# Muon Counting using Silicon Photomultipliers in the AMIGA detector of the Pierre Auger Observatory

## TL;DR

This paper presents a new muon detection system for the Pierre Auger Observatory using silicon photomultipliers, achieving high efficiency and low false counts, enhancing cosmic ray shower measurements.

## Contribution

Introduction of SiPM-based detectors with a calibration method suitable for remote deployment, improving muon counting performance in cosmic ray observatories.

## Key findings

- 98% detection efficiency at high overvoltage
- Approximately 2% accidental counting probability
- Effective calibration method for remote detector deployment

## Abstract

AMIGA (Auger Muons and Infill for the Ground Array) is an upgrade of the Pierre Auger Observatory designed to extend its energy range of detection and to directly measure the muon content of the cosmic ray primary particle showers. The array will be formed by an infill of surface water-Cherenkov detectors associated with buried scintillation counters employed for muon counting. Each counter is composed of three scintillation modules, with a 10 m$^2$ detection area per module. In this paper, a new generation of detectors, replacing the current multi-pixel photomultiplier tube (PMT) with silicon photo sensors (aka. SiPMs), is proposed. The selection of the new device and its front-end electronics is explained. A method to calibrate the counting system that ensures the performance of the detector is detailed. This method has the advantage of being able to be carried out in a remote place such as the one where the detectors are deployed. High efficiency results, i.e. 98 % efficiency for the highest tested overvoltage, combined with a low probability of accidental counting ($\sim$2 %), show a promising performance for this new system.