AUTHOR=Hinger Viktoria , Barten Rebecca , Baruffaldi Filippo , Bergamaschi Anna , Borghi Giacomo , Boscardin Maurizio , Brückner Martin , Carulla Maria , Centis Vignali Matteo , Dinapoli Roberto , Ebner Simon , Ficorella Francesco , Fröjdh Erik , Greiffenberg Dominic , Hammad Ali Omar , Hasanaj Shqipe , Heymes Julian , King Thomas , Kozłowski Pawel , Lopez-Cuenca Carlos , Mezza Davide , Mozzanica Aldo , Moustakas Konstantinos , Paternoster Giovanni , Paton Kirsty A. , Ronchin Sabina , Ruder Christian , Schmitt Bernd , Sieberer Patrick , Thattil Dhanya , Xie Xiangyu , Zhang Jiaguo TITLE=Resolving soft X-ray photons with a high-rate hybrid pixel detector JOURNAL=Frontiers in Physics VOLUME=12 YEAR=2024 URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2024.1352134 DOI=10.3389/fphy.2024.1352134 ISSN=2296-424X ABSTRACT=

Due to their high frame rates and dynamic range, large area coverage, and high signal-to-noise ratio, hybrid silicon pixel detectors are an established standard for photon science applications at X-ray energies between 2 keV and 20 keV. These properties also make hybrid detectors interesting for experiments with soft X-rays between 200 eV and 2 keV. In this energy range, however, standard hybrid detectors are limited by the quantum efficiency of the sensor and the noise of the readout electronics. These limitations can be overcome by utilizing inverse Low-Gain Avalanche Diode (iLGAD) sensors with an optimized X-ray entrance window. We have developed and characterized a prototype soft X-ray iLGAD sensor bonded to the charge integrating 75 µm pixel JUNGFRAU chip. Cooled to −22°C, the system multiplication factor of the signal generated by an impinging photon is ≥ 11. With this gain, the effective equivalent noise charge of the system is ≤5.5 electrons root-mean-square at a 5 µs integration time. We show that by cooling the system below −50°C, single photon resolution at 200 eV becomes feasible with a signal-to-noise ratio better than 5.