Latest results of ultra-high-energy cosmic ray measurements with prototypes of the Fluorescence detector Array of Single-pixel Telescopes (FAST)

TL;DR

This paper reports on the latest results from FAST prototypes, a next-generation ground-based observatory for ultra-high-energy cosmic rays, highlighting calibration, atmospheric monitoring, electronics upgrades, reconstruction methods, and detections.

Contribution

It presents the development, deployment, and initial results of FAST prototypes, demonstrating progress towards a large-area, cost-effective UHECR observatory.

Findings

Successful deployment of prototypes in both hemispheres

Calibration and atmospheric monitoring established

Detection of ultra-high-energy cosmic rays achieved

Abstract

The origin and nature of ultra-high-energy cosmic rays (UHECRs) remain an open question in astroparticle physics. Motivated by the need for an unprecedented aperture for further advancements, the Fluorescence detector Array of Single-pixel Telescopes (FAST) is a prospective next-generation, ground-based UHECR observatory that aims to cover a huge area by deploying a large array of low-cost fluorescence detectors. The full-scale FAST prototype consists of four 20 cm photomultiplier tubes at the focus of a segmented mirror 1.6 m in diameter. Over the last five years, three prototypes have been installed at the Telescope Array Experiment in Utah, USA, and one prototype at the Pierre Auger Observatory in Mendoza, Argentina, commencing remote observation of UHECRs in both hemispheres. We report on the latest results of these FAST prototypes, including telescope calibrations, atmospheric monitoring, ongoing electronics upgrades, development of sophisticated reconstruction methods, and UHECR detections.