Prototype muon detectors for the AMIGA component of the Pierre Auger Observatory

TL;DR

This paper details the design, fabrication, and deployment of muon detectors for the AMIGA upgrade of the Pierre Auger Observatory, focusing on resolving engineering challenges and understanding muon detection uncertainties.

Contribution

It introduces the mechanical design and deployment process of the muon counters, including testing and initial air shower measurements, advancing detector technology for cosmic ray studies.

Findings

Successful deployment of muon counters underground

Initial air shower measurements obtained

Detector response and integrity validated

Abstract

Auger Muons and Infill for the Ground Array) is an upgrade of the Pierre Auger Observatory to extend its range of detection and to directly measure the muon content of the particle showers. It consists of an infill of surface water-Cherenkov detectors accompanied by buried scintillator detectors used for muon counting. The main objectives of the AMIGA engineering array, referred to as the Unitary Cell, are to identify and resolve all engineering issues as well as to understand the muon-number counting uncertainties related to the design of the detector. The mechanical design, fabrication and deployment processes of the muon counters of the Unitary Cell are described in this document. These muon counters modules comprise sealed PVC casings containing plastic scintillation bars, wavelength-shifter optical fibers, 64 pixel photomultiplier tubes, and acquisition electronics. The modules are buried approximately 2.25 m below ground level in order to minimize contamination from electromagnetic shower particles. The mechanical setup, which allows access to the electronics for maintenance, is also described in addition to tests of the modules' response and integrity. The completed Unitary Cell has measured a number of air showers of which a first analysis of a sample event is included here.