An experiment on the measurements of the Cherenkov light yield from inclined cosmic ray muon bundles in water is being conducted at the Experimental complex NEVOD (MEPhI). The total number of ...Cherenkov photons is nearly proportional to the muon energy deposit (including secondary particles produced by muons and cascades from them) within the detector volume. Since at muon energies above a hundred GeV the energy loss is almost linearly related to the energy of muons, the average energy loss of the bundles carries information about the mean muon energy in such events. The complex includes the Cherenkov water calorimeter NEVOD with a volume of 2000 m3 and the coordinate-tracking detector DECOR with a total area of 70 m2. DECOR data are used to determine the local muon densities in the bundle events and their arrival directions, while the energy deposits are evaluated from the Cherenkov calorimeter response. The detection of the bundles in a wide range of muon multiplicities and zenith angles gives the opportunity to explore the energy range of primary cosmic ray particles from about 10 PeV to 1000 PeV and even higher in frame of a single experiment. Experimental results on the dependence of the muon bundle energy deposit on the zenith angle and the local muon density are presented and compared with expectations based on simulation of the EAS muon component by means of the CORSIKA code.
A new NEVOD-EAS array for detection of extensive air showers (EAS) in the energy range 1015–1017 eV is being created in MEPhI (Moscow, Russia) on the basis of the Experimental complex NEVOD. It will ...be operated in conjunction with the Cherenkov water detector NEVOD and coordinate detector DECOR, as well as with detectors URAN and TREK which are now being constructed. The array will allow determining of the size, axis position and arrival direction of EAS registered by aforementioned installations. The NEVOD-EAS registering system is organized in a cluster principle. Each cluster of the shower array is an independent system which includes 16 scintillation counters of EAS electron-photon component combined in 4 detector stations and registering electronics. Cluster electronics performs digitizing of analog signals, selection of events according to intra-cluster triggering conditions, time-stamping of events and monitoring of cluster operational parameters. Information on events and operational parameters is transferred to the central DAQ post of control and synchronization. In 2015–2016, the central part of the NEVOD-EAS array was created and launched into operation. It includes 4 clusters located at different altitudes at area of 104 m2 around the complex. The paper discribes the features of the distributed cluster type registering system of the NEVOD-EAS shower array, as well as the main characteristics of clusters and their elements.
The possibility of measuring the characteristics of the response of optical modules of neutrino telescopes to various classes events registered in the volume of the Cherenkov water detector NEVOD is ...discussed. Results are presented from measuring the response of a prototype optical module with a Hamamatsu R877 photomultiplier to single muons and high-energy events.
A description of the detection and data-acquisition systems of the Cherenkov water calorimeter of the NEVOD Experimental Complex, which is a unique scientific facility located on the Earth’s surface, ...is presented. In the development of these systems, a solution is sought to the problem of measuring the energy of cascade showers initiated by single muons and the energy deposited by high-multiplicity muon bundles in a wide energy range.
The results of experiments of the last decades have shown that with the increase of energy of primary cosmic rays a clear excess of muon groups in comparison with the existing models of extensive air ...shower development (even assuming pure iron composition of PCR) appears. The problem is called 'muon puzzle' and it can be explained either by cosmo- or nuclear-physical reasons. One of the experiments in which the excess of muon groups was registered is a NEVOD-DECOR. The new large-scale coordinate-tracking detector of 254 m2 area based on drift chambers will increase the coverage of the side aperture of the Cherenkov water detector (CWD) NEVOD and significantly improve the resolution of close tracks. Multi-wire drift chambers TREK developed in IHEP for experiments at the neutrino channel of U-70 accelerator have large effective area (1.85 m2), a good coordinate and angular resolution with a small number of measuring channels. The first part of the detector named Coordinate-Tracking Unit based on the Drift Chambers (CTUDC) representing two coordinate planes of 8 drift chambers in each has been developed and mounted on the opposite sides of the CWD. It has the same principle of joint operation with NEVOD-DECOR triggering system so the main features of the TREK detector will be examined. Results of an examination of drift chambers at muon hodoscope URAGAN, a calibration of the CTUDC with DECOR and the first results of its joint operation with NEVOD triggering system are presented.
To solve the problem of the excess of multi-muon events observed in several cosmic ray experiments at ultra-high energies (so-called “muon puzzle”), an analysis of the energy characteristics of the ...muon component of extensive air showers (EAS) is required. A possible approach to such investigations is the measurement of the energy deposit of muon bundles in the detector, which provides information on the mean muon energy. In the experiment now being conducted at the NEVOD-DECOR complex, the local muon density and EAS arrival direction are determined according to the data of the coordinate-tracking detector DECOR, whereas the energy deposit is measured by means of the Cherenkov water calorimeter NEVOD. Results of the measurements of the energy deposit of inclined muon bundles based on the data accumulated during more than 23,200 h observations in 2012 – 2016 are presented and compared with simulations performed by means of the CORSIKA code.
The calibration telescope system of the NEVOD Cherenkov water detector is described. Scintillation counters are used in the setup as detecting elements. The detection system is equipped with logical ...and amplitude channels and provides the calibration of the Cherenkov water detector. It can also be used to investigate the electron and muon components of an extensive air shower. A method for amplitude calibration of the scintillation counters is described, with which it is possible to estimate the number of detected charged particles. The results for the 1.5-year operation of the setup as a detector of extensive air showers are presented.
The Russian-Italian NEVOD-DECOR experiment on measurements of the local muon density spectra at various zenith angles gave the possibility to obtain important information on the primary cosmic ray ...flux and interaction characteristics in a wide energy range from 1015 to more than 1018 eV. At large zenith angles and high muon densities, a considerable excess of muon bundles has been found in comparison with expectation. In this paper, an update of these investigations is presented and some new results obtained by the collaboration are discussed.
Energy characteristics of the muon component of extensive air showers (EASes) are investigated at the NEVOD experimental complex in order to solve the problem of a detected excess of muons in EASes ...at ultrahigh energies, relative to simulation results. The dependences of the energy deposit of muon bundles on the zenith angle and the local muon density are obtained for primary energies of 10–1000 PeV. The results from comparing the data to simulations performed with the CORSIKA program are presented.
In 2014, the creation of a new cluster type shower array NEVOD-EAS was started around the Cherenkov Water Detector NEVOD and coordinate detector DECOR. The shower array will allow to determine the ...size, axis position and arrival direction of EAS registered by these detectors. In 2015–2016, the NEVOD-EAS central part, including 4 clusters of scintillation detector stations located on an area of about 104 m2, was deployed and started operation. This article presents the description of the NEVOD-EAS arrangement, detecting elements and data acquisition system, as well as the first results on EAS detection.
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