The demonstrated performance and cost-effectiveness of complementary metal–oxide–semiconductor (CMOS) sensors make them a potentially attractive option for low-cost space-based X-ray observatories. We have previously reported on the performance of a commercially available backside-illuminated Sony IMX290LLR-C CMOS sensor and found it to offer X-ray spectral resolutions comparable to the charged coupled devices (CCDs) aboard Suzaku and Chandra and to have a sufficient radiation hardness for use in low Earth orbit. In this work, we report on the quantum efficiency (QE) of this sensor, an essential metric for modeling the sensitivity of an instrument as an X-ray detector. Using the Advanced Photon Source at Argonne National Laboratory, we measure the soft X-ray QE of this CMOS sensor to be 0.28±0.02 at a photon energy of 490.5 eV. This energy was chosen for its proximity to the astrophysically important O VII triplet emission lines (∼574 eV) studied by the HaloSat mission. Although not surpassing that of the back-illuminated CCDs aboard Suzaku and Chandra, this QE compares favorably to that of the front-illuminated CCDs aboard the same observatories and is competitive with that of the silicon drift detectors used aboard HaloSat, making it a strong candidate for use on future X-ray small satellite (SmallSat) missions.

中文翻译：

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商用 CMOS 成像传感器的软 X 射线量子效率


互补金属氧化物半导体 (CMOS) 传感器所展示的性能和成本效益使其成为低成本天基 X 射线天文台的潜在有吸引力的选择。我们之前曾报道过市售背照式索尼 IMX290LLR-C CMOS 传感器的性能，发现它提供的 X 射线光谱分辨率可与朱雀和钱德拉上的电荷耦合器件 (CCD) 相媲美，并且具有足够的辐射硬度用于近地轨道。在这项工作中，我们报告了该传感器的量子效率 (QE)，这是对 X 射线探测器等仪器的灵敏度进行建模的重要指标。使用阿贡国家实验室的先进光子源，我们测量该 CMOS 传感器在光子能量为 490.5 eV 时的软 X 射线 QE 为 0.28±0.02。选择这种能量是因为它接近 HaloSat 任务研究的天体物理学上重要的 O VII 三重态发射线（∼574 eV）。虽然没有超过 Suzaku 和 Chandra 上的背照式 CCD，但该 QE 与同一天文台上的前照式 CCD 相比毫不逊色，并且与 HaloSat 上使用的硅漂移探测器具有竞争力，使其成为强有力的候选者用于未来的 X 射线小型卫星 (SmallSat) 任务。