The ability to utilize a hybrid-photon-counting detector to its full potential can significantly influence data quality, data collection speed, as well as development of elaborate data acquisition schemes. This paper facilitates the optimal use of EIGER2 detectors by providing theory and practical advice on (i) the relation between detector design, technical specifications and operating modes, (ii) the use of corrections and calibrations, and (iii) new acquisition features: a double-gating mode, 8-bit readout mode for increasing temporal resolution, and lines region-of-interest readout mode for frame rates up to 98 kHz. Examples of the implementation and application of EIGER2 at several synchrotron sources (ESRF, PETRA III/DESY, ELETTRA, AS/ANSTO) are presented: high accuracy of high-throughput data in serial crystallography using hard X-rays; suppressing higher harmonics of undulator radiation, improving peak shapes, increasing data collection speed in powder X-ray diffraction; faster ptychography scans; and cleaner and faster pump-and-probe experiments.

IBEX is a novel mixed-mode CMOS ASIC, developed at DECTRIS Ltd., dedicated to the readout of Hybrid Photon Counting (HPC) semiconductor pixel detectors. The chip has been strictly designed in a radiation tolerant enclosed transistor layout and is fabricated in a 110 nm CMOS technology with 8 metal layers. It consists of a 256×256 matrix of 75×75 μm2 pixels, what results in an overall chip size of 19.27×19.76 mm2 with periphery, supply and I/O pads included. A so-called merging mode allows for an increased pixel size of 150×150 μm2. The pixel readout electronics supports electrons and holes collection, and consists of a charge sensitive preamplifier with programmable gain, a shaper, and two comparators that allow for two independent energy thresholds. In the merging mode the number of energy thresholds is increased up to four. In order to minimize the pixel-to-pixel energy threshold variation, each pixel comparator can be adjusted with a 6-bit trim DAC. The ASIC can operate in a continuous readout mode with two independent 16-bit counters or in a high counting range mode with a single 32-bit counter per energy threshold level. The chip features counter overflow handling and an instant retrigger technology with an adjustable retrigger time for a significantly improved high-rate counting performance. The ASIC offers a selectable external data bus width of 4, 8, or 16-bit. The count rate limit of the ROC DCcoupled with a silicon sensor lies at around 10 Mcts/s/pix. The measurements show an electronic pixel noise of 89 e- rms and the detectable photon energy range between 3 keV and 160 keV.

This study presents the performance assessment of a novel hybrid pixel detector. The electron counting application-specific integrated circuit (ASIC), named KITE, was optimized for 4D STEM applications and bump-bonded to a silicon sensor that is suitable for electron energies in the range 30–200 keV. The KITE ASIC was developed for high frame rates, currently up to 120 kfps, and high count rates, owing to fast signal shaping times and instant retrigger technology, which allows operation in a unique non-paralyzable counting mode. Investigated quantities include the spectral response, the identification of optimal threshold energies, an estimation of the threshold trimming accuracy, the analysis of the single-event multiplicity distributions, the count rate capabilities, and imaging performance metrics MTF and DQE. To highlight the capabilities of the detector, the best value of 10% of linearity loss was achieved at 84 Mcts/s/pix, the best value of count rate “cutoff” at nearly 150 Mcts/s/pix, and DQE (0) between 0.75 and 0.82 up to the electron energy of 160 keV.

We developed a novel, accurate and robust energy calibration algorithm for single X-ray photon counting detectors suitable for the use of high-Z sensor materials. The calibratable energy range was demonstrated to extend over a wide interval from 12 keV up to 150 keV and the same method can also be applied to lower or higher X-ray energies. Fluorescence lines of several elemental targets are used as reference up to 75 keV. For higher energies, the reference is given by direct X-ray tube spectra end-points – extracted with a semi-empirical model independently of the broadening by electronic noise. The pixel-wise threshold trimming relies on a target curve fitting iterative procedure which is able to cope with offset, gain and flat-field variations. The algorithm is highly parallelizable and can profit from modern multi-core machines. The proposed method is able to deal with the spectral complexity introduced by atomic fluorescence effects arising in high-Z sensor materials such as CdTe, CdZnTe and GaAs for energies above the corresponding K-edges and enhanced by a decreasing pixel size. We report the qualification results for the case study of a 1 mm-thick CdTe sensor with 150 $\mathrm{\mu }$m pixel size, bonded to an IBEX ASIC and calibrated in the range 12–150 keV. The validity of the method was assessed by analyzing calibrated pulse height spectra recorded with Sn and W fluorescence samples and with a ^99mTc radioactive source. The global deviation was found to be smaller than 0.5% at 140.5 keV. The residual threshold dispersion was 0.54 keV rms at the Sn K${}_{\alpha }$ peak and 1.71 keV rms at the ^99mTc $\gamma$-decay peak, still with a limited impact on the overall energy resolution of the system.