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The URAN array operates as part of the NEVOD experimental complex for studying the hadron component of extensive air showers by recording the neutrons that accompany a shower. The first results are presented from studying characteristics of the neutron component of extensive air showers (i.e., the lateral distribution and dependence of the number of neutrons on the size of a shower). The characteristics were recorded by the URAN array in 2019.

Two installations that allow to detect the EAS hadron component in a continuous mode, the Cherenkov water calorimeter (CWC) NEVOD and PRISMA-32 are operated in MEPhI. The comparison of the characteristics of EAS simultaneously registered by CWC NEVOD and PRISMA-32 are presented. Groups of events with different positions of the shower axis are considered.

The NEVOD experimental complex was created at MEPhI. It includes several facilities for studying the electron–photon, muon, and hadron components of the EAS in the energy range of 1 PeV to 1 EeV. This work presents the first results for two months of the joint operation of five facilities (NEVOD-EAS, CWD, CTS, PRISMA-32, and DECOR). The problems of synchronizing the facilities and selecting joint events are considered. The experimental data of these facilities are analyzed for different components of the EAS in overlapping energy ranges.

The method of flicker-noise spectroscopy is used for remote identification of geoeffective disturbances of the solar wind. The method is based on the study of short-term variations in the cosmic-ray flux that arise when it crosses the perturbed regions in the inner heliosphere. The magnitude of the effect is usually small and it is hidden in statistical noise. The analysis uses data from a continuous flux of secondary atmospheric muons. Bumps of the “nonstationarity” parameter of time series of muons indicate the emergence of advanced signals (predictors) 1–3 days before the disturbances enter the Earth’s magnetosphere. Geoeffective events with a low threshold (Ap > 30 nT) for various types of solar wind are analyzed. The results are obtained using a ground-based muon hodoscope URAGAN (Moscow). The technique can be used for continuous monitoring of space weather.

Data on the EAS neutron component obtained using the PRISMA-32 array are presented. Secondary neutrons are first moderated and then detected by specialized scintillation electron–neutron detectors (en-detectors) within 20 ms of the arrival of the shower front. The PRISMA-32 array comprises 32 en-detectors and has been operated in the continuous data acquisition mode for more than five years.

Thermal neutrons are detected using a scintillator compound based on ZnS(Ag) with B2O3 added to it. The pulse height generated by single charged particles in a scintillator of small thickness (50 mg/cm2) is not larger than that of a noise signal due to a low sensitivity to single charged particles. As a result, the detector satisfies the requirements of a low-background one in the context of cosmic-ray experiments. The detector is to be used for neutron detection in extensive air showers.

The results of measurements of the spectrum of extensive air showers (EASs) by the number of neutrons detected by the PRISMA-32 setup are presented. The neutron component is formed during the interaction of high-energy shower hadrons with nuclei of atmospheric and Earth’s surface atoms. The PRISMA-32 setup consists of 32 en-detectors and operates in the continuous mode for about 5 years.

The URAN array is designed to study primary cosmic rays in the region of the knee by detecting neutrons produced as a result of interaction between EAS particles and nuclei in the atmosphere or matter near the installation. It consists of 72 detectors mounted on the roofs of experimental buildings and combined into cluster structures of 12 detectors. The registering element is scintillator based on natural boron. The area of each detector is 0.36 m2.

The URAN array was created in the Scientific and Educational Centre NEVOD (MEPhI). The URAN facility was designed to register neutrons that accompany EAS at the energies of the primary cosmic rays around and above the “knee”. It includes 72 detectors based on a thin inorganic scintillator for registration of the charged and neutron components of the EAS. The total area of the facility is about 103 m2. For the correct interpretation of the experimental data of the URAN, the response of the URAN facility to the passage of EAS was simulated using the CORSIKA7.6900 program and Geant4.10.5 software package. It gave a possibility to study neutron generation in the experimental complex building. Experimental data were processed and analyzed. Results of simulation and experimental data are presented.

Flicker-noise spectroscopy (FNS) is used to identify high energy phenomena on the Sun and in the heliosphere. Such processes as the generation of solar cosmic rays (SCRs) or the eruption and propagation of coronal mass ejections (CMEs) in the heliosphere result in short-lived flux variations in both primary cosmic rays and secondary atmospheric muons. Flare and modulation effects at high energies are barely noticeable and are in most cases hidden in the statistical noise of the muon flux at ground level. Generalized FNS allows us to identify such processes. The identification of GLE event #70 is given as an example; this event of ground level enhancement (GLE) was recorded by the URAGAN muon hodoscope and a number of neutron monitors with high geomagnetic cutoffs. The developed technique can be used to analyze a wide range of different helio- and geophysical processes.

