Measuring the Cherenkov light yield from cosmic ray muon bundles in the water detector

Abstract

Abstract 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.