillation detectors of the TAIGA gamma-observatory in the Tunka valley, Russia. The new design of scintillation detector with wavelength shifting bars and PMTs is developed. The first prototype of the counter was installed and tested using infrastructure of the Tunka-GRANDE installation in 2017. The mass production of counters has begun in 2018 at the Novosibirsk State University.

The Tunka Radio Extension (Tunka-Rex) is a digital antenna array for the detection of radio emission from cosmic-ray air showers in the frequency band of 30 to 80 MHz and for primary energies above 100 PeV. The standard analysis of Tunka-Rex includes events with zenith angle of up to 50$^\circ$. This cut is determined by the efficiency of the external trigger. However, due to the air-shower footprint increasing with zenith angle and due to the more efficient generation of radio emission (the magnetic field in the Tunka valley is almost vertical), there are a number of ultra-high-energy inclined events detected by Tunka-Rex. In this work we present a first analysis of a subset of inclined events detected by Tunka-Rex. We estimate the energies of the selected events and test the efficiency of Tunka-Rex antennas for detection of inclined air showers., ARENA2018 proceedings

The Tunka Radio Extension (Tunka-Rex) is a digital radio array operating in the frequency band of 30-80 MHz and detecting radio emission from air-showers produced by cosmic rays with energies above 100 PeV. The experiment is installed at the site of the TAIGA (Tunka Advanced Instrument for cosmic rays and Gamma Astronomy) observatory and performs joint measurements with the co-located particle and air-Cherenkov detectors in passive mode receiving a trigger from the latter. Tunka-Rex collects data since 2012, and during the last five years went through several upgrades. As a result the density of the antenna field was increased by three times since its commission. In this contribution we present the latest results of Tunka-Rex experiment, particularly an updated analysis and efficiency study, which have been applied to the measurement of the mean shower maximum as a function of energy for cosmic rays of energies up to EeV. The future plans are also discussed: investigations towards an energy spectrum of cosmic rays with Tunka-Rex and their mass composition using a combination of Tunka-Rex data with muon measurements by the particle detector Tunka-Grande., Comment: ARENA2018 proceedings

The Tunka-Grande scintillation array is described. The first results from its operation are presented. The prospects for studying primary cosmic rays in the energy range of 1016 to 1018 eV during simultaneous registration of the Cherenkov and charged particle components along with radio emissions from extensive air showers are discussed.

The combination of a wide angle timing Cherenkov array and Imaging Atmospheric Cherenkov Telescopes operated in mono mode offers a cost-effective way to construct a few square kilometers array for ultrahigh-energy gamma astronomy. The first stage of the TAIGA Observatory (Tunka Advanced Instrument for cosmic ray physics and Gamma Astronomy) is described here. It will comprise TAIGA-HiSCORE - 120 wide angle Cherenkov stations distributed over an area of 1.0 km2 and three IACTs (TAIGA-IACT).

Baikal-GVD is a kilometer-scale neutrino telescope under construction in Lake Baikal, which will be formed by multi-megaton subarrays – clusters of strings. A first demonstration cluster “Dubna” has been deployed in 2015 and comprises 192 optical modules (OMs). In 2016 this cluster was upgraded to the baseline configuration which comprises 288 OMs arranged at eight strings. The second full-scale GVD-cluster was deployed and put in operation in 2017. We review the present activity towards the GVD implementation and discuss some selected results obtained with the “Dubna” cluster.

A central question of Astroparticle Physics, the origin of cosmic rays, still remains unsolved. HiSCORE (Hundred*i Square-km Cosmic ORigin Explorer) is a concept for a large-area wide-angle non-imaging air shower detector, addressing this question by searching for cosmic ray pevatrons in the energy range from 10TeV to few PeV and cosmic rays in the energy range above 100TeV. In the framework of the Tunka-HiSCORE project, first prototypes have been deployed on the site of the Tunka-133 experiment, where we plan to install an engineering array covering an area of the order of 1km2. On the same site, also imaging and particle detectors are planned, potentially allowing a future hybrid detector system. Here we present the HiSCORE detector principle, its potential for cosmic ray origin search and the status of ongoing activities in the framework of the Tunka-HiSCORE experiment.

