Measurement of the all-particle cosmic ray energy spectrum with IceTop

IceTop is an air shower array at the geographic South Pole forming the surface component of the IceCube Neutrino Observatory. In this paper, a method to reconstruct shower size and primary energy spectrum from data measured by IceTop is described. Data were divided into three zenith angle bins. Using Monte Carlo based on the SIBYLL and Fluka hadronic interaction models, agreement with an isotropic flux can only be achieved under the assumption of a mixed composition. A preliminary all-particle energy spectrum is presented.