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Abstract The 64k pixel DEPFET module is the key sensitive component of the DEPFET Sensor with Signal Compression (DSSC), a large area 2D hybrid detector for capturing and measuring soft X-rays at the European XFEL. The final 1-megapixel camera has to detect photons with energies between $$250\,\text{eV}$$ 250 eV and $$6\,\text{keV}$$ 6 keV , and must provide a peak frame rate of $$4.5\,\text{MHz}$$ 4.5 MHz to cope with the unique bunch structure of the European XFEL. This work summarizes the functionalities and properties of the first modules assembled with full-format CMOS-DEPFET arrays, featuring $$512\,\times \,128$$ 512 × 128 hexagonally-shaped pixels with a side length of 136 μm. The pixel sensors utilize the DEPFET technology to realize an extremely low input capacitance for excellent energy resolution and, at the same time, an intrinsic capability of signal compression without any gain switching. Each pixel of the readout ASIC includes a DEPFET-bias current cancellation circuitry, a trapezoidal-shaping filter, a 9-bit ADC and a 800-word long digital memory. The trimming, calibration and final characterization were performed in a laboratory test-bench at DESY. All detector features are assessed at $$18\,^{\circ }\text{C}$$ 18 ∘ C . An outstanding equivalent noise charge of $$9.8$$ 9.8 e−rms is achieved at 1.1-MHz frame rate and gain of 26.8 Analog-to-Digital Unit per keV ( $$\,\text {ADU}/\text{keV}$$ ADU / keV ). At $$4.5\,\text{MHz}$$ 4.5 MHz and $$3.1\,\,\text {ADU}/\text{keV}$$ 3.1 ADU / keV , a noise of $$25.5$$ 25.5 e−rms and a dynamic range of $$26\,\text{k}\text {e}^{-}$$ 26 ke - are obtained. The highest dynamic range of $$1.345\,\text{M}\text {e}^{-}$$ 1.345 Me - is reached at $$2.25\,\text{MHz}$$ 2.25 MHz and $$1.6\,\text {ADU}/\text{keV}$$ 1.6 ADU / keV . These values can fulfill the specification of the DSSC project.

The advent of X-ray free-electron lasers (XFELs) has revolutionized fundamental science, from atomic to condensed matter physics, from chemistry to biology, giving researchers access to X-rays with unprecedented brightness, coherence and pulse duration. All XFEL facilities built until recently provided X-ray pulses at a relatively low repetition rate, with limited data statistics. Here, results from the first megahertz-repetition-rate X-ray scattering experiments at the Spectroscopy and Coherent Scattering (SCS) instrument of the European XFEL are presented. The experimental capabilities that the SCS instrument offers, resulting from the operation at megahertz repetition rates and the availability of the novel DSSC 2D imaging detector, are illustrated. Time-resolved magnetic X-ray scattering and holographic imaging experiments in solid state samples were chosen as representative, providing an ideal test-bed for operation at megahertz rates. Our results are relevant and applicable to any other non-destructive XFEL experiments in the soft X-ray range.