In TAIGA (Tunka Advanced Instrument for cosmic ray physics and Gamma-ray Astronomy) detector we are commissioning the first Imaging Atmospheric Cherenkov Telescope (IACT). The telescope drive system comprises a motor controller and two stepper motors for axis control. For the pointing calibration of the telescope a CCD-camera is installed on the reflector dish of the telescope. The position of the CCD-camera allows us capturing both the Cherenkov camera and the observed source. In this report we describe the telescope positioning and the drive system software as well as the control of the CCD-camera data acquisition, archiving and processing system.

We report the first ground-based observation of the CATS-LIDAR onboard the ISS by the TAIGA-HiSCORE gamma-ray facility, and the MASTER-Tunka Robotic telescope. HiSCORE detects unscattered laser light directly from the ISS, at up to km-scale distance from the laser beam spot on ground. The ISS-LIDAR turns out to be a unique calibration tool, in particular to verify the absolute astronomical pointing of HiSCORE. We detected the LIDAR for 11 ISS-passages; among these were observations of forward scattering of the laser beam in dense clouds, which might carry information complementary to the LIDAR technique. We expect other air Cherenkov installations like IACTs to benefit from this light source.

In April 2015, the first part (cluster) of the newly constructed next-generation neutrino telescope, Gigaton Volume Detector (GVD), was put into operation in the lake Baikal and started with data taking followed by another cluster installed in April 2017 thus doubling the number of installed Optical Modules (OMs) and instrumented volume. Moreover, the substantial extension of this detector is planned in the next few years. Specifically, another two clusters are going to be installed every consecutive year. In total 8 clusters consisting of 2304 OMs with overall effective volume ~0.4 km3 is going to be deployed by 2020. The vital condition for high angular resolution of reconstructed tracks of particles detected in GVD is a precise timing of individual channels which can be achieved with specialized time calibration systems. In this article, the different light sources and procedures used for time calibration of the GVD in the past as well as the newly developed ones are described and the results of the 2016 time calibration of the cluster Dubna are presented, especially the precision of intra and intersection calibrations and variations of calibration parameters in time.

The Tunka Radio Extension (Tunka-Rex) is an array of 63 antennas located in the Tunka Valley, Siberia. It detects radio pulses in the 30-80 MHz band produced during the air-shower development. As shown by Tunka-Rex, a sparse radio array with about 200 m spacing is able to reconstruct the energy and the depth of the shower maximum with satisfactory precision using simple methods based on parameters of the lateral distribution of amplitudes. The LOFAR experiment has shown that a sophisticated treatment of all individually measured amplitudes of a dense antenna array can make the precision comparable with the resolution of existing optical techniques. We develop these ideas further and present a method based on the treatment of time series of measured signals, i.e. each antenna station provides several points (trace) instead of a single one (amplitude or power). We use the measured shower axis and energy as input for CoREAS simulations: for each measured event we simulate a set of air-showers with proton, helium, nitrogen and iron as primary particle (each primary is simulated about ten times to cover fluctuations in the shower maximum due to the first interaction). Simulated radio pulses are processed with the Tunka-Rex detector response and convoluted with the measured signals. A likelihood fit determines how well the simulated event fits to the measured one. The positions of the shower maxima are defined from the distribution of chi-square values of these fits. When using this improved method instead of the standard one, firstly, the shower maximum of more events can be reconstructed, secondly, the resolution is increased. The performance of the method is demonstrated on the data acquired by the Tunka-Rex detector in 2012-2014.

The Baikal-GVD is a cubic kilometer scale neutrino telescope which is deployed in Lake Baikal, that will perform neutrino astronomy studies. It consists of sub-arrays - clusters of about 300 optical modules each, that detect the Cherenkov light radiated by charged particles induced by neutrino interactions with the surrounding medium. The performance of the neutrino telescope relies on the precise timing and positioning calibration of the detector elements, continuous control and monitoring of a behavior of measuring systems, as well as environmental conditions which may affect light detection and event selection. This contribution describes the units which are used in GVD for calibration and monitoring purposes.