Results of comparing events detected with two detectors of the Experimental complex NEVOD: PRISMA-32 array and Cherenkov water calorimeter (CWC) NEVOD – are presented. The PRISMA-32 is an array for simultaneous registration of the EAS electron-photon and neutron components. It consists of 32 en-detectors deployed over the area of about 500 m2, along the perimeter of the CWC NEVOD. The CWC NEVOD is a detector of a calorimetric type with a volume of 2000 cubic meters in which the registration system of 91 quasispherical modules (546 FEU-200 photomultipliers) is placed. CWC provides measurement of the intensity of Cherenkov radiation from any direction with practically the same efficiency.

We present physical motivations and advantages of the new gamma-observatory TAIGA (Tunka Advanced Instrument for cosmic ray physics and gamma-ray astronomy). TAIGA will be located in the Tunka valley, 50 km to the west of Lake Baikal, at the same place as the integrating air Cherenkov detector for cosmic rays Tunka-133. 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 array will consist of a wide angle Cherenkov array – TAIGA-HiSCORE with 5km2 area, a net of 16 IACT telescopes (with FOV of about 9.72°×9.72°) as well as muon and other detectors. We present the current status of the array construction.

First prototypes of PRISMA-32 neutron detectors based on the ZnS (Ag) scintillator demonstrated the perspectives of their application for detection of neutrons in extensive air showers. Detected thermal neutrons are generated due to interactions of the hadronic component with the nuclei of the atmosphere or the matter surrounding the detector and carry important information about the energy of primary particles. A mixture of zinc sulfide with natural boron (ZnS + B2O3) is used in the URAN setup. Detectors of the URAN array are located on the roofs of NEVOD and neighboring laboratory buildings; the area of each detector is 0.36 m2. The array consists of independent clusters of 12 detectors in each and is united by a central station of collection and processing of information. Two new clusters of the array were put into operation in 2017, synchronization with other NEVOD setups (NEVOD-EAS array and NEVOD-DECOR-SCT) was provided, and collection of experimental data was started with the area of about 103 m2. The first events of the EAS with neutrons have been registered and data on the temporal distribution of EAS neutrons have been obtained.

The description of the recording system of a new installation for registration of atmospheric neutrons (URAN array) which is created as a part of the experimental complex NEVOD is presented. The recording system is based on 12-bit ADC with a sampling frequency of 200 MHz and possibility to reduce a clock frequency to 1 MHz for detection of neutrons after their thermalization. The setup has an independent cluster structure. The URAN first stage includes 6 clusters of 12 detectors each located on the roofs of two buildings: complex NEVOD and its neighbor.

Some results on the EAS neutron component measurements by means of the PRISMA-32 array are presented. The array consists of 32 electron-neutron detectors (en-detectors) capable to detect two main EAS components: electromagnetic one consisting of charged particles, and hadronic one by measuring delayed thermal neutrons accompanying the showers. For thermal neutrons detection, a compound of a well-known inorganic scintillator ZnS(Ag) and LiF, enriched to 90 % with 6Li isotope is used. The setup allows us to record neutron component over the whole array area.

The TAIGA project is aimed at solving the fundamental problems of gamma-ray astronomy and physics of ultrahigh energy cosmic rays with the help of the complex of detectors, located in the Tunka valley (Siberia, Russia). TAIGA includes a wide-angle large area Tunka-HiSCORE array, designed to detect gamma-rays of ultrahigh energies in the range 20 - 1000 TeV and charged cosmic rays with energies of 100 TeV - 100 PeV, large area muon detector to improve the rejection of background EAS protons and nuclei and a network of imaging atmospheric Cherenkov telescopes for gamma radiation detection. We discuss the goals and objectives of the complex features of each detector and the results obtained in the first stage of the HiSCORE installation.

The description of the new data acquisition and triggering systems for the DECOR coordinate-tracking detector is presented. The hardware of the DECOR supermodule controller providing effective triggering events of various classes, their readout and transmission to the central computer of the detector was designed and manufactured. The description of the structural solutions used in the design is presented. The results of comparing of the performance of the old and new systems are discussed.