The XGIS instrument on-board THESEUS: the detection plane and on-board electronics

TL;DR

The paper details the design and development of the XGIS instrument on the THESEUS mission, focusing on its detection plane, modular architecture, and innovative low-noise electronics using custom ASICs.

Contribution

It introduces the design of the XGIS detection plane, including modularity, redundancy, and the development of low-noise front-end electronics with custom ASICs.

Findings

Prototype detector-electronics results demonstrate system feasibility.

Innovative ASIC-based front-end electronics achieve low noise performance.

Design choices enhance modularity and redundancy for mission reliability.

Abstract

The X and Gamma Imaging Spectrometer instrument on-board the THESEUS mission (selected by ESA in the framework of the Cosmic Vision M5 launch opportunity, currently in phase A) is based on a detection plane composed of several thousands of single active elements. Each element comprises a 4.5x4.5x30 mm 3 CsI(Tl) scintillator bar, optically coupled at both ends to Silicon Drift Detectors (SDDs). The SDDs acts both as photodetectors for the scintillation light and as direct X-ray sensors. In this paper the design of the XGIS detection plane is reviewed, outlining the strategic choices in terms of modularity and redundancy of the system. Results on detector-electronics prototypes are also described. Moreover, the design and development of the low-noise front-end electronics is presented, emphasizing the innovative architectural design based on custom-designed Application-Specific Integrated Circuits (ASICs).