Abstract:3D silicon pixel detectors have been investigated as radiation-hard candidates for the innermost layers of the HL-LHC upgrade of the ATLAS pixel detector. 3D detectors are already in use today in the ATLAS IBL and AFP experiments. These are based on 50×250 µm 2 large pixels connected to the FE-I4 readout chip. Detectors of this generation were irradiated to HL-LHC fluences and demonstrated excellent radiation hardness with operational voltages as low as 180 V and power dissipation of 12-15 mW/cm 2 at a fluence of about 10 16 n eq /cm 2 , measured at -25 • C. Moreover, to cope with the higher occupancies expected at the HL-LHC, a first run of a new generation of 3D detectors designed for the HL-LHC was produced at CNM with small pixel sizes of 50×50 and 25×100 µm 2 , matched to the FE-I4 chip. They demonstrated a good performance in the laboratory and in beam tests with hit efficiencies of about 97% at already 1-2 V before irradiation.

The polarization characteristics of ohmic and (Al-)Schottky type CdTe sensors supplied by Acrorad have been characterized with the low noise, charge integrating readout chip JUNGFRAU, revealing defined areas in the Schottky type sensors, which were irradiated with 20 keV photons in previous experiments more than one year ago. These areas, which have absorbed doses of up to 1079 kGy, show a more robust charge collection compared to unirradiated areas. In contrast to this, no alteration of the polarization characteristics could be found in ohmic type CdTe sensors after irradiation. The polarization behavior of the sensors has been characterized in-situ over time and at different temperatures by using an homogeneous, low flux molybdenum fluorescence illumination. An increase of the leakage current in the irradiated areas was found and quantified as a function of absorbed dose as well as its influence on the stability on the number of photon counts. In addition to the influence of X-ray irradiation, the effect of thermal annealing on the polarization characteristics of Schottky type CdTe sensors has been studied. Possible routes for the usage of Schottky type CdTe sensors in synchrotron applications are outlined in this publication.