Observation of Parallel Muons 1350 hg/cm² Underground

Abstract

An experiment was carried out at vertical depths of 1350 hg/cm² underground in order to investigate the high energy, \gtrsim450 GeV, muon bundles. The muon bundles, upto the highest observed multiplicity of 18, were observed in a stack of three horizontal layers of wide gap spark chambers and three lead absorber layers of area 8.35 m² each.
The experimental set-ups and the procedures in correcting for various experimental biases are described. The result for the average zenith angle of 20° and the average slant depth of 1380 hg/cm² in standard rock is presented in the from of multiplicity distribution.