Performance of a focal plane detector for soft X-ray imaging spectroscopy based on back-illuminated sCMOS

TL;DR

This paper presents a back-illuminated sCMOS detector designed for X-ray mirror alignment in space telescopes, demonstrating its characteristics and application in testing and calibration for high-precision X-ray imaging.

Contribution

The study introduces a large-area back-illuminated sCMOS detector for X-ray alignment, including its characterization and application in mirror module testing.

Findings

Detector exhibits low readout noise and dark current.

Energy calibration and non-linearity are successfully characterized.

The detector effectively assists in X-ray mirror alignment tests.

Abstract

Spectroscopy focusing array (SFA) and Polarimetry focusing array (PFA) are the two major payloads of enhanced X-ray Timing and Polarimetry mission (eXTP). Nested Wolter-\RNum{1} X-ray mirror module is implemented in SFA and PFA to achive high effective area. When evaluating the properties of the mirror module, the alignment of the optical axis of the X-ray mirror module and a quasi-parallel X-ray beam is a prerequisite to ensure the accuracy of the results. Hence, to assist the alignment of the X-ray mirror module, an X-ray focal plane detector is designed based on the back-illuminated scientific Complementary Metal-Oxide-Semiconductor Transistor (sCMOS) sensor GSENSE6060BSI, one of the largest detection areas, is produced by \textit{Gpixel Inc}. Then the characteristics of readout noise, dark current, and split-pixel event properties of the detector are studied with the self-developed multi-target fluorescence X-ray source in a 100 m long X-ray test facility. The energy calibration is carried out with the single-pixel event and the energy non-linearity of the detector is also obtained. Eventually, the simulation of the eXTP mirror module based on the optical model is conducted and the alignment test of the Wolter-\RNum{1} X-ray mirror module designed for \textit{EP/FXT} (Einstein Probe/Follow-up X-ray Telescope) with "Burkert test" method is shown.