Relevance of multiple muons detected underground to the mass composition of primary cosmic rays

Calculations have been made of the expected frequencies of multiple muons in the Soudan underground proton decay detector. It is concluded that the flux of heavy nuclei (z 10) in the range 10 to the 15th power to 10 to the 16th power eV/nucleus is at most 25% of the total particle flux in the same range.