Ultra-high energy cosmic ray investigations by means of EAS muon density measurements

Abstract

A new approach to investigations of ultra-high energy cosmic rays based on the ground-level measurements of the spectra of local density of EAS muons at various zenith angles is considered. Basic features of the local muon density phenomenology are illustrated using a simple semi-analytical model. It is shown that muon density spectra are sensitive to the spectrum slope, primary composition, and to the features of hadronic interaction. New experimental data on muon bundles at zenith angles from 30° to horizon obtained with the coordinate detector DECOR are compared with CORSIKAbased simulations. It is found that measurements of muon density spectra in inclined EAS give possibility to study characteristics of primary cosmic ray flux in a very wide energy range from 10 15 to 10 19 eV.

Investigation of cascade showers in the Cherenkov water detector NEVOD

“…We assume that the directions of the shower particles are close to the shower axis, and that this axis coincides with the track of the muon. The track is divided into bins equal to one radiation length (for water, 36.1 g/cm 2 ). The number of light-emitting charged particles on a bin of the track, N i , is calculated as the ratio between the PMT response to the event, A PMT , and the PMT response to a single charged particle with the same geometric parameters of the track, A 1 :…”

“…The reasons are the so-called 'muon puzzle' [1] (the excess of both muon bundles [2,3] and UHE muons [4,5] with the energy increase) and the discovery of the excess of UHE neutrinos that apparently are indicative of their extraterrestrial origin [6]. In both cases, one of the most important tasks is to measure the energy of cascade showers generated by muons and neutrinos, in particular in Cherenkov water detectors (CWD).…”

Experimental complex for multi-component registration of the EAS in a wide energy range $(10^{15} - 10^{19} eV)$

“…A distinctive feature of the complex is the possibility of detection of different components of cosmic rays at ground level including groups of quasi-parallel muons at large zenith angles, up to the horizon. During 2002 -2007 experimental series at the EC NEVOD, a new approach to the study of primary cosmic rays based on a new EAS variable -the local muon density spectra (LMDS) -has been developed [1,2]. The measurements were conducted with main detectors of the complex -the large volume Cherenkov water detector NEVOD [3] and the large area coordinate detector DECOR.…”

New installation for inclined EAS investigations

“…The aim of the large-scale coordinate-tracking detector is solving the problem of the excess of muon bundles that increases with the energy of the primary cosmic rays [1,2], that can be caused by both cosmo-or nuclear-physical reasons [3]. The only characteristic that responds differently to changes in the composition of cosmic rays and the inclusion of new physical processes is the energy of the muon component of extensive air showers [3] which, up to now, has not been investigated enough.…”