CONICET | Buscador de Institutos y Recursos Humanos

The proﬁle of the longitudinal development of showers produced by ultra-highenergy cosmic rays carries information related to the interaction properties of the primary particles with atmospheric nuclei. In this work, we present the ﬁrst measurement of the average shower proﬁle in traversed atmospheric depth at the Pierre Auger Observatory. The shapes of proﬁles are well reproduced by the Gaisser-Hillas parametrization within the range studied, for E > 10^17.8 eV. A detailed analysis of the systematic uncertainties is performed using ten years of data and a full detector simulation. The average shape is quantiﬁed usingtwo variables related to the width and asymmetry of the proﬁle, and the results are compared with predictions of hadronic interaction models for diﬀerent primary particles.