Estimation of the exposure of the TUS space-based cosmic ray observatory

TL;DR

This paper estimates the exposure of the TUS space-based cosmic ray observatory, analyzing various environmental and operational factors affecting its detection capabilities during its mission.

Contribution

It presents a detailed methodology for calculating TUS's exposure, including the impact of clouds, storms, and other environmental factors, and discusses future applications.

Findings

Calculated TUS's geographical exposure distribution.

Quantified effects of clouds, storms, and moon phases on exposure.

Provided a framework for future space-based cosmic ray observatory studies.

Abstract

The TUS observatory was the first orbital detector aimed at the detection of ultra-high energy cosmic rays (UHECRs). It was launched on April 28, 2016, from the Vostochny cosmodrome in Russia and operated until December 2017. It collected $\sim80,000$ events with a time resolution of 0.8~$\mu$s. A fundamental parameter to be determined for cosmic ray studies is the exposure of an experiment. This parameter is important to estimate the average expected event rate as a function of energy and to calculate the absolute flux in case of event detection. Here we present results of a study aimed to calculate the exposure that TUS accumulated during its mission. The role of clouds, detector dead time, artificial sources, storms, lightning discharges, airglow and moon phases is studied in detail. An exposure estimate with its geographical distribution is presented. We report on the applied technique and on the perspectives of this study in view of the future missions of the JEM-EUSO program.