The XGIS instrument on-board THESEUS: Monte Carlo simulations for response, background, and sensitivity

TL;DR

This paper presents Monte Carlo simulations of the XGIS instrument on THESEUS, modeling its response, background sources, and sensitivity to evaluate its performance in Low Earth Orbit for the ESA Cosmic Vision M5 mission.

Contribution

It provides detailed Monte Carlo simulations of the XGIS instrument's response and background environment, aiding in mission performance assessment.

Findings

Simulated background sources include cosmic rays and Earth albedo emission.

Background effects impact the instrument's sensitivity and detection capabilities.

Response modeling informs instrument calibration and data analysis strategies.

Abstract

The response of the X and Gamma Imaging Spectrometer (XGIS) instrument onboard the Transient High Energy Sky and Early Universe Surveyor (THESEUS) mission, selected by ESA for an assessment phase in the framework of the Cosmic Vision M5 launch opportunity, has been extensively modeled with a Monte Carlo Geant-4 based software. In this paper, the expected sources of background in the Low Earth Orbit foreseen for THESEUS are described (e.g. diffuse photon backgrounds, cosmic-ray populations, Earth albedo emission) and the simulated on-board background environment and its effects on the instrumental performance is shown.