Speaker
Description
High resistivity gallium arsenide compensated by chromium has demonstrated a good suitability as a sensor material for hybrid pixel detectors used in X-ray imaging systems with photon energies up to 60 keV. The material is available with thickness up to 1 mm and thanks to its Z number and fully active volume of the sensor high absorption efficiency in this energy region is provided. Although GaAs:Cr-based detectors are mostly designed for X-ray applications, it can be used for charged particle tracks registration, that will be shown.
In this work the results of the GaAs:Cr-based Timepix detectors tests with various particles sources are reported. The energy and spatial resolution, mu-tau distribution over sensor area have been determined. By means of scanning the detector with pencil photon beam generated by synchrotron facility, the geometrical mapping of pixel sensitivity is obtained as well as the energy resolution of a single pixel. The long-term stability of the detector has been evaluated based on the measurements performed over one year. It’s well known that the main performance limitation of thick GaAs:Cr-based detectors is caused by readout electronic with relatively small pixels due to the charge sharing effect. But by optimizing the bias voltage it was possible to achieve an FWHM of 2.5 keV at 25 keV in a single photon counting mode. Also the radiation hardness of GaAs:Cr sensors was investigated by means of irradiation with 20 MeV electrons and some results will be presented.
