Study of cosmic ray composition in the knee region using multiple muon events in the Soudan 2 detector

Abstract

Deep underground muon events recorded by the Soudan 2 detector, located at a depth of 2100 m of water equivalent, have been used to infer the nuclear composition of cosmic rays in the “knee” region of the cosmic ray energy spectrum. The observed muon multiplicity distribution favors a composition model with a substantial proton content in the energy region 8×105–1.3×107 GeV/nucleus.Received 4 December 1996DOI:https://doi.org/10.1103/PhysRevD.55.5282©1997 American Physical Society