Analysis of Charge Sharing and of Its Spectral Components in DEPFET Pixels with Hexagonal Geometry

The purpose of this work is to study charge sharing in X-ray imaging detectors based on hexagonal pixels with integrated DEPFET (Depleted P-type Field-Effect Transistor). The aim is to improve Xray spectra modeling for more accurate gain calibration and to optimize detector's performance. The framework is the DSSC detector (DEPFET Sensor with Signal Compression), an ultra-fast hybrid pixel detector developed for soft X-ray experiments at the European XFEL. Experimental campaigns on one DSSC detector module (128×512 pixel) were carried out at the European XFEL with photon energies in the range 462−8048eV. Data has been analyzed on a frame-by-frame basis to classify events based on the type of pixel cluster (e.g. single-pixel events, sharing with two pixels, etc.) and photon multiplicity. The analysis of the corresponding spectral components gives a deep insight into charge collection efficiency, the non-isotropic behavior of charge-sharing and the size of the charge cloud. An analysis has been carried out for different photon energies to assess the trend of the relevant charge-sharing properties.