Composition observables for the photon search at 10 17 eV at the Pierre Auger Observatory

F. SÁNCHEZ; N. GONZÁLEZ; A. ETCHEGOYEN; M. ROTH

Muenster

Conferencia; Reunión Anual de la Sociedad Física Alemana (DPG); 2017

p { margin-bottom: 0.21cm; }ThePierre Auger Observatory studies the ultra-high energy (UHE) cosmicrays (CR) which arrive to Earth with energies up to 3x10$^{20}$eV. The composition of these primary nuclei varies between proton andiron, and no event compatible with a photon primary has been observedyet. The discovery of UHE photons with energies in the10$^{17}$-10$^{18}$ region could be of particular interest since theyare tracers of the highest-energy processes in the Universe.The Auger Collaborationhas proposed several parameters to distinguish between hadron andphoton primaries with energies above 10$^{18}$ eV. The muon componentin extensive air showers (EAS) developed from the interaction betweenthe CR and atmospheric nuclei is one of the most promisingapproaches. The AMIGA detection system, an upgrade of the AugerObservatory, is composed by buried scintillation muon counters in adenser infilled area. As such, it offers a unique oportunity toenhance the sensibility of the Observatory to a photon signal.In this work, severalpossible observables to distinguish a weak photon signal within thevast hadronic background will be explored in the 10$^{17}$ eV energyregion. The detector response will be studied using the Offlinepackage developed by the Auger Collaboration. Information from theAMIGA muon counters combined with the signal spatial distributiongenerated by the EAS in an associated surface detector will becombined in order to generate a complete hadronic rejectioncriterion. This criterion would be exploited in order to either findphotons or to improve the existing upper limits to the photon flux.