A compact and light-weight refractive telescope for the observation of extensive air showers

TL;DR

This paper introduces a compact, lightweight refractive telescope with wide field-of-view for detecting Cherenkov and fluorescence light from extensive air showers, suitable for large-scale deployment in astrophysical observatories.

Contribution

The paper presents a novel, cost-effective refractive telescope design with a wide field-of-view and robust operation, suitable for large-scale air shower detection projects.

Findings

Successful first measurements demonstrating functionality

High photon detection efficiency of SiPM sensors

Operational robustness in harsh environments

Abstract

A general purpose instrument for imaging of Cherenkov light or fluorescence light emitted by extensive air showers is presented. Its refractive optics allows for a compact and light-weight design with a wide field-of-view of 12{\deg}. The optical system features a 0.5 m diameter Fresnel lens and a camera with 61 pixels composed of Winston cones and large-sized 6x6 mm photo sensors. As photo sensors, semi conductor light sensors (SiPMs) are utilized. The camera provides a high photon detection efficiency together with robust operation. The enclosed optics permit operation in regions of harsh environmental conditions. The low price of the telescope allows the production of a large number of telescopes and the application of the instrument in various projects, such as FAMOUS for the Pierre Auger Observatory, HAWC's Eye for HAWC or IceAct for IceCube. In this paper the novel design of this telescope and first measurements are presented.