High-flux CdZnTe sensors are promising candidates for detecting high energy photons at 4th generation synchrotron and free-electron laser experiments. Especially in the unique case of the MHz pulse rates of European XFEL, it is imperative that the sensor collects the full deposited charge in 120ns or less, and that there is negligible residual charge or dynamic changes in the detector properties at high fluxes. In that context, the Transient Current Technique (TCT) was used to study HF-CZT planar sensors, to characterize the charge transport properties of the sensors for various applied bias voltages. Two different electrode technologies were compared: one planar sensor had platinum contacts on both sides, while the other had platinum cathode and titanium-gold anode. The sensors were tested in a TCT station with a pulsed 660nm laser and also taken to the P07-EH1 beamline at Petra III during a pulsed operation mode of the storage ring; transients were collected for different positions in the sensors and different X-ray beam intensities at 87keV. Both studied sensors showed remarkable uniformity, good electron transport properties and fast charge collection for electric field strengths above 2000V/cm; the titanium/gold anode device showed evidence of significant bias-induced polarization at low field strengths, while localized excess leakage current effects were observed to be more significant in the device with both platinum electrodes.
As part of the development of a future radiation-hard transverse profile monitor for the North Area at CERN, here we report on the development of a 5mm diameter thin-walled straw tube detector. We show a novel 3D-printed straw endcap design, and verify that the endcaps keep the correct wire tension. We demonstrate agreement within 2% between a Garfield++ simulation of the straw detector gain and a measurement made using an X-ray source, and agreement within 3% for data taken at the T10 beamline at CERN. With the validated simulation, we calculate a possible single-straw resolution of 0.20mm with the current 50/50 Ar/CO2 gas mixture. Future work includes verifying this with a beam telescope, as well as studying the straw behaviour at higher beam intensities. The radiation damage effects on the straw should also be studied.
