Measuring the Soft X-Ray Quantum Efficiency of a Hybrid CMOS Detector

TL;DR

This study measures the quantum efficiency of a hybrid CMOS detector across soft X-ray energies, demonstrating high efficiency suitable for future X-ray space observatories.

Contribution

It provides the first detailed QE measurements of a Teledyne H2RG hybrid CMOS detector across key soft X-ray energies, validating its potential for space missions.

Findings

Achieves 94.6% QE at 5.9 keV

Achieves 98.3% QE at 1.49 keV

Maintains 61.3% QE at 0.28 keV

Abstract

Next-generation X-ray observatories, such as the Lynx X-ray Observatory Mission Concept or other similar concepts in the coming decade, will require detectors with high quantum efficiency (QE) across the soft X-ray band to observe the faint objects that drive their mission science objectives. Hybrid CMOS Detectors (HCDs), a form of active-pixel sensor, are promising candidates for use on these missions because of their fast read-out, low power consumption, and intrinsic radiation hardness. In this work, we present QE measurements of a Teledyne H2RG HCD, performed using a gas-flow proportional counter as a reference detector. We find that this detector achieves high QE across the soft X-ray band, with an effective QE of $94.6 \pm 1.1 \%$ at the Mn K$\alpha$/K$\beta$ energies (5.90/6.49 keV), $98.3 \pm 1.9 \%$ at the Al K$\alpha$ energy (1.49 keV), $85.6 \pm 2.8 \%$ at the O K$\alpha$ energy (0.52 keV), and $61.3 \pm 1.1 \%$ at the C K$\alpha$ energy (0.28 keV). These values are in good agreement with our model, based on the absorption of detector layers. We find similar results in a more restrictive analysis considering only high-quality events, with only somewhat reduced QE at lower energies.