Improved setup and characterization of cadmium telluride detector for in-beam X-ray spectrometry up to 300 kV at Czech Metrology Institute

Abstract The paper describes the measurement geometry and summarizes the improvement in the setup and methods used at Czech Metrology Institute for the spectrometry of X-ray beams with cadmium telluride X-123CdTe detector. The front, lateral, and rear shielding of the detector was enlarged and sources of parasitic contribution to the characteristic peaks in the measured spectrum were supressed. Methodology for an accurate positioning of the detector towards the focus point was improved with a tool allowing to visualize projections of two pinholes using a pixel detector. The estimated uncertainty of the alignment was 0.2 ∘ . The tilt of the aperture axis of tungsten collimation disks with 50 μm and 100 μm aperture diameters, which caused distortion of measured spectra, was determined allowing, together with the improved methodology for the detector alignment, to use these disks in the same way as the other collimation disks with larger aperture diameters. As a result, the range of measurable photon flux was increased roughly by a factor of 19. The instrumentation and methods adopted and optimized at CMI allow to perform mobile in-beam X-ray spectrometry up to 300 kV in laboratory and clinical conditions with the range of collimation disks of nominal aperture diameters starting from 50 μm.