AMIGA-Grande: a beyond 2015 proposal with muon counters

A. ALMELA, B. DANIEL, L. DEL PERAL, A. ETCHEGOYEN, B. GARCÍA, M. GÓMEZ BERISSO, N. GONZÁLEZ, J. M. FIGUEIRA, M. JOSEBACHUILI, E. KEMP, ; A. LUCERO, D. MELO, M. PLATINO, D. RAVIGNANI, F. SÁNCHEZ, F. SCHRÖDER, F. SUAREZ, A. D. SUPANITSKY, A. TAPIA CASANOVA, M. VIDELA, O. WAINBERG, B. WUNDHEILER

Encuentro; Pierre Auger Internal GAP Note Nº 2013-003; 2013

AMIGA has undergone reviews setup by the Collaboration and has produced several gap notes as below‐shown in the bibliography. Suffice to say that composition studies are of paramount importance to understand the transition from galactic to extragalactic sources, to discriminate exotic mechanisms, and for anisotropy searches (e.g. to study composition from the CEN A region). Longitudinal profiles and muon numbers are the most sensitive parameters for such studies. Gamma initiated showers are discriminated straight forwards by their negligible muon contents (more sturdy results are obtained by looking at the change in muon density rather than at its absolute values since the former are less dependent on hadronic models and require less statistics). The current Auger Xmax studies show a tendency to increasing primary mass with energy which is even more clearly appreciated from the Xmax fluctuations. On the other hand both HiRes and Telescope Array find a composition compatible with proton primaries. An independent muon contents measurement will strengthen and cast light on the FD results.