Fluctuations in the EAS radio signal derived with improved Monte Carlo   simulations based on CORSIKA
  Cosmic ray air showers are known to emit pulsed radio emission which can be understood as coherent geosynchrotron radiation arising from the deflection of electron-positron pairs in the earth's magnetic field. Here, we present simulations carried out with an improved version of our Monte Carlo code for the calculation of geosynchrotron radiation. Replacing the formerly analytically parametrised longitudinal air shower development with CORSIKA-generated longitudinal profiles, we study the radio flux variations arising from inherent fluctuations between individual air showers. Additionally, we quantify the dependence of the radio emission on the nature of the primary particle by comparing the emission generated by proton- and iron-induced showers. This is only the first step in the incorporation of a more realistic air shower model into our Monte Carlo code. The inclusion of highly realistic CORSIKA-based particle energy, momentum and spatial distributions together with an analytical treatment of ionisation losses will soon allow simulations of the radio emission with unprecedented detail. This is especially important to assess the emission strengths at large radial distances, needed for event-to-event comparisons of the radio signals measured by LOPES in conjunction with KASCADE-Grande and for considerations regarding large arrays of radio antennas intended to measure the radio emission from ultra-high energy cosmic rays, as with LOFAR or in the Pierre Auger Observatory. 
Tim Huege (Forschungszentrum Karlsruhe/MPIfR Bonn) (for the LOPES   Collaboration)