Methods for Calibrating the Gain and Offset of the DSSC Detector for the European XFEL

The DEPFET Sensor with Signal Compression (DSSC) will be a 2d 1Mpx imaging detector for the European X-ray Free Electron Laser facility (XFEL.EU), that is currently under construction in Hamburg. The DSSC is foreseen as a photon counting detector for soft X-ray radiation from 0.5 keV up to 6 keV. Driven by its scientific requirements, the design goals of the detector system are foremost low noise, a high dynamic range and a high frame rate of up to 4.5 MHz. Signal compression, amplification and digitization will be performed in the focal plane. Utilizing an in-pixel active filtering stage and an 8/9-bit ADC, the detector will provide parallel readout of all pixels. A critical step of calibrating the detector is the determination of the system gain and offset based on peak energies of X-ray calibration line sources such as $-{55}Fe$. This is demanding due to the intrinsically low spectral resolution of the DSSC. The results of studies on the stability and performance of automated procedures for peak fitting in single pixel spectra with a low energy resolution were presented on a poster