  We report on measurements of the all-particle cosmic ray energy spectrum and
composition in the PeV to EeV energy range using three years of data from the
IceCube Neutrino Observatory. The IceTop detector measures cosmic ray induced
air showers on the surface of the ice, from which the energy spectrum of cosmic
rays is determined by making additional assumptions about the mass composition.
A separate measurement is performed when IceTop data are analyzed in
coincidence with the high-energy muon energy loss information from the deep
in-ice IceCube detector. In this measurement, both the spectrum and the mass
composition of the primary cosmic rays are simultaneously reconstructed using a
neural network trained on observables from both detectors. The performance and
relative advantages of these two distinct analyses are discussed, including the
systematic uncertainties and the dependence on the hadronic interaction models,
and both all-particle spectra as well as individual spectra for elemental
groups are presented.
