Abstract
In this work, we use muon bundles, which are formed in extensive air showers and detected at the ground level, as a tool for searching for anisotropy in high-energy cosmic rays. Such choice ...is explained by the penetrating ability of muons that allows them to retain the direction of primary particles with good accuracy. In 2012–2022, we performed long-term muon-bundle detection with the coordinate-tracking detector DECOR, which is a part of the Experimental Complex NEVOD (MEPhI, Moscow). To search for cosmic-ray anisotropy, muon bundles arriving at zenith angles in the range from 15° to 75° in the local coordinate system are used. During the entire period of data taking, about 14 million of such events have been accumulated. In this paper, we describe some methods developed in the Experimental Complex NEVOD and implemented in our research, including: the method for compensating for the influence of meteorological conditions on the intensity of muon bundles at the Earth’s surface, the method for accounting for the design features of the detector and the inhomogeneity of the detection efficiency for different directions, as well as the method for estimating the primary energies of cosmic rays. Here we present the results of the search for the dipole anisotropy of cosmic rays with energies in the PeV region and also compare them with the results obtained at other scientific facilities.
Muon Tomography of Large-Scale Objects Yashin, I. I.; Davidenko, N. N.; Dovgopoly, A. O. ...
Physics of atomic nuclei,
11/2021, Letnik:
84, Številka:
6
Journal Article
Recenzirano
Cosmic ray muons arriving from the upper hemisphere to the Earth’s surface, are currently used to develop methods of muonography (analogous to radiography) of the internal structure of large-scale ...objects and relief, such as volcanoes, blast furnaces, nuclear reactors, etc. The article discusses various aspects, methods and specific examples of penetrating muonography, in particular, as applied to the study of the structure of nuclear reactors.
In comparison with calculations, the excess of multimuon events found in many experiments at ultrahigh energies of extensive air showers (EASs) cannot be explained using modern models of hadron ...interactions. The existence of muon excess is called the muon puzzle. One of the ways to solve this problem is to study the energy characteristics of the EAS muon component. For this purpose, the energy deposit of cosmic ray muon bundles is measured in the NEVOD–DECOR experiment. Registration of muon bundles in a wide range of zenith angles allows one to explore a wide range of energies of the primary particles of cosmic rays (from 10 to 1000 PeV) within a single experiment. The results of measurements of the energy deposit of muon bundles over a long observation period are presented.
The new large-scale coordinate-tracking detector TREK is under construction in MEPhI. It is based on 264 multi-wire drift chambers (4000×508×112 mm3 size) developed in IHEP for experiments on the ...neutrino channel of the U-70 accelerator, and will have 250 m2 of continuous effective area. The main goal of the project is the solution of so-called “muon puzzle”: the unpredicted by any theory excess of high multiplicity muon bundles generated by ultra-high energy primary cosmic rays. Besides of a set of field-forming wires, each multi-wire drift chamber has 4 signal ones. The current from these wires is processed by the shaper-amplifier AMP-4, mounted on the front of the chamber. It generates LVDS pulses that should be processed by multi-channel TDC that faces two main requirements: large matching window (more than 6000 ns) with last significant digit (LSD) less than 10 ns and capability to hold more than 50 hits per channel in a single event. These conditions were fulfilled by the new time-to-digital converter developed on the basis of Cyclone V FPGA in MEPhI. This paper presents the design of the TDC, its main features and the first benchmarks of its performance.
NEVOD-DECOR is the unique experiment where systematic studies of cosmic ray muon bundles in a wide range of zenith angles and, accordingly, the energies of primary cosmic rays are carried out. ...Impressive experimental material (more than 100 thousand events) has been accumulated over a long time period from May 2012 to December 2022. The earlier developed method of local muon density spectra allows us to compare experimental data on muon bundles with the results of the EAS muon component simulations. The analysis showed that the observed intensity of muon bundles at primary cosmic ray energies of about 1 EeV and higher can be compatible with the expectation (in frame of widely used hadronic interaction models) only under the assumption of an extremely heavy mass composition. It is consistent with data of several other experiments on investigations of air shower muon content, but contradicts the available measurements of the depth of the shower maximum in the atmosphere by means of fluorescent technique, which favor a light mass composition at these energies. This probably leads to the need to revise the existing hadronic interaction models.
The paper is devoted to the development of a new summator-multiplexor (SM) for the block of electronics of the cluster of detector stations (BECDS) of the NEVOD-EAS air-shower array. The new ...summator-multiplexor is designed to replace the currently used SMs based on CAEN N169 units. The developed basic circuit diagram and the operation principle of the new SM are described. The results of testing of a prototype of the new summator-multiplexor for the BECDS of the NEVOD-EAS array are discussed.
Investigations of the energy loss of muon bundles are being conducted at the Experimental complex NEVOD. Such investigations are directed to detailed study of “muon puzzle” (the excess of multi-muon ...events observed in several cosmic ray experiments at ultra-high energies). Results of measurements of the muon bundle energy deposit during a long period of observations in primary cosmic ray energy range 10–1000 PeV have been obtained and have been compared with simulations performed on the basis of the CORSIKA code.
A hybrid muon hodoscope for muonography of large-scale objects has been created in the Scientific and Educational Centre NEVOD (MEPhI) with the participation of the National Research Center ...“KI”–IHEP. The multichannel detecting system of the hodoscope consists of a scintillation strip detector and a detector on drift tubes and is designed to detect tracks of charged particles, mainly muons, flying through the detector volume. The drift tube detector is an important recording element of the muon hodoscope, providing high angular and spatial accuracy of muon track reconstruction. The article describes the design of the drift tube detector, the principles of operation of the readout electronics, and also provides the main technical characteristics.
Data of NEVOD-DECOR experiment on investigations of inclined cosmic ray muon bundles for a long time period (May 2012 - May 2020) are presented. Their comparison with the results of calculations ...based on simulations of extensive air shower hadron and muon components is carried out. The analysis showed that the observed intensity of muon bundles at primary particle energies of about 1018 eV and higher can be compatible with the expectation only under the assumption of an extremely heavy mass composition of cosmic rays. On the contrary, measurements of the depth of the shower maximum in the atmosphere in the experiments using air fluorescence technique, favour a light mass composition of primary cosmic rays at these energies.
In this paper, we describe the quasi-spherical optical module QSM-6M to detect Cherenkov radiation in water. The module is based on six photomultiplier tubes (PMTs) with flat photocathodes Hamamatsu ...R877. We discuss the results of the photomultiplier testing, as well as the choice of the high-voltage divider providing the PMT dynamic range from 1 to 105 photoelectrons. The techniques for studying QSM-6M characteristics, as well as the results of the underwater testing of the module for an 18-month period are presented. We also present the results of the analysis of the QSM-6M response to single-muon and multiparticle events detected by the installations of the Experimental Complex NEVOD.
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