X-ray imaging detector based on a position sensitive THCOBRA with resistive line

Abstract

A new X-ray imaging detector based on a 2D-THCOBRA micropatterned structure using a simple position readout is proposed. It consists of a hybrid device that combines the properties of a THGEM and a 2D-MHSP in a single structure, having two charge multiplication stages reaching the demanded gains for the use of charge division readout methods. For position determination, the new 10 × 10 cm2 2D-THCOBRA structure uses two orthogonal resistive lines located at the end of the anode and top electrodes. The charge signal pulses collected at the end of each resistive line are digitized and processed in order to determine the center-of-gravity of the electron avalanche distribution. The detector uses a preamplification stage performed by a THGEM, followed by the 2D-THCOBRA, being operated in Ne/5%CH4 at atmospheric pressure. A characterization of the detector in terms of charge gain was made as a function of the voltage applied to the electrodes of the 2D-THCOBRA structure. The energy resolution of the system was also measured, envisaging Energy Weighting Technique (EWT) applications. The system characterization in terms of spatial resolution is presented together with imaging examples to evaluate its performance in X-ray imaging applications.