Developments of scientific CMOS as focal plane detector for Einstein Probe mission

China’s Einstein Probe (EP) mission is designed for time-domain astrophysics with energy band of 0.5-4 keV. The payloads of EP include a wide-field X-ray telescope (WXT) and a follow-up X-ray telescope (FXT). The field of view (FOV) of WXT is about 3600 square degrees with sensitivity at least 10 times better than traditional X-ray all-sky monitors applying collimators or coded-masks. Back-side illuminated scientific CMOS (BSI sCMOS) is the best choice for WXT after several types of X-ray detectors are investigated. In this work, we study a BSI sCMOS sensor, GSENSE400BSI developed by Gpixel Inc., which is treated as a pathfinder for the focal plane detector of WXT. GSENSE400BSI has a pixel array of 2048×2048 with pixel size of 11 μm. We have characterized this BSI sCMOS as an X-ray detector. Based on the excellent performance of GSENSE400BSI, a new BSI sCMOS device with large sensitive area of 6×6 cm 2 has been proposed as the focal plane detector for WXT.