Calibration and testing of the JEM-EUSO detectors using stars observed in the UV band

TL;DR

This paper discusses the calibration and testing of JEM-EUSO UV detectors using star signals observed during sky observations, enabling absolute calibration and condition assessment of the detectors in space-based cosmic ray research.

Contribution

It introduces a novel calibration method for JEM-EUSO detectors using star signals, enhancing detector accuracy and reliability during cosmic ray observations.

Findings

Successful calibration of detectors using star signals

Validation of detector condition during observations

Potential for improved measurement accuracy

Abstract

The JEM-EUSO program is focused on observations of Ultra High Energy Cosmic Rays (UHECRs) from space. For this purpose, a series of detectors based on multi-anode photomultiplier tubes with a time resolution of the order of $\mu$s have been developed. The detectors work in the UV band to search for ultra-fast signals produced in the Earth's atmosphere during an Extensive Air Shower (EAS) development. Since 2014, various signals have been detected by ground-, ballon- and space-based detectors. A single photodetector module consists of a focal surface with a matrix of 36 multi-anode photomultiplier tubes containing 2304 pixels. The detector's structure allows probing it during the mission if a point-like source emitting in a UV band is in the field of view. In this work, we present the idea and results of calibration of the JEM--EUSO detectors using signals from stars registered during sky observations from the ground. Registered signals can be used for the absolute calibration of the detectors and for testing the detector condition during observations. The presented analysis is based on the data taken by the EUSO-TA and EUSO-TA2 experiments.