The AMIGA underground muon detector of the Pierre Auger Observatory - performance and event reconstruction

A. M. BOTTI, FOR THE PIERRE AUGER COLLABORATION (VER F. SANCHEZ EN LISTA AUGER)

Madison

Conferencia; 36th International Cosmic Ray Conference (ICRC 2019); 2019

The Auger Muons and Infill for the Ground Array (AMIGA) aims to both lower the detectionthreshold of the Pierre Auger Observatory down to energies of ∼ 10 16.5 eV and to directly mea-sure the muon content of extensive air showers. AMIGA consists of an array of coupled water-Cherenkov and buried scintillation detectors deployed in two superimposed triangular grids of433 m and 750 m spacings. Each underground detector has a total area of 30 m 2 buried at a depthof 2.3 m, to shield it from the shower electromagnetic component. The scintillation plane is seg-mented in plastic-scintillator strips with embedded wavelength-shifter optical fibers coupled to acommon optical sensor. Before proceeding to the construction of the full-size array, an engineer-ing array was operated until November 2017 to validate and optimize the design, and to evaluatethe performance of the detection system. During this phase, scintillation areas of 5 m 2 and 10 m 2and two optical sensors, photomultiplier tubes and silicon photomultipliers, were tested. In thiswork, we present the status and performance of the array currently equipped with silicon photo-multipliers, along with the timing performance and geometry reconstruction of modules equippedwith photomultiplier tubes. Analyses and results are based on both laboratory and field measure-ments. Scintillation areas of 10 m 2 and silicon photomultipliers as readout have been selected asthe baseline design for the full-scale AMIGA array