Full Monte Carlo simulations of radio emission from extensive air showers with CoREAS

摘要

CoREAS is a Monte Carlo simulation code for the calculation of radio emissionfrom extensive air showers. It is based on the "endpoint formalism" forradiation from moving charges implemented directly in CORSIKA. Consequently,the full complexity of the air-shower physics is taken into account without theneed for approximations or assumptions on the emission mechanism. We presentresults of simulations for an unthinned shower performed with CoREAS for bothMHz and GHz frequencies. At MHz frequencies, the simulations predict thewell-known mixture of geomagnetic and charge excess radiation. At GHzfrequencies, the emission is strongly influenced by Cherenkov effects arisingfrom the varying refractive index in the atmosphere. In addition, a qualitativedifference in the symmetry of the GHz radiation pattern is observed whencompared to the ones at lower frequencies. We also discuss the strong increasein the ground area subtended by the radio emission when going fromnear-vertical to very inclined geometries, making very inclined air showers themost promising ones for cosmic ray radio detection.