  Data from the IceCube detector in its 22-string configuration (IC22) were
used to directly measure the atmospheric muon energy spectrum near the horizon.
After passage through more than 10 km of ice, muon bundles from air showers are
reduced to single muons, whose energy can be estimated from the total number of
photons registered in the detector. The energy distribution obtained in this
way is sensitive to the cosmic ray composition around the knee and is
complementary to measurements by air shower arrays. The method described
extends the physics potential of neutrino telescopes and can easily be applied
in similar detectors. Presented is the result from the analysis of one month of
IC22 data.
