Lateral Distribution for Aligned Events in Muon Groups Deep Underground

Abstract

The paper concerns the so-called aligned events observed in cosmic rays. The phenomenon of the alignment of the most energetic subcores of gamma-ray--hadron ($\gamma-h$) families (particles of the highest energies in the central EAS core) was firstly found in the "Pamir" emulsion chamber experiment and related to a coplanar particle production at $E_0>10^{16}$ eV. Here a separation distribution (distances between pairs of muons) for aligned events has been analyzed throughout muon groups measured by Baksan Underground Scintillation Telescope (BUST) for threshold energies $0.85 \div 3.2$ TeV during a period of 7.7 years. Only muon groups of multiplicity $m\geq 4$ with inclined trajectories for an interval of zenith angles $50^\circ - 60^\circ$ were selected for the analysis. The analysis has revealed that the distribution complies with the exponential law. Meanwhile the distributions become steeper with the increase of threshold energy. There has been no difference between the lateral distribution of all the groups and the distribution of the aligned groups.