Testing the superposition model in small CORSIKA shower simulations

Abstract

The idea of superposition in the high-energy interactions of cosmic ray nuclei and the development of extensive air showers initiated by them has been known for more than half a century. It has been thoroughly and successfully tested in a number of simulations for primary energies around 1015 and above. In this work, we will investigate its applicability to lower energies. At the lowest energies, when the shower contains on average about one charged particle (or even less), deviations from the superposition model can be seen in the simulation results. Fluctuations of higher moments of the main shower parameters are systematically broader than expected. Further studies to confirm superposition in particular in the shower longitudinal profile are in progress. A correct description of the longitudinal development of the small shower, a precise description of its fluctuations on the observational level with a correct implementation of the superposition principle will enable to construct a simple and fast phenomenological algorithm generating small showers indispensable for the interpretation of measurements made using a small local shower array and determination of the flux of single, incoherent, secondary cosmic ray particles.