The very to ultra high energy gamma-ray regime up to several 100 TeV is the key to spectrally resolve the cutoff regime of the long-sought Pevatrons, the Galactic cosmic-ray PeV accelerators. One component of the TAIGA hybrid detector is the TAIGA-HiSCORE shower-front sampling timing array, which currently consists of 28 wide angle (0.6\,sr) air Cherenkov timing stations distributed on an area of 0.25 km$^{2}$, and which will be doubled in area by fall 2017. We report on the status and first results of the HiSCORE timing array after the first 2 operation seasons, including calibration studies on timing and pointing, cross calibration with data from the first TAIGA-IACT, observations with the timing array of a LIDAR operating on the ISS, a measurement of the Cosmic Ray spectrum, and a systematic search for high energy gamma-rays from Galactic sources such as the Crab.

Deep underwater neutrino telescope „Dubna“ – the first, demonstration cluster of Baikal-GVD, has been deployed in April 2015 and was operating up to February 2016 in Lake Baikal. In 2016 this array was upgraded to baseline configuration of GVD-cluster by adding additional 96 optical modules. The next step of array extension was provided in 2017 by deployment of second GVD-cluster in Lake Baikal. We present here preliminary results of a search for cascade events using data sample recorded in 2015 by Dubna array and corresponding to 41 live days of data taking.

Tunka-Rex (Tunka Radio Extension) is an antenna array for cosmic-ray detection located in Siberia. Previous studies of cosmic rays with Tunka-Rex have shown high precision in determining the energy of the primary particle and the possibility to reconstruct the depth of the shower maximum. The next step is the reconstruction of the mass composition and the energy spectrum of cosmic rays. One of the main problems appearing within this task is to estimate the detection efficiency of the instrument, and the exposure of the observations. The detection efficiency depends on properties of the primary cosmic rays, such as energy and arrival direction, as well as on many parameters of the instrument: density of the array, efficiency of the receiving antennas, signal-detection threshold, data-acquisition acceptance, and trigger properties. More than that, the configuration of detector changes with time. During the measurements some parts of the detector can provide corrupted data or sometimes do not operate. All these features should be taken into account for an estimation of the detection efficiency. For each energy and arrival direction we estimate the detection probability and effective area of the instrument. To estimate the detection probability of a shower we use a simple Monte Carlo model, which predicts the size of the footprint of the radio emission as function of the primary energy and arrival direction (taking into account the geometry of Earth's magnetic field). Combining these approaches we calculate the event statistics and exposure for each run. This is the first accurate study of the exposure for irregular large-scale radio arrays taking into account most important features of detection, which will be used for the measurement of primary cosmic-ray spectra with Tunka-Rex.

The physics motivations and characteristics of the new gamma-experiment TAIGA (Tunka Advanced Instrument for cosmic ray physics and Gamma Astronomy) are presented. The TAIGA experiment addresses ground-based gamma-ray astronomy at energies from a few TeV to several PeV, as well as cosmic ray physics from $100$ TeV to several EeV. For the energy range $30 - 200$ TeV the sensitivity of the planned for future extension of TAIGA up to $5$ km$^2$ area for detection of the local sources is expected to be $10^{-13}$ erg cm$^{-2}$ sec$^{-1}$ for $500$ h of observation. The combination of the wide angle Cherenkov timing detectors of the TAIGA-HiSCORE array and the $4$ m class Imaging Atmospheric Cherenkov Telescopes of the TAIGA-IACT array with their FoV of $10x10$ degrees offers a cost effective-way to construct a $5$ km$^2$ array. Reconstruction of an EAS energy, direction and core position based on the TAIGA-HiSCORE data will allow us to increase the distance between comparatively expensive IACTs up to $800 - 1200$ m. The low investments together with the high sensitivity for energies $\geqslant 30-50$ TeV make this pioneering technique very attractive for exploring the galactic PeVatrons and cosmic rays. In addition to the Cherenkov light detectors we intend to deploy an array of muon detectors (TAIGA-Muon array) over an area of 1 km$^2$ with a total area of about $2000 - 3000$ m$^2$. The TAIGA-IACT-HiSCORE together with the TAIGA-Muon array will be used for selection of gamma-ray induced EAS. At present the first stage of TAIGA have been constructed in the Tunka valley, $\sim 50$ km West from the Lake Baikal in Siberia. Now it consists of 28 TAIGA-HiSCORE Cherenkov stations distributed over an area of $0.25$ km$^2$ and the first IACT of the TAIGA-IACT array. We are planning to test operation of the single telescope in coincidence with the HiSCORE up to shower impact distances of $\sim 500 - 600$ m; for this purpose we already started construction of the second imaging telescope at $300$ m distance from the first one. During 2017 -- 2019 years we intend to increase the number of the TAIGA-HiSCORE stations up to $100 - 120$, spread on the area of $1$ km$^2$ and to deploy $2$ additional IACTs.

