  The differential energy distribution for electrons and taus produced from
lepton pair production from muons in transit through materials is numerically
evaluated. We use the differential cross section to calculate underground
lepton fluxes from an incident atmospheric muon flux, considering contributions
from both conventional and prompt fluxes. An approximate form for the charged
current differential neutrino cross section is provided and used to calculate
single lepton production from atmospheric neutrinos. We compare the fluxes of
underground leptons produced from incident muons with those produced from
incident neutrinos and photons from muon bremsstrahlung. We discuss their
relevance for underground detectors.
