High-Z Sensors for Synchrotron Sources and FELs

High-Z compound semiconductors aim to replace silicon as sensor material for X-ray energies above 15 keV thanks to their superior absorption efficiency. However, compared to silicon, high-Z sensors still lack in several aspects such as homogeneity, charge transport properties, charge trapping (leading to polarization and afterglow effects), long ranged fluorescence photons, and others.The aim of this study is to identify sensor materials that can widen the usable energy range of our detector systems at synchrotron sources and free electron lasers (FELs) towards higher photon energies. The main characterization tool was the 75 μm pitch JUNGFRAU charge integrating detector in combination with various high-Z sensors. As charge integrating detectors allow the direct measurement of the collected charge of every single photon with a high spatial resolution, these detectors offer interesting insights into temporal as well as spatial sensor effects which affect the charge collection.As one of the major challenges of the upcoming 4 th generation of synchrotrons or FELs are very intense and potentially pulsed photon beams, the sensors needs to be able to reliably measure highly intense signals and to have no afterglow phenomena after illumination. Measurements performed at the Material Science (MS) beamline of the SLS using photon fluxes up to 5×10 10 ph/(mm 2 • s) and at the FXE beamline of the EuXFEL focused on understanding the dynamic behavior (like signal stability, polarization and afterglow effects) of various high-Z sensor materials like GaAs:Cr (from different suppliers), as well as CdTe (Ohmic and Schottky type) and CdZnTe.The presentation will give an overview of the specific needs of the sensors for the different photon sources and will show how the results obtained fulfill these requirements.