Temperature Effect Observed for the Muon Component in the Yakutsk Cosmic-Ray Spectrograph
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EMENTARY PARTICLES AND FIELDS Experiment
Temperature Effect Observed for the Muon Component in the Yakutsk Cosmic-Ray Spectrograph M. D. Berkova1), V. G. Grigoryev2), M. S. Preobrazhensky1) , A. S. Zverev2) , and V. G. Yanke1)* Received April 13, 2018
Abstract—The temperature effect is studied for the muon detectors of the Yakutsk cosmic-ray spectrograph, which consists of an ionization chamber and ground-level and underground muon counter telescope deployed at depths of 0, 7, 20, 40, and 60 mwe. This array makes it possible to study muon fluxes over a wide energy range (from 2 to 200 GeV). The dependence of the temperature effect for muon component on the depth and on the zenith angle (that is, on the energy of detected particles, as well as on the solar-activity cycle) is studied. A brief description of the muon detector database (mddb) created at IZMIRAN is given. This database includes observational data from muon detectors and data on the atmospheric pressure and vertical profiles of the atmospheric temperature at standard isobaric levels. DOI: 10.1134/S1063778818050046
1. INTRODUCTION An extensive use of muon detectors in studying cosmic-ray variations has been hindered for several decades by the presence of a large temperature effect inherent in the muon component of secondary cosmic rays. The temperature effect for the muon component is due to the competition between the decay of pions/kaons and muons and their interaction with air nuclei as the geometric dimensions of the atmosphere change in response to a change in its temperature regime. The application of crossed-telescope method to the particular case of determining the anisotropy of cosmic rays provided an elegant solution to the problem of excluding the meteorological effects for the muon component, but there is still no universal solution to the problem of taking into account temperature effects. In order to rule out such effects, one needs data from aerologic sounding in the vicinity of the detector position, but, most frequently, such data either are absent and do not admit a retrospective reconstruction or have an irregular character. Instead of data on the temperature distribution in the atmosphere that were obtained experimentally by means of vertical sounding, we therefore use data based on global atmospheric models. Such models
rely on generalized meteorological data and make it possible to obtain temperature behavior in the atmosphere at any point and at any instant, as well as to implement a real-time mode in the forecasting regime. Our group used such an approach in [1, 2], for example, to estimate the temperature effect for underground detectors or detectors recording the hard component of secondary cosmic rays. The relative role of meteorological effects for cosmic rays is determined by the type of variations; in some cases, the inclusion of meteorological effects is especially important—for example, in the case of studying annual and solar-diurnal variations of an extra-atmospheric origin. Indeed, the amplitude of the diurnal wave of the temperatu
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