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

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-I 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, a 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 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 ∗Corresponding author. Email address: wangyusa@ihep.ac.cn Preprint submitted to Journal of LTEX Templates November 24, 2021 ar X iv :2 11 1. 11 61 0v 1 [ ph ys ic s. in sde t] 2 3 N ov 2 02 1 optical model is conducted and the alignment test of the Wolter-I X-ray mirror module designed for EP/FXT (Einstein Probe/Follow-up X-ray Telescope) with “Burkert test” method is shown.