Measuring the Lateral Distribution of Muons in IceTop

Cosmic rays interact in the Earth’s atmosphere and produce a cascade of millions of secondary particles known as an extensive air shower (EAS). Ground-based cosmic ray detectors observe EASs and must infer information about the primary particle via comparison of their measurements with simulated EASs. The simulation of EASs relies on phenomenological models and is thus subject to large systematic uncertainties, especially as related to the production and distribution of muons. One method of constraining those models is via a measurement of the lateral distribution of muons in EASs.

An experiment uniquely suited to muon measurements is the IceCube Neutrino Observatory, a neutrino telescope deployed underneath 1.5 kilometers of ice at the geographic South Pole. The in-ice detector is complemented by a surface array, IceTop, that consists of 81 detector stations used to measure the electromagnetic and low-energy muon content of cosmic ray-initiated extensive air showers. In this work, we present a preliminary measurement of the muon lateral distribution function (LDF) in IceTop utilizing a novel reconstruction method. The measured LDF is compared to the predictions from several common EAS simulation models.