The Baikal-GVD neutrino telescope is being constructed in lake Baikal. The robust Baikal Analysis and Reconstruction Software (BARS) has been developed to convert raw data into physics results. To provide a stable and continuous analysis of all the data an automatic data processing using database is developed. The flexibility of the concept makes it easy to add new steps at any point of the analysis chain. The software is ROOT based collection of C++ classes driven by a central event loop. Now the basic algorithms have been implemented in the system such as event building, signal extraction, background rejection and simple reconstruction.

In April of 2013, the first stage of the experimental cluster of the NT1000 deep-water neutrino telescope consisting of three strings with 24 optical modules in each was installed at Lake Baikal and switched on in the continuous exposure mode. The detection and data acquisition systems of this setup are described.

The Tunka Radio Extension (Tunka-Rex) is a digital antenna array, which measures the radio emission of the cosmic-ray air-showers in the frequency band of 30-80 MHz. Tunka-Rex is co-located with TAIGA experiment in Siberia and consists of 63 antennas, 57 of them are in a densely instrumented area of about 1 km\textsuperscript{2}. In the present work we discuss the improvements of the signal reconstruction applied for the Tunka-Rex. At the first stage we implemented matched filtering using averaged signals as template. The simulation study has shown that matched filtering allows one to decrease the threshold of signal detection and increase its purity. However, the maximum performance of matched filtering is achievable only in case of white noise, while in reality the noise is not fully random due to different reasons. To recognize hidden features of the noise and treat them, we decided to use convolutional neural network with autoencoder architecture. Taking the recorded trace as an input, the autoencoder returns denoised trace, i.e. removes all signal-unrelated amplitudes. We present the comparison between standard method of signal reconstruction, matched filtering and autoencoder, and discuss the prospects of application of neural networks for lowering the threshold of digital antenna arrays for cosmic-ray detection., Comment: ARENA2018 proceedings

The history, current status, and prospects for the development of the Baikal Neutrino Project are considered. The main physical results obtained with the help of NT200 and NT200+ neutrino telescopes are presented.

HiSCORE is a non-imaging wide-angle Cherenkov array for the detection of extensive air showers induced by ultrahigh energy gamma-rays above 10 TeV and cosmic ray studies above 100 TeV. In October 2013 a 9-station engineering array has been deployed in Tunka valley. For HiSCORE-9, two DAQ systems are being used. The second system is a DRS4 based acquisition system with WhiteRabbit integrated time synchronization. We present the first results on the amplitude calibration from the data of this DAQ system.

The TAIGA observatory addresses ground-based gamma-ray astronomy at energies from a few TeV to several PeV, as well as cosmic ray physics from 100 TeV to several EeV . TAIGA will be located in the Tunka valley, ~ 50 km West from Lake Baikal. The different detectors of the TAIGA will be grouped in 6 arrays to measure Cherenkov and radio emission as well as electron and muon components of atmospheric showers. The combination of the wide angle Cherenkov detectors of the TAIGA-HiSCORE array and the 4-m Imaging Atmospheric Cherenkov Telescopes of the TAIGA-IACT array with their FoV of 10×10 degrees and underground muon detectors offers a very cost effective way to construct a 5 km2 array for gamma-ray astronomy.

