Imaging performance above 150 keV of the wide field monitor on board the ASTENA concept mission

TL;DR

This paper presents the design and simulation results of the ASTENA Wide Field Monitor's imaging performance above 150 keV, utilizing innovative Silicon Drift Detectors and scintillator technology for broad energy detection.

Contribution

It introduces a novel detection system combining SDDs and scintillators for high-energy X-ray and gamma-ray astronomy, extending imaging capabilities beyond 150 keV.

Findings

Effective area and imaging performance evaluated through simulations.

Potential to extend imaging capabilities above 150 keV.

Innovative detector technology for broad energy passband.

Abstract

A new detection system for X-/Gamma-ray broad energy passband detectors for astronomy has been developed. This system is based on Silicon Drift Detectors (SDDs) coupled with scintillator bars; the SDDs act as a direct detector of soft (<30 keV) X-ray photons, while hard X-/Gamma-rays are stopped by the scintillator bars and the scintillation light is collected by the SDDs. With this configuration, it is possible to build compact, position sensitive detectors with unprecedented energy passband (2 keV - 10/20 MeV). The X and Gamma-ray Imaging Spectrometer (XGIS) on board the THESEUS mission, selected for Phase 0 study for M7, exploits this innovative detection system. The Wide Field Monitor - Imager and Spectrometer (WFM-IS) of the ASTENA (Advanced Surveyor of Transient Events and Nuclear Astrophysics) mission concept consists of 12 independent detection units, also based on this new technology. For the WFM-IS, a coded mask provides imaging capabilities up to 150 keV, while above this limit the instrument will act as a full sky spectrometer. However, it is possible to extend imaging capabilities above this limit by alternatively exploiting the Compton kinematics reconstruction or by using the information from the relative fluxes measured by the different cameras. In this work, we present the instrument design and results from MEGAlib simulations aimed at evaluating the effective area and the imaging performances of the WFM-IS above 150 keV.