X-ray hybrid CMOS detectors: recent development and characterization progress

Abstract

X-ray Hybrid CMOS Detectors (HCDs) have advantages over X-ray CCDs due to their higher readout rate abilities, flexible readout, inherent radiation hardness, and low power, which make them more suitable for the next generation large-area X-ray telescope missions. The Penn State high energy astronomy laboratory has been working on the development and characterization of HCDs in collaboration with Teledyne Imaging Sensors (TIS). A custom-made H2RG detector with 36 µm pixel pitch and 18 µm ROIC shows an improved performance over standard H1RG detectors, primarily due to a reduced level of inter-pixel capacitance crosstalk (IPC). However, the energy resolution and the noise of the detector and readout system are still limited when utilizing a SIDECAR at non-cryogenic temperatures. We characterized an H2RG detector with a Cryo-SIDECAR readout and controller, and we find an improved energy resolution of ∼2.7 % at 5.9 keV and read noise of ∼6.5 e-. Detections of the ∼0.525 keV Oxygen Kα and ∼0.277 keV Carbon Kα lines with this detector display an improved sensitivity level at lower energies. This detector was successfully flown on NASA's first water recovery sounding rocket flight on April 4 th , 2018. We have also been developing several new HCDs with potential applications for future X-ray astronomy missions. We are characterizing the performance of small-pixel HCDs (12.5 µm pitch), which are important for the development of a next-generation high-resolution imager with HCDs. The latest results on these small pixel detectors has shown them to have the best read noise and energy resolution to-date for any X-ray HCD, with a measured 5.5 e-read noise for a detector with in-pixel correlated double sampling. Event recognition in HCDs is another exciting prospect. We characterized a 64 × 64 pixel prototype Speedster-EXD detector that uses comparators in each pixel to read out only those pixels having detectable signal, thereby providing an order of magnitude improvement in the effective readout rate. Currently, we are working on the development of a large area Speedster-EXD with a 550 × 550 pixel array. HCDs can also be utilized as a large FOV instrument to study the prompt and afterglow emissions of GRBs and detect black hole transients. In this context, we are characterizing a Lobster-HCD system for future CubeSat experiments. This paper briefly presents these new developments and experimental results.

Hybrid CMOS detectors for the Lynx x-ray surveyor high definition x-ray imager

“…5.2 and 5.4 for descriptions of read noise and energy resolution). 20 Figure 2 shows an H2RG spectrum with several low energy x-ray lines.…”

The high definition x-ray imager (HDXI) instrument on the Lynx X-ray Surveyor

“…They offer low power relative to existing CCDs, and they have displayed high readout rates with multiplexed readout lines (>5 MHz per line through 32 lines). X-ray Hybrid CMOS detectors that were developed for other purposes have been demonstrated to TRL 9 in a recent rocket flight (Chattopadhyay et al 2018) and non-X-ray versions have flown on recent observatories (e.g. OCO-2), but these devices have moderate noise levels and large pixels.…”

Tiny-box: A tool for the versatile development and characterization of low noise fast X-ray imaging detectors

“…The past decade has seen significant progress in the development of fast readout, small pixel size, low power X-ray detectors (see [6] for an overview). Active Pixel Sensors (APS) such as X-ray Hybrid CMOS detectors [7,8,9,10], the depleted field effect transistor (DEPFET) sensors being developed for the ATHENA Wide-Field Imager (WFI, [11]), and Silicon-On-Insulator technology [12] promise to fulfill some of these requirements. While most of the requirements are also met with modern X-ray CCDs, major challenges to increase the readout speed and operate at a lower power remain.…”