As a non-imaging wide-angle Cherenkov air shower detector array with an area of up to 100 km 2 , the HiSCORE (Hundred⁎i Square km Cosmic ORigin Explorer) detector concept allows measurements of gamma rays and cosmic rays in an energy range of 10 TeV up to 1 EeV. In the framework of the Tunka-HiSCORE project we have started measurements with a small prototype array, and planned to build an engineering array (1 km 2 ) on the site of the Tunka experiment in Siberia. The first results and the most important hardware components are presented here.

Data obtained with two detectors located at the Tunka Cosmic Ray facility are presented. The Cherenkov light array for registration of extensive air showers (EAS) Tunka-133 collected data during 5 winter seasons since 2009 to 2014. The differential energy spectrum of all particles and the dependence of the average maximum depth on the energy in the range of 6 · 10 15 −10 18 eV measured for 1540 hours of observation are presented.The preliminary all particle energy spectrum by the data of Tunka-HiSCORE prototype array, installed in 2013, is presented. Some additional experiments in the Tunka Valley are briefly described.

Addressing the mysteries of cosmic rays requires a comprehensive observational approach, including information on mass composition and spectrum (from CR nuclei) as well as directional information (gamma-rays or neutrinos). HiSCORE covers both approaches using indirect air-shower observations of cosmic rays from 100 TeV to 1 EeV and gamma-rays in the so far poorly covered energy range from 10 TeV to several PeV. Among other questions of astroparticle and particle physics, HiSCORE will allow cosmic ray composition and spectral measurements in the transition range between Galactic and Extragalactic origin. Searching for gamma-rays from the PeV-accelerators, the pevatrons, will consititute a crucial building-block for solving the question of the origin of Galactic cosmic rays. HiSCORE is an array of non-imaging light-collecting stations for Cherenkov light-front sampling. The lateral Cherenkov photon density and arrival-time distribution are measured, allowing the reconstruction of the direction, the energy, and the particle type (mainly shower depth) of the primary particle. A prototype detector station was developed and first air-shower measurements were performed in the Tunka valley (Siberia). The deployment of an engineering array of up to 1 square-km is planned on the Tunka cosmic ray experiment site in Siberia for 2012/2013.

The objective of the Baikal Project is the creation of a kilometer-scale high-energy neutrino observatory: the Gigaton Volume Detector (GVD) in Lake Baikal. Basic elements of the GVD – new optical modules, FADC readout units, and underwater communication systems – were investigated and tested in Lake Baikal with prototype strings in 2008–2010. We describe the results of prototype strings operation and review the preliminary design and expected sensitivity of the GVD telescope.

The Cherenkov light array for the registration of extensive air showers (EAS) Tunka-133 collected data during 5 winter seasons from 2009 to 2014. The differential energy spectrum of all particles and the dependence of the average maximum depth on the energy in the range of 6 · 10 15 -10 18 eV measured for 1540 hours of observation are presented.

The first IACT as part of the gamma and cosmic-ray experiment TAIGA was installed in the Tunka Valley near Lake Baikal in fall 2016. In the following months different systems of the telescope were put into test operation. We started the commissioning phase of operating the telescope in time coincidence with the wide angle integrating air Cherenkov HiSCORE array, which for the time being comprises 28 working stations. We anticipate that the hybrid operation of the non-imaging and imaging telescopes will lead to a cost-efficient, highly sensitive detector operating in the energy range from 30-50 TeV till several PeV. Here we want to report on the first test results of operating the prototype hybrid array. We will focus on the analysis of count rates and image size spectra for all events detected by the IACT and the joint events detected also by the HiSCORE array, comparing these with expectations from MC simulations.

