Long-term stability of scientific X-ray CMOS detectors

TL;DR

This study demonstrates that scientific CMOS detectors maintain stable performance over more than 1.5 years, showing minimal degradation, thus confirming their suitability for long-term space X-ray astronomy missions.

Contribution

It provides the first long-term stability assessment of scientific CMOS sensors in space-like conditions, confirming their reliability for extended space applications.

Findings

No observable degradation after 610 days of aging.

Gain decreases predicted to be less than 1% over 3 years.

Fewer than 50 pixels show significant bias decrease.

Abstract

In recent years, complementary metal-oxide-semiconductor (CMOS) sensors have been demonstrated to have significant potential in X-ray astronomy, where long-term reliability is crucial for space X-ray telescopes. This study examines the long-term stability of a scientific CMOS sensor, focusing on its bias, dark current, readout noise, and X-ray spectral performance. The sensor was initially tested at -30 $^\circ$C for 16 months, followed by accelerated aging at 20 $^\circ$C. After a total aging period of 610 days, the bias map, dark current, readout noise, gain, and energy resolution exhibited no observable degradation. There are less than 50 pixels within the 4 k $\times$ 4 k array which show a decrease of the bias under 50 ms integration time by over 10 digital numbers (DNs). First-order kinetic fitting of the gain evolution predicts a gain degeneration of 0.73% over 3 years and 2.41% over 10 years. These results underscore the long-term reliability of CMOS sensors for application in space missions.