Study of extensive air showers at Mount Norikura. IV. Lateral distribution of muons for types of EAS

Abstract

Muons accompanied by EAS have been observed by a neon hodoscope array 6 m2 in area placed 36 m from the center of the EAS array. The lateral density distribution function of muons and an average density at fixed distance are studied with respect to the size and age parameter of EAS. The EAS are in a size range of 106 to 107, and the muon density at distances of 15–55 m from the axis of EAS has been observed for muons which penetrate 20 cm of lead.Preliminary results obtained in this experiment are as follows: (1) The lateral density distribution of muons shows clear correlation with that of electrons: assuming the distribution function to be a power function of the distance from the axis, the exponent varies from steeper than −1.5 to flatter than −1.0 for younger and older EAS respectively. (2) The size dependence of muon density can be expressed as [Formula: see text], and is independent of the age parameter of EAS.