A Two-Component Lateral Distribution Function for the Reconstruction of Air-Shower Events in IceTop

Abstract: The surface component of the IceCube Neutrino Observatory, IceTop, consists of an array of ice-Cherenkov tanks measuring the electromagnetic signal as well as low-energy ($\sim\rm{GeV}$) muons from cosmic-ray air showers. In addition, accompanying high-energy (above a few $100\,\rm{GeV}$) muons can be observed in coincidence in the deep in-ice detector. A combined measurement of the low- and high-energy muon content is of particular interest for tests of hadronic interaction models as well as for cosmic-ray mass discrimination. However, since IceTop does not feature dedicated muon detectors, an estimation of the low-energy muon component of individual air showers is challenging. In this work, a two-component lateral distribution function (LDF), using separate descriptions for the electromagnetic and muon lateral distributions of the detector signals, is introduced as a new approach for the estimation of low-energy muons in air showers on an event-by-event basis. The principle of the air-shower reconstruction using the two-component LDF, as well as its reconstruction performance with respect to primary energy and number of low-energy muons will be discussed.