The TAIGA (Tunka Advanced Instrument for cosmic rays and Gamma-Astronomy) observatory is designed to study the gamma ray sources and galactic cosmic rays. It is located in the Tunka Valley 50 km from the lake Baikal (Siberia). The first part of TAIGA called the EAS Cherenkov array TAIGA-HiSCORE currently consists of 28 wide-angle (0.6 sr) stations, distributed over an area of 0.25 km^2. The Crab observation exposure was about 115 hours during the winter seasons of 2016-2017. The expected gamma quanta excess depends on the array energy threshold and a model of the Crab energy spectrum extrapolation to the higher energies. We present preliminary results of experimental data and MC simulations comparison as well as energy threshold and angular resolutions. The experimental data is in a good agreement with the simulations. An excess of events (about 25 events in the region 30-63 TeV) observed from the Crab direction is compatible with the expected one.

Baikal-GVD is a kilometer scale neutrino telescope under construction in Lake Baikal, which will be formed by multimegaton subarrays – clusters of strings. First demonstration cluster “Dubna” has been deployed in 2015 and comprises 192 optical modules (OMs). In 2016 cluster “Dubna” was upgraded to baseline configuration which comprises 288 OMs arranged at eight strings. The second full scale GVD-cluster was deployed and put in operation in 2017 in Lake Baikal. We review a present activity towards the GVD implementation and discuss some selected results obtained with array “Dubna”.

The Baikal-GVD neutrino telescope with an km3 scale detection volume is currently under construction at Lake Baikal. The telescope will be composed of functionally independent setups - clusters of strings of optical modules based on photomultiplier tubes (with eight strings in each cluster). First cluster of GVD in its baseline configuration was deployed in 2016. Spatial positions of light sensors are controlled by dedicated acoustic positioning system. The basic elements and the layout of the acoustic positioning system for the Baikal-GVD neutrino telescope are described, and selected results of system operation are presented.

36th International Cosmic Ray Conference, Madison, USA, 24 Jul 2019 - 1 Aug 2019; PoS-ICRC2019-320 (2019)., Digital radio arrays are widely used for the low-frequency radio astronomy as well as for detection of air-showers induced by high-energy cosmic rays and neutrinos. Since the radio emission from air-showers forms short broadband pulses with duration of tens nanoseconds, the data acquisition strategies of cosmic-ray and astronomical arrays have significant differences. To perform precise measurement of cosmic rays, the radio array should have absolute amplitude calibration and record the entire electric field on the antenna in the broad frequency range. These requirements are similar to ones defined for the experiments aimed at the detection of weak signal from neutral hydrogen at redshifts of $z$>10, what led us to the application of our experience with Tunka-Rex to this problem. We are developing new experimental setup comprising of four antenna stations, placed on the area of 100 sq.m. Each antenna station consists of two perpendicular loop antennas measuring electric field in the frequency band of 30-80 MHz. The setup records electric fields from all antennas in portions of 50 $\mu$s reaching the spectral resolution of 20 kHz. We expect a flow of redundant data of about 10 GB/day, and plan to exploit this redundancy in order to decrease systematic uncertainty of the measurements by application of digital beam-forming, matched filtering and RFI suppression with neural networks. In the present contribution we describe the design and calibration of the setup, expected performance and data analysis techniques.

The first imaging atmospheric Cherenkov telescope as a part of the TAIGA (Tunka Advanced Instrument for cosmic rays and Gamma Astronomy) detector was put into commission in the Tunka valley in December 2016. The reflector of the telescope follows the Davis-Cotton design. It is composed of 34 glassmirror tiles, each of 60 cm diameter, and has a diameter of 4.3 m. The focal length is 4.75 m. The imaging camera includes 560 photomultiplier-based pixels, providing a FoV of ~10×10 degrees. The imaging camera is made by using a modular principle and includes trigger, data acquisition and processing systems based on MAROC3 chips. The slow control system monitors the count rate and the PMT anode currents as well as controls the high voltage. For monitoring performance of the camera a dedicated calibration system based on nanosecond pulsed LED light